10-Q

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

 _____________________________________________

FORM 10-Q

 ____________________________________________

(Mark One)
☒	QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the quarterly period ended March 31, 2022

OR

☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from                      to                     

Commission file number 001-35714

_____________________________________________ 

MPLX LP

(Exact name of registrant as specified in its charter)

 _____________________________________________

	Delaware	27-0005456
(State or other jurisdiction of incorporation or organization)		(I.R.S. Employer Identification No.)

200 E. Hardin Street,	Findlay,	Ohio	45840
(Address of principal executive offices)			(Zip code)

(419) 421-2414

(Registrant’s telephone number, including area code)

 _____________________________________________

Securities Registered pursuant to Section 12(b) of the Act
Title of each class	Trading symbol(s)	Name of each exchange on which registered
Common Units Representing Limited Partnership Interests	MPLX	New York Stock Exchange

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes  x     No  ¨

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files.) Yes  x    No  ¨

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

Large accelerated filer	x	Accelerated filer	☐
Non-accelerated filer	☐	Smaller reporting company	☐
		Emerging growth company	☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.  ¨

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act) Yes  ☐    No  x

MPLX LP had 1,012,303,833 common units outstanding at April 29, 2022.

Table of Contents

	Page
PART I – FINANCIAL INFORMATION
Item 1.   Financial Statements:
Consolidated Statements of Income (Unaudited)	3
Consolidated Statements of Comprehensive Income (Unaudited)	4
Consolidated Balance Sheets (Unaudited)	5
Consolidated Statements of Cash Flows (Unaudited)	6
Consolidated Statements of Equity and Series A Preferred Units (Unaudited)	7
Notes to Consolidated Financial Statements (Unaudited)	8
Item 2.   Management’s Discussion and Analysis of Financial Condition and Results of Operations	22
Item 3.   Quantitative and Qualitative Disclosures about Market Risk	40
Item 4.   Controls and Procedures	41
PART II – OTHER INFORMATION
Item 1.    Legal Proceedings	41
Item 1A. Risk Factors	42
Item 2.    Unregistered Sales of Equity Securities and Use of Proceeds	42
Item 6.    Exhibits	43
Signatures	44

Unless the context otherwise requires, references in this report to “MPLX LP,” “MPLX,” “the Partnership,” “we,” “our,” “us,” or like terms refer to MPLX LP and its subsidiaries. Additionally, throughout this Quarterly Report on Form 10-Q, we have used terms in our discussion of the business and operating results that have been defined in our Glossary of Terms.

1

Glossary of Terms

The abbreviations, acronyms and industry technology used in this report are defined as follows.

ASC	Accounting Standards Codification
ASU	Accounting Standards Update
Barrel	One stock tank barrel, or 42 U.S. gallons of liquid volume, used in reference to crude oil or other liquid hydrocarbons
Btu	One British thermal unit, an energy measurement
DCF (a non-GAAP financial measure)	Distributable Cash Flow
EBITDA (a non-GAAP financial measure)	Earnings Before Interest, Taxes, Depreciation and Amortization
GAAP	Accounting principles generally accepted in the United States of America
G&P	Gathering and Processing segment
LIBOR	London Interbank Offered Rate
L&S	Logistics and Storage segment
mbpd	Thousand barrels per day
MMBtu	One million British thermal units, an energy measurement
MMcf/d	One million cubic feet of natural gas per day
NGL	Natural gas liquids, such as ethane, propane, butanes and natural gasoline
SEC	U.S. Securities and Exchange Commission
VIE	Variable interest entity

2

Part I—Financial Information

Item 1. Financial Statements

MPLX LP

Consolidated Statements of Income (Unaudited)

	Three Months Ended March 31,
(In millions, except per unit data)	2022		2021
Revenues and other income:
Service revenue	$	554	$	589
Service revenue - related parties	915		872
Service revenue - product related	123		77
Rental income	91		99
Rental income - related parties	165		242
Product sales	497		282
Product sales - related parties	45		42
Sales-type lease revenue - related parties	111		37
Income from equity method investments	99		70
Other income (loss)	(17)		1
Other income - related parties	27		28
Total revenues and other income	2,610		2,339
Costs and expenses:
Cost of revenues (excludes items below)	287		273
Purchased product costs	467		276
Rental cost of sales	37		32
Rental cost of sales - related parties	15		39
Purchases - related parties	319		298
Depreciation and amortization	313		329
General and administrative expenses	78		86
Other taxes	34		32
Total costs and expenses	1,550		1,365
Income from operations	1,060		974
Related party interest and other financial costs	4		—
Interest expense (net of amounts capitalized of $2 million, $5 million, respectively)	198		198
Other financial costs	20		27
Income before income taxes	838		749
Provision for income taxes	5		1
Net income	833		748
Less: Net income attributable to noncontrolling interests	8		9
Net income attributable to MPLX LP	825		739
Less: Series A preferred unitholders interest in net income	21		20
Less: Series B preferred unitholders interest in net income	11		11
Limited partners’ interest in net income attributable to MPLX LP	$	793	$	708
Per Unit Data (See Note 6)
Net income attributable to MPLX LP per limited partner unit:
Common - basic	$	0.78	$	0.68
Common - diluted	$	0.78	$	0.68
Weighted average limited partner units outstanding:
Common - basic	1,015		1,037
Common - diluted	1,015		1,037

The accompanying notes are an integral part of these consolidated financial statements.

3

MPLX LP

Consolidated Statements of Comprehensive Income (Unaudited)

	Three Months Ended March 31,
(In millions)	2022		2021
Net income	$	833	$	748
Other comprehensive income, net of tax:
Remeasurements of pension and other postretirement benefits related to equity method investments, net of tax	9		(2)
Comprehensive income	842		746
Less comprehensive income attributable to:
Noncontrolling interests	8		9
Comprehensive income attributable to MPLX LP	$	834	$	737

The accompanying notes are an integral part of these consolidated financial statements.

4

MPLX LP

Consolidated Balance Sheets (Unaudited)

 

(In millions)	March 31, 2022		December 31, 2021
Assets
Current assets:
Cash and cash equivalents	$	42	$	13
Receivables, net	741		654
Current assets - related parties	813		644
Inventories	149		142
Other current assets	53		54
Total current assets	1,798		1,507
Equity method investments	4,079		3,981
Property, plant and equipment, net	19,912		20,042
Intangibles, net	800		831
Goodwill	7,657		7,657
Right of use assets, net	280		268
Noncurrent assets - related parties	1,151		1,161
Other noncurrent assets	50		60
Total assets	35,727		35,507
Liabilities
Current liabilities:
Accounts payable	214		172
Accrued liabilities	396		363
Current liabilities - related parties	687		1,780
Accrued property, plant and equipment	91		97
Long-term debt due within one year	999		499
Accrued interest payable	192		202
Operating lease liabilities	47		59
Other current liabilities	232		176
Total current liabilities	2,858		3,348
Long-term deferred revenue	405		383
Long-term liabilities - related parties	305		302
Long-term debt	18,757		18,072
Deferred income taxes	14		10
Long-term operating lease liabilities	228		205
Deferred credits and other liabilities	159		170
Total liabilities	22,726		22,490
Commitments and contingencies (see Note 14)
Series A preferred units (30 million and 30 million units issued and outstanding)	965		965
Equity
Common unitholders - public (366 million and 369 million units issued and outstanding)	8,505		8,579
Common unitholders - MPC (647 million and 647 million units issued and outstanding)	2,698		2,638
Series B preferred units (0.6 million and 0.6 million units issued and outstanding)	601		611
Accumulated other comprehensive loss	(8)		(17)
Total MPLX LP partners’ capital	11,796		11,811
Noncontrolling interests	240		241
Total equity	12,036		12,052
Total liabilities, preferred units and equity	$	35,727	$	35,507

The accompanying notes are an integral part of these consolidated financial statements.

5

MPLX LP

Consolidated Statements of Cash Flows (Unaudited)

	Three Months Ended March 31,
(In millions)	2022		2021
Operating activities:
Net income	$	833	$	748
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of deferred financing costs	18		17
Depreciation and amortization	313		329
Deferred income taxes	4		—
Loss on disposal of assets	18		—
Income from equity method investments	(99)		(70)
Distributions from unconsolidated affiliates	120		119
Change in fair value of derivatives	(9)		3
Changes in:
Current receivables	(87)		(67)
Inventories	(7)		(11)
Current accounts payable and accrued liabilities	73		26
Current assets/current liabilities - related parties	(112)		(8)
Right of use assets/operating lease liabilities	(1)		(1)
Deferred revenue	16		24
All other, net	45		15
Net cash provided by operating activities	1,125		1,124
Investing activities:
Additions to property, plant and equipment	(169)		(126)
Disposal of assets	3		70
Investments in unconsolidated affiliates	(110)		(35)
All other, net	—		1
Net cash used in investing activities	(276)		(90)
Financing activities:
Long-term debt - borrowings	2,385		1,910
- repayments	(1,201)		(2,020)
Related party debt - borrowings	1,849		2,241
- repayments	(2,976)		(2,241)
Debt issuance costs	(16)		—
Unit repurchases	(100)		(155)
Distributions to noncontrolling interests	(9)		(10)
Distributions to Series A preferred unitholders	(21)		(20)
Distributions to Series B preferred unitholders	(21)		(21)
Distributions to unitholders and general partner	(716)		(713)
Contributions from MPC	10		7
All other, net	(4)		(3)
Net cash used in financing activities	(820)		(1,025)
Net increase in cash, cash equivalents and restricted cash	29		9
Cash, cash equivalents and restricted cash at beginning of period	13		15
Cash, cash equivalents and restricted cash at end of period	$	42	$	24

The accompanying notes are an integral part of these consolidated financial statements.

6

MPLX LP

Consolidated Statements of Equity and Series A Preferred Units (Unaudited)

	Partnership
(In millions)	Common Unit-holders Public		Common Unit-holder MPC		Series B Preferred Unit-holders		Accumulated Other Comprehensive Loss		Non-controlling Interests		Total		Series A Preferred Unit-holders
Balance at December 31, 2020	$	9,384	$	2,792	$	611	$	(15)	$	245	$	13,017	$	968
Net income	266		443		11		—		9		729		20
Unit Repurchases	(155)		—		—		—		—		(155)		—
Distributions	(269)		(445)		(21)		—		(10)		(745)		(20)
Contributions	—		7		—		—		—		7		—
Other	—		(1)		—		(2)		—		(3)		—
Balance at March 31, 2021	$	9,226	$	2,796	$	601	$	(17)	$	244	$	12,850	$	968
Balance at December 31, 2021	$	8,579	$	2,638	$	611	$	(17)	$	241	$	12,052	$	965
Net income	287		506		11		—		8		812		21
Unit Repurchases	(100)		—		—		—		—		(100)		—
Distributions	(260)		(456)		(21)		—		(9)		(746)		(21)
Contributions	—		10		—		—		—		10		—
Other	(1)		—		—		9		—		8		—
Balance at March 31, 2022	$	8,505	$	2,698	$	601	$	(8)	$	240	$	12,036	$	965

The accompanying notes are an integral part of these consolidated financial statements.

7

Notes to Consolidated Financial Statements (Unaudited)

1. Description of the Business and Basis of Presentation

Description of the Business

MPLX LP is a diversified, large-cap master limited partnership formed by Marathon Petroleum Corporation that owns and operates midstream energy infrastructure and logistics assets, and provides fuels distribution services. References in this report to “MPLX LP,” “MPLX,” “the Partnership,” “we,” “ours,” “us,” or like terms refer to MPLX LP and its subsidiaries. References to “MPC” refer collectively to Marathon Petroleum Corporation as our sponsor and its subsidiaries, other than the Partnership. We are engaged in the gathering, transportation, storage and distribution of crude oil, refined products and other hydrocarbon-based products; the gathering, processing and transportation of natural gas; and the gathering, transportation, fractionation, storage and marketing of NGLs. MPLX’s principal executive office is located in Findlay, Ohio.

MPLX’s business consists of two segments based on the nature of services it offers: Logistics and Storage (“L&S”), which relates primarily to crude oil, refined products and other hydrocarbon-based products; and Gathering and Processing (“G&P”), which relates primarily to natural gas and NGLs. See Note 7 for additional information regarding the operations and results of these segments.

Basis of Presentation

The accompanying interim consolidated financial statements are unaudited; however, in the opinion of MPLX’s management, these statements reflect all adjustments necessary for a fair statement of the results for the periods reported. All such adjustments are of a normal, recurring nature unless otherwise disclosed. These interim consolidated financial statements, including the notes, have been prepared in accordance with the rules and regulations of the SEC applicable to interim period financial statements and do not include all of the information and disclosures required by GAAP for complete financial statements. Certain information derived from our audited annual financial statements, prepared in accordance with GAAP, has been condensed or omitted from these interim financial statements.

These interim consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2021. The results of operations for the three months ended March 31, 2022 are not necessarily indicative of the results to be expected for the full year.

MPLX’s consolidated financial statements include all majority-owned and controlled subsidiaries. For non-wholly owned consolidated subsidiaries, the interests owned by third parties have been recorded as “Noncontrolling interests” on the accompanying Consolidated Balance Sheets. Intercompany investments, accounts and transactions have been eliminated. MPLX’s investments in which MPLX exercises significant influence but does not control and does not have a controlling financial interest are accounted for using the equity method. MPLX’s investments in VIEs in which MPLX exercises significant influence but does not control and is not the primary beneficiary are also accounted for using the equity method.

Certain prior period financial statement amounts have been reclassified to conform to current period presentation.

2. Accounting Standards

Recently Adopted

ASU 2021-10, Government Assistance (Topic 832): Disclosures by Business Entities about Government Assistance

In November 2021, the FASB issued guidance requiring disclosures for certain types of government assistance that have been accounted for by analogy to grant or contribution models. Disclosures will include information about the type of transactions, accounting and the impact on financial statements. MPLX prospectively adopted this standard in the first quarter of 2022. The adoption of this standard did not have a material impact on our financial statements or disclosures.

8

3. Investments and Noncontrolling Interests

The following table presents MPLX’s equity method investments at the dates indicated:

	Ownership as of	Carrying value at
	March 31,	March 31,		December 31,
(In millions, except ownership percentages)	2022	2022		2021
L&S
MarEn Bakken Company LLC(1)	25%	$	502	$	449
Illinois Extension Pipeline Company, L.L.C.	35%	249		243
LOOP LLC	41%	274		265
Andeavor Logistics Rio Pipeline LLC(2)	67%	181		183
Minnesota Pipe Line Company, LLC	17%	182		183
Whistler Pipeline LLC(2)	38%	166		155
Explorer Pipeline Company	25%	65		66
W2W Holdings LLC(2)	50%	56		58
Other(2)		125		116
Total L&S		1,800		1,718
G&P
MarkWest Utica EMG, L.L.C.(2)	57%	681		680
Sherwood Midstream LLC(2)	50%	539		544
MarkWest EMG Jefferson Dry Gas Gathering Company, L.L.C.(2)	67%	336		332
MarkWest Torñado GP, L.L.C.(2)	60%	266		246
Rendezvous Gas Services, L.L.C.(2)	78%	145		147
Sherwood Midstream Holdings LLC(2)	51%	133		136
Centrahoma Processing LLC	40%	133		133
Other(2)		46		45
Total G&P		2,279		2,263
Total		$	4,079	$	3,981

(1)    The investment in MarEn Bakken Company LLC includes our 9.19 percent indirect interest in a joint venture (“Dakota Access”) that owns and operates the Dakota Access Pipeline and Energy Transfer Crude Oil Pipeline projects, collectively referred to as the Bakken Pipeline system or DAPL.    

(2)    Investments deemed to be VIEs. Some investments included within “Other” have also been deemed to be VIEs.

For those entities that have been deemed to be VIEs, neither MPLX nor any of its subsidiaries have been deemed to be the primary beneficiary due to voting rights on significant matters. While we have the ability to exercise influence through participation in the management committees which make all significant decisions, we have equal influence over each committee as a joint interest partner and all significant decisions require the consent of the other investors without regard to economic interest; as such, we have determined that these entities should not be consolidated and apply the equity method of accounting with respect to our investments in each entity.

Sherwood Midstream LLC (“Sherwood Midstream”) has been deemed the primary beneficiary of Sherwood Midstream Holdings LLC (“Sherwood Midstream Holdings”) due to its controlling financial interest through its authority to manage the joint venture. As a result, Sherwood Midstream consolidates Sherwood Midstream Holdings. Therefore, MPLX also reports its portion of Sherwood Midstream Holdings’ net assets as a component of its investment in Sherwood Midstream. As of March 31, 2022, MPLX has a 24.55 percent indirect ownership interest in Sherwood Midstream Holdings through Sherwood Midstream.

MPLX’s maximum exposure to loss as a result of its involvement with equity method investments includes its equity investment, any additional capital contribution commitments and any operating expenses incurred by the subsidiary operator in excess of its compensation received for the performance of the operating services. MPLX did not provide any financial support to equity method investments that it was not contractually obligated to provide during the three months ended March 31, 2022.

9

Summarized financial information for MPLX’s equity method investments for the three months ended March 31, 2022 and 2021 is as follows:

	Three Months Ended March 31, 2022
(In millions)	VIEs		Non-VIEs		Total
Revenues and other income	$	249	$	308	$	557
Costs and expenses	137		129		266
Income from operations	112		179		291
Net income	103		166		269
Income from equity method investments	$	55	$	44	$	99

	Three Months Ended March 31, 2021
(In millions)	VIEs		Non-VIEs		Total
Revenues and other income	$	163	$	284	$	447
Costs and expenses	107		131		238
Income from operations	56		153		209
Net income	64		140		204
Income from equity method investments	$	39	$	31	$	70

Summarized balance sheet information for MPLX’s equity method investments as of March 31, 2022 and December 31, 2021 is as follows:

	March 31, 2022
(In millions)	VIEs		Non-VIEs		Total
Current assets	$	386	$	370	$	756
Noncurrent assets	7,482		4,875		12,357
Current liabilities	773		259		1,032
Noncurrent liabilities	$	1,929	$	789	$	2,718

	December 31, 2021
(In millions)	VIEs		Non-VIEs		Total
Current assets	$	335	$	411	$	746
Noncurrent assets	7,439		4,895		12,334
Current liabilities	217		310		527
Noncurrent liabilities	$	2,461	$	788	$	3,249

4. Related Party Agreements and Transactions

MPLX engages in transactions with both MPC and certain of its equity method investments as part of its normal business; however, transactions with MPC make up the majority of MPLX’s related party transactions. Transactions with related parties are further described below.

MPLX has various long-term, fee-based commercial agreements with MPC. Under these agreements, MPLX provides transportation, gathering, terminal, fuels distribution, marketing, storage, management, operational and other services to MPC. MPC has committed to provide MPLX with minimum quarterly throughput volumes on crude oil and refined products, other fees for storage capacity, operating and management fees, as well as reimbursements for certain direct and indirect costs. MPC has also committed to provide a fixed fee for 100 percent of available capacity for boats, barges and third-party chartered equipment under the marine transportation service agreement. MPLX also has a keep-whole commodity agreement with MPC under which MPC pays us a processing fee for NGLs related to keep-whole agreements and delivers shrink gas to the producers on our behalf. We pay MPC a marketing fee in exchange for assuming the commodity risk. Additionally, MPLX has obligations to MPC for services provided to MPLX by MPC under omnibus and employee services-type agreements as well as other agreements.

10

Related Party Loan

MPLX is party to a loan agreement with MPC Investment LLC (“MPC Investment”) (the “MPC Loan Agreement”). Under the terms of the agreement, MPC Investment extends loans to MPLX on a revolving basis as requested by MPLX and as agreed to by MPC Investment. The borrowing capacity of the MPC Loan Agreement is $1.5 billion aggregate principal amount of all loans outstanding at any one time. The loan agreement is scheduled to expire, and borrowings under the loan agreement are scheduled to mature and become due and payable, on July 31, 2024, provided that MPC Investment may demand payment of all or any portion of the outstanding principal amount of the loan, together with all accrued and unpaid interest and other amounts (if any), at any time prior to maturity. Borrowings under the MPC Loan Agreement bear interest at LIBOR plus 1.25 percent or such lower rate as would be applicable to such loans under the MPLX Credit Agreement as discussed in Note 11.

Activity on the MPC Loan Agreement was as follows:

	Three Months Ended March 31,
(In millions)	2022			2021
Borrowings	$	1,849		$	2,241
Average interest rate of borrowings	1.400		%	1.371		%
Repayments	$	2,976		$	2,241
Outstanding balance at end of period	$	323		$	—

Related Party Revenue

Related party sales to MPC primarily consist of crude oil and refined products pipeline and trucking transportation services based on tariff or contracted rates; storage, terminal and fuels distribution services based on contracted rates; and marine transportation services. Related party sales to MPC also consist of revenue related to volume deficiency credits.

MPLX also has operating agreements with MPC under which it receives a fee for operating MPC’s retained pipeline assets and a fixed annual fee for providing oversight and management services required to run the marine business. MPLX also receives management fee revenue for engineering, construction and administrative services for operating certain of its equity method investments. These agreements are classified as “Other income - related parties” on the Consolidated Statements of Income.

Certain product sales to MPC net to zero within the consolidated financial statements as the transactions are recorded net due to the terms of the agreements under which such product was sold. For the three months ended March 31, 2022 and March 31, 2021, these sales totaled $293 million and $168 million, respectively.

Related Party Expenses

MPC charges MPLX for executive management services and certain general and administrative services to MPLX under the terms of our omnibus agreements (“Omnibus charges”). Omnibus charges included in “Rental cost of sales - related parties” primarily relate to services that support MPLX’s rental operations and maintenance of assets available for rent, as well as compensation expenses. Omnibus charges included in “Purchases - related parties” primarily relate to services that support MPLX’s operations and maintenance activities, as well as compensation expenses. Omnibus charges included in “General and administrative expenses” primarily relate to services that support MPLX’s executive management, accounting and human resources activities. MPLX also obtains employee services from MPC under employee services agreements (“ESA charges”). ESA charges for personnel directly involved in or supporting operations and maintenance activities related to rental services are classified as “Rental cost of sales - related parties.” ESA charges for personnel directly involved in or supporting operations and maintenance activities related to other services are classified as “Purchases - related parties.” ESA charges for personnel involved in executive management, accounting and human resources activities are classified as “General and administrative expenses.” In addition to these agreements, MPLX purchases products from MPC, makes payments to MPC in its capacity as general contractor to MPLX, and has certain lease agreements with MPC.

For the three months ended March 31, 2022 and March 31, 2021, “General and administrative expenses” incurred from MPC totaled $55 million and $57 million, respectively.

Some charges incurred under the omnibus and ESA agreements are related to engineering services and are associated with assets under construction. These charges are added to “Property, plant and equipment, net” on the Consolidated Balance Sheets. For the three months ended March 31, 2022 and March 31, 2021, these charges totaled $19 million and $12 million, respectively.

11

Related Party Assets and Liabilities

Assets and liabilities with related parties appearing on the Consolidated Balance Sheets are detailed in the table below. This table identifies the various components of related party assets and liabilities, including those associated with leases and deferred revenue on minimum volume commitments. If MPC fails to meet its minimum committed volumes, MPC will pay MPLX a deficiency payment based on the terms of the agreement. The deficiency amounts received under these agreements (excluding payments received under agreements classified as sales-type leases) are recorded as “Current liabilities - related parties.” In many cases, MPC may then apply the amount of any such deficiency payments as a credit for volumes in excess of its minimum volume commitment in future periods under the terms of the applicable agreements. MPLX recognizes related party revenues for the deficiency payments when credits are used for volumes in excess of minimum quarterly volume commitments, where it is probable the customer will not use the credit in future periods or upon the expiration of the credits. The use or expiration of the credits is a decrease in “Current liabilities - related parties.” Deficiency payments under agreements that have been classified as sales-type leases are recorded as a reduction against the corresponding lease receivable. In addition, capital projects MPLX undertakes at the request of MPC are reimbursed in cash and recognized as revenue over the remaining term of the applicable agreements or in some cases, as a contribution from MPC.

(In millions)	March 31, 2022		December 31, 2021
Current assets - related parties
Receivables	$	707	$	555
Prepaid	17		4
Other	3		3
Lease receivables	86		82
Total	813		644
Noncurrent assets - related parties
Long-term receivables	30		31
Right of use assets	229		229
Long-term lease receivables	828		854
Unguaranteed residual asset	64		47
Total	1,151		1,161
Current liabilities - related parties
MPC loan agreement and other payables(1)	606		1,702
Operating lease liabilities	1		1
Deferred revenue - Minimum volume deficiencies	38		35
Deferred revenue - Project reimbursements	42		42
Total	687		1,780
Long-term liabilities - related parties
Long-term operating lease liabilities	228		228
Long-term deferred revenue - Project reimbursements	77		74
Total	$	305	$	302

(1) Includes $323 million as of March 31, 2022 and $1,450 million as of December 31, 2021 related to outstanding borrowings on the intercompany loan with MPC, which are included in “Current liabilities - related parties” on the Consolidated Balance Sheets.

5. Equity

The changes in the number of common units during the three months ended March 31, 2022 are summarized below:

(In units)	Common
Balance at December 31, 2021	1,016,178,378
Unit-based compensation awards	148,951
Units redeemed in unit repurchase program	(3,119,522)
Balance at March 31, 2022	1,013,207,807

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Unit Repurchase Program

On November 2, 2020, MPLX announced the board authorization of a unit repurchase program for the repurchase of up to $1 billion of MPLX’s outstanding common units held by the public. MPLX may utilize various methods to effect the repurchases, which could include open market repurchases, negotiated block transactions, tender offers, accelerated unit repurchases or open market solicitations for units, some of which may be effected through Rule 10b5-1 plans. The timing and amount of repurchases will depend upon several factors, including market and business conditions, and repurchases may be initiated, suspended or discontinued at any time. The repurchase authorization has no expiration date. During the three months ended March 31, 2022, we repurchased 3,119,522 common units at an average cost per unit of $32.06 per unit and paid $100 million of cash. As of March 31, 2022, we had $237 million remaining under our repurchase authorization.

Series B Preferred Units

MPLX has 600,000 outstanding units of 6.875 percent Fixed-to-Floating Rate Cumulative Redeemable Perpetual Preferred Units representing limited partner interests of MPLX with a price to the public of $1,000 per unit (the “Series B preferred units”). The Series B preferred units are pari passu with the Series A preferred units with respect to distribution rights and rights upon liquidation. Series B preferred unitholders are entitled to receive a fixed distribution of $68.75 per unit, per annum, payable semi-annually in arrears on the 15th day, or the first business day thereafter, of February and August of each year up to and including February 15, 2023. After February 15, 2023, the holders of Series B preferred units are entitled to receive cumulative, quarterly distributions payable in arrears on the 15th day of February, May, August and November of each year, or the first business day thereafter, based on a floating annual rate equal to the three-month LIBOR plus 4.652 percent, in each case assuming a distribution is declared by the Board of Directors. MPLX has the right to redeem some or all of the Series B preferred units, at any time, on or after February 15, 2023 at the Series B preferred unit redemption price of $1,000 per unit, plus any accumulated and unpaid distributions up to the redemption date.

Cash distributions

On April 26, 2022, MPLX declared a cash distribution for the first quarter of 2022, totaling $713 million, or $0.7050 per common unit. This distribution will be paid on May 13, 2022 to common unitholders of record on May 6, 2022. This rate will also be received by Series A preferred unitholders.

Quarterly distributions for 2022 and 2021 are summarized below:

(Per common unit)	2022		2021
March 31,	$	0.7050	$	0.6875

In accordance with the distribution rights discussed above, MPLX made a cash distribution totaling $21 million to Series B unitholders on February 15, 2022.

The allocation of total quarterly cash distributions to limited and preferred unitholders is as follows for the three months ended March 31, 2022 and 2021. Distributions, although earned, are not accrued until declared. MPLX’s distributions are declared subsequent to quarter end; therefore, the following table represents total cash distributions applicable to the period in which the distributions were earned.

	Three Months Ended March 31,
(In millions)	2022		2021
Common and preferred unit distributions:
Common unitholders, includes common units of general partner	$	713	$	707
Series A preferred unit distributions	21		20
Series B preferred unit distributions	11		11
Total cash distributions declared	$	745	$	738

6. Net Income/(Loss) Per Limited Partner Unit

Net income/(loss) per unit applicable to common units is computed by dividing net income attributable to MPLX LP less income allocated to participating securities by the weighted average number of common units outstanding.

During the three months ended March 31, 2022 and 2021, MPLX had participating securities consisting of common units, certain equity-based compensation awards, Series A preferred units and Series B preferred units and had dilutive potential common units consisting of certain equity-based compensation awards. Potential common units omitted from the diluted earnings per unit calculation for the three months ended March 31, 2022 and 2021 were less than 1 million.

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	Three Months Ended March 31,
(In millions)	2022		2021
Net income attributable to MPLX LP	$	825	$	739
Less: Distributions declared on Series A preferred units	21		20
Distributions declared on Series B preferred units	11		11
Limited partners’ distributions declared on MPLX common units (including common units of general partner)	713		707
Undistributed net gain attributable to MPLX LP	$	80	$	1

	Three Months Ended March 31, 2022
(In millions, except per unit data)	Limited Partners’ Common Units		Series A Preferred Units		Series B Preferred Units		Total
Basic and diluted net income attributable to MPLX LP per unit
Net income attributable to MPLX LP:
Distributions declared	$	713	$	21	$	11	$	745
Undistributed net gain attributable to MPLX LP	78		2		—		80
Net income attributable to MPLX LP(1)	$	791	$	23	$	11	$	825
Weighted average units outstanding:
Basic	1,015
Diluted	1,015
Net income attributable to MPLX LP per limited partner unit:
Basic	$	0.78
Diluted	$	0.78

(1)    Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.

	Three Months Ended March 31, 2021
(In millions, except per unit data)	Limited Partners’ Common Units		Series A Preferred Units		Series B Preferred Units		Total
Basic and diluted net income attributable to MPLX LP per unit
Net income attributable to MPLX LP:
Distributions declared	$	707	$	20	$	11	$	738
Undistributed net gain attributable to MPLX LP	1		—		—		1
Net income attributable to MPLX LP(1)	$	708	$	20	$	11	$	739
Weighted average units outstanding:
Basic	1,037
Diluted	1,037
Net income attributable to MPLX LP per limited partner unit:
Basic	$	0.68
Diluted	$	0.68

(1)    Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.

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7. Segment Information

MPLX’s chief operating decision maker is the chief executive officer (“CEO”) of its general partner. The CEO reviews MPLX’s discrete financial information, makes operating decisions, assesses financial performance and allocates resources on a type of service basis. MPLX has two reportable segments: L&S and G&P. Each of these segments is organized and managed based upon the nature of the products and services it offers.

•L&S – transports, gathers, stores and distributes crude oil, refined products, and other hydrocarbon-based products. Also includes the operation of refining logistics, fuels distribution and inland marine businesses, terminals, rail facilities, and storage caverns.

•G&P – gathers, processes and transports natural gas; and gathers, transports, fractionates, stores and markets NGLs.

Our CEO evaluates the performance of our segments using Segment Adjusted EBITDA. Amounts included in net income and excluded from Segment Adjusted EBITDA include: (i) depreciation and amortization; (ii) interest and other financial costs; (iii) impairment expense; (iv) income/(loss) from equity method investments; (v) distributions and adjustments related to equity method investments; (vi) noncontrolling interests; and (vii) other adjustments as deemed necessary. These items are either: (i) believed to be non-recurring in nature; (ii) not believed to be allocable or controlled by the segment; or (iii) are not tied to the operational performance of the segment.

The tables below present information about revenues and other income, Segment Adjusted EBITDA, restructuring expenses, capital expenditures and investments in unconsolidated affiliates for our reportable segments:

	Three Months Ended March 31,
(In millions)	2022		2021
L&S
Service revenue	$	983	$	953
Rental income	175		249
Product related revenue	4		4
Sales-type lease revenue	111		37
Income from equity method investments	52		36
Other income	12		15
Total segment revenues and other income(1)	1,337		1,294
Segment Adjusted EBITDA(2)	904		896
Capital expenditures	77		59
Investments in unconsolidated affiliates	68		9
G&P
Service revenue	486		508
Rental income	81		92
Product related revenue	661		397
Income from equity method investments	47		34
Other income/(loss)	(2)		14
Total segment revenues and other income(1)	1,273		1,045
Segment Adjusted EBITDA(2)	489		456
Capital expenditures	95		30
Investments in unconsolidated affiliates	$	42	$	26

(1)    Within the total segment revenues and other income amounts presented above, third party revenues for the L&S segment were $135 million and $129 million for the three months ended March 31, 2022 and March 31, 2021, respectively. Third party revenues for the G&P segment were $1,212 million and $989 million for the three months ended March 31, 2022 and March 31, 2021, respectively.

(2)    See below for the reconciliation from Segment Adjusted EBITDA to “Net income.”

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The table below provides a reconciliation between “Net income” and Segment Adjusted EBITDA.

	Three Months Ended March 31,
(In millions)	2022		2021
Reconciliation to Net income:
L&S Segment Adjusted EBITDA	$	904	$	896
G&P Segment Adjusted EBITDA	489		456
Total reportable segments	1,393		1,352
Depreciation and amortization(1)	(313)		(329)
Interest and other financial costs	(222)		(225)
Income from equity method investments	99		70
Distributions/adjustments related to equity method investments	(132)		(121)
Other	(1)		(9)
Adjusted EBITDA attributable to noncontrolling interests	9		10
Net income	$	833	$	748

(1)    Depreciation and amortization attributable to L&S was $130 million and $147 million for the three months ended March 31, 2022 and March 31, 2021, respectively. Depreciation and amortization attributable to G&P was $183 million and $182 million for the three months ended March 31, 2022 and March 31, 2021, respectively.

8. Property, Plant and Equipment

Property, plant and equipment with associated accumulated depreciation is shown below:

	March 31, 2022						December 31, 2021
(In millions)	Gross PP&E		Accumulated Depreciation		Net PP&E		Gross PP&E		Accumulated Depreciation		Net PP&E
L&S	$	12,438	$	3,347	$	9,091	$	12,371	$	3,227	$	9,144
G&P	14,253		3,432		10,821		14,175		3,277		10,898
Total	$	26,691	$	6,779	$	19,912	$	26,546	$	6,504	$	20,042

9. Fair Value Measurements

Fair Values – Recurring

Fair value measurements and disclosures relate primarily to MPLX’s derivative positions as discussed in Note 10.

Level 3 instruments relate to an embedded derivative liability for a natural gas purchase commitment embedded in a keep-whole processing agreement. The fair value calculation for these Level 3 instruments used significant unobservable inputs including: (1) NGL prices interpolated and extrapolated due to inactive markets ranging from $0.73 to $2.38 per gallon with a weighted average of $0.97 per gallon and (2) the probability of renewal of 100 percent for the five-year renewal term of the gas purchase commitment and related keep-whole processing agreement. Increases or decreases in the fractionation spread result in an increase or decrease in the fair value of the embedded derivative liability, respectively. Beyond the embedded derivative discussed above, we had no outstanding commodity derivative contracts as of March 31, 2022 or December 31, 2021.

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Changes in Level 3 Fair Value Measurements

The following table is a reconciliation of the net beginning and ending balances recorded for net assets and liabilities classified as Level 3 in the fair value hierarchy.

	Three Months Ended March 31,
	2022		2021
(In millions)	Embedded Derivatives in Commodity Contracts (net)		Embedded Derivatives in Commodity Contracts (net)
Fair value at beginning of period	$	(108)	$	(63)
Total gain/(loss) (realized and unrealized) included in earnings(1)	4		(6)
Settlements	5		3
Fair value at end of period	(99)		(66)
The amount of total gain/(loss) for the period included in earnings attributable to the change in unrealized gain/(loss) relating to liabilities still held at end of period	$	5	$	(5)

(1)     Gain/(loss) on derivatives embedded in commodity contracts are recorded in “Purchased product costs” on the Consolidated Statements of Income.

Fair Values – Reported

MPLX’s primary financial instruments are cash and cash equivalents, receivables, receivables from related parties, lease receivables from related parties, accounts payable, payables to related parties and debt. MPLX’s fair value assessment incorporates a variety of considerations, including (1) the duration of the instruments, (2) MPC’s investment-grade credit rating and (3) the historical incurrence of and expected future insignificance of bad debt expense, which includes an evaluation of counterparty credit risk. MPLX believes the carrying values of its current assets and liabilities approximate fair value. The recorded value of the amounts outstanding under the bank revolving credit facility, if any, approximates fair value due to the variable interest rate that approximate current market rates. Derivative instruments are recorded at fair value, based on available market information (see Note 10).

The fair value of MPLX’s debt is estimated based on recent market non-binding indicative quotes. The debt fair values are considered Level 3 measurements. The following table summarizes the fair value and carrying value of our third-party debt, excluding finance leases and unamortized debt issuance costs:

	March 31, 2022				December 31, 2021
(In millions)	Fair Value		Carrying Value		Fair Value		Carrying Value
Outstanding debt(1)	$	20,392	$	19,864	$	20,779	$	18,664

(1)    Amounts outstanding under the MPC Loan Agreement are not included in the table above, as the carrying value approximates fair value. This balance is reflected in “Current liabilities - related parties” on the Consolidated Balance Sheets.

10. Derivative Financial Instruments

As of March 31, 2022, MPLX had no commodity contracts beyond the embedded derivative discussed below.

Embedded Derivative - MPLX has a natural gas purchase commitment embedded in a keep-whole processing agreement with a producer customer in the Southern Appalachian region expiring in December 2027. The customer has the unilateral option to extend the agreement for one five-year term through December 2032. For accounting purposes, the natural gas purchase commitment and the term extending option has been aggregated into a single compound embedded derivative. The probability of the customer exercising its option is determined based on assumptions about the customer’s potential business strategy decision points that may exist at the time they would elect whether to renew the contract. The changes in fair value of this compound embedded derivative are based on the difference between the contractual and index pricing, the probability of the producer customer exercising its option to extend and the estimated favorability of these contracts compared to current market conditions. The changes in fair value are recorded in earnings through “Purchased product costs” on the Consolidated Statements of Income. For further information regarding the fair value measurement of derivative instruments, see Note 9. As of March 31, 2022 and December 31, 2021, the estimated fair value of this contract was a liability of $99 million and $108 million, respectively.

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Certain derivative positions are subject to master netting agreements, therefore, MPLX has elected to offset derivative assets and liabilities that are legally permissible to be offset. As of March 31, 2022 and December 31, 2021, there were no derivative assets or liabilities that were offset on the Consolidated Balance Sheets. The impact of MPLX’s derivative instruments on its Consolidated Balance Sheets is summarized below:

(In millions)	March 31, 2022				December 31, 2021
Derivative contracts not designated as hedging instruments and their balance sheet location	Asset		Liability		Asset		Liability
Commodity contracts(1)
Other current assets / Other current liabilities	$	—	$	(16)	$	—	$	(15)
Other noncurrent assets / Deferred credits and other liabilities	—		(83)		—		(93)
Total	$	—	$	(99)	$	—	$	(108)

(1)     Includes the embedded derivative in the commodity contract discussed above.

We make a distinction between realized or unrealized gains and losses on derivatives. During the period when a derivative contract is outstanding, changes in the fair value of the derivative are recorded as an unrealized gain or loss. When a derivative contract matures or is settled, the previously recorded unrealized gain or loss is reversed and the realized gain or loss of the contract is recorded. The impact of MPLX’s derivative contracts not designated as hedging instruments and the location of gains and losses recognized on the Consolidated Statements of Income is summarized below:

	Three Months Ended March 31,
(In millions)	2022		2021
Purchased product costs
Realized loss	$	(5)	$	(3)
Unrealized gain/(loss)	9		(3)
Purchased product cost derivative gain/(loss)	$	4	$	(6)

11. Debt

MPLX’s outstanding borrowings consist of the following:

(In millions)	March 31, 2022		December 31, 2021
MPLX LP:
MPLX Credit Agreement	$	—	$	300
Fixed rate senior notes	20,032		18,532
Consolidated subsidiaries:
MarkWest	23		23
ANDX	45		45
Financing lease obligations	8		9
Total	20,108		18,909
Unamortized debt issuance costs	(116)		(102)
Unamortized discount/premium	(236)		(236)
Amounts due within one year	(999)		(499)
Total long-term debt due after one year	$	18,757	$	18,072

Credit Agreement

MPLX’s amended and restated credit agreement (as amended, the “MPLX Credit Agreement”), provides for borrowings up to $3.5 billion and a term that extends to July 2024. During the three months ended March 31, 2022, MPLX borrowed $900 million under the MPLX Credit Agreement, at an average interest rate of 1.451 percent, and repaid $1,200 million. At March 31, 2022, MPLX had no outstanding borrowings and less than $1 million in letters of credit outstanding under the MPLX Credit Agreement, resulting in total availability of $3.5 billion, or 100 percent of the borrowing capacity.

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Fixed Rate Senior Notes

MPLX’s senior notes, including those issued by consolidated subsidiaries, consist of various series of senior notes maturing between 2022 and 2058 with interest rates ranging from 1.750 percent to 5.500 percent. Interest on each series of notes is payable semi-annually in arrears on various dates depending on the series of the notes.

On March 14, 2022, MPLX issued $1.5 billion aggregate principal amount of 4.950 percent senior notes due March 2052 (the “2052 Senior Notes”) in an underwritten public offering. The 2052 Senior Notes were offered at a price to the public of 98.982 percent with interest payable semi-annually in arrears, commencing on September 14, 2022. The net proceeds were used to repay amounts outstanding under the MPC Intercompany Loan Agreement and the MPLX Credit Agreement.

12. Revenue

Disaggregation of Revenue

The following tables represent a disaggregation of revenue for each reportable segment for the three months ended March 31, 2022 and 2021:

	Three Months Ended March 31, 2022
(In millions)	L&S		G&P		Total
Revenues and other income:
Service revenue	$	72	$	482	$	554
Service revenue - related parties	911		4		915
Service revenue - product related	—		123		123
Product sales	1		496		497
Product sales - related parties	3		42		45
Total revenues from contracts with customers	$	987	$	1,147	2,134
Non-ASC 606 revenue(1)					476
Total revenues and other income					$	2,610

	Three Months Ended March 31, 2021
(In millions)	L&S		G&P		Total
Revenues and other income:
Service revenue	$	84	$	505	$	589
Service revenue - related parties	869		3		872
Service revenue - product related	—		77		77
Product sales	1		281		282
Product sales - related parties	3		39		42
Total revenues from contracts with customers	$	957	$	905	1,862
Non-ASC 606 revenue(1)					477
Total revenues and other income					$	2,339

(1)    Non-ASC 606 Revenue includes rental income, sales-type lease revenue, income from equity method investments, and other income.

Contract Balances

Contract assets typically relate to deficiency payments related to minimum volume commitments and aid in construction agreements where the revenue recognized and MPLX’s rights to consideration for work completed exceeds the amount billed to the customer. Contract assets are included in “Other current assets” and “Other noncurrent assets” on the Consolidated Balance Sheets.

Contract liabilities, which we refer to as “Deferred revenue” and “Long-term deferred revenue,” typically relate to advance payments for aid in construction agreements and deferred customer credits associated with makeup rights and minimum volume commitments. Related to minimum volume commitments, breakage is estimated and recognized into service revenue in

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instances where it is probable the customer will not use the credit in future periods. We classify contract liabilities as current or long-term based on the timing of when we expect to recognize revenue.

“Receivables, net” primarily relate to our commodity sales. Portions of the “Receivables, net” balance are attributed to the sale of commodity product controlled by MPLX prior to sale while a significant portion of the balance relates to the sale of commodity product on behalf of our producer customers. The sales and related “Receivables, net” are commingled and excluded from the table below. MPLX remits the net sales price back to our producer customers upon completion of the sale. Each period end, certain amounts within accounts payable relate to our payments to producer customers. Such amounts are not deemed material at period end as a result of when we settle with each producer.

The tables below reflect the changes in our contract balances for the three-month periods ended March 31, 2022 and 2021:

(In millions)	Balance at December 31, 2021(1)		Additions/ (Deletions)		Revenue Recognized(2)		Balance at March 31, 2022
Contract assets	$	25	$	(18)	$	—	$	7
Long-term contract assets	2		—		—		2
Deferred revenue	56		11		(9)		58
Deferred revenue - related parties	60		34		(26)		68
Long-term deferred revenue	135		2		—		137
Long-term deferred revenue - related parties	31		—		—		31
Long-term contract liabilities	$	5	$	—	$	—	$	5

(In millions)	Balance at December 31, 2020(1)		Additions/ (Deletions)		Revenue Recognized(2)		Balance at March 31, 2021
Contract assets	$	40	$	(27)	$	—	$	13
Long-term contract assets	2		—		—		2
Deferred revenue	37		7		(1)		43
Deferred revenue - related parties	91		21		(20)		92
Long-term deferred revenue	119		4		—		123
Long-term deferred revenue - related parties	48		(4)		—		44
Long-term contract liabilities	$	6	$	—	$	—	$	6

(1)    Balance represents ASC 606 portion of each respective line item.

(2)     No significant revenue was recognized related to past performance obligations in the current periods.

Remaining Performance Obligations

The table below includes estimated revenue expected to be recognized in the future related to performance obligations that are unsatisfied (or partially unsatisfied) at the end of the reporting period.

As of March 31, 2022, the amounts allocated to contract assets and contract liabilities on the Consolidated Balance Sheets are $293 million and are reflected in the amounts below. This will be recognized as revenue as the obligations are satisfied, which is expected to occur over the next 22 years. Further, MPLX does not disclose variable consideration due to volume variability in the table below.

(In millions)
2022	$	1,432
2023	1,771
2024	1,633
2025	1,560
2026 and thereafter	3,362
Total revenue on remaining performance obligations(1)(2)(3)	$	9,758

(1)    All fixed consideration from contracts with customers is included in the amounts presented above. Variable consideration that is constrained or not required to be estimated as it reflects our efforts to perform is excluded.

(2)    Arrangements deemed implicit leases and sales-type leases are excluded from this table.

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(3)    Only minimum volume commitments that are deemed fixed are included in the table above. MPLX has various minimum volume commitments in processing arrangements that vary based on the actual Btu content of the gas received. These amounts are deemed variable consideration and are excluded from the table above.

We do not disclose information on the future performance obligations for any contract with an original expected duration of one year or less.

13. Supplemental Cash Flow Information

	Three Months Ended March 31,
(In millions)	2022		2021
Net cash provided by operating activities included:
Interest paid (net of amounts capitalized)	$	213	$	231

The Consolidated Statements of Cash Flows exclude changes to the Consolidated Balance Sheets that do not affect cash. The following is the change of additions to property, plant and equipment related to capital accruals:

	Three Months Ended March 31,
(In millions)	2022		2021
Increase/(decrease) in capital accruals	$	3	$	(37)

14. Commitments and Contingencies

MPLX is the subject of, or a party to, a number of pending or threatened legal actions, contingencies and commitments involving a variety of matters, including laws and regulations relating to the environment. Some of these matters are discussed below. For matters for which MPLX has not recorded a liability, MPLX is unable to estimate a range of possible loss because the issues involved have not been fully developed through pleadings, discovery or court proceedings. However, the ultimate resolution of some of these contingencies could, individually or in the aggregate, be material.

Environmental Matters

MPLX is subject to federal, state and local laws and regulations relating to the environment. These laws generally provide for control of pollutants released into the environment and require responsible parties to undertake remediation of hazardous waste disposal sites. Penalties may be imposed for non-compliance.

At March 31, 2022 and December 31, 2021, accrued liabilities for remediation totaled $42 million and $23 million, respectively. It is not presently possible to estimate the ultimate amount of all remediation costs that might be incurred or the penalties, if any, that may be imposed.

MPLX is involved in environmental enforcement matters arising in the ordinary course of business. While the outcome and impact to MPLX cannot be predicted with certainty, management believes the resolution of these environmental matters will not, individually or collectively, have a material adverse effect on its consolidated results of operations, financial position or cash flows.

MPLX is also a party to a number of other lawsuits and other proceedings arising in the ordinary course of business. While the ultimate outcome and impact to MPLX cannot be predicted with certainty, management believes the resolution of these other lawsuits and proceedings will not, individually or collectively, have a material adverse effect on its consolidated financial position, results of operations or cash flows.

Guarantees

Over the years, MPLX has sold various assets in the normal course of its business. Certain of the related agreements contain performance and general guarantees, including guarantees regarding inaccuracies in representations, warranties, covenants and agreements, and environmental and general indemnifications that require MPLX to perform upon the occurrence of a triggering event or condition. These guarantees and indemnifications are part of the normal course of selling assets. MPLX is typically not able to calculate the maximum potential amount of future payments that could be made under such contractual provisions because of the variability inherent in the guarantees and indemnities. Most often, the nature of the guarantees and indemnities is such that there is no appropriate method for quantifying the exposure because the underlying triggering event has little or no past experience upon which a reasonable prediction of the outcome can be based.

We hold a 9.19 percent indirect interest in a joint venture (“Dakota Access”) that owns and operates the Dakota Access Pipeline and Energy Transfer Crude Oil Pipeline projects, collectively referred to as the Bakken Pipeline system or DAPL. In 2020, the

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U.S. District Court for the District of Columbia (the “D.D.C.”) ordered the U.S. Army Corps of Engineers (“Army Corps”), which granted permits and an easement for the Bakken Pipeline system, to prepare an environmental impact statement (“EIS”) relating to an easement under Lake Oahe in North Dakota. The D.D.C. later vacated the easement. The EIS is currently expected to be completed in the second half of 2022.

In May 2021, the D.D.C. denied a renewed request for an injunction to shut down the pipeline while the EIS is being prepared. In June 2021, the D.D.C. issued an order dismissing without prejudice the tribes’ claims against the Dakota Access Pipeline. The litigation could be reopened or new litigation challenging the EIS, once completed, could be filed. The pipeline remains operational.

We have entered into a Contingent Equity Contribution Agreement whereby MPLX LP, along with the other joint venture owners in the Bakken Pipeline system, has agreed to make equity contributions to the joint venture upon certain events occurring to allow the entities that own and operate the Bakken Pipeline system to satisfy their senior note payment obligations. The senior notes were issued to repay amounts owed by the pipeline companies to fund the cost of construction of the Bakken Pipeline system. If the pipeline were temporarily shut down, MPLX would have to contribute its 9.19 percent pro rata share of funds required to pay interest accruing on the notes and any portion of the principal that matures while the pipeline is shutdown. MPLX also expects to contribute its 9.19 percent pro rata share of any costs to remediate any deficiencies to reinstate the permit and/or return the pipeline into operation. If the vacatur of the easement permit results in a permanent shutdown of the pipeline, MPLX would have to contribute its 9.19 percent pro rata share of the cost to redeem the bonds (including the one percent redemption premium required pursuant to the indenture governing the notes) and any accrued and unpaid interest. As of March 31, 2022, our maximum potential undiscounted payments under the Contingent Equity Contribution Agreement were approximately $170 million.

Other Legal Proceedings

In July 2020, Tesoro High Plains Pipeline Company, LLC (“THPP”), a subsidiary of MPLX, received a Notification of Trespass Determination from the Bureau of Indian Affairs (“BIA”) relating to a portion of the Tesoro High Plains Pipeline that crosses the Fort Berthold Reservation in North Dakota. The notification demanded the immediate cessation of pipeline operations and assessed trespass damages of approximately $187 million. On appeal, the Assistant Secretary - Indian Affairs issued an order vacating the BIA’s trespass order and remanded to the Regional Director for the BIA Great Plains Region to issue a new decision based on specific criteria. On December 15, 2020, the Regional Director of the BIA issued a new trespass notice to THPP, finding that THPP was in trespass and assessing trespass damages of approximately $4 million (including interest), which has been paid. The order also required that THPP immediately cease and desist use of the portion of the pipeline that crosses the property at issue. THPP has complied with the Regional Director’s December 15, 2020 notice. In March 2021, THPP received a copy of an order purporting to vacate all orders related to THPP’s alleged trespass issued by the BIA between July 2, 2020 and January 14, 2021. The order directs the Regional Director of the BIA to reconsider the issue of THPP’s alleged trespass and issue a new order, if necessary, after all interested parties have had an opportunity to be heard. Subsequently, landowners voluntarily dismissed the suit filed in the District of North Dakota. On April 23, 2021, THPP filed a lawsuit in the District of North Dakota against the United States of America, the U.S. Department of the Interior and the BIA (together, the “U.S. Government Parties”) challenging the March order purporting to vacate all previous orders related to THPP’s alleged trespass.

On February 8, 2022, the U.S. Government Parties filed their answer to THPP’s suit, asserting counterclaims for trespass and ejectment. The U.S. Government Parties claim THPP is in continued trespass with respect to the pipeline and seek disgorgement of pipeline profits from June 1, 2013 to present, removal of the pipeline and remediation. We intend to vigorously defend ourselves against these counterclaims. We continue to work towards a settlement of this matter with holders of the property rights at issue.

Contractual Commitments and Contingencies

From time to time and in the ordinary course of business, MPLX and its affiliates provide guarantees of MPLX’s subsidiaries payment and performance obligations in the G&P segment. Certain natural gas processing and gathering arrangements require MPLX to construct new natural gas processing plants, natural gas gathering pipelines and NGL pipelines and contain certain fees and charges if specified construction milestones are not achieved for reasons other than force majeure. In certain cases, certain producers may have the right to cancel the processing arrangements if there are significant delays that are not due to force majeure. As of March 31, 2022, management does not believe there are any indications that MPLX will not be able to meet the construction milestones, that force majeure does not apply or that such fees and charges will otherwise be triggered.

Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations

Management’s Discussion and Analysis of Financial Condition and Results of Operations should also be read in conjunction with the unaudited consolidated financial statements and accompanying footnotes included under Item 1. Financial Statements and in conjunction with our Annual Report on Form 10-K for the year ended December 31, 2021.

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Disclosures Regarding Forward-Looking Statements

This Quarterly Report on Form 10-Q, particularly Management’s Discussion and Analysis of Financial Condition and Results of Operations and Quantitative and Qualitative Disclosures about Market Risk, includes forward-looking statements that are subject to risks, contingencies or uncertainties. You can identify forward-looking statements by words such as “anticipate,” “believe,” “commitment,” “could,” “design,” “estimate,” “expect,” “forecast,” “goal,” “guidance,” “imply,” “intend,” “may,” “objective,” “opportunity,” “outlook,” “plan,” “policy,” “position,” “potential,” “predict,” “priority,” “project,” “proposition,” “prospective,” “pursue,” “seek,” “should,” “strategy,” “target,” “will,” “would” or other similar expressions that convey the uncertainty of future events or outcomes.

Forward-looking statements include, among other things, statements regarding:

•future financial and operating results;

•environmental, social and governance (“ESG”) goals and targets, including those related to greenhouse gas emissions, diversity and inclusion and ESG reporting;

•our plans to achieve our ESG goals and targets and to monitor and report progress thereon;

•the success or timing of completion of ongoing or anticipated capital or maintenance projects;

•the timing and amount of future distributions or unit repurchases; and

•the anticipated effects of actions of third parties such as competitors, activist investors, federal, foreign, state or local regulatory authorities, or plaintiffs in litigation.

Our forward-looking statements are not guarantees of future performance and you should not rely unduly on them, as they involve risks, uncertainties and assumptions. Material differences between actual results and any future performance suggested in our forward-looking statements could result from a variety of factors, including the following:

•the continuance or escalation of the military conflict between Russia and Ukraine, and related sanctions;

•general economic, political or regulatory developments, including inflation, changes in governmental policies relating to refined petroleum products, crude oil, natural gas or NGLs, or taxation;

•the magnitude, duration and extent of future resurgences of the COVID-19 pandemic and its restrictions, including travel restrictions, business and school closures, increased remote work, stay-at-home orders and other actions taken by individuals, governments and the private sector to stem the spread of the virus;

•the ability of MPC to achieve its strategic objectives and the effects of those strategic decisions on us;

•further impairments;

•negative capital market conditions, including an increase of the current yield on common units;

•the ability to achieve strategic and financial objectives, including with respect to distribution coverage, future distribution levels, proposed projects and completed transactions;

•the success of MPC’s portfolio optimization, including the ability to complete any divestitures on commercially reasonable terms and/or within the expected timeframe, and the effects of any such divestitures on our business, financial condition, results of operations and cash flows;

•the adequacy of capital resources and liquidity, including the availability of sufficient cash flow to pay distributions and access to debt on commercially reasonable terms, and the ability to successfully execute business plans, growth strategies and self-funding models;

•the timing and extent of changes in commodity prices and demand for crude oil, refined products, feedstocks or other hydrocarbon-based products;

•volatility in or degradation of market and industry conditions;

•changes to the expected construction costs and timing of projects and planned investments, and the ability to obtain regulatory and other approvals with respect thereto;

•completion of midstream infrastructure by competitors;

•disruptions due to equipment interruption or failure, including electrical shortages and power grid failures;

•the suspension, reduction or termination of MPC’s obligations under MPLX’s commercial agreements;

•modifications to financial policies, capital budgets, and earnings and distributions;

•the ability to manage disruptions in credit markets or changes to credit ratings;

•compliance with federal and state environmental, economic, health and safety, energy and other policies and regulations or enforcement actions initiated thereunder;

•adverse results in litigation;

•the effect of restructuring or reorganization of business components;

•the potential effects of changes in tariff rates on our business, financial condition, results of operations and cash flows;

•changes in foreign imports and exports of crude oil, refined products, natural gas and NGLs;

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•changes in producer customers’ drilling plans or in volumes of throughput of crude oil, natural gas, NGLs, refined products or other hydrocarbon-based products;

•changes in the cost or availability of third-party vessels, pipelines, railcars and other means of transportation for crude oil, natural gas, NGLs, feedstocks and refined products;

•the price, availability and acceptance of alternative fuels and alternative-fuel vehicles and laws mandating such fuels or vehicles;

•actions taken by our competitors, including pricing adjustments and the expansion and retirement of pipeline capacity, processing, fractionation and treating facilities in response to market conditions;

•expectations regarding joint venture arrangements and other acquisitions or divestitures of assets;

•midstream and refining industry overcapacity or under capacity;

•accidents or other unscheduled shutdowns affecting our machinery, pipelines, processing, fractionation and treating facilities or equipment, means of transportation, or those of our suppliers or customers;

•acts of war, terrorism or civil unrest that could impair our ability to gather, process, fractionate or transport crude oil, natural gas, NGLs or refined products; and

•political pressure and influence of environmental groups upon policies and decisions related to the production, gathering, refining, processing, fractionation, transportation and marketing of crude oil or other feedstocks, refined products, natural gas, NGLs or other hydrocarbon-based products.

For additional risk factors affecting our business, see the risk factors described in our Annual Report on Form 10-K for the year ended December 31, 2021. We undertake no obligation to update any forward-looking statement except to the extent required by applicable law.

MPLX Overview

We are a diversified, large-cap MLP formed by MPC, that owns and operates midstream energy infrastructure and logistics assets, and provides fuels distribution services. The business consists of two segments based on the nature of services it offers: Logistics and Storage (“L&S”), and Gathering and Processing (“G&P”). The L&S segment is engaged in the gathering, transportation, storage and distribution of crude oil, refined products and other hydrocarbon-based products. The L&S segment also includes the operation of our refining logistics, fuels distribution and inland marine businesses, terminals, rail facilities and storage caverns. The G&P segment provides gathering, processing and transportation of natural gas; and the gathering, transportation, fractionation, storage and marketing of NGLs.

Significant Financial and Other Highlights

Significant financial highlights including revenues and other income, income from operations, net income, adjusted EBITDA attributable to MPLX and DCF attributable to GP and LP unitholders for the three months ended March 31, 2022 and March 31, 2021 are shown in the chart below. See the Non-GAAP Financial Information section below for the definitions of Adjusted EBITDA and DCF and the Results of Operations section for further details regarding changes in these metrics.

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Other Highlights

•Generated net cash provided by operating activities of $1,125 million and free cash flow of $850 million in the first quarter of 2022.

•Announced a first quarter 2022 distribution of $0.7050 per common unit, resulting in a distribution coverage ratio of 1.65x for the first quarter.

•Returned $100 million of cash to unitholders through the repurchase of over 3 million common units under our unit repurchase program.

•Issued $1.5 billion aggregate principal amount of 4.950 percent senior notes due March 2052 (the “2052 Senior Notes”) in an underwritten public offering. The net proceeds were used to repay amounts outstanding under the MPC Intercompany Loan Agreement and the MPLX Credit Agreement.

Current Economic Environment

Through the first three months of 2022, we continue to see recovery in the environment in which our business operates. We are unable to predict the potential effects that further resurgences of COVID-19 or the continuance or escalation of the military conflict between Russia and Ukraine may have on our financial position and results. In response to this business environment, MPLX remains focused on executing its strategic priorities of strict capital discipline, embedding a low-cost culture, and portfolio optimization.

Non-GAAP Financial Information

Our management uses a variety of financial and operating metrics to analyze our performance. These metrics are significant factors in assessing our operating results and profitability and include the non-GAAP financial measures of Adjusted EBITDA, DCF, free cash flow (“FCF”) and free cash flow after distributions. The amount of Adjusted EBITDA and DCF generated is considered by the board of directors of our general partner in approving MPLX’s cash distributions. Management also utilizes Segment Adjusted EBITDA in evaluating the financial performance of our segments. The use of this measure allows investors to understand how management evaluates financial performance to make operating decisions and allocate resources.

We define Adjusted EBITDA as net income adjusted for: (i) depreciation and amortization; (ii) provision/(benefit) for income taxes; (iii) interest and other financial costs; (iv) impairment expense; (v) income from equity method investments; (vi) distributions and adjustments related to equity method investments; (vii) noncontrolling interests; and (viii) other adjustments as deemed necessary. We also use DCF, which we define as Adjusted EBITDA adjusted for: (i) deferred revenue impacts; (ii) sales-type lease payments, net of income; (iii) net interest and other financial costs; (iv) net maintenance capital expenditures; (v) equity method investment capital expenditures paid out; and (vi) other adjustments as deemed necessary. Segment Adjusted EBITDA represents Adjusted EBITDA attributable to the reportable segments.

We define FCF as net cash provided by operating activities adjusted for (i) net cash used in investing activities; (ii) cash contributions from MPC; (iii) cash contributions from noncontrolling interests and (iv) cash distributions to noncontrolling interests. We define free cash flow after distributions as FCF less base distributions to common and preferred unitholders.

We believe that the presentation of Adjusted EBITDA, DCF, FCF and free cash flow after distributions provides useful information to investors in assessing our financial condition and results of operations. The GAAP measures most directly comparable to Adjusted EBITDA and DCF are net income and net cash provided by operating activities while the GAAP measure most directly comparable to FCF and free cash flow after distributions is net cash provided by operating activities. These non-GAAP financial measures should not be considered alternatives to GAAP net income or net cash provided by operating activities as they have important limitations as analytical tools because they exclude some but not all items that affect net income and net cash provided by operating activities or any other measure of financial performance or liquidity presented in accordance with GAAP. These non-GAAP financial measures should not be considered in isolation or as substitutes for analysis of our results as reported under GAAP. Additionally, because non-GAAP financial measures may be defined differently by other companies in our industry, our definitions may not be comparable to similarly titled measures of other companies, thereby diminishing their utility. For a reconciliation of Adjusted EBITDA and DCF to their most directly comparable measures calculated and presented in accordance with GAAP, see the Results of Operations section. For a reconciliation of FCF and free cash flow after distributions to their most directly comparable measure calculated and presented in accordance with GAAP, see the Liquidity and Capital resources section.

Comparability of our Financial Results

The Javelina divestiture, which was completed on February 12, 2021, has impacted comparability of our financial results. Prior to the sale, Javelina was reported within the G&P segment.

During the normal course of business, we amend or modify our contractual agreements with customers. These amendments or modifications require the agreements to be reassessed under ASC 842, which can impact the classification of revenues or costs associated with the agreement. These reassessments may impact the comparability of our financial results.

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Results of Operations

The following tables and discussion are a summary of our results of operations for the three months ended March 31, 2022 and 2021, including a reconciliation of Adjusted EBITDA and DCF from “Net income” and “Net cash provided by operating activities,” to the most directly comparable GAAP financial measures.

	Three Months Ended March 31,
(In millions)	2022		2021		Variance
Revenues and other income:
Total revenues and other income	$	2,610	$	2,339	$	271
Costs and expenses:
Cost of revenues (excludes items below)	287		273		14
Purchased product costs	467		276		191
Rental cost of sales	37		32		5
Rental cost of sales - related parties	15		39		(24)
Purchases - related parties	319		298		21
Depreciation and amortization	313		329		(16)
General and administrative expenses	78		86		(8)
Other taxes	34		32		2
Total costs and expenses	1,550		1,365		185
Income from operations	1,060		974		86
Related party interest and other financial costs	4		—		4
Interest expense, net of amounts capitalized	198		198		—
Other financial costs	20		27		(7)
Income before income taxes	838		749		89
Provision for income taxes	5		1		4
Net income	833		748		85
Less: Net income attributable to noncontrolling interests	8		9		(1)
Net income attributable to MPLX LP	825		739		86
Adjusted EBITDA attributable to MPLX LP(1)	1,393		1,352		41
DCF attributable to GP and LP unitholders(1)	$	1,178	$	1,106	$	72

(1)    Non-GAAP measure. See reconciliation below to the most directly comparable GAAP measures.

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	Three Months Ended March 31,
(In millions)	2022		2021		Variance
Reconciliation of Adjusted EBITDA attributable to MPLX LP and DCF attributable to GP and LP unitholders from Net income:
Net income	$	833	$	748	$	85
Provision for income taxes	5		1		4
Interest and other financial costs	222		225		(3)
Income from operations	1,060		974		86
Depreciation and amortization	313		329		(16)
Income from equity method investments	(99)		(70)		(29)
Distributions/adjustments related to equity method investments	132		121		11
Other	(4)		8		(12)
Adjusted EBITDA	1,402		1,362		40
Adjusted EBITDA attributable to noncontrolling interests	(9)		(10)		1
Adjusted EBITDA attributable to MPLX LP	1,393		1,352		41
Deferred revenue impacts	24		22		2
Sales-type lease payments, net of income	5		—		5
Net interest and other financial costs(1)	(204)		(220)		16
Maintenance capital expenditures, net of reimbursements	(14)		(11)		(3)
Equity method investment capital expenditures paid out	(3)		(1)		(2)
Other	9		(5)		14
DCF	1,210		1,137		73
Preferred unit distributions	(32)		(31)		(1)
DCF attributable to GP and LP unitholders	$	1,178	$	1,106	$	72

(1)    Excludes gain/ loss on extinguishment of debt and amortization of deferred financing costs.

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	Three Months Ended March 31,
(In millions)	2022		2021		Variance
Reconciliation of Adjusted EBITDA attributable to MPLX LP and DCF attributable to GP and LP unitholders from Net cash provided by operating activities:
Net cash provided by operating activities	$	1,125	$	1,124	$	1
Changes in working capital items	118		37		81
All other, net	(45)		(15)		(30)
Gain on extinguishment of debt	—		(12)		12
Net interest and other financial costs(1)	204		220		(16)
Other adjustments to equity method investment distributions	12		2		10
Other	(12)		6		(18)
Adjusted EBITDA	1,402		1,362		40
Adjusted EBITDA attributable to noncontrolling interests	(9)		(10)		1
Adjusted EBITDA attributable to MPLX LP	1,393		1,352		41
Deferred revenue impacts	24		22		2
Sales-type lease payments, net of income	5		—		5
Net interest and other financial costs(1)	(204)		(220)		16
Maintenance capital expenditures, net of reimbursements	(14)		(11)		(3)
Equity method investment capital expenditures paid out	(3)		(1)		(2)
Other	9		(5)		14
DCF	1,210		1,137		73
Preferred unit distributions	(32)		(31)		(1)
DCF attributable to GP and LP unitholders	$	1,178	$	1,106	$	72

(1)    Excludes gain/ loss on extinguishment of debt and amortization of deferred financing costs.

Three months ended March 31, 2022 compared to three months ended March 31, 2021

Total revenues and other income increased $271 million in the first quarter of 2022 compared to the same period of 2021. This was primarily due to higher prices and volumes in most regions in the G&P segment of approximately $274 million. There were also increased pipeline fees in the L&S segment due to higher pipeline throughput outweighing decreased average tariff rates, as well as increased equity method income across both segments. These increases were partially offset by a loss on disposal of assets.

Cost of revenues increased $14 million in the first quarter of 2022 compared to the same period of 2021. This was primarily due to higher environmental response and remediation costs.

Purchased product costs increased $191 million in the first quarter of 2022 compared to the same period of 2021 This was primarily due to higher prices of $143 million in the Southwest and Southern Appalachia and higher volumes in the Southwest.

Rental cost of sales and rental cost of sales - related parties decreased $19 million in the first quarter of 2022 compared to the same period of 2021. This was primarily due to modifications to lease contracts which resulted in costs now being recorded to purchases - related parties, as noted below, as opposed to rental cost of sales - related parties.

Purchases - related parties increased $21 million in the first quarter of 2022 compared to the same period of 2021. This was primarily due to modifications to lease contracts which resulted in costs now being recorded to purchases - related parties as opposed to rental cost of sales - related parties, as noted above.

Depreciation and amortization decreased $16 million in the first quarter of 2022 compared to the same period of 2021. This was primarily due to the prior year derecognition of assets reclassified as sales-type leases due to contract modifications.

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Segment Results

We classify our business in the following reportable segments: L&S and G&P. Segment Adjusted EBITDA represents Adjusted EBITDA attributable to the reportable segments. Amounts included in net income and excluded from Segment Adjusted EBITDA include: (i) depreciation and amortization; (ii) interest and other financial costs; (iii) impairment expense; (iv) income/(loss) from equity method investments; (v) distributions and adjustments related to equity method investments; (vi) noncontrolling interests; and (vii) other adjustments as deemed necessary. These items are either: (i) believed to be non-recurring in nature; (ii) not believed to be allocable or controlled by the segment; or (iii) are not tied to the operational performance of the segment.

The tables below present information about Segment Adjusted EBITDA for the reported segments for the three months ended March 31, 2022 and 2021.

L&S Segment

First Quarter L&S Segment Financial Highlights (in millions)

	Three Months Ended March 31,
(In millions)	2022		2021		Variance
Service revenue	$	983	$	953	$	30
Rental income	175		249		(74)
Product related revenue	4		4		—
Sales-type lease revenue	111		37		74
Income from equity method investments	52		36		16
Other income	12		15		(3)
Total segment revenues and other income	1,337		1,294		43
Cost of revenues	141		144		(3)
Purchases - related parties	239		215		24
Depreciation and amortization	130		147		(17)
General and administrative expenses	43		46		(3)
Other taxes	21		19		2
Segment income from operations	763		723		40
Depreciation and amortization	130		147		(17)
Income from equity method investments	(52)		(36)		(16)
Distributions/adjustments related to equity method investments	58		58		—
Other	5		4		1
Segment adjusted EBITDA(1)	904		896		8
Capital expenditures	77		59		18
Investments in unconsolidated affiliates(2)	$	68	$	9	$	59

(1)     See the Reconciliation of Adjusted EBITDA attributable to MPLX LP and DCF attributable to GP and LP unitholders from Net income table for the reconciliation to the most directly comparable GAAP measure.

(2)    The three months ended March 31, 2022 includes a contribution of $60 million to our Bakken Pipeline joint venture to fund our share of a debt repayment by the joint venture.

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Three months ended March 31, 2022 compared to three months ended March 31, 2021

Service revenue increased $30 million in the first quarter of 2022 compared to the same period of 2021. This was primarily due to a net increase in pipeline fees due to increased throughput outweighing lower average tariff rates, as well as to an increase of $15 million from changes in the presentation of lease income between service revenue, rental income and sales-type lease revenue due to modifications to lease contracts. Fee escalations also contributed to the increase.

Rental income decreased $74 million in the first quarter of 2022 compared to the same period of 2021. This was primarily due to a net decrease of $88 million from changes in the presentation of lease income between service revenue, rental income and sales-type lease revenue due to modifications to lease contracts. The decrease was partially offset by fee escalations.

Sales-type lease revenue - related parties increased $74 million in the first quarter of 2022 compared to the same period of 2021. This was primarily due to an increase of $73 million from changes in the presentation of lease income between service revenue, rental income and sales-type lease revenue due to modifications to lease contracts.

Income from equity methods investments increased $16 million in the first quarter of 2022 compared to the same period of 2021. This was primarily due to increased throughput on equity method investment pipeline systems, including the Whistler pipeline which was placed into service in the third quarter of 2021.

Cost of revenues decreased $3 million in the first quarter of 2022 compared to the same period of 2021. This was primarily due to modifications to lease contracts which resulted in costs being recorded to purchases - related parties, as noted below, as opposed to rental cost of sales - related parties, which is included in the decrease being explained here. The decrease was partially offset by higher environmental response and remediation costs compared to the first quarter of 2021.

Purchases - related parties increased $24 million in the first quarter of 2022 compared to the same period of 2021. This was primarily due to modifications to lease contracts which resulted in costs now being recorded to purchases - related parties as opposed to rental cost of sales - related parties, which is included in cost of revenues as noted above. This increase, and other miscellaneous increases, were partially offset by decreased employee-related costs from MPC.

Depreciation and amortization decreased $17 million in the first quarter of 2022 compared to the same period of 2021. This was primarily due to the derecognition of fixed assets due to the modification of certain lease contracts and accelerated depreciation on refining logistics assets at MPC’s idled Gallup refinery.

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L&S Operating Data

	Three Months Ended March 31,
	2022		2021
L&S
Pipeline throughput (mbpd)
Crude oil pipelines	3,380		3,282
Product pipelines	1,956		1,858
Total pipelines	5,336		5,140
Average tariff rates ($ per barrel)(1)
Crude oil pipelines	$	0.93	$	0.96
Product pipelines	0.82		0.79
Total pipelines	$	0.89	$	0.90
Terminal throughput (mbpd)	2,941		2,613
Marine Assets (number in operation)(2)
Barges	296		297
Towboats	23		23

(1)     Average tariff rates calculated using pipeline transportation revenues divided by pipeline throughput barrels.

(2)     Represents total at end of period.

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G&P Segment

First Quarter G&P Segment Financial Highlights (in millions)

	Three Months Ended March 31,
(In millions)	2022		2021		Variance
Service revenue	$	486	$	508	$	(22)
Rental income	81		92		(11)
Product related revenue	661		397		264
Income from equity method investments	47		34		13
Other income/(loss)	(2)		14		(16)
Total segment revenues and other income	1,273		1,045		228
Cost of revenues	198		200		(2)
Purchased product costs	467		276		191
Purchases - related parties	80		83		(3)
Depreciation and amortization	183		182		1
General and administrative expenses	35		40		(5)
Other taxes	13		13		—
Segment income from operations	297		251		46
Depreciation and amortization	183		182		1
Income from equity method investments	(47)		(34)		(13)
Distributions/adjustments related to equity method investments	74		63		11
Other	(9)		4		(13)
Adjusted EBITDA attributable to noncontrolling interests	(9)		(10)		1
Segment Adjusted EBITDA(1)	489		456		33
Capital expenditures	95		30		65
Investments in unconsolidated affiliates	$	42	$	26	$	16

(1)     See the Reconciliation of Adjusted EBITDA attributable to MPLX LP and DCF attributable to GP and LP unitholders from Net income table for the reconciliation to the most directly comparable GAAP measure.

Three months ended March 31, 2022 compared to three months ended March 31, 2021

Service revenue decreased $22 million in the first quarter of 2022 compared to the same period of 2021. This was primarily due to lower fees from lower volumes in the Rockies and Marcellus as well as a decrease in volumes due to the Javelina divestiture in the Southwest of $34 million, partially offset by an increase in fees due to a 2021 contract modification in the Marcellus resulting in a change in the presentation of the related income from rental income to service revenue.

Rental income decreased $11 million in the first quarter of 2022 compared to the same period of 2021. This was primarily due to a 2021 contract modification in the Marcellus resulting in a change in the presentation of the related income from rental income to service revenue.

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Product related revenue increased $264 million in the first quarter of 2022 compared to the same period of 2021. This was primarily due to higher prices across all regions of approximately $187 million and higher processed volumes in the Southwest of $87 million. This was partially offset by a decrease in volumes primarily due to the Javelina divestiture in the Southwest.

Income from equity method investments increased $13 million in the first quarter of 2022 compared to the same period of 2021, primarily due to higher volumes and rates associated with joint ventures in the Utica, Marcellus and Southwest regions.

Other income/(loss) decreased $16 million in the first quarter of 2022 compared to the same period of 2021 primarily due to a loss on disposal of assets.

Purchased product costs increased $191 million in the first quarter of 2022 compared to the same period of 2021. This was primarily due to higher prices of $143 million in the Southwest and Southern Appalachia and higher volumes in the Southwest.

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G&P Operating Data

	Three Months Ended  March 31, 2022		Three Months Ended  March 31, 2021
	MPLX LP(1)	MPLX LP Operated(2)	MPLX LP(1)	MPLX LP Operated(2)
G&P
Gathering Throughput (MMcf/d)
Marcellus Operations	1,314	1,314	1,298	1,298
Utica Operations	—	1,813	—	1,566
Southwest Operations	1,307	1,476	1,373	1,448
Bakken Operations	147	147	146	146
Rockies Operations	394	526	470	627
Total gathering throughput	3,162	5,276	3,287	5,085
Natural Gas Processed (MMcf/d)
Marcellus Operations	4,015	5,529	4,249	5,677
Utica Operations	—	423	—	513
Southwest Operations(3)	1,384	1,541	1,295	1,367
Southern Appalachian Operations	224	224	227	227
Bakken Operations	143	143	145	145
Rockies Operations	407	407	441	441
Total natural gas processed	6,173	8,267	6,357	8,370
C2 + NGLs Fractionated (mbpd)
Marcellus Operations(4)	468	468	489	489
Utica Operations(4)	—	23	—	28
Southwest Operations(3)	—	—	8	8
Southern Appalachian Operations	10	10	11	11
Bakken Operations	21	21	19	19
Rockies Operations	4	4	4	4
Total C2 + NGLs fractionated(5)	503	526	531	559

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	Three Months Ended March 31,
	2022		2021
Pricing Information
Natural Gas NYMEX HH ($ per MMBtu)	$	4.57	$	2.72
C2 + NGL Pricing ($ per gallon)(6)	$	1.15	$	0.73

(1)     This column represents operating data for entities that have been consolidated into the MPLX financial statements.

(2)     This column represents operating data for entities that have been consolidated into the MPLX financial statements as well as operating data for MPLX-operated equity method investments.

(3)     The Southwest Operations for the three months ended March 31, 2021 include the Javelina complex, which was sold on February 12, 2021. The processing and fractionated volumes calculated for the number of days MPLX owned these assets during 2021 were 96 MMcf/d and 17 mbpd, respectively.

(4)    Entities within the Marcellus and Utica Operations jointly own the Hopedale fractionation complex. Hopedale throughput is included in the Marcellus and Utica Operations and represent each region’s utilization of the complex.

(5)     Purity ethane makes up approximately 188 mbpd and 199 mbpd of total MPLX Operated, fractionated products for the three months ended March 31, 2022 and 2021, respectively. Purity ethane makes up approximately 184 mbpd and 194 mbpd of total MPLX LP consolidated, fractionated products for the three months ended March 31, 2022 and 2021, respectively.

(6)    C2 + NGL pricing based on Mont Belvieu prices assuming an NGL barrel of approximately 35 percent ethane, 35 percent propane, six percent Iso-Butane, 12 percent normal butane and 12 percent natural gasoline.

Seasonality

The volume of crude oil and refined products transported and stored utilizing our assets is affected by the level of supply and demand for crude oil and refined products in the markets served directly or indirectly by our assets. The majority of effects of seasonality on the L&S segment’s revenues will be mitigated through the use of our fee-based transportation and storage services agreements with MPC that include minimum volume commitments.

In our G&P segment, we experience minimal impacts from seasonal fluctuations which impact the demand for natural gas and NGLs and the related commodity prices caused by various factors including variations in weather patterns from year to year. We are able to manage the seasonality impacts through the execution of our marketing strategy and via our storage capabilities. Overall, our exposure to the seasonality fluctuations is declining due to our growth in fee-based business.

Liquidity and Capital Resources

Cash Flows

Our cash and cash equivalents were $42 million at March 31, 2022 and $13 million at December 31, 2021. The change in cash, cash equivalents and restricted cash was due to the factors discussed below. Net cash provided by (used in) operating activities, investing activities and financing activities were as follows:

	Three Months Ended March 31,
(In millions)	2022		2021
Net cash provided by (used in):
Operating activities	$	1,125	$	1,124
Investing activities	(276)		(90)
Financing activities	(820)		(1,025)
Total	$	29	$	9

Net cash provided by operating activities increased $1 million in the first three months of 2022 compared to the first three months of 2021. The increase in net income was offset by working capital requirements.

Net cash used in investing activities increased $186 million in the first three months of 2022 compared to the first three months of 2021, primarily due to an increase in capital spending and an increase in contributions to equity method investments, which included the $60 million contribution to our Bakken Pipeline joint venture to fund our share of a debt repayment by the joint venture. The first quarter of 2021 also included proceeds from the sale of our Javelina plant, which further reduced the use of cash in that period.

Financing activities were an $820 million use of cash in the first three months of 2022 compared to a $1,025 million use of cash in the first three months of 2021. The primary reason for the decrease in the use of cash was due to net debt borrowings of $57 million in the first quarter of 2022 compared to net debt repayments of $110 million in the first quarter of 2021, as well as decreased spending on the unit repurchase program of $55 million in the first quarter of 2022 compared to the first quarter of 2021.

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Free Cash Flow

The following table provides a reconciliation of FCF and free cash flow after distributions from net cash provided by operating activities for the three months ended March 31, 2022 and March 31, 2021.

	Three Months Ended March 31,
(In millions)	2022		2021
Net cash provided by operating activities	$	1,125	$	1,124
Adjustments to reconcile net cash provided by operating activities to free cash flow
Net cash used in investing activities	(276)		(90)
Contributions from MPC	10		7
Distributions to noncontrolling interests	(9)		(10)
Free cash flow	850		1,031
Distributions paid to common and preferred unitholders	(758)		(754)
Free cash flow after distributions	$	92	$	277

Debt and Liquidity Overview

On March 14, 2022, MPLX issued $1.5 billion aggregate principal amount of 4.950 percent senior notes due March 2052 (the “2052 Senior Notes”) in an underwritten public offering. The 2052 Senior Notes were offered at a price to the public of 98.982 percent with interest payable semi-annually in arrears, commencing on September 14, 2022. The net proceeds were used to repay amounts outstanding under the MPC Intercompany Loan Agreement and the MPLX Credit Agreement.

As of March 31, 2022, we had $20.1 billion in aggregate principal amount of senior notes outstanding. The increase compared to year-end 2021 resulted from the issuance of the 2052 Senior Notes, as discussed above.

Our intention is to maintain an investment-grade credit profile. As of March 31, 2022, the credit ratings on our senior unsecured debt were at or above investment grade level as follows:

Rating Agency	Rating
Moody’s	Baa2 (stable outlook)
Standard & Poor’s	BBB (stable outlook)
Fitch	BBB (stable outlook)

The ratings reflect the respective views of the rating agencies. Although it is our intention to maintain a credit profile that supports an investment grade rating, there is no assurance that these ratings will continue for any given period of time. The ratings may be revised or withdrawn entirely by the rating agencies if, in their respective judgments, circumstances so warrant.

The MPLX Credit Agreement contains certain representations and warranties, affirmative and restrictive covenants and events of default that we consider to be usual and customary for an agreement of this type. The financial covenant requires MPLX to maintain a ratio of Consolidated Total Debt as of the end of each fiscal quarter to Consolidated EBITDA (both as defined in the MPLX Credit Agreement) for the prior four fiscal quarters of no greater than 5.0 to 1.0 (or 5.5 to 1.0 during the six-month period following certain acquisitions). Consolidated EBITDA is subject to adjustments for certain acquisitions completed and capital projects undertaken during the relevant period. Other covenants restrict us and/or certain of our subsidiaries from incurring debt, creating liens on assets and entering into transactions with affiliates. As of March 31, 2022, we were in compliance with the covenants, including the financial covenant with a ratio of Consolidated Total Debt to Consolidated EBITDA of 3.64 to 1.0.

The agreements governing our debt obligations do not contain credit rating triggers that would result in the acceleration of interest, principal or other payments solely in the event that our credit ratings are downgraded. However, any downgrades in the credit ratings of our senior unsecured debt ratings to below investment grade ratings could, among other things, increase the applicable interest rates and other fees payable under the MPLX Credit Agreement and may limit our ability to obtain future financing, including refinancing existing indebtedness.

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Our liquidity totaled $4.7 billion at March 31, 2022 consisting of:

	March 31, 2022
(In millions)	Total Capacity		Outstanding Borrowings		Available Capacity
MPLX Credit Agreement(1)	$	3,500	$	—	$	3,500
MPC Loan Agreement	1,500		(323)		1,177
Total liquidity	$	5,000	$	(323)	4,677
Cash and cash equivalents					42
Total liquidity					$	4,719

(1)     Outstanding borrowings include less than $1 million in letters of credit outstanding under this facility.

We expect our ongoing sources of liquidity to include cash generated from operations and borrowings under the MPC Loan Agreement, the MPLX Credit Agreement and access to capital markets. We believe that cash generated from these sources will be sufficient to meet our short-term and long-term funding requirements, including working capital requirements, capital expenditure requirements, contractual obligations, and quarterly cash distributions. We may also, from time to time, repurchase our senior notes or preferred units in the open market, in tender offers, in privately negotiated transactions or otherwise in such volumes, at market prices and upon such other terms as we deem appropriate and execute unit repurchases under our unit repurchase program. MPC manages our cash and cash equivalents on our behalf directly with third-party institutions as part of the treasury services that it provides to us under our omnibus agreement. From time to time, we may also consider utilizing other sources of liquidity, including the formation of joint ventures or sales of non-strategic assets.

Equity and Preferred Units Overview

Common units

The table below summarizes the changes in the number of units outstanding through March 31, 2022:

(In units)	Common
Balance at December 31, 2021	1,016,178,378
Unit-based compensation awards	148,951
Units redeemed in unit repurchase program	(3,119,522)
Balance at March 31, 2022	1,013,207,807

Unit Repurchase Program

During the three months ended March 31, 2022, we repurchased approximately 3 million common units at an average cost per unit of $32.06 per unit and paid $100 million of cash. As of March 31, 2022, we had repurchased a total of approximately 28 million units at an average cost per unit of $27.76 per unit for a total of $763 million under the unit repurchase program. We have $237 million remaining under our repurchase authorization.

Distributions

We intend to pay a minimum quarterly distribution to the holders of our common units of $0.2625 per unit, or $1.05 per unit on an annualized basis, to the extent we have sufficient cash from our operations after the establishment of cash reserves and the payment of costs and expenses, including reimbursements of expenses to our general partner. The amount of distributions paid under our policy and the decision to make any distributions is determined by our general partner, taking into consideration the terms of our partnership agreement. Such minimum distribution would equate to $266 million per quarter, or $1,064 million per year, based on the number of common units outstanding at March 31, 2022.

On April 26, 2022, MPLX declared a cash distribution for the first quarter of 2022, totaling $713 million, or $0.7050 per common unit. This distribution will be paid on May 13, 2022 to common unitholders of record on May 6, 2022. Although our partnership agreement requires that we distribute all of our available cash each quarter, we do not otherwise have a legal obligation to distribute any particular amount per common unit. This rate will also be received by Series A preferred unitholders.

Series B preferred unitholders are entitled to receive a fixed distribution of $68.75 per unit, per annum, payable semi-annually in arrears on February 15 and August 15, or the first business day thereafter, up to and including February 15, 2023. After February 15, 2023, the holders of Series B preferred units are entitled to receive cumulative, quarterly distributions payable in arrears on the 15th day of February, May, August and November of each year, or the first business day thereafter, based on a floating annual rate equal to the three-month LIBOR plus 4.652 percent, in each case assuming a distribution is declared by the board of directors. Accordingly, a cash distribution payment totaling $21 million was paid to Series B unitholders on February 15, 2022.

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MPLX has the right to redeem some or all of the Series B preferred units, at any time, on or after February 15, 2023. MPLX will pay unitholders the Series B preferred unit redemption price of $1,000 per unit plus any accumulated and unpaid distributions up to the redemption date.

The allocation of total cash distributions is as follows for the three months ended March 31, 2022 and 2021. MPLX’s distributions are declared subsequent to quarter end; therefore, the following table represents total cash distributions applicable to the period in which the distributions were earned.

	Three Months Ended March 31,
(In millions, except per unit data)	2022		2021
Distribution declared:
Limited partner units - public	$	257	$	262
Limited partner units - MPC	456		445
Total LP distribution declared	713		707
Series A preferred units	21		20
Series B preferred units	11		11
Total distribution declared	745		738
Quarterly cash distributions declared per limited partner common unit	$	0.7050	$	0.6875

Capital Expenditures

Our operations are capital intensive, requiring investments to expand, upgrade, enhance or maintain existing operations and to meet environmental and operational regulations. Our capital requirements consist of maintenance capital expenditures and growth capital expenditures. Examples of maintenance capital expenditures are those made to replace partially or fully depreciated assets, to maintain the existing operating capacity of our assets and to extend their useful lives, or other capital expenditures that are incurred in maintaining existing system volumes and related cash flows. In contrast, growth capital expenditures are those incurred for acquisitions or capital improvements that we expect will increase our operating capacity for volumes gathered, processed, transported or fractionated, decrease operating expenses within our facilities or increase operating income over the long term. Examples of growth capital expenditures include costs to develop or acquire additional pipeline, terminal, processing or storage capacity. In general, growth capital includes costs that are expected to generate additional or new cash flow for MPLX.

MPLX’s initial capital investment plan for 2022 totaled $900 million which includes growth capital of $700 million, maintenance capital of $140 million and a $60 million investment in unconsolidated affiliates for the repayment of our 9.19 percent indirect share of the Bakken Pipeline joint venture’s debt due in 2022. Growth capital expenditures and investments in affiliates during the three months ended March 31, 2022 were primarily for gas gathering, processing and de-ethanization projects in our Bakken, Marcellus, and Southwest basins and the expansion of our crude gathering systems in the Permian and Bakken basins. Spending for the quarter also included the $60 million contribution to our Bakken Pipeline joint venture to fund our share of a debt repayment by the joint venture. We continuously evaluate our capital plan and make changes as conditions warrant.

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Our capital expenditures are shown in the table below:

	Three Months Ended March 31,
(In millions)	2022		2021
Capital expenditures:
Growth capital expenditures	$	148	$	71
Investments in unconsolidated affiliates	110		35
Capitalized interest	(2)		(5)
Total growth capital expenditures	256		101
Maintenance capital expenditures	24		18
Maintenance capital reimbursements	(10)		(7)
Total maintenance capital expenditures	14		11
Total growth and maintenance capital expenditures	270		112
Investments in unconsolidated affiliates(1)	(110)		(35)
Growth and maintenance capital reimbursements(2)	10		7
Decrease in capital accruals	(3)		37
Capitalized interest	2		5
Additions to property, plant and equipment, net(1)	$	169	$	126

(1)    Investments in unconsolidated affiliates and additions to property, plant and equipment, net are shown as separate lines within investing activities in the Consolidated Statements of Cash Flows.

(2)    Growth and maintenance capital reimbursements are included in the Contributions from MPC line within financing activities in the Consolidated Statements of Cash Flows.

Contractual Cash Obligations

As of March 31, 2022, our contractual cash obligations included third-party and related party debt, finance and operating lease obligations, purchase obligations for services and to acquire property, plant and equipment, and other liabilities. During the three months ended March 31, 2022, our third-party long-term debt obligations increased by $1.2 billion, primarily due to the issuance of the $1.5 billion aggregate principal amount of 4.950 percent 2052 Senior Notes, discussed above. A portion of the issuance was used to repay amounts outstanding on the MPLX Credit Agreement. There were no other material changes to our contractual obligations outside the ordinary course of business since December 31, 2021.

Off-Balance Sheet Arrangements

Off-balance sheet arrangements comprise those arrangements that may potentially impact our liquidity, capital resources and results of operations, even though such arrangements are not recorded as liabilities under U.S. GAAP. Our off-balance sheet arrangements are limited to indemnities and guarantees that are described in Note 14. Although these arrangements serve a variety of our business purposes, we are not dependent on them to maintain our liquidity and capital resources, and we are not aware of any circumstances that are reasonably likely to cause the off-balance sheet arrangements to have a material adverse effect on our liquidity and capital resources.

Transactions with Related Parties

At March 31, 2022, MPC owned our non-economic general partnership interest and held approximately 64 percent of our outstanding common units.

We provide MPC with crude oil and product pipeline and trucking transportation services based on regulated tariff/contracted rates, as well as storage, terminal, fuels distribution, and inland marine transportation services based on contracted rates. We also have agreements with MPC under which we receive fees for operating MPC’s retained pipeline assets, providing management services for the marine business, and operating certain of MPC’s equity method investments. MPC provides us with certain services related to information technology, engineering, legal, accounting, treasury, human resources and other administrative services under employee services and omnibus services agreements.

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The below table shows the percentage of “Total revenues and other income” as well as “Total costs and expenses” with MPC:

	Three Months Ended March 31,
	2022		2021
Total revenues and other income	48	%	51	%
Total costs and expenses	24	%	29	%

For further discussion of agreements and activity with MPC and related parties see Item 1. Business in our Annual Report on Form 10-K for the year ended December 31, 2021 and Note 4 of the Notes to the Consolidated Financial Statements in this report.

Environmental Matters and Compliance Costs

We have incurred and may continue to incur substantial capital, operating and maintenance, and remediation expenditures as a result of environmental laws and regulations. If these expenditures, as with all costs, are not ultimately reflected in the prices of our products and services, our operating results will be adversely affected. We believe that substantially all of our competitors must comply with similar environmental laws and regulations. However, the specific impact on each competitor may vary depending on a number of factors, including, but not limited to, the age and location of its operating facilities.

During the three months ended March 31, 2022, environmental remediation costs increased due to a release of crude oil on our pipeline near Edwardsville, Illinois in March of 2022. There have been no additional changes to our environmental matters and compliance costs since our Annual Report on Form 10-K for the year ended December 31, 2021.

Critical Accounting Estimates

As of March 31, 2022, there have been no significant changes to our critical accounting estimates since our Annual Report on Form 10-K for the year ended December 31, 2021.

Accounting Standards Not Yet Adopted

While new financial accounting pronouncements will be effective for our financial statements in the future, there are no standards that have not yet been adopted that are expected to have a material impact on our financial statements. Accounting standards are discussed in Note 2 of the Notes to the Consolidated Financial Statements.

Item 3. Quantitative and Qualitative Disclosures about Market Risk

We are exposed to market risks related to the volatility of commodity prices. We employ various strategies, including the potential use of commodity derivative instruments, to economically hedge the risks related to these price fluctuations. We are also exposed to market risks related to changes in interest rates. As of March 31, 2022, we did not have any open financial or commodity derivative instruments to hedge the economic risks related to interest rate fluctuations or the volatility of commodity prices, respectively; however, we continually monitor the market and our exposure and may enter into these arrangements in the future.

Commodity Price Risk

The information about commodity price risk for the three months ended March 31, 2022 does not differ materially from that discussed in Item 7A. Quantitative and Qualitative Disclosures about Market Risk of our Annual Report on Form 10-K for the year ended December 31, 2021.

Outstanding Derivative Contracts

See Notes 9 and 10 to the unaudited consolidated financial statements for more information about the fair value measurement of our natural gas embedded derivative, as well as the amounts recorded in our consolidated balance sheets and statements of income. We do not designate any of our commodity derivative instruments as hedges for accounting purposes.

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Table of Contents

Interest Rate Risk and Sensitivity Analysis

Sensitivity analysis of the effect of a hypothetical 100-basis-point change in interest rates on third-party outstanding debt, excluding finance leases, is provided in the following table. Fair value of cash and cash equivalents, receivables, accounts payable and accrued interest approximate carrying value and are relatively insensitive to changes in interest rates due to the short-term maturity of the instruments. Accordingly, these instruments are excluded from the table.

(In millions)	Fair Value as of March 31, 2022(1)		Change in Fair Value(2)		Change in Income Before Income Taxes for the Three Months Ended March 31, 2022(3)
Outstanding debt
Fixed-rate	$	20,392	$	1,832	N/A
Variable-rate(4)	$	—	$	—	$	1

(1)    Fair value was based on market prices, where available, or current borrowing rates for financings with similar terms and maturities.

(2)    Assumes a 100-basis-point decrease in the weighted average yield-to-maturity at March 31, 2022.

(3)    Assumes a 100-basis-point change in interest rates. The change to net income was based on the weighted average balance of all outstanding variable-rate debt for the three months ended March 31, 2022.

(4)    MPLX had no outstanding borrowings on the MPLX Credit Agreement as of March 31, 2022.

At March 31, 2022, our portfolio of long-term debt consisted of fixed-rate instruments and also provides for borrowings under our revolving credit facility. The fair value of our fixed-rate debt is relatively sensitive to interest rate fluctuations. Our sensitivity to interest rate declines and corresponding increases in the fair value of our debt portfolio unfavorably affects our results of operations and cash flows only when we elect to repurchase or otherwise retire fixed-rate debt at prices above carrying value. Interest rate fluctuations generally do not impact the fair value of borrowings under our MPLX Credit Agreement, but may affect our results of operations and cash flows.

See Note 9 to the unaudited consolidated financial statements for additional information on the fair value of our debt.

Item 4. Controls and Procedures

Disclosure Controls and Procedures

An evaluation of the effectiveness of the design and operation of our disclosure controls and procedures (as defined in Rules 13a-15(e) and 15d-15(e) under the Securities Exchange Act of 1934, as amended) was carried out under the supervision and with the participation of management, including the chief executive officer and chief financial officer of our general partner. Based upon that evaluation, the chief executive officer and chief financial officer of our general partner concluded that the design and operation of these disclosure controls and procedures were effective as of March 31, 2022, the end of the period covered by this report.

Changes in Internal Control Over Financial Reporting

During the quarter ended March 31, 2022, there were no changes in our internal control over financial reporting that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

Part II – Other Information

Item 1. Legal Proceedings

We are the subject of, or a party to, a number of pending or threatened legal actions, contingencies and commitments involving a variety of matters, including laws and regulations relating to the environment. While it is possible that an adverse result in one or more of the lawsuits or proceedings in which we are a defendant could be material to us, based upon current information and our experience as a defendant in other matters, we believe that these lawsuits and proceedings, individually or in the aggregate, will not have a material adverse effect on our consolidated results of operations, financial position or cash flows.

Item 103 of Regulation S-K promulgated by the SEC requires disclosure of certain environmental matters when a governmental authority is a party to the proceedings and such proceedings involve potential monetary sanctions, unless we reasonably believe that the matter will result in no monetary sanctions, or in monetary sanctions, exclusive of interest and costs, of less than $300,000.

Except as described below, there have been no material changes to the legal matters previously disclosed in our Annual Report on Form 10-K for the year ended December 31, 2021.

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Edwardsville Incident

In March 2022, the State of Illinois brought an action against Marathon Pipe Line LLC, an indirect wholly owned subsidiary of MPLX LP, asserting various violations and demanding a permanent injunction and civil penalties in connection with a March 2022 release of crude oil on a pipeline near Edwardsville, Illinois. We are negotiating a settlement of the allegations and cannot currently estimate the timing of the resolution of this matter.

Item 1A. Risk Factors

There have been no material changes from the risk factors previously disclosed in our Annual Report on Form 10-K for the year ended December 31, 2021.

Item 2. Unregistered Sales of Equity Securities and Use of Proceeds

The following table sets forth a summary of our purchases during the quarter ended March 31, 2022, of equity securities that are registered by MPLX pursuant to Section 12 of the Securities Exchange Act of 1934, as amended.

					Millions of Dollars
Period	Total Number of Units Purchased	Average Price Paid per Unit(1)		Total Number of Units Purchased as Part of Publicly Announced Plans or Programs	Maximum Dollar Value of Units that May Yet Be Purchased Under the Plans or Programs(2)
1/01/2022-1/31/2022	1,371,325	$	31.36	1,371,325	$	294
2/01/2022-2/28/2022	570,396	32.37		570,396	275
3/01/2022-3/31/2022	1,177,801	32.72		1,177,801	$	237
Total	3,119,522	$	32.06	3,119,522

(1)Amounts in this column reflect the weighted average price paid for units purchased under our unit repurchase authorization. The weighted average price includes commissions paid to brokers during the quarter.

(2)On November 2, 2020, we announced the board authorization of a unit repurchase program for the repurchase of up to $1 billion of MPLX’s common units held by the public. This unit repurchase authorization has no expiration date.

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Item 6. Exhibits  

		Incorporated by Reference From
Exhibit Number	Exhibit Description	Form	Exhibit	Filing Date	SEC File No.	Filed Herewith	Furnished Herewith
3.1	Certificate of Limited Partnership of MPLX LP	S-1	3.1	7/2/2012	333-182500
3.2	Amendment to the Certificate of Limited Partnership of MPLX LP	S-1/A	3.2	10/9/2012	333-182500
3.3	Sixth Amended and Restated Agreement of Limited Partnership of MPLX LP, dated as of February 1, 2021	8-K	3.1	2/3/2021	001-35714
10.1	Form of 2022 MPLX Phantom Unit Award Agreement					X
10.2	CEO Phantom Unit Award Agreement, as Amended					X
10.3	CEO Performance Unit Award Agreement – 2020-2022 Performance Cycle, as Amended					X
31.1	Certification of Chief Executive Officer pursuant to Rule 13a-14 and 15d-14 under the Securities Exchange Act of 1934					X
31.2	Certification of Chief Financial Officer pursuant to Rule 13a-14 and 15d-14 under the Securities Exchange Act of 1934					X
32.1	Certification of Chief Executive Officer pursuant to 18 U.S.C. Section 1350						X
32.2	Certification of Chief Financial Officer pursuant to 18 U.S.C. Section 1350						X
101.INS	XBRL Instance Document: The instance document does not appear in the interactive data file because its XBRL tags are embedded within the Inline XBRL document.
101.SCH	Inline XBRL Taxonomy Extension Schema Document.					X
101.CAL	Inline XBRL Taxonomy Extension Calculation Linkbase Document.					X
101.DEF	Inline XBRL Taxonomy Extension Definition Linkbase Document.					X
101.LAB	Inline XBRL Taxonomy Extension Label Linkbase Document.					X
101.PRE	Inline XBRL Taxonomy Extension Presentation Linkbase Document.					X
104	Cover Page Interactive Data File (formatted as Inline XBRL and contained in Exhibit 101).

Pursuant to Item 601(b)(4) of Regulation S-K, certain instruments with respect to long-term debt issues have been omitted where the amount of securities authorized under such instruments does not exceed 10 percent of the total consolidated assets of the Registrant. The Registrant hereby agrees to furnish a copy of any such instrument to the Securities and Exchange Commission upon its request.

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SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

	MPLX LP
	By:	MPLX GP LLC
		Its general partner
Date: May 3, 2022	By:	/s/ Kelly D. Wright
		Kelly D. Wright
		Vice President and Controller of MPLX GP LLC (the general partner of MPLX LP)

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EX-10.1

Exhibit 10.1

MPLX LP

PHANTOM UNIT AWARD AGREEMENT

As evidenced by this Award Agreement and under the MPLX LP 2018 Incentive Compensation Plan, as amended (the “Plan”), MPLX GP LLC, a Delaware limited liability company (the “Company”), the general partner of MPLX LP, a Delaware limited partnership (the “Partnership”) has granted to {Participant Name} (the “Participant”), an Employee and/or Officer of the Company, Partnership or an Affiliate, on {Grant Date} (the “Grant Date”), {Number of Awards Granted} Phantom Units (the “Award”), with each Phantom Unit representing the right to receive a Unit of the Partnership, subject to the terms and conditions in the Plan and this Award Agreement. The number of Phantom Units awarded is subject to adjustment as provided in the Plan, and the Phantom Units hereby granted are also subject to the following terms and conditions:

1.    Relationship to the Plan. This Award is subject to all of the terms, conditions and provisions of the Plan and administrative interpretations thereunder, if any, that have been adopted by the Board. Except as defined in this Award Agreement, capitalized terms shall have the same meanings given to them under the Plan. To the extent that any provision of this Award Agreement conflicts with the express terms of the Plan, the terms of the Plan shall control and, if necessary, the applicable provisions of this Award Agreement shall be hereby deemed amended so as to carry out the purpose and intent of the Plan.

2.    Vesting and Forfeiture of Phantom Units.

(a)    Subject to Paragraph 3, the Phantom Units shall vest as follows:

(i)    one-third of the Phantom Units shall vest on the first anniversary of the Grant Date;

(ii)    an additional one-third of the Phantom Units shall vest on the second anniversary of the Grant Date; and

(iii)    all remaining Phantom Units shall vest on the third anniversary of the Grant Date;

provided, however, that the Participant must be in continuous Employment from the Grant Date through the applicable vesting date in order for the applicable Phantom Units to vest. If the Employment of the Participant is terminated for any reason other than one listed in subparagraph (b)(i) – (iv) of this Paragraph 2, any Phantom Units that have not vested as of the date of such termination of Employment shall be immediately forfeited to the Company.

(b)    Subject to Paragraph 3, the Phantom Units shall immediately vest in full, irrespective of the limitations set forth in subparagraph (a) of this Paragraph 2, upon the occurrence of any of the following events:

(i)    the Participant’s death;

(ii)    the Participant’s Approved Separation, provided the Participant has been in continuous Employment from the Grant Date to the Approved Separation;

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(iii)    the termination of the Participant’s Employment due to Mandatory Retirement, provided the Participant has been in continuous Employment from the Grant Date to the Mandatory Retirement; or

(iv)    the Participant’s Qualified Termination, provided, that the Participant has been in continuous Employment from the Grant Date to the Qualified Termination.

3.    Forfeiture of Phantom Units if Award Not Timely Accepted. This Award is conditioned upon and subject to the Participant accepting the Award by signing and delivering to the Company this Award Agreement, or otherwise electronically accepting the Award in such manner as the Board may in its discretion determine, no later than 11 months after the Grant Date. If the Participant does not timely accept this Award, all Phantom Units subject to this Award shall be forfeited to the Company. In the event of the Participant’s death or incapacitation prior to accepting the Award, the Company shall deem the Award as having been accepted by the Participant.

4.    Distribution Equivalent Right (“DER”). This Award includes a DER, the terms of which are set forth in this Paragraph 4. During the period between the Grant Date and the date the Phantom Units are settled, for any distributions from the Partnership on outstanding Units of the Partnership, the Participant shall be credited with the equivalent of all of the distributions that would be payable with respect to the Unit of the Partnership represented by each Phantom Unit, including any fractional Phantom Units, then credited to the Participant and the amount related to such credited distributions shall be accrued as a credit to the Participant’s account on the date such distribution is made. Any additional cash or Phantom Units credited pursuant to this Paragraph 4 shall be subject to the same terms and conditions applicable to the Phantom Units to which these distributions relate, including, without limitation, the same vesting, restrictions on transfer, forfeiture, settlement, distribution, tax withholding, repayment and other terms, conditions and restrictions.

5.    Settlement and Issuance of Units. Subject to the terms of the Plan, all vested amounts payable to the Participant in respect of the Phantom Units, including the issuance of Units of the Partnership pursuant to this Paragraph 5, shall be settled in Units and for cash accruals credited under Paragraph 4 above, in cash, within 60 days following the vesting date, however, provided that any Phantom Units that vest on account of the Participant’s Approved Separation, Mandatory Retirement or Qualified Termination under Paragraphs 2(b)(ii), (iii) or (iv) shall be released and settled as provided herein, but according to the same payment timing resulting from the normal course vesting schedule set forth in Paragraph 2(a), and in such circumstance the Participant must only be in continuous Employment from the Grant Date to the applicable vesting event (i.e., the Participant’s Approved Separation, Mandatory Retirement or Qualified Termination is a vesting event and not a payment event). During the period of time between the Grant Date and the date the Phantom Units settle, the Phantom Units will be evidenced by a credit to a bookkeeping account evidencing the unfunded and unsecured right of the Participant to receive Units, subject to the terms and conditions applicable to the Phantom Units. Following vesting and upon the settlement date as described above, the Participant shall be entitled to receive a number of Units of the Partnership equal to the total of the number of Phantom Units granted, with any fractional Phantom Units remaining settled in cash. Such Units shall be issued and registered in the name of the Participant. The Participant shall not have the right or be entitled to exercise any voting rights, receive distributions or have or be entitled to any rights as a

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Partnership unitholder in respect of the Phantom Units until such time as the Phantom Units have vested and been settled and corresponding Units of the Partnership have been issued. Notwithstanding the preceding sentence of this Paragraph 5, if the event of death, any Units that are otherwise deliverable under this Award (including Units resulting from the vesting of any Phantom Units on account of death) will be distributed to the correlated brokerage account (or the SPS Participant Trust if an international employee) and will be subject to the designated beneficiary on file and then in effect with the recordkeeper for such brokerage (or the SPS Participant Trust, where applicable), or in the absence of a designated beneficiary, to the executor or administrator of the estate.

6.    Taxes. Pursuant to the applicable provisions of the Plan, the Company or its designated representative shall have the right to withhold applicable taxes from the Units otherwise deliverable to the Participant due to the vesting of Phantom Units pursuant to Paragraph 2, or from other compensation payable to the Participant, at the time of the vesting and delivery of such Units. Because the Participant is an employee of an Affiliate, and provides beneficial services to the Company and/or the Partnership through such employment with that Affiliate, such Affiliate as the employer of Participant shall be the designated representative for purposes of payroll administration of the Award and withholding of applicable taxes at the time of vesting.

7.    Conditions Precedent.

This Paragraph 7 shall apply to this Award notwithstanding any other provision of this Award Agreement to the contrary. The Participant’s services to the Company, the Partnership and MPC and their Affiliates (the “Company Group”) are unique, extraordinary and essential to the business of the Company Group, particularly in view of the Participant’s access to the confidential information and trade secrets of members of the Company Group, such as, the Company, the Partnership and MPC. Accordingly, in consideration of this Award Agreement and by accepting this Award, the Participant agrees that in order to otherwise vest in any right to payment of Phantom Units under this Award, the Participant must satisfy the following conditions to and including the vesting date and the payment date for each applicable annual installment or other applicable portion of this Award:

(a)    The Participant agrees that the Participant will not, without the prior written approval of the Board, at any time during the term of the Participant’s Employment and for a period of one year following the date on which the Participant’s Employment terminates (the “Restricted Period”), directly or indirectly, serve as an officer, director, owner, contractor, consultant, or employee of any the following organizations (or any of their respective subsidiaries or divisions): BP plc; Chevron Corporation; ExxonMobil Corporation; HollyFrontier Corporation; PBF Energy Inc.; Phillips 66; Valero Energy Corporation; Buckeye Partners, L.P.; DCP Midstream Partners, L.P; Enterprise Product Partners; Genesis Energy, L.P.; Holly Energy Partners L.P.; Magellan Midstream Partners, L.P.; Phillips 66 Partners, L.P.; Plains All American Pipeline L.P.; Western Midstream Partners, or otherwise engage in any business activity directly or indirectly competitive with the business of the any member of the Company Group as in effect from time to time.

(b)    The Participant agrees that during the term of the Participant’s Employment and for a period of one year following the date on which the Participant’s Employment terminates, the Participant will not, alone or in

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conjunction with another party, hire, solicit for hire, aid in or facilitate the hire, or cause to be hired, either as an employee, contractor or consultant, any individual who is currently engaged, or was engaged at any time during the six month period prior such event, as an employee, contractor or consultant of any member of the Company Group.

(c)    The Participant agrees that the Participant may not, either during the Participant’s Employment or thereafter, make or encourage others to make any public statement or release any information or otherwise engage in any conduct that is intended to, or reasonably could be foreseen to, embarrass, criticize or harm the reputation or goodwill of the any member of the Company Group, or any of their employees, directors or shareholders; provided that this shall not preclude the Participant from reporting to the Company’s management or directors or to the government or a regulator conduct the Participant believes to be in violation of the law or the Code of Business Conduct (or similar code or rules) of any member of the Company Group or responding truthfully to questions or requests for information to the government, a regulator or in a court of law in connection with a legal or regulatory investigation or proceeding.

(d)    The Participant agrees and understands that the members of the Company Group own and/or control information and material which is not generally available to third parties and which the members of the Company Group consider confidential, including, without limitation, methods, products, processes, customer lists, trade secrets and other information applicable to its business and that it may from time to time acquire, improve or produce additional methods, products, processes, customers lists, trade secrets and other information (collectively, the “Confidential Information”). The Participant acknowledges that each element of the Confidential Information constitutes a unique and valuable asset of the members of the Company Group, and that certain items of the Confidential Information have been acquired from third parties upon the express condition that such items would not be disclosed to all or certain members of the Company Group and the officers and agents thereof other than in the ordinary course of business. The Participant acknowledges that disclosure of the Confidential Information to and/or use by anyone other than in the Company, the Partnership’s, or MPC’s or other Company Group member’s ordinary course of business would result in irreparable and continuing damage to the Company, the Partnership and/or MPC and/or other members of the Company Group. Accordingly, the Participant agrees to hold the Confidential Information in the strictest secrecy, and covenants that, during the term of the Participant’s Employment or at any time thereafter, the Participant will not, without the prior written consent of the Board, directly or indirectly, allow any element of the Confidential Information to be disclosed, published or used, nor permit the Confidential Information to be discussed, published or used, either by the Participant or by any third parties, except in effecting the Participant’s duties for the Company, the Partnership and/or MPC and/or other Company Group members in the ordinary course of business.

(e)    The Participant agrees that in addition to the forfeiture provisions otherwise provided for in this Award Agreement, upon the Participant’s failure to satisfy in any respect of any of the conditions described in Paragraphs 7 (a), (b), (c) or (d), any unvested or unpaid portion of this Award (including any otherwise vested, but unpaid portion of this Award) at the time of such failure shall be forfeited, and the rights of the Participant and the

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obligations of the Company under this Award Agreement shall be satisfied in full, in each case to the extent permitted by applicable law.

8.     Forfeiture or Repayment Resulting from Forfeiture Event.

(a)    If there is a Forfeiture Event during the Participant’s Employment or within two years after termination of the Participant’s Employment, then the Board may, but is not obligated to, cause all of the Participant’s unvested Phantom Units and vested, but unpaid Phantom Units to be forfeited by the Participant and returned to the Company.

(b)    If there is a Forfeiture Event either during the Participant’s Employment or within two years after termination of the Participant’s Employment, then with respect to Phantom Units granted under this Award Agreement that have vested and have been paid to the Participant, the Board may, but is not obligated to, require that the Participant pay to the Company an amount (the “Forfeiture Amount”) up to (but not in excess of) the lesser of (i) the value of such previously vested Phantom Units as of the date such Phantom Units vested or (ii) the value of such previously vested Phantom Units as of the date on which the Board makes a demand for payment of the Forfeiture Amount. Any Forfeiture Amount shall be paid by the Participant within 60 days of receipt from the Company of written notice requiring payment of such Forfeiture Amount.

(c)    This Paragraph 8 shall apply notwithstanding any provision of this Award Agreement to the contrary and is meant to provide the Company with rights in addition to any other remedy which may exist in law or in equity. This Paragraph 8 shall not apply to the Participant following the effective time of a Change in Control.

(d)    Notwithstanding the any other provision of this Award Agreement to the contrary, the Participant agrees that the Company may also require that the Participant repay to the Partnership (or the Company or an Affiliate) any compensation paid to the Participant under this Award Agreement, as is required by the provisions of the Dodd-Frank Wall Street Reform and Consumer Protection Act and the regulations thereunder or any other “clawback” provisions as required by law or by the applicable listing standards of the exchange on which the Units of the Partnership are listed for trading.

9.    Nonassignability. Upon the Participant’s death, the Phantom Units credited to the Participant under this Award Agreement shall be transferred to the Participant’s designated beneficiary, personal representative or estate as provided in Paragraph 5. Otherwise, the Participant may not sell, transfer, assign, pledge or otherwise encumber any portion of the Phantom Units, and any attempt to sell, transfer, assign, pledge or encumber any portion of the Phantom Units shall have no effect.

10.    Nature of the Grant. Under this Award Agreement, the Participant is subject to condition that this Award of Phantom Units is voluntary and occasional and this Award Agreement does not create any contractual or other right to receive future Awards of Phantom Units, or benefits in lieu of Phantom Units even if Phantom Units have been awarded repeatedly in the past.

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11.    No Employment Guaranteed. Nothing in this Award Agreement shall give the Participant any rights to (or impose any obligations for) continued Employment by the Company or any Affiliate or successor, nor shall it give such entities any rights (or impose any obligations) with respect to continued performance of duties by the Participant.

12.    Modification of Agreement. Any modification of this Award Agreement shall be binding only if evidenced in writing and signed by an authorized representative of the Company, provided that no modification may, without the consent of the Participant, adversely affect the rights of the Participant hereunder.

13.    Specified Employee; Section 409A of the Code. This Award is intended to comply with or be exempt from the requirements of Section 409A of the Code. Notwithstanding the foregoing or any other provision of this Award to the contrary, if the Participant is a “specified employee” within the meaning of Section 409A of the Code as determined by the Company in accordance with its established policy, any settlement of any amount in this Award Agreement which would be a payment of deferred compensation within the meaning of Section 409A of the Code with respect to the Participant as a result of the Participant’s separation from service as defined under Section 409A of the Code (other than as a result of death) and which would otherwise be paid within six months of the Participant’s separation from service shall be paid on the date that is one day after the earlier of (i) the date that is six months after the Participant’s separation from service or (ii) the date that otherwise complies with the requirements of Section 409A of the Code. In addition, notwithstanding any provision of the Plan or this Award Agreement to the contrary, any settlement of the Phantom Units granted in this Award Agreement that would be a payment of deferred compensation within the meaning of Section 409A of the Code with respect to the Participant and is a settlement as a result of the Participant’s separation from service in connection with a Change in Control, the term “Change in Control” under the Plan shall mean a change in ownership or change in effective control for purposes of Section 409A of the Code. The payment of each amount under this Award Agreement is deemed as a “separate payment” for purposes of Section 409A of the Code. For all purposes under this Award, “termination of Employment” and similar terms shall mean “separation from service” as defined and determined under Section 409A of the Code.

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14.Definitions. For purposes of this Award Agreement:

“Approved Separation” means termination of Employment on or after the date the Participant has attained age 55 and completed five years of Employment, provided, that, the termination of Employment occurs no earlier than the later of: (a) six month anniversary of the Grant Date; and (b) 180 days after the Participant has provided notice to the Committee or its delegate of the date of his or her termination of Employment. The Committee may, in its sole discretion, waive the notice requirement under clause (b) of the preceding sentence if the Participant is an Employee under its purview for the grant and administration of the Award, and the Chief Executive Officer of MPC may, in his or her sole discretion, waive the notice requirement under clause (b) of the preceding sentence if the Participant is an Employee not under the Committee’s purview for the grant and administration of the Award.

“Employment” means employment with the Company or any of its subsidiaries or Affiliates including but not limited to MPC and its subsidiaries and Affiliates. The length of any period of Employment shall be determined by the Company or the subsidiary or Affiliate that either (a) employs the Participant or (b) employed the Participant immediately prior to the Participant’s termination of Employment.

“Forfeiture Event” means the occurrence of at least one of the following events: (a) the Partnership is required, pursuant to a determination made by the Securities and Exchange Commission or by the Board, or an authorized subcommittee of the Board, to prepare a material accounting restatement due to the noncompliance of the Partnership with any financial reporting requirement under applicable securities laws as a result of misconduct, and the Board determines that (i) the Participant knowingly engaged in the misconduct, (ii) the Participant was grossly negligent with respect to such misconduct or (iii) the Participant knowingly or grossly negligently failed to prevent the misconduct or (b) the Board concludes that the Participant engaged in fraud, embezzlement or other similar misconduct materially detrimental to the Company or the Partnership.

“Mandatory Retirement” means termination of Employment as a result of the Company’s or an Affiliate’s policy, if any, in effect at the time of the Grant Date, requiring the mandatory retirement of officers and/or other employees upon reaching a certain age or milestone.

“MPC” means Marathon Petroleum Corporation or its successor.

“Qualified Termination” for purposes of this Award Agreement shall have the same definition as under the MPLX LP Executive Change in Control Severance Benefits Plan, as in effect on the Grant Date, and such definition and associated terms are hereby incorporated into this Award Agreement by reference.

MPLX GP LLC
By	/s/ Fiona C. Laird
	Authorized Officer

{ACCEPTANCE DATE}

{ELECTRONIC SIGNATURE}

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EX-10.2

Exhibit 10.2

MPLX LP
2018 INCENTIVE COMPENSATION PLAN

PHANTOM UNIT AWARD AGREEMENT

(as amended effective January 25, 2022)

MPLX OFFICER

As evidenced by this Award Agreement and under the MPLX LP 2018 Incentive Compensation Plan (the “Plan”), MPLX GP LLC, a Delaware limited liability company (the “Company”), the general partner of MPLX LP, a Delaware limited partnership (the “Partnership”) has granted to MICHAEL J. HENNIGAN (the “Participant”), an officer of the Company, on 03/01/2020 (the “Grant Date”), 22,920 Phantom Units, with each Phantom Unit representing the right to receive a Unit of the Partnership, subject to the terms and conditions in the Plan and this Award Agreement. The number of Phantom Units awarded is subject to adjustment as provided in the Plan, and the Phantom Units hereby granted are also subject to the following terms and conditions (a) which were provided in the original Award effective March 1, 2020, and (b) the additional terms and conditions in the amendment to this Award as approved by the Board effective January 25, 2022 (the additional terms and conditions are shown in double-underlined text and shall be deemed to have been accepted by the Participant; and this Award Agreement supersedes and replaces the original Award Agreement):

1.    Relationship to the Plan. This grant of Phantom Units is subject to all of the terms, conditions and provisions of the Plan and administrative interpretations thereunder, if any, that have been adopted by the Board. Except as defined in this Award Agreement, capitalized terms shall have the same meanings given to them under the Plan. To the extent that any provision of this Award Agreement conflicts with the express terms of the Plan, the terms of the Plan shall control and, if necessary, the applicable provisions of this Award Agreement shall be hereby deemed amended so as to carry out the purpose and intent of the Plan.

2.    Vesting and Forfeiture of Phantom Units.

(a)    Subject to paragraph 3, the Phantom Units shall vest in three cumulative annual installments, as follows:

(i)one-third of the Phantom Units shall vest on the first anniversary of the Grant Date;

(ii)     an additional one-third of the Phantom Units shall vest on the second anniversary of the     Grant Date; and

(iii)     all remaining Phantom Units shall vest on the third anniversary of the Grant Date;

provided, however, that the Participant must be in continuous Employment from the Grant Date through the applicable vesting date in order for the applicable Phantom Units to vest. If the Employment of the Participant is terminated for any reason (including non-Mandatory Retirement) other than one listed in subparagraph (b)(i) – (iii) of this Paragraph 2, any Phantom Units that have not vested as of the date of such termination of Employment shall be immediately and 100% forfeited to the Company.

(b)    Subject to paragraph 3, the Phantom Units shall immediately vest in full, irrespective of the limitations set forth in subparagraph (a) above, upon the occurrence of any of the following events,

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provided such termination of Participant’s Employment constitutes a separation from service (within the meaning of Section 409A of the Code):

(i)the Participant’s death;

(ii)the termination of the Participant’s Employment due to Mandatory Retirement;

(iii)the Participant’s Qualified Termination, provided, that the Participant has been in continuous Employment from the Grant Date to the Qualified Termination; or

(iv)on the Qualifying Date, provided, that the Participant has been in continuous Employment from the Grant Date to the Qualifying Date.

3.Forfeiture of Phantom Unit if Award Not Timely Accepted. This Award is conditioned upon and subject to the Participant accepting the Award by signing and delivering to the Company this Award Agreement, or otherwise electronically accepting the Award in such manner as the Board may in its discretion determine, no later than 11 months after the Grant Date. If the Participant does not timely accept this Award, all Phantom Units subject to this Award shall be forfeited to the Company. In the event of the Participant’s death or incapacitation prior to accepting the Award, the Company shall deem the Award as being accepted by the Participant.

4.    Distributions. During the period of time between the Grant Date and the date the Phantom Units are settled, for any distributions from the Partnership on outstanding Units of the Partnership, the Participant shall be credited with the equivalent of all of the distributions that would be payable with respect to the Unit of the Partnership represented by each Phantom Unit, including any fractional Phantom Units, then credited to the Participant and the amount related to such credited distributions shall be accrued as a credit to the Participant’s account on the date such distribution is made. Any additional cash or Phantom Units granted pursuant to this Paragraph 4 shall be subject to the same terms and conditions applicable to the Phantom Units to which these distributions relate, including, without limitation, the restrictions on transfer, forfeiture, settlement and distribution provisions contained in this Award Agreement or the Plan.

5.    Settlement and Issuance of Units. Subject to the terms of the Plan, all vested amounts payable to the Participant in respect of the Phantom Units, including the issuance of Units of the Partnership pursuant to this Paragraph 5, shall be settled in Units and for cash accruals credited under Paragraph 4 above, in cash, within 60 days following the vesting date; provided, that, any Phantom Units that vest on account of the Participant’s meeting the Qualifying Date condition under Paragraph 2(b)(iv) shall be released and settled as provided herein, but according to the same payment timing resulting from the normal course vesting schedule set forth in Paragraph 2(a), and in such circumstance the Participant must only be in continuous Employment from the Grant Date to the Participant’s having met the Qualifying Date condition (i.e., the Participant’s having met the Qualifying Date condition is a vesting event and not a payment event). During the period of time between the Grant Date and the date the Phantom Units settle, the Phantom Units will be evidenced by a credit to a bookkeeping account evidencing the unfunded and unsecured right of the Participant to receive Units, subject to the terms and conditions applicable to the Phantom Units. Following vesting and upon the settlement date as described above, the Participant shall be entitled to receive a number of Units of the Partnership equal to the total of the number of Phantom Units granted, with any fractional Phantom Units remaining settled in cash. Such Units shall be issued and registered in the name of the Participant. The Participant shall not have the right or be entitled to exercise any voting rights, receive distributions or have or be

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entitled to any rights as a Partnership unitholder in respect of the Phantom Units until such time as the Phantom Units have vested and been settled and corresponding Units of the Partnership have been issued.

6.    Taxes. Pursuant to the applicable provisions of the Plan, the Company or its designated representative shall have the right to withhold applicable taxes from the Units otherwise deliverable to the Participant due to the vesting of Phantom Units pursuant to Paragraph 2, or from other compensation payable to the Participant, at the time of the vesting and delivery of such Units. Because the Participant is an employee of Marathon Petroleum Corporation (“MPC”), and provides beneficial services to the Company through Participant’s Employment with MPC, MPC as the employer of Participant shall be the designated representative for purposes of payroll administration of the Award and withholding of applicable taxes at the time of vesting.

7.    Conditions Precedent. This Paragraph 7 shall apply to this Award notwithstanding any other provision of this Award Agreement to the contrary. The Participant’s services to the Company, the Partnership and MPC and their Affiliates (the “Company Group”) are unique, extraordinary and essential to the business of the Company Group, particularly in view of the Participant’s access to the confidential information and trade secrets of members of the Company Group, such as, the Company, the Partnership and MPC. Accordingly, in consideration of this Award Agreement and by accepting this Award, the Participant agrees that in order to otherwise vest in any right to payment of Phantom Units under Paragraph 2, the Participant must satisfy the following conditions to and including the vesting date for each applicable annual installment or other applicable portion of the Award, and including any distribution right under the Award, under the vesting provisions in Paragraph 2:

(a)    The Participant agrees that the Participant will not, without the prior written approval of the Board, at any time during the term of the Participant’s Employment and for a period of one year following the date on which the Participant’s Employment terminates (the “Restricted Period”), directly or indirectly, serve as an officer, director, owner, contractor, consultant, or employee of any the following organizations (or any of their respective subsidiaries or divisions): BP plc, Chevron Corporation; ExxonMobil Corporation, HollyFrontier Corporation; PBF Energy Inc.; Phillips 66; Valero Energy Corporation; Buckeye Partners, L.P.; DCP Midstream Partners, L.P; Enterprise Product Partners; Gas; Genesis Energy, L.P.; Holly Energy Partners L.P.; Magellan Midstream Partners, L.P.; Phillips 66 Partners, L.P.; Plains All American Pipeline L.P.; Western Gas Equity Partners, or otherwise engage in any business activity directly or indirectly competitive with the business of the any member of the Company Group as in effect from time to time.

(b)    The Participant agrees that during the term of the Participant’s Employment and for a period of one year following the date on which the Participant’s Employment terminates, the Participant will not, alone or in conjunction with another party, hire, solicit for hire, aid in or facilitate the hire, or cause to be hired, either as an employee, contractor or consultant, any individual who is currently engaged, or was engaged at any time during the six month period prior such event, as an employee, contractor or consultant of any member of the Company Group.

(c)    The Participant agrees that the Participant may not, either during the Participant’s Employment or thereafter, make or encourage others to make any public statement or release any information or otherwise engage in any conduct that is intended to, or reasonably could be foreseen to, embarrass, criticize or harm the reputation or goodwill of the any member of the Company Group, or any of their employees, directors or shareholders; provided that this shall not preclude the Participant from reporting to the Company’s management or directors or to the government or a regulator conduct the Participant believes to be in violation of the law or the Code of Business Conduct (or similar code or rules) of any member of the Company Group or responding truthfully to questions or

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requests for information to the government, a regulator or in a court of law in connection with a legal or regulatory investigation or proceeding.

(d)    The Participant agrees and understands that the members of the Company Group own and/or control information and material which is not generally available to third parties and which the members of the Company Group consider confidential, including, without limitation, methods, products, processes, customer lists, trade secrets and other information applicable to its business and that it may from time to time acquire, improve or produce additional methods, products, processes, customers lists, trade secrets and other information (collectively, the “Confidential Information”). The Participant acknowledges that each element of the Confidential Information constitutes a unique and valuable asset of the members of the Company Group, and that certain items of the Confidential Information have been acquired from third parties upon the express condition that such items would not be disclosed to all or certain members of the Company Group and the officers and agents thereof other than in the ordinary course of business. The Participant acknowledges that disclosure of the Confidential Information to and/or use by anyone other than in the Company, the Partnership’s, or MPC’s or other Company Group member’s ordinary course of business would result in irreparable and continuing damage to the Company, the Partnership and/or MPC and/or other members of the Company Group. Accordingly, the Participant agrees to hold the Confidential Information in the strictest secrecy, and covenants that, during the term of the Participant’s Employment or at any time thereafter, the Participant will not, without the prior written consent of the Board, directly or indirectly, allow any element of the Confidential Information to be disclosed, published or used, nor permit the Confidential Information to be discussed, published or used, either by the Participant or by any third parties, except in effecting the Participant’s duties for the Company, the Partnership and/or MPC and/or other Company Group members in the ordinary course of business.

(e)    The Participant agrees that in addition to the forfeiture provisions otherwise provided for in this Award Agreement, upon the Participant’s failure to satisfy in any respect of any of the conditions described in Paragraphs 7 (a), (b), (c) or (d), any unvested and unpaid portion of this Award at the time of such breach shall be forfeited, andthe rights of the Participant and the obligations of the Company under this Award Agreement shall be satisfied in full, in each case to the extent permitted by applicable law.

8.    Forfeiture or Repayment Resulting from Forfeiture Event.

(a)    If there is a Forfeiture Event either during the Participant’s Employment or within two years after termination of the Participant’s Employment, then the Board may, but is not obligated to, cause all of the Participant’s unvested Phantom Units to be forfeited by the Participant and returned to the Company.

(b)    If there is a Forfeiture Event either during the Participant’s Employment or within two years after termination of the Participant’s Employment, then with respect to Phantom Units granted under this Award Agreement that have vested, the Board may, but is not obligated to, require that the Participant pay to the Company an amount (the “Forfeiture Amount”) up to (but not in excess of) the lesser of (i) the value of such previously vested Phantom Units as of the date such Phantom Units vested or (ii) the value of such previously vested Phantom Units as of the date on which the Board makes a demand for payment of the Forfeiture Amount. Any Forfeiture Amount shall be paid by the Participant within 60 days of receipt from the Company of written notice requiring payment of such Forfeiture Amount.

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(c)    This Paragraph 8 shall apply notwithstanding any provision of this Award Agreement to the contrary and is meant to provide the Company with rights in addition to any other remedy which may exist in law or in equity. This Paragraph 8 shall not apply to the Participant following the effective time of a Change in Control.

(d)    Notwithstanding the any other provision of this Award Agreement to the contrary, the Participant agrees that the Company may also require that the Participant repay to the Company any compensation paid to the Participant under this Award Agreement, as is required by the provisions of the Dodd-Frank Wall Street Reform and Consumer Protection Act and the regulations thereunder or any other “clawback” provisions as required by law or by the applicable listing standards of the exchange on which the Units of the Partnership are listed for trading.

9.    Nonassignability. Upon the Participant’s death, the Phantom Units credited to the Participant under this Award Agreement shall be transferred to the Participant’s estate and upon such transfer settled in Units of the Partnership. Otherwise, the Participant may not sell, transfer, assign, pledge or otherwise encumber any portion of the Phantom Units, and any attempt to sell, transfer, assign, pledge or encumber any portion of the Phantom Units shall have no effect.

10.    Nature of the Grant. Under this Award Agreement, the Participant is subject to condition that this Award of Phantom Units is voluntary and occasional and this Award Agreement does not create any contractual or other right to receive future Awards of Phantom Units, or benefits in lieu of Phantom Units even if Phantom Units have been awarded repeatedly in the past.

11.    No Employment Guaranteed. Nothing in this Award Agreement shall give the Participant any rights to (or impose any obligations for) continued Employment by the Company or any subsidiary or successor, nor shall it give such entities any rights (or impose any obligations) with respect to continued performance of duties by the Participant.

12.    Modification of Instrument. Any modification of this Award Agreement shall be binding only if evidenced in writing and signed by an authorized representative of the Company, provided that no modification may, without the consent of the Participant, adversely affect the rights of the Participant hereunder.

13.Officer Holding Requirement. Participant agrees that any Units of the Partnership received by the Participant in settlement of this Award shall be subject an additional holding period of one year from the date on which the Award is settled, during which holding period such Units (net of any Units of the Partnership used to satisfy the applicable tax withholding requirements) may not be sold or transferred by the Participant. This holding requirement shall cease to apply upon the death, retirement or other separation from service of the Participant during the holding period.

14.Section 409A. This Award is intended to comply with or be exempt from the requirements of Section 409A of the Code. Notwithstanding the foregoing, if the Participant is a “specified employee” as determined by the Company in accordance with its established policy, any settlement of any amount in this Award Agreement which would be a payment of deferred compensation within the meaning of Section 409A of the Code with respect to the Participant as a result of the Participant’s separation from service as defined under Section 409A of the Code (other than as a result of death) and which would otherwise be paid within six months of the Participant’s separation from service shall be paid on the date that is one day after the earlier of (i) the date that is six months after the Participant’s separation from service or (ii) the date that otherwise complies with the requirements

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of Section 409A of the Code. In addition, notwithstanding any provision of the Plan or this Award Agreement to the contrary, any settlement of the Phantom Units granted in this Award Agreement that would be a payment of deferred compensation within the meaning of Section 409A of the Code with respect to the Participant and is a settlement as a result of the Participant’s separation from service in connection with a Change in Control, the term “Change in Control” under the Plan shall mean a change in ownership or change in effective control for purposes of Section 409A of the Code. The payment of each amount under this Award Agreement is deemed as a “separate payment” for purposes of Section 409A of the Code.

15.    Definitions. For purposes of this Award Agreement:

“Employment” means employment with the Company or any of its subsidiaries or Affiliates including but not limited to MPC and its subsidiaries and Affiliates. For purposes of this Award Agreement, Employment shall also include any period of time during which the Participant is on Disability status. The length of any period of Employment shall be determined by the Company or the subsidiary or Affiliate that either (a) employs the Participant or (b) employed the Participant immediately prior to the Participant’s termination of Employment.

        “Forfeiture Event” means the occurrence of at least one of the following events: (a) the Company is required, pursuant to a determination made by the Securities and Exchange Commission or by the Board, or an authorized subcommittee of the Board, to prepare a material accounting restatement due to the noncompliance of the Company with any financial reporting requirement under applicable securities laws as a result of misconduct, and the Board determines that (i) the Participant knowingly engaged in the misconduct, (ii) the Participant was grossly negligent with respect to such misconduct or (iii) the Participant knowingly or grossly negligently failed to prevent the misconduct or (b) the Board concludes that the Participant engaged in fraud, embezzlement or other similar misconduct materially detrimental to the Company.

“Mandatory Retirement” means termination of Employment as a result of the Company’s policy, if any, in effect at the time of the Grant Date, requiring the mandatory retirement of officers and/or other employees upon reaching a certain age or milestone.

“Qualifying Date” means July 1, 2022.

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        “Qualified Termination” for purposes of this Award Agreement shall have the same definition as under the MPLX LP Executive Change in Control Severance Benefits Plan, as in effect on the Grant Date, and such definition and associated terms are hereby incorporated into this Award Agreement by reference.

		MPLX GP LLC
	By	/s/ Fiona C. Laird
		Authorized Officer - Fiona C. Laird
/s/ Michael J. Hennigan
Signature
February 21, 2022
Date

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EX-10.3

Exhibit 10.3

MPLX LP
2018 INCENTIVE COMPENSATION PLAN

PERFORMANCE UNIT AWARD AGREEMENT

2020-2022 PERFORMANCE CYCLE

MPLX OFFICER

(amended effective January 25, 2022)

As evidenced by this Award Agreement and under the MPLX LP 2018 Incentive Compensation Plan (the “Plan”), MPLX GP LLC, a Delaware limited liability company (the “Company”), the general partner of MPLX LP, a Delaware limited partnership (the “Partnership”) has granted to MICHAEL J. HENNIGAN (the “Participant”), an officer of the Company, on 03/01/2020 (the “Grant Date”), 460,000 performance units (“Performance Units”), conditioned upon the Company’s total unitholder return (or “TUR”) ranking relative to the Peer Group and the DCF Payout Percentages for the Performance Cycle as established by the Board, and as set forth herein. The Performance Units are subject to the following terms and conditions (a) which were provided in the original Award effective March 1, 2020, and (b) the additional terms and conditions in the amendment to this Award as approved by the Committee effective January 25, 2022 (the additional terms and conditions are shown in double-underlined text and shall be deemed to have been accepted by the Participant; and this Award Agreement supersedes and replaces the original Award Agreement):

    1.    Relationship to the Plan. This grant of Performance Units is subject to all of the terms, conditions and provisions of the Plan and administrative interpretations thereunder, if any, that have been adopted by the Board. Except as otherwise defined in this Award Agreement, capitalized terms shall have the same meanings given to them under the Plan. To the extent that any provision of this Award Agreement conflicts with the express terms of the Plan, the terms of the Plan shall control and, if necessary, the applicable provisions of this Award Agreement shall be hereby deemed amended so as to carry out the purpose and intent of the Plan. References to the Participant also include the heirs or other legal representatives of the Participant.

    2.    Forfeiture of Performance Units if Award Not Timely Accepted. This Award is conditioned upon and subject to the Participant accepting the Award by signing and delivering to the Company this Award Agreement, or otherwise electronically accepting the Award in such manner as the Committee may in its discretion determine, no later than 11 months after the Grant Date. If the Participant does not timely accept this Award, all Performance Units subject to this Award shall be forfeited to the Company. In the event of the Participant’s death or incapacitation prior to accepting the Award, the Company shall deem the Award as being accepted by the Participant.

    3.    Determination of TUR Payout Percentage and DCF Payout Percentages; Calculation of Payout Value. As soon as administratively feasible following the close of the Performance Cycle, the Board shall determine and certify the TUR Payout Percentage and the DCF Payout Percentages (collectively, “the Payout Percentages”). The final Payout Value will be the sum of the TUR Payout Value and the DCF Payout Value, each as determined in accordance with this Paragraph 3.

    (a)    The “TUR Payout Percentage” is the simple average of the TUR Period Percentages for each of the following four performance periods:

(i)January 1, 2020 through December 31, 2020;

(ii)January 1, 2021 through December 31, 2021;

(iii)January 1, 2022 through December 31, 2022; and

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(iv)January 1, 2020 through December 31, 2022.

The Board shall determine the TUR Period Percentage for each performance period as follows:

(I)     First, the Board shall determine the TUR Performance Percentile, and then the TUR Period Percentage as follows (using straight-line interpolation between threshold level (30th percentile) and target level (50th percentile) and between target level and maximum (100th percentile)):

TUR Performance Percentile	TUR Period Percentage
Ranked below 30th percentile	0%
Ranked at 30th percentile	50%
Ranked at 50th percentile	100%
Ranked at the 100th percentile	200%

(II)    Notwithstanding anything herein to the contrary, if the Partnership’s Total Unitholder Return calculated for the applicable performance period is negative, then the TUR Period Percentage for that performance period will not exceed 100% regardless of the TUR Performance Percentile for the performance period.

(III)    Notwithstanding anything herein to the contrary, the Board has sole and absolute authority and discretion to reduce the TUR Payout Percentage as it may deem appropriate.

    (b)    The “TUR Payout Value” for each Performance Unit is the product of the TUR Payout Percentage and $0.50.

    (c)    A DCF Payout Percentage will be determined for each of the following three performance periods:

(i)    January 1, 2020 through December 31, 2020;

(ii)    January 1, 2021 through December 31, 2021; and

(iii)    January 1, 2022 through December 31, 2022.

The Board shall determine the DCF Payout Percentage for each performance period based upon the Partnership’s DCF Per Common Unit for such performance period (each a “DCF Measurement Period”) as follows (using straight-line interpolation between levels above threshold):

DCF Per Common Unit	DCF Payout Percentage
Below Threshold	0%
Threshold	50%
Target	100%
Maximum	200%

The threshold, target and maximum performance levels for each DCF Measurement Period will be those certain levels that are established by the Board for purposes of this Award, which level shall be set forth in a confidential memorandum or other written communication provided to the Participant, as such levels may be adjusted pursuant to the provisions of the

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Plan, as applicable. The confidential memorandum or other written communication containing the threshold, target and maximum performance levels for the first DCF Measurement Period is being provided to the Participant on or around the Grant Date and the confidential memorandum or other written communication containing the threshold, target and maximum performance levels for subsequent DCF Measurement Periods will be provided to the Participant following the determination of such levels by the Board at or near the beginning of such periods.

    (d)    The “DCF Payout Value” for each Performance Unit will be the sum of:

(i)     the product of the DCF Payout Percentage for first performance period and $0.167;

(ii)    the product of the DCF Payout Percentage for second performance period and $0.167; and

(iii)    the product of the DCF Payout Percentage for the third performance period and $0.166.

Notwithstanding anything herein to the contrary, the Board has sole and absolute authority and discretion to reduce some or all of the DCF Payout Percentages as it may deem appropriate.

    4.    Vesting and Payment of Performance Units; Payment Amount; Time and Form of Payment. Unless the Participant’s right to the Performance Units is previously forfeited or vested in accordance with Paragraphs 5, 6, 7, 8, 9 or 10 the Participant shall vest in the Performance Units on December 31, 2021, provided the Participant has not terminated Employment on or before that date. The Participant will be entitled to an amount equal to the product of the vested number of Performance Units and the Payout Value, and such amount shall be distributed 75% in cash and 25% in common units.  The number of common units distributed shall be calculated by dividing 25% of the total amount payable by the Fair Market Value of the common units on the date on which the Payout Percentages are certified by the Board, rounding down to the nearest whole unit.  The remainder shall be paid in cash.  Such payments shall be made as soon as administratively feasible following the Board’s determinations under Paragraph 3 and, in any event, between January 1 and March 15th immediately following the end of the Performance Cycle. If, in accordance with the Board’s determination under Paragraph 3, the Payout Value is zero, the Participant shall immediately forfeit any and all rights to the Performance Units. Upon the vesting and/or forfeiture of the Performance Units pursuant to this Paragraph 4 and the making of the related payment, if any, the rights of the Participant and the obligations of the Company under this Award Agreement shall be satisfied in full.

    5.    Termination of Employment. Except as provided in Paragraph 10,if the Participant’s Employment is terminated prior to the close of the Performance Cycle for any reason other than death, Retirement, Qualified Termination, or Mandatory Retirement, as set forth in Paragraphs 6, 7, 8 and 9 below, the Participant’s Performance Units shall be settled based on the performance for the Performance Cycle and shall vest and be payable on a pro-rata basis as follows, and in each case subject to the negative discretion of the Board:

    (a)    If the Participant’s Employment is terminated prior to January 1, 2021, the Participant’s right to the Performance Units shall be forfeited in its entirety as of the date of such termination, and the rights of the Participant and the obligations of the Company under this Award Agreement shall be terminated;

    (b)    If the Participant’s Employment is terminated during the period January 1, 2021 and December 31, 2021, the Participant will be entitled to receive a payment equal to the product of (i) one-third the number of Performance Units and (ii) the Payout Value;

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    (c)    If the Participant’s Employment is terminated during the period January 1, 2022 and December 31, 2022, the Participant will be entitled to receive a payment equal to the product of (i) two-thirds the number of Performance Units and (ii) the Payout Value.

Payment of such vested value of Performance Units under subparagraphs (b) or (c) of this Paragraph 5, as applicable, shall otherwise be made in accordance with Paragraph 4. If, in accordance with the Board’s determinations under Paragraph 3, the Payout Value is zero, the Participant shall immediately forfeit any and all rights to the Performance Units. Upon the vesting and/or forfeiture of the Performance Units pursuant to this Paragraph 5 and the making of the related cash payment, if any, the rights of the Participant and the obligations of the Company under this Award Agreement shall be satisfied in full. The death of the Participant following Retirement but prior to the close of the Performance Cycle shall have no effect on this Paragraph 5.

    6.    Termination of Employment due to Death. If the Participant’s Employment is terminated by reason of death prior to the close of the Performance Cycle, the Participant’s right to receive the Performance Units shall vest in full as of the date of death and the Payout Value shall be determined as if the Payout Percentages are each 100%. The payment on the vested Performance Units shall be made in accordance with Paragraph 4 as soon as administratively feasible but in all cases no later than the last day of the calendar year following the calendar year in which the Participant’s death occurs; provided, however, that the timing of the payment shall be determined in the sole discretion of the Board and no other individual or entity shall directly or indirectly designate the taxable year of payment. Such vesting shall satisfy the rights of the Participant and the obligations of the Company under this Award Agreement in full.

    7.    Termination of Employment due to Retirement. In the event of the Retirement of the Participant after nine months of the Performance Cycle have elapsed, the Participant’s Performance Units shall be settled based on the performance for the Performance Cycle and shall vest and be payable on a pro-rata basis as determined and certified by the Board after the close of the Performance Cycle as described below. Subject to the negative discretion of the Board, the Participant will be entitled to receive a payment equal to the product of (i) the pro-rata vesting percentage equal to the days of the Participant’s Employment during the Performance Cycle divided by the total days in the Performance Cycle and (ii) the Payout Value. Payment of such vested value of Performance Units under this Paragraph 7 shall otherwise be made in accordance with Paragraph 4. If, in accordance with the Board’s determinations under Paragraph 3, the Payout Value is zero, the Participant shall immediately forfeit any and all rights to the Performance Units. Upon the vesting and/or forfeiture of the Performance Units pursuant to this Paragraph 7 and the making of the related cash payment, if any, the rights of the Participant and the obligations of the Company under this Award Agreement shall be satisfied in full. The death of the Participant following Retirement but prior to the close of the Performance Cycle shall have no effect on this Paragraph 7.

    8.Vesting Upon a Qualified Termination. Notwithstanding anything herein to the contrary, upon the Participant’s Qualified Termination prior to the end of the Performance Cycle, the Participant’s right to receive the Performance Units, unless previously forfeited pursuant to Paragraph 5, shall vest in full. The TUR Payout Percentage shall be determined as follows (subject to the negative discretion of the Board): (i) for the time period from the beginning of the Performance Cycle to the date of the Change in Control (as defined in the Marathon Petroleum Corporation Amended and Restated Executive Change in Control Severance Benefits Plan), based upon actual TUR Performance Percentile and (ii) for the time period from the date of the Change in Control to the end of the Performance Cycle, the TUR Payout Percentage shall be 100%. The DCF Payout Percentages shall be determined as follows (subject to the negative discretion of the Board): (i) for the time period from the beginning of the Performance Cycle to the date of the Change in Control (as

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defined in the Marathon Petroleum Corporation Amended and Restated Executive Change in Control Severance Benefits Plan), based upon actual DCF Payout Percentages and (ii) for the time period from the date of the Change in Control to the end of the Performance Cycle, the DCF Payout Percentages shall be 100%. A payment equal to the vested value of the Performance Units shall be made in accordance with Paragraph 4, except that it shall be made 100% in cash.

9.    Termination of Employment due to Mandatory Retirement. In the event the Participant’s Employment is terminated as a result of Mandatory Retirement prior to the end of the Performance Cycle, the Participant’s right to receive the Performance Units shall vest in full, and such vested and shall be settled based on the Payout Value determined under Paragraph 3. Payment of such vested value of Performance Units under this Paragraph 9 shall otherwise be made in accordance with Paragraph 4. If, in accordance with the Board’s determinations under Paragraph 3, the Payout Value is zero, the Participant shall immediately forfeit any and all rights to the Performance Units. Upon the vesting and/or forfeiture of the Performance Units pursuant to this Paragraph 9 and the making of the related cash payment, if any, the rights of the Participant and the obligations of the Company under this Award Agreement shall be satisfied in full. The death of the Participant following Mandatory Retirement but prior to the close of the Performance Cycle shall have no effect on this Paragraph 9.

    10.    Qualifying Date. Provided that the Participant has been in continuous Employment from the Grant Date to the Qualifying Date, the Performance Units shall vest in full as of the Qualifying Date, and such vested Performance Units shall be determined and paid as otherwise provided in Paragraphs 3 and 4; provided, in the event of the Participant’s death prior to the end of the Performance Cycle, the Payout Percentage, Payout Value and the payment timing provisions of Paragraph 6 shall apply.

    11.    Specified Employee. Notwithstanding any other provision of this Award Agreement to the contrary, if the Participant is a “specified employee” within the meaning of Section 409A of the Code as determined by the Company in accordance with its established policy, any settlement of any amount described in this Award Agreement which would be a payment of deferred compensation within the meaning of Section 409A of the Code with respect to the Participant as a result of the Participant’s “separation from service” as defined under Section 409A of the Code (other than as a result of death) and which would otherwise be paid within six months of the Participant’s separation from service shall be paid on the date that is one day after the earlier of (i) the date that is six months after the Participant’s separation from service or (ii) the date that otherwise complies with the requirements of Section 409A of the Code. In addition, notwithstanding any provision of the Plan or this Award Agreement to the contrary, any settlement of this Award which would be a payment of deferred compensation within the meaning of Section 409A of the Code with respect to the Participant and is a settlement as a result of the Participant’s separation from service in connection with a Change in Control, the term “Change in Control” under the Plan shall mean a change in ownership or change in effective control for purposes of Section 409A of the Code. The payment of each amount under this Award Agreement is deemed as a “separate payment” for purposes of Section 409A of the Code.

    12.    Conditions Precedent. This Paragraph 12 shall apply to this Award notwithstanding any other provision of this Award Agreement to the contrary. The Participant’s services to the Company, the Partnership and MPC and their Affiliates (the “Company Group”) are unique, extraordinary and essential to the business of the Company Group, particularly in view of the Participant’s access to the confidential information and trade secrets of members of the Company Group, such as, the Company, the Partnership and MPC. Accordingly, in consideration of this Award Agreement and by accepting this Award, the Participant agrees that in order to otherwise vest in any right to payment of Performance Units under Paragraph 4, the Participant must satisfy the following conditions to and including the vesting date for each applicable annual installment or other applicable portion of the Award, under the vesting provisions in Paragraph 4:

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    (a)    The Participant agrees that the Participant will not, without the prior written approval of the Board, at any time during the term of the Participant’s Employment and for a period of one year following the date on which the Participant’s Employment terminates (the “Restricted Period”), directly or indirectly, serve as an officer, director, owner, contractor, consultant, or employee of any the following organizations (or any of their respective subsidiaries or divisions): BP plc, Chevron Corporation; ExxonMobil Corporation, HollyFrontier Corporation; PBF Energy Inc.; Phillips 66; Valero Energy Corporation; Buckeye Partners, L.P.; DCP Midstream Partners, L.P; Enterprise Product Partners; Gas; Genesis Energy, L.P.; Holly Energy Partners L.P.; Magellan Midstream Partners, L.P.; Phillips 66 Partners, L.P.; Plains All American Pipeline L.P.; Western Gas Equity Partners, or otherwise engage in any business activity directly or indirectly competitive with the business of the any member of the Company Group as in effect from time to time.

    (b)    The Participant agrees that during the term of the Participant’s Employment and for a period of one year following the date on which the Participant’s Employment terminates, the Participant will not, alone or in conjunction with another party, hire, solicit for hire, aid in or facilitate the hire, or cause to be hired, either as an employee, contractor or consultant, any individual who is currently engaged, or was engaged at any time during the six month period prior such event, as an employee, contractor or consultant of any member of the Company Group.

    (c)    The Participant agrees that the Participant may not, either during the Participant’s Employment or thereafter, make or encourage others to make any public statement or release any information or otherwise engage in any conduct that is intended to, or reasonably could be foreseen to, embarrass, criticize or harm the reputation or goodwill of the any member of the Company Group, or any of their employees, directors or shareholders; provided that this shall not preclude the Participant from reporting to the Company’s management or directors or to the government or a regulator conduct the Participant believes to be in violation of the law or the Code of Business Conduct (or similar code or rules) of any member of the Company Group or responding truthfully to questions or requests for information to the government, a regulator or in a court of law in connection with a legal or regulatory investigation or proceeding.

    (d)    The Participant agrees and understands that the members of the Company Group own and/or control information and material which is not generally available to third parties and which the members of the Company Group consider confidential, including, without limitation, methods, products, processes, customer lists, trade secrets and other information applicable to its business and that it may from time to time acquire, improve or produce additional methods, products, processes, customers lists, trade secrets and other information (collectively, the “Confidential Information”). The Participant acknowledges that each element of the Confidential Information constitutes a unique and valuable asset of the members of the Company Group, and that certain items of the Confidential Information have been acquired from third parties upon the express condition that such items would not be disclosed to all or certain members of the Company Group and the officers and agents thereof other than in the ordinary course of business. The Participant acknowledges that disclosure of the Confidential Information to and/or use by anyone other than in the Company, the Partnership’s, or MPC’s or other Company Group member’s ordinary course of business would result in irreparable and continuing damage to the Company, the Partnership and/or MPC and/or other members of the Company Group. Accordingly, the Participant agrees to hold the Confidential Information in the strictest secrecy, and covenants that, during the term of the Participant’s Employment or at any time thereafter, the Participant will not, without the prior written consent of the Board, directly or indirectly, allow any element of the Confidential Information to be disclosed, published or used, nor permit the Confidential Information to be discussed, published or used, either by the Participant or by any third parties, except in effecting the Participant’s duties for the Company, the Partnership and/or MPC and/or other Company Group members in the ordinary course of business.

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    (e)    The Participant agrees that in addition to the forfeiture provisions otherwise provided for in this Award Agreement, upon the Participant’s failure to satisfy in any respect of any of the conditions described in Paragraphs 12(a), (b), (c) or (d), any unvested and unpaid portion of this Award at the time of such breach shall be forfeited, andthe rights of the Participant and the obligations of the Company under this Award Agreement shall be satisfied in full, in each case to the extent permitted by applicable law.

    13.    Repayment or Forfeiture Resulting from Forfeiture Event.

    (a)    If there is a Forfeiture Event either during the Participant’s Employment or within three years after termination of the Participant’s Employment, then the Board may, but is not obligated to, cause some or all of the Participant’s outstanding Performance Units to be forfeited by the Participant.

    (b)    If there is a Forfeiture Event either during the Participant’s Employment or within three years after termination of the Participant’s Employment and a payment has previously been made in settlement of Performance Units granted under this Award Agreement, the Board may, but is not obligated to, require that the Participant pay to the Company an amount in cash (the “Forfeiture Amount”) up to (but not in excess of) the amount paid in settlement of the Performance Units.

    (c)     This Paragraph 13 shall apply notwithstanding any provision of this Award Agreement to the contrary and is meant to provide the Company with rights in addition to any other remedy which may exist in law or in equity. This Paragraph 13 shall not apply to the Participant following the effective time of a Change in Control.

    (d)     Notwithstanding the foregoing or any other provision of this Award Agreement to the contrary, the Participant agrees that the Company may also require that the Participant repay to the Company any compensation paid to the Participant under this Award Agreement, as is required by the provisions of the Dodd-Frank Wall Street Reform and Consumer Protection Act and the regulations thereunder or any other “clawback” provisions as required by law or by the applicable listing standards of the exchange on which the common units of the Partnership are listed for trading.

    14.    Taxes. Pursuant to the applicable provisions of the Plan, the Company or its designated representative shall have the right to withhold applicable taxes from the common units and cash amount otherwise payable to the Participant due to the vesting of Performance Units pursuant to Paragraph 4, or from other compensation payable to the Participant (to the extent consistent with Section 409A of the Code), at the time of the vesting of the Performance Units and delivery of the cash settlement amount. Because the Participant is an employee of MPC, and provides beneficial services to the Company through Participant’s employment with MPC, MPC as the employer of Participant, shall be the designated representative for purposes of payroll administration of the Award and withholding of applicable taxes at the time of vesting.

    15.    No Unitholder Rights. The Participant shall in no way be entitled to any of the rights of a unitholder as a result of this Award Agreement.

    16.    Nonassignability. Upon the Participant’s death, the Performance Units may be transferred by will or by the laws governing the descent and distribution of the Participant’s estate. Otherwise, the Participant may not sell, transfer, assign, pledge or otherwise encumber any portion of the Performance Units, and any attempt to sell, transfer, assign, pledge or encumber any portion of the Performance Units shall have no effect.

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    17.    No Employment Guaranteed. Nothing in this Award Agreement shall give the Participant any rights to (or impose any obligations for) continued Employment by the Company or any affiliate thereof or successor thereto, nor shall it give such entities any rights (or impose any obligations) with respect to continued performance of duties by the Participant.

    18.    Modification of Agreement. Any modification of this Award Agreement shall be binding only if evidenced in writing and signed by an authorized representative of the Company, provided that no modification may, without the consent of the Participant, adversely affect the rights of the Participant hereunder.

    19.    Officer Holding Requirement. Participant agrees that any common units received by the Participant in settlement of this Award shall be subject an additional holding period of one year from the date on which the Award is settled, during which holding period such common units (net of any common units used to satisfy the applicable tax withholding requirements) may not be sold or transferred by the Participant. This holding requirement shall cease to apply upon the death, retirement or other separation from service of the Participant during the holding period.

    20.    Definitions. For purposes of this Award Agreement:

“Beginning Unit Price”means the average of the daily closing price of a common unit of the Partnership for the 20 trading days immediately prior to the commencement of the Performance Cycle, historically adjusted, if necessary, for any split, dividend, recapitalizations, or similar corporate events that occur during the measurement period.

“DCF Per Common Unit”for an applicable DCF Measurement Period means the quotient obtained by dividing (A) the Partnership’s distributable cash flow available to general and limited partners (as reported in the Partnership’s financial statements) for such DCF Measurement Period less all such amounts attributable to the general partner interest and the incentive distribution rights in the Partnership, by (B) the weighted average number of common units in the Partnership outstanding during such DCF Measurement Period.

“Employment” means employment with the Company or any of its subsidiaries or affiliates including but not limited to MPC and its subsidiaries and affiliates. For purposes of this Award Agreement, Employment shall also include any period of time during which the Participant is on Disability status. The length of any period of Employment shall be determined by the Company or the Subsidiary or affiliate that either (a) employs the Participant or (b) employed the Participant immediately prior to the Participant’s termination of Employment.

“End Unit Price”means the average of the daily closing price of a common unit of the Partnership for the 20 trading days prior to the end of the Performance Cycle.

“Forfeiture Event” means the occurrence of at least one of the following events: (a) the Company is required, pursuant to a determination made by the Securities and Exchange Commission or by the Board, or any authorized subcommittee of the Board, to prepare a material accounting restatement due to the noncompliance of the Company with any financial reporting requirement under applicable securities laws as a result of misconduct, and the Board determines that (i) the Participant knowingly engaged in the misconduct, (ii) the Participant was grossly negligent with respect to such misconduct or

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(iii) the Participant knowingly or grossly negligently failed to prevent the misconduct or (b) the Board concludes that the Participant engaged in fraud, embezzlement or other similar misconduct materially detrimental to the Company.

“Mandatory Retirement” means, as determined by the Board of Directors of MPC, the mandatory retirement age of 65 for Participants who are in bona fide executive or in high policymaking positions and in Grades 19 and above if: (1) the Participant has been employed in such capacity for the two-year period immediately prior to mandatory retirement; and (2) the Participant is entitled to the minimum retirement benefit specified by federal law for persons who hold positions to which mandatory retirement may lawfully apply. Mandatory Retirement is required by the earlier of the first of the month coincident with or immediately following the Participant’s 65th birthday.

“Peer Group” means the group of companies that are pre-established by the Board which principally represent a group of selected peers, or such other group of companies as selected and pre-established by the Board. For this Award, the Board has determined that the Peer Group for each applicable measurement period will be the ten companies in the Alerian MLP Index with the highest market capitalization as determined on the last day of the measurement period.

“Performance Cycle”means the period from January 1, 2020 to December 31, 2022.

“Qualifying Date”means July 1, 2022.

“Qualified Termination” for purposes of this Award Agreement shall have the same definition as under the MPLX LP Executive Change in Control Severance Benefits Plan, as in effect on the Grant Date (disregarding subsection II of such definition) (the “CIC Plan”), and such definition and associated terms are hereby incorporated into this Award Agreement by reference. Notwithstanding the definition of a “Change in Control” under the terms of the CIC Plan, for purposes of this Award Agreement such Change in Control for purposes of determining whether a separation from service is a Qualified Termination shall include a Change in Control of either MPC, as the direct employer of the Participant, or a Change in Control of the Partnership, as the issuer of the Award.

“Retirement”means (a) for a Participant with ten or more years of Employment, termination on or after the Participant’s 50th birthday, or (b) termination on or after the Participant’s 65th birthday.

“Total Unitholder Return” or “TUR” means for the Company and each entity in the Peer Group the number derived using the following formula:

(End Unit Price – Beginning Unit Price) + Cumulative Cash Distributions

         Beginning Unit Price.

“TUR Performance Percentile” means the percentile ranking of the Company’s Total Unitholder Return for a performance period among the Total Unitholder Returns of the Peer Group companies, ranked in descending order, for the performance period as determined at the end of the Performance Cycle.

9

		MPLX GP LLC
	By	/s/ Fiona C. Laird
		Authorized Officer - Fiona C. Laird
/s/ Michael J. Hennigan
Signature
February 21, 2022
Date

10

EX-31.1

Exhibit 31.1

CERTIFICATION PURSUANT TO SECTION 302 OF

THE SARBANES-OXLEY ACT OF 2002

I, Michael J. Hennigan, certify that:

1.I have reviewed this report on Form 10-Q of MPLX LP;

2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3.Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4.The registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

(a)Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b)Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c)Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

(d)Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5.The registrant's other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant's auditors and the audit committee of the registrant's board of directors (or persons performing the equivalent functions):

(a)All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant's ability to record, process, summarize and report financial information; and

(b)Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant's internal control over financial reporting.

Date: May 3, 2022	/s/ Michael J. Hennigan
	Michael J. Hennigan
	Chairman of the Board, President and Chief Executive Officer of MPLX GP LLC (the general partner of MPLX LP)

EX-31.2

Exhibit 31.2

CERTIFICATION PURSUANT TO SECTION 302 OF

THE SARBANES-OXLEY ACT OF 2002

I, John J. Quaid, certify that:

1.I have reviewed this report on Form 10-Q of MPLX LP;

2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3.Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4.The registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

(a)Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b)Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c)Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

(d)Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5.The registrant's other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant's auditors and the audit committee of the registrant's board of directors (or persons performing the equivalent functions):

(a)All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant's ability to record, process, summarize and report financial information; and

(b)Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant's internal control over financial reporting.

Date: May 3, 2022	/s/ John J. Quaid
	John J. Quaid
	Executive Vice President and Chief Financial Officer of MPLX GP LLC (the general partner of MPLX LP)

EX-32.1

Exhibit 32.1

CERTIFICATION PURSUANT TO

18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report of MPLX LP (the “Partnership”) on Form 10-Q for the quarter ended March 31, 2022 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Michael J. Hennigan, Chairman of the Board, President and Chief Executive Officer of MPLX GP LLC, the general partner of the Partnership, certify, pursuant to 18 U.S.C. §1350, as adopted pursuant to §906 of the Sarbanes-Oxley Act of 2002, that to the best of my knowledge:

(1)The Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

(2)The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Partnership.

Date: May 3, 2022

/s/ Michael J. Hennigan

Michael J. Hennigan

Chairman of the Board, President and Chief Executive Officer of MPLX GP LLC (the general partner of MPLX LP)

EX-32.2

Exhibit 32.2

CERTIFICATION PURSUANT TO

18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report of MPLX LP (the “Partnership”) on Form 10-Q for the quarter ended March 31, 2022 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, John J. Quaid, Executive Vice President and Chief Financial Officer of MPLX GP LLC, the general partner of the Partnership, certify, pursuant to 18 U.S.C. §1350, as adopted pursuant to §906 of the Sarbanes-Oxley Act of 2002, that to the best of my knowledge:

(1)The Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

(2)The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Partnership.

Date: May 3, 2022

/s/ John J. Quaid

John J. Quaid

Executive Vice President and Chief Financial Officer of MPLX GP LLC (the general partner of MPLX LP)

XML

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2022	Apr. 29, 2022
Document Information [Line Items]
Document Transition Report	false
Document Quarterly Report	true
Title of 12(b) Security	Common Units Representing Limited Partnership Interests
Entity Incorporation, State or Country Code	DE
Document Type	10-Q
Document Period End Date	Mar. 31, 2022
Amendment Flag	false
Entity File Number	001-35714
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q1
Trading Symbol	MPLX
Entity Registrant Name	MPLX LP
Entity Central Index Key	0001552000
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Common Stock, Shares Outstanding		1,012,303,833
Entity Address, Address Line One	200 E. Hardin Street,
Entity Address, City or Town	Findlay,
Entity Address, State or Province	OH
Entity Address, Postal Zip Code	45840
City Area Code	419
Local Phone Number	421-2414
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
Security Exchange Name	NYSE
Entity Tax Identification Number	27-0005456

XML

Consolidated Statements of Income - USD ($) shares in Millions, $ in Millions		3 Months Ended
		Mar. 31, 2022	Mar. 31, 2021
Income from equity method investments		$ 99	$ 70
Other Income		(17)	1
Related Party Transaction, Other Revenues from Transactions with Related Party		27	28
Revenues		2,610	2,339
Related Party Transaction, Purchases from Related Party		319	298
Cost, Depreciation and Amortization	[1]	313	329
Taxes, Miscellaneous		34	32
Costs and Expenses		1,550	1,365
Interest And Other Financial Costs From Related Parties		4	0
Other Nonoperating Income (Expense)		20	27
Interest Expense, Debt, Excluding Amortization		198	198
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent, Total		1,060	974
Provision for income taxes		5	1
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest, Total		838	749
Less: Net income (loss) attributable to noncontrolling interest		8	9
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest, Total		833	748
Limited partners' interest in net income (loss) attributable to MPLX LP		793	708
Net income (loss) attributable to MPLX LP	[2]	825	739
Related Party and Third Party
General and Administrative Expense		78	86
Third Party [Member]
Operating Lease, Lease Income		91	99
Rental cost of sales
Labor and Related Expense		$ 37	$ 32
Limited Partners Common Units [Member]
Net income (loss) attributable to MPLX LP per limited partner unit:
Net Income (Loss), Per Outstanding Limited Partnership Unit, Basic, Net of Tax		$ 0.78	$ 0.68
Common - diluted (in USD per unit)		$ 0.78	$ 0.68
Weighted average limited partner units outstanding:
Common - basic (in shares)		1,015	1,037
Common - diluted (in shares)		1,015	1,037
Service [Member]
Total revenues from contracts with customers		$ 554	$ 589
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		915	872
Service, Other [Member]
Total revenues from contracts with customers		123	77
Product [Member]
Total revenues from contracts with customers		497	282
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		45	42
Oil and Gas, Refining and Marketing [Member]
Cost of Goods and Services Sold		287	273
Natural Gas, Midstream [Member]
Cost of Goods and Services Sold		467	276
Series A Preferred Stock [Member] | Preferred Partner [Member]
Dividends, Preferred Stock		21	20
Net income (loss) attributable to MPLX LP	[2]	23	20
Series B Preferred Stock [Member] | Preferred Partner [Member]
Dividends, Preferred Stock		11	11
Net income (loss) attributable to MPLX LP	[2]	11	11
Affiliated Entity
Sales-type Lease, Revenue		111	37
Operating Lease, Lease Income, Related Party [Line Items]		165	242
Affiliated Entity | Rental cost of sales - related parties
Labor and Related Expense		15	39
Affiliated Entity | Service [Member]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		915	872
Affiliated Entity | Product [Member]
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		$ 45	$ 42

[1] Depreciation and amortization attributable to L&S was $130 million and $147 million for the three months ended March 31, 2022 and March 31, 2021, respectively. Depreciation and amortization attributable to G&P was $183 million and $182 million for the three months ended March 31, 2022 and March 31, 2021, respectively.

[2] Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.

XML

Consolidated Statements of Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Income Statement [Abstract]
Interest Costs Capitalized	$ 2	$ 5

XML

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Statement of Comprehensive Income [Abstract]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 833	$ 748
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest, Total	842	746
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest [Abstract]
Less: Net income (loss) attributable to noncontrolling interest	8	9
Comprehensive Income (Loss), Net of Tax, Attributable to Parent, Total	834	737
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Statement of Comprehensive Income [Abstract]
Other Comprehensive Income (Loss), Net of Tax	9	(2)
Other Comprehensive Income (Loss), Net of Tax	$ 9	$ (2)

XML

Consolidated Balance Sheets - USD ($) shares in Millions, $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Assets
Cash and cash equivalents	$ 42	$ 13
Receivables, net	741	654
Inventories	149	142
Total current assets	1,798	1,507
Equity method investments	4,079	3,981
Property, plant and equipment, net	19,912	20,042
Intangibles, net	800	831
Goodwill	7,657	7,657
Other noncurrent assets	50	60
Total assets	35,727	35,507
Liabilities
Accounts Payable, Current	214	172
Accrued Liabilities, Current	396	363
Accrued Property Plant and Equipment Current	91	97
Long-term Debt and Lease Obligation, Current	999	499
Interest Payable, Current	192	202
Operating Lease, Liability, Current	47	59
Other current liabilities	232	176
Total current liabilities	2,858	3,348
Long-term deferred revenue	405	383
Long-term debt	18,757	18,072
Deferred Income Taxes and Other Tax Liabilities, Noncurrent	14	10
Operating Lease, Liability, Noncurrent	228	205
Deferred credits and other liabilities	159	170
Total liabilities	22,726	22,490
Commitments and contingencies (see Note 14)
Equity
Total MPLX LP partners’ capital	11,796	11,811
Noncontrolling interests	240	241
Total equity	12,036	12,052
Total liabilities, preferred units and equity	35,727	35,507
Third Party [Member]
Assets
Other current assets	53	54
Operating Lease, Right-of-Use Asset	280	268
Affiliated Entity
Assets
Current Assets, Related Parties	813	644
Other current assets	3	3
Operating Lease, Right-of-Use Asset	229	229
Due from Related Parties, Noncurrent	1,151	1,161
Liabilities
Due to Related Parties, Current	687	1,780
Liabilities, Related Parties, Noncurrent	$ 305	$ 302
Series B Preferred Stock [Member]
Liabilities
Preferred Units, Issued	0.6	0.6
Preferred Units, Outstanding	0.6	0.6
Equity
Preferred Units, Preferred Partners' Capital Accounts	$ 601	$ 611
Limited Partners Common Units [Member] | Public [Member]
Liabilities
Units issued	366.0	369.0
Equity
Limited Partners' Capital Account	$ 8,505	$ 8,579
Units Outstanding	366.0	369.0
Limited Partners Common Units [Member] | Marathon Petroleum Corporation [Member]
Liabilities
Units issued	647.0	647.0
Equity
Limited Partners' Capital Account	$ 2,698	$ 2,638
Units Outstanding	647.0	647.0
Series A Convertible Preferred Units
Liabilities
Preferred Units, Issued	30.0	30.0
Preferred Units, Outstanding	30.0	30.0
Series A Preferred Stock [Member]
Liabilities
Series A preferred units (30 million and 30 million units issued and outstanding)	$ 965	$ 965
LOOP and Explorer
Equity
Accumulated other comprehensive loss	$ (8)	$ (17)

XML

Consolidated Balance Sheets (Parenthetical) - Limited Partners Common Units [Member] - shares shares in Millions	Mar. 31, 2022	Dec. 31, 2021
Public [Member]
Units issued	366	369
Units Outstanding	366	369
Marathon Petroleum Corporation [Member]
Units issued	647	647
Units Outstanding	647	647

XML

Consolidated Statements of Cash Flows - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2022	Mar. 31, 2021
Operating activities:
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		$ 833	$ 748
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of deferred financing costs		18	17
Cost, Depreciation and Amortization	[1]	313	329
Deferred income taxes		4	0
Income from equity method investments		(99)	(70)
Proceeds from Equity Method Investment, Distribution		120	119
Increase (Decrease) in Derivative Assets and Liabilities		(9)	3
Changes in:
Current receivables		(87)	(67)
Inventories		(7)	(11)
Current accounts payable and accrued liabilities		73	26
Current assets/current liabilities - related parties		(112)	(8)
Increase (Decrease) in Other Operating Assets and Liabilities, Net		(1)	(1)
Deferred revenue		16	24
All other, net		45	15
Net cash provided by operating activities		1,125	1,124
Net Cash Provided by (Used in) Investing Activities [Abstract]
Additions to property, plant and equipment		(169)	(126)
Disposal of assets		3	70
Payments to Acquire Equity Method Investments		(110)	(35)
Payments for (Proceeds from) Other Investing Activities		0	1
Net cash used in investing activities		(276)	(90)
Net Cash Provided by (Used in) Financing Activities [Abstract]
Long-term debt - borrowings		2,385	1,910
Long-term debt - repayments		(1,201)	(2,020)
Payments of Debt Issuance Costs		16	0
Payments for Repurchase of Common Stock		(100)	(155)
Distributions to noncontrolling interests		(9)	(10)
Distributions to unitholders and general partner		(716)	(713)
Proceeds from Contributions from Parent		10	7
All other, net		(4)	(3)
Net cash used in financing activities		(820)	(1,025)
Net increase in cash, cash equivalents and restricted cash		29	9
Cash, cash equivalents and restricted cash at beginning of period		13	15
Cash, cash equivalents and restricted cash at end of period		42	24
Loss on disposal of assets		18	0
Related Party Revolving Credit Agreement [Member] | MPC Investment [Member]
Net Cash Provided by (Used in) Financing Activities [Abstract]
Related party debt - borrowings		1,849	2,241
Repayments of Related Party Debt		(2,976)	(2,241)
Series A Preferred Stock [Member] | Preferred Partner [Member]
Net Cash Provided by (Used in) Financing Activities [Abstract]
Distributions to preferred unitholders		(21)	(20)
Series B Preferred Stock [Member] | Preferred Partner [Member]
Net Cash Provided by (Used in) Financing Activities [Abstract]
Distributions to preferred unitholders		$ (21)	$ (21)

[1] Depreciation and amortization attributable to L&S was $130 million and $147 million for the three months ended March 31, 2022 and March 31, 2021, respectively. Depreciation and amortization attributable to G&P was $183 million and $182 million for the three months ended March 31, 2022 and March 31, 2021, respectively.

XML

Consolidated Statements of Equity - USD ($) $ in Millions	Total	LOOP and Explorer	Series B Preferred Stock [Member]	Series A Preferred Stock [Member]	Public [Member] Limited Partners Common Units [Member]	Marathon Petroleum Corporation [Member] Limited Partners Common Units [Member]	AOCI Attributable to Parent [Member]	Noncontrolling Interest [Member]
Preferred Units, Preferred Partners' Capital Accounts			$ 611
Limited Partners' Capital Account					$ 9,384	$ 2,792
Noncontrolling interests	$ 245
Accumulated other comprehensive loss		$ (15)
Series A preferred units (30 million and 30 million units issued and outstanding)				$ 968
Beginning Balance at Dec. 31, 2020	13,017
Distributions to:	729		11		266	443	$ 0	$ 9
Stock Repurchased and Retired During Period, Value	(155)		0	0	(155)	0	0	0
Partners' Capital Account, Distributions	(745)		(21)	(20)	(269)	(445)	0	(10)
Other	(3)		0		0	(1)	(2)	0
Ending Balance at Mar. 31, 2021	12,850
Temporary Equity, Net Income				20
Partners' Capital Account, Contributions	7		0	0	0	7	0	0
Temporary Equity, Other Changes				0
Preferred Units, Preferred Partners' Capital Accounts			601
Limited Partners' Capital Account					9,226	2,796
Noncontrolling interests	244
Accumulated other comprehensive loss		(17)
Series A preferred units (30 million and 30 million units issued and outstanding)				968
Preferred Units, Preferred Partners' Capital Accounts			611
Limited Partners' Capital Account					8,579	2,638
Noncontrolling interests	241
Accumulated other comprehensive loss		(17)
Series A preferred units (30 million and 30 million units issued and outstanding)				965
Beginning Balance at Dec. 31, 2021	12,052
Distributions to:	812		11		287	506	0	8
Stock Repurchased and Retired During Period, Value	(100)		0	0	(100)	0	0	0
Partners' Capital Account, Distributions	(746)		(21)	(21)	(260)	(456)	0	(9)
Other	8		0		(1)	0	9	0
Ending Balance at Mar. 31, 2022	12,036
Temporary Equity, Net Income				21
Partners' Capital Account, Contributions	10		0	0	0	10	$ 0	$ 0
Temporary Equity, Other Changes				0
Preferred Units, Preferred Partners' Capital Accounts			$ 601
Limited Partners' Capital Account					$ 8,505	$ 2,698
Noncontrolling interests	$ 240
Accumulated other comprehensive loss		$ (8)
Series A preferred units (30 million and 30 million units issued and outstanding)				$ 965

XML

Description of the Business and Basis of Presentation

3 Months Ended

Mar. 31, 2022

Accounting Policies [Abstract]

Business Description and Basis of Presentation [Text Block]

Description of the Business and Basis of Presentation

Description of the Business

MPLX LP is a diversified, large-cap master limited partnership formed by Marathon Petroleum Corporation that owns and operates midstream energy infrastructure and logistics assets, and provides fuels distribution services. References in this report to “MPLX LP,” “MPLX,” “the Partnership,” “we,” “ours,” “us,” or like terms refer to MPLX LP and its subsidiaries. References to “MPC” refer collectively to Marathon Petroleum Corporation as our sponsor and its subsidiaries, other than the Partnership. We are engaged in the gathering, transportation, storage and distribution of crude oil, refined products and other hydrocarbon-based products; the gathering, processing and transportation of natural gas; and the gathering, transportation, fractionation, storage and marketing of NGLs. MPLX’s principal executive office is located in Findlay, Ohio.

MPLX’s business consists of two segments based on the nature of services it offers: Logistics and Storage (“L&S”), which relates primarily to crude oil, refined products and other hydrocarbon-based products; and Gathering and Processing (“G&P”), which relates primarily to natural gas and NGLs. See Note 7 for additional information regarding the operations and results of these segments.

Basis of Presentation

The accompanying interim consolidated financial statements are unaudited; however, in the opinion of MPLX’s management, these statements reflect all adjustments necessary for a fair statement of the results for the periods reported. All such adjustments are of a normal, recurring nature unless otherwise disclosed. These interim consolidated financial statements, including the notes, have been prepared in accordance with the rules and regulations of the SEC applicable to interim period financial statements and do not include all of the information and disclosures required by GAAP for complete financial statements. Certain information derived from our audited annual financial statements, prepared in accordance with GAAP, has been condensed or omitted from these interim financial statements.

These interim consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2021. The results of operations for the three months ended March 31, 2022 are not necessarily indicative of the results to be expected for the full year.

MPLX’s consolidated financial statements include all majority-owned and controlled subsidiaries. For non-wholly owned consolidated subsidiaries, the interests owned by third parties have been recorded as “Noncontrolling interests” on the accompanying Consolidated Balance Sheets. Intercompany investments, accounts and transactions have been eliminated. MPLX’s investments in which MPLX exercises significant influence but does not control and does not have a controlling financial interest are accounted for using the equity method. MPLX’s investments in VIEs in which MPLX exercises significant influence but does not control and is not the primary beneficiary are also accounted for using the equity method.

Certain prior period financial statement amounts have been reclassified to conform to current period presentation.

XML

Accounting Standards Accounting Standards

3 Months Ended

Mar. 31, 2022

Accounting Changes and Error Corrections [Abstract]

Accounting Standards Update and Change in Accounting Principle [Text Block]

Accounting Standards

Recently Adopted

ASU 2021-10, Government Assistance (Topic 832): Disclosures by Business Entities about Government Assistance

In November 2021, the FASB issued guidance requiring disclosures for certain types of government assistance that have been accounted for by analogy to grant or contribution models. Disclosures will include information about the type of transactions, accounting and the impact on financial statements. MPLX prospectively adopted this standard in the first quarter of 2022. The adoption of this standard did not have a material impact on our financial statements or disclosures.

XML

Investments and Noncontrolling Interest

3 Months Ended

Mar. 31, 2022

Equity Method Investments and Joint Ventures [Abstract]

Investments and Noncontrolling Interests [Text Block]

Investments and Noncontrolling Interests

The following table presents MPLX’s equity method investments at the dates indicated:

	Ownership as of	Carrying value at
	March 31,	March 31,		December 31,
(In millions, except ownership percentages)	2022	2022		2021
L&S
MarEn Bakken Company LLC(1)	25%	$	502	$	449
Illinois Extension Pipeline Company, L.L.C.	35%	249		243
LOOP LLC	41%	274		265
Andeavor Logistics Rio Pipeline LLC(2)	67%	181		183
Minnesota Pipe Line Company, LLC	17%	182		183
Whistler Pipeline LLC(2)	38%	166		155
Explorer Pipeline Company	25%	65		66
W2W Holdings LLC(2)	50%	56		58
Other(2)		125		116
Total L&S		1,800		1,718
G&P
MarkWest Utica EMG, L.L.C.(2)	57%	681		680
Sherwood Midstream LLC(2)	50%	539		544
MarkWest EMG Jefferson Dry Gas Gathering Company, L.L.C.(2)	67%	336		332
MarkWest Torñado GP, L.L.C.(2)	60%	266		246
Rendezvous Gas Services, L.L.C.(2)	78%	145		147
Sherwood Midstream Holdings LLC(2)	51%	133		136
Centrahoma Processing LLC	40%	133		133
Other(2)		46		45
Total G&P		2,279		2,263
Total		$	4,079	$	3,981

(1)    The investment in MarEn Bakken Company LLC includes our 9.19 percent indirect interest in a joint venture (“Dakota Access”) that owns and operates the Dakota Access Pipeline and Energy Transfer Crude Oil Pipeline projects, collectively referred to as the Bakken Pipeline system or DAPL.    

(2)    Investments deemed to be VIEs. Some investments included within “Other” have also been deemed to be VIEs.

For those entities that have been deemed to be VIEs, neither MPLX nor any of its subsidiaries have been deemed to be the primary beneficiary due to voting rights on significant matters. While we have the ability to exercise influence through participation in the management committees which make all significant decisions, we have equal influence over each committee as a joint interest partner and all significant decisions require the consent of the other investors without regard to economic interest; as such, we have determined that these entities should not be consolidated and apply the equity method of accounting with respect to our investments in each entity.

Sherwood Midstream LLC (“Sherwood Midstream”) has been deemed the primary beneficiary of Sherwood Midstream Holdings LLC (“Sherwood Midstream Holdings”) due to its controlling financial interest through its authority to manage the joint venture. As a result, Sherwood Midstream consolidates Sherwood Midstream Holdings. Therefore, MPLX also reports its portion of Sherwood Midstream Holdings’ net assets as a component of its investment in Sherwood Midstream. As of March 31, 2022, MPLX has a 24.55 percent indirect ownership interest in Sherwood Midstream Holdings through Sherwood Midstream.

MPLX’s maximum exposure to loss as a result of its involvement with equity method investments includes its equity investment, any additional capital contribution commitments and any operating expenses incurred by the subsidiary operator in excess of its compensation received for the performance of the operating services. MPLX did not provide any financial support to equity method investments that it was not contractually obligated to provide during the three months ended March 31, 2022.

Summarized financial information for MPLX’s equity method investments for the three months ended March 31, 2022 and 2021 is as follows:

	Three Months Ended March 31, 2022
(In millions)	VIEs		Non-VIEs		Total
Revenues and other income	$	249	$	308	$	557
Costs and expenses	137		129		266
Income from operations	112		179		291
Net income	103		166		269
Income from equity method investments	$	55	$	44	$	99

	Three Months Ended March 31, 2021
(In millions)	VIEs		Non-VIEs		Total
Revenues and other income	$	163	$	284	$	447
Costs and expenses	107		131		238
Income from operations	56		153		209
Net income	64		140		204
Income from equity method investments	$	39	$	31	$	70

Summarized balance sheet information for MPLX’s equity method investments as of March 31, 2022 and December 31, 2021 is as follows:

	March 31, 2022
(In millions)	VIEs		Non-VIEs		Total
Current assets	$	386	$	370	$	756
Noncurrent assets	7,482		4,875		12,357
Current liabilities	773		259		1,032
Noncurrent liabilities	$	1,929	$	789	$	2,718

	December 31, 2021
(In millions)	VIEs		Non-VIEs		Total
Current assets	$	335	$	411	$	746
Noncurrent assets	7,439		4,895		12,334
Current liabilities	217		310		527
Noncurrent liabilities	$	2,461	$	788	$	3,249

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Related Party Agreements and Transactions

3 Months Ended

Mar. 31, 2022

Related Party Transactions [Abstract]

Related Party Agreements and Transactions

Related Party Agreements and Transactions

MPLX engages in transactions with both MPC and certain of its equity method investments as part of its normal business; however, transactions with MPC make up the majority of MPLX’s related party transactions. Transactions with related parties are further described below.

MPLX has various long-term, fee-based commercial agreements with MPC. Under these agreements, MPLX provides transportation, gathering, terminal, fuels distribution, marketing, storage, management, operational and other services to MPC. MPC has committed to provide MPLX with minimum quarterly throughput volumes on crude oil and refined products, other fees for storage capacity, operating and management fees, as well as reimbursements for certain direct and indirect costs. MPC has also committed to provide a fixed fee for 100 percent of available capacity for boats, barges and third-party chartered equipment under the marine transportation service agreement. MPLX also has a keep-whole commodity agreement with MPC under which MPC pays us a processing fee for NGLs related to keep-whole agreements and delivers shrink gas to the producers on our behalf. We pay MPC a marketing fee in exchange for assuming the commodity risk. Additionally, MPLX has obligations to MPC for services provided to MPLX by MPC under omnibus and employee services-type agreements as well as other agreements.

Related Party Loan

MPLX is party to a loan agreement with MPC Investment LLC (“MPC Investment”) (the “MPC Loan Agreement”). Under the terms of the agreement, MPC Investment extends loans to MPLX on a revolving basis as requested by MPLX and as agreed to by MPC Investment. The borrowing capacity of the MPC Loan Agreement is $1.5 billion aggregate principal amount of all loans outstanding at any one time. The loan agreement is scheduled to expire, and borrowings under the loan agreement are scheduled to mature and become due and payable, on July 31, 2024, provided that MPC Investment may demand payment of all or any portion of the outstanding principal amount of the loan, together with all accrued and unpaid interest and other amounts (if any), at any time prior to maturity. Borrowings under the MPC Loan Agreement bear interest at LIBOR plus 1.25 percent or such lower rate as would be applicable to such loans under the MPLX Credit Agreement as discussed in Note 11.

Activity on the MPC Loan Agreement was as follows:

	Three Months Ended March 31,
(In millions)	2022			2021
Borrowings	$	1,849		$	2,241
Average interest rate of borrowings	1.400		%	1.371		%
Repayments	$	2,976		$	2,241
Outstanding balance at end of period	$	323		$	—

Related Party Revenue

Related party sales to MPC primarily consist of crude oil and refined products pipeline and trucking transportation services based on tariff or contracted rates; storage, terminal and fuels distribution services based on contracted rates; and marine transportation services. Related party sales to MPC also consist of revenue related to volume deficiency credits.

MPLX also has operating agreements with MPC under which it receives a fee for operating MPC’s retained pipeline assets and a fixed annual fee for providing oversight and management services required to run the marine business. MPLX also receives management fee revenue for engineering, construction and administrative services for operating certain of its equity method investments. These agreements are classified as “Other income - related parties” on the Consolidated Statements of Income.

Certain product sales to MPC net to zero within the consolidated financial statements as the transactions are recorded net due to the terms of the agreements under which such product was sold. For the three months ended March 31, 2022 and March 31, 2021, these sales totaled $293 million and $168 million, respectively.

Related Party Expenses

MPC charges MPLX for executive management services and certain general and administrative services to MPLX under the terms of our omnibus agreements (“Omnibus charges”). Omnibus charges included in “Rental cost of sales - related parties” primarily relate to services that support MPLX’s rental operations and maintenance of assets available for rent, as well as compensation expenses. Omnibus charges included in “Purchases - related parties” primarily relate to services that support MPLX’s operations and maintenance activities, as well as compensation expenses. Omnibus charges included in “General and administrative expenses” primarily relate to services that support MPLX’s executive management, accounting and human resources activities. MPLX also obtains employee services from MPC under employee services agreements (“ESA charges”). ESA charges for personnel directly involved in or supporting operations and maintenance activities related to rental services are classified as “Rental cost of sales - related parties.” ESA charges for personnel directly involved in or supporting operations and maintenance activities related to other services are classified as “Purchases - related parties.” ESA charges for personnel involved in executive management, accounting and human resources activities are classified as “General and administrative expenses.” In addition to these agreements, MPLX purchases products from MPC, makes payments to MPC in its capacity as general contractor to MPLX, and has certain lease agreements with MPC.

For the three months ended March 31, 2022 and March 31, 2021, “General and administrative expenses” incurred from MPC totaled $55 million and $57 million, respectively.

Some charges incurred under the omnibus and ESA agreements are related to engineering services and are associated with assets under construction. These charges are added to “Property, plant and equipment, net” on the Consolidated Balance Sheets. For the three months ended March 31, 2022 and March 31, 2021, these charges totaled $19 million and $12 million, respectively.

Related Party Assets and Liabilities

Assets and liabilities with related parties appearing on the Consolidated Balance Sheets are detailed in the table below. This table identifies the various components of related party assets and liabilities, including those associated with leases and deferred revenue on minimum volume commitments. If MPC fails to meet its minimum committed volumes, MPC will pay MPLX a deficiency payment based on the terms of the agreement. The deficiency amounts received under these agreements (excluding payments received under agreements classified as sales-type leases) are recorded as “Current liabilities - related parties.” In many cases, MPC may then apply the amount of any such deficiency payments as a credit for volumes in excess of its minimum volume commitment in future periods under the terms of the applicable agreements. MPLX recognizes related party revenues for the deficiency payments when credits are used for volumes in excess of minimum quarterly volume commitments, where it is probable the customer will not use the credit in future periods or upon the expiration of the credits. The use or expiration of the credits is a decrease in “Current liabilities - related parties.” Deficiency payments under agreements that have been classified as sales-type leases are recorded as a reduction against the corresponding lease receivable. In addition, capital projects MPLX undertakes at the request of MPC are reimbursed in cash and recognized as revenue over the remaining term of the applicable agreements or in some cases, as a contribution from MPC.

(In millions)	March 31, 2022		December 31, 2021
Current assets - related parties
Receivables	$	707	$	555
Prepaid	17		4
Other	3		3
Lease receivables	86		82
Total	813		644
Noncurrent assets - related parties
Long-term receivables	30		31
Right of use assets	229		229
Long-term lease receivables	828		854
Unguaranteed residual asset	64		47
Total	1,151		1,161
Current liabilities - related parties
MPC loan agreement and other payables(1)	606		1,702
Operating lease liabilities	1		1
Deferred revenue - Minimum volume deficiencies	38		35
Deferred revenue - Project reimbursements	42		42
Total	687		1,780
Long-term liabilities - related parties
Long-term operating lease liabilities	228		228
Long-term deferred revenue - Project reimbursements	77		74
Total	$	305	$	302

(1) Includes $323 million as of March 31, 2022 and $1,450 million as of December 31, 2021 related to outstanding borrowings on the intercompany loan with MPC, which are included in “Current liabilities - related parties” on the Consolidated Balance Sheets.

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Equity

3 Months Ended

Mar. 31, 2022

Equity [Abstract]

Equity

Equity

The changes in the number of common units during the three months ended March 31, 2022 are summarized below:

(In units)	Common
Balance at December 31, 2021	1,016,178,378
Unit-based compensation awards	148,951
Units redeemed in unit repurchase program	(3,119,522)
Balance at March 31, 2022	1,013,207,807

Unit Repurchase Program

On November 2, 2020, MPLX announced the board authorization of a unit repurchase program for the repurchase of up to $1 billion of MPLX’s outstanding common units held by the public. MPLX may utilize various methods to effect the repurchases, which could include open market repurchases, negotiated block transactions, tender offers, accelerated unit repurchases or open market solicitations for units, some of which may be effected through Rule 10b5-1 plans. The timing and amount of repurchases will depend upon several factors, including market and business conditions, and repurchases may be initiated, suspended or discontinued at any time. The repurchase authorization has no expiration date. During the three months ended March 31, 2022, we repurchased 3,119,522 common units at an average cost per unit of $32.06 per unit and paid $100 million of cash. As of March 31, 2022, we had $237 million remaining under our repurchase authorization.

Series B Preferred Units

MPLX has 600,000 outstanding units of 6.875 percent Fixed-to-Floating Rate Cumulative Redeemable Perpetual Preferred Units representing limited partner interests of MPLX with a price to the public of $1,000 per unit (the “Series B preferred units”). The Series B preferred units are pari passu with the Series A preferred units with respect to distribution rights and rights upon liquidation. Series B preferred unitholders are entitled to receive a fixed distribution of $68.75 per unit, per annum, payable semi-annually in arrears on the 15th day, or the first business day thereafter, of February and August of each year up to and including February 15, 2023. After February 15, 2023, the holders of Series B preferred units are entitled to receive cumulative, quarterly distributions payable in arrears on the 15th day of February, May, August and November of each year, or the first business day thereafter, based on a floating annual rate equal to the three-month LIBOR plus 4.652 percent, in each case assuming a distribution is declared by the Board of Directors. MPLX has the right to redeem some or all of the Series B preferred units, at any time, on or after February 15, 2023 at the Series B preferred unit redemption price of $1,000 per unit, plus any accumulated and unpaid distributions up to the redemption date.

Cash distributions

On April 26, 2022, MPLX declared a cash distribution for the first quarter of 2022, totaling $713 million, or $0.7050 per common unit. This distribution will be paid on May 13, 2022 to common unitholders of record on May 6, 2022. This rate will also be received by Series A preferred unitholders.

Quarterly distributions for 2022 and 2021 are summarized below:

(Per common unit)	2022		2021
March 31,	$	0.7050	$	0.6875

In accordance with the distribution rights discussed above, MPLX made a cash distribution totaling $21 million to Series B unitholders on February 15, 2022.

The allocation of total quarterly cash distributions to limited and preferred unitholders is as follows for the three months ended March 31, 2022 and 2021. Distributions, although earned, are not accrued until declared. MPLX’s distributions are declared subsequent to quarter end; therefore, the following table represents total cash distributions applicable to the period in which the distributions were earned.

	Three Months Ended March 31,
(In millions)	2022		2021
Common and preferred unit distributions:
Common unitholders, includes common units of general partner	$	713	$	707
Series A preferred unit distributions	21		20
Series B preferred unit distributions	11		11
Total cash distributions declared	$	745	$	738

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Net Income Per Limited Partner Unit

3 Months Ended

Mar. 31, 2022

Earnings Per Share [Abstract]

Earnings Per Share [Text Block]

Net Income/(Loss) Per Limited Partner Unit

Net income/(loss) per unit applicable to common units is computed by dividing net income attributable to MPLX LP less income allocated to participating securities by the weighted average number of common units outstanding.

During the three months ended March 31, 2022 and 2021, MPLX had participating securities consisting of common units, certain equity-based compensation awards, Series A preferred units and Series B preferred units and had dilutive potential common units consisting of certain equity-based compensation awards. Potential common units omitted from the diluted earnings per unit calculation for the three months ended March 31, 2022 and 2021 were less than 1 million.

	Three Months Ended March 31,
(In millions)	2022		2021
Net income attributable to MPLX LP	$	825	$	739
Less: Distributions declared on Series A preferred units	21		20
Distributions declared on Series B preferred units	11		11
Limited partners’ distributions declared on MPLX common units (including common units of general partner)	713		707
Undistributed net gain attributable to MPLX LP	$	80	$	1

	Three Months Ended March 31, 2022
(In millions, except per unit data)	Limited Partners’ Common Units		Series A Preferred Units		Series B Preferred Units		Total
Basic and diluted net income attributable to MPLX LP per unit
Net income attributable to MPLX LP:
Distributions declared	$	713	$	21	$	11	$	745
Undistributed net gain attributable to MPLX LP	78		2		—		80
Net income attributable to MPLX LP(1)	$	791	$	23	$	11	$	825
Weighted average units outstanding:
Basic	1,015
Diluted	1,015
Net income attributable to MPLX LP per limited partner unit:
Basic	$	0.78
Diluted	$	0.78

(1)    Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.

	Three Months Ended March 31, 2021
(In millions, except per unit data)	Limited Partners’ Common Units		Series A Preferred Units		Series B Preferred Units		Total
Basic and diluted net income attributable to MPLX LP per unit
Net income attributable to MPLX LP:
Distributions declared	$	707	$	20	$	11	$	738
Undistributed net gain attributable to MPLX LP	1		—		—		1
Net income attributable to MPLX LP(1)	$	708	$	20	$	11	$	739
Weighted average units outstanding:
Basic	1,037
Diluted	1,037
Net income attributable to MPLX LP per limited partner unit:
Basic	$	0.68
Diluted	$	0.68

(1)    Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.

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Segment Information

3 Months Ended

Mar. 31, 2022

Segment Reporting [Abstract]

Segment Reporting Disclosure [Text Block]

Segment Information

MPLX’s chief operating decision maker is the chief executive officer (“CEO”) of its general partner. The CEO reviews MPLX’s discrete financial information, makes operating decisions, assesses financial performance and allocates resources on a type of service basis. MPLX has two reportable segments: L&S and G&P. Each of these segments is organized and managed based upon the nature of the products and services it offers.

•L&S – transports, gathers, stores and distributes crude oil, refined products, and other hydrocarbon-based products. Also includes the operation of refining logistics, fuels distribution and inland marine businesses, terminals, rail facilities, and storage caverns.

•G&P – gathers, processes and transports natural gas; and gathers, transports, fractionates, stores and markets NGLs.

Our CEO evaluates the performance of our segments using Segment Adjusted EBITDA. Amounts included in net income and excluded from Segment Adjusted EBITDA include: (i) depreciation and amortization; (ii) interest and other financial costs; (iii) impairment expense; (iv) income/(loss) from equity method investments; (v) distributions and adjustments related to equity method investments; (vi) noncontrolling interests; and (vii) other adjustments as deemed necessary. These items are either: (i) believed to be non-recurring in nature; (ii) not believed to be allocable or controlled by the segment; or (iii) are not tied to the operational performance of the segment.

The tables below present information about revenues and other income, Segment Adjusted EBITDA, restructuring expenses, capital expenditures and investments in unconsolidated affiliates for our reportable segments:

	Three Months Ended March 31,
(In millions)	2022		2021
L&S
Service revenue	$	983	$	953
Rental income	175		249
Product related revenue	4		4
Sales-type lease revenue	111		37
Income from equity method investments	52		36
Other income	12		15
Total segment revenues and other income(1)	1,337		1,294
Segment Adjusted EBITDA(2)	904		896
Capital expenditures	77		59
Investments in unconsolidated affiliates	68		9
G&P
Service revenue	486		508
Rental income	81		92
Product related revenue	661		397
Income from equity method investments	47		34
Other income/(loss)	(2)		14
Total segment revenues and other income(1)	1,273		1,045
Segment Adjusted EBITDA(2)	489		456
Capital expenditures	95		30
Investments in unconsolidated affiliates	$	42	$	26

(1)    Within the total segment revenues and other income amounts presented above, third party revenues for the L&S segment were $135 million and $129 million for the three months ended March 31, 2022 and March 31, 2021, respectively. Third party revenues for the G&P segment were $1,212 million and $989 million for the three months ended March 31, 2022 and March 31, 2021, respectively.

(2)    See below for the reconciliation from Segment Adjusted EBITDA to “Net income.”

The table below provides a reconciliation between “Net income” and Segment Adjusted EBITDA.

	Three Months Ended March 31,
(In millions)	2022		2021
Reconciliation to Net income:
L&S Segment Adjusted EBITDA	$	904	$	896
G&P Segment Adjusted EBITDA	489		456
Total reportable segments	1,393		1,352
Depreciation and amortization(1)	(313)		(329)
Interest and other financial costs	(222)		(225)
Income from equity method investments	99		70
Distributions/adjustments related to equity method investments	(132)		(121)
Other	(1)		(9)
Adjusted EBITDA attributable to noncontrolling interests	9		10
Net income	$	833	$	748

(1)    Depreciation and amortization attributable to L&S was $130 million and $147 million for the three months ended March 31, 2022 and March 31, 2021, respectively. Depreciation and amortization attributable to G&P was $183 million and $182 million for the three months ended March 31, 2022 and March 31, 2021, respectively.

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Property, Plant and Equipment

3 Months Ended

Mar. 31, 2022

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

Property, Plant and Equipment

Property, plant and equipment with associated accumulated depreciation is shown below:

	March 31, 2022						December 31, 2021
(In millions)	Gross PP&E		Accumulated Depreciation		Net PP&E		Gross PP&E		Accumulated Depreciation		Net PP&E
L&S	$	12,438	$	3,347	$	9,091	$	12,371	$	3,227	$	9,144
G&P	14,253		3,432		10,821		14,175		3,277		10,898
Total	$	26,691	$	6,779	$	19,912	$	26,546	$	6,504	$	20,042

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Fair Value Measurements

3 Months Ended

Mar. 31, 2022

Fair Value Disclosures [Abstract]

Fair Value Measurements

Fair Value Measurements

Fair Values – Recurring

Fair value measurements and disclosures relate primarily to MPLX’s derivative positions as discussed in Note 10.

Level 3 instruments relate to an embedded derivative liability for a natural gas purchase commitment embedded in a keep-whole processing agreement. The fair value calculation for these Level 3 instruments used significant unobservable inputs including: (1) NGL prices interpolated and extrapolated due to inactive markets ranging from $0.73 to $2.38 per gallon with a weighted average of $0.97 per gallon and (2) the probability of renewal of 100 percent for the five-year renewal term of the gas purchase commitment and related keep-whole processing agreement. Increases or decreases in the fractionation spread result in an increase or decrease in the fair value of the embedded derivative liability, respectively. Beyond the embedded derivative discussed above, we had no outstanding commodity derivative contracts as of March 31, 2022 or December 31, 2021.

Changes in Level 3 Fair Value Measurements

The following table is a reconciliation of the net beginning and ending balances recorded for net assets and liabilities classified as Level 3 in the fair value hierarchy.

	Three Months Ended March 31,
	2022		2021
(In millions)	Embedded Derivatives in Commodity Contracts (net)		Embedded Derivatives in Commodity Contracts (net)
Fair value at beginning of period	$	(108)	$	(63)
Total gain/(loss) (realized and unrealized) included in earnings(1)	4		(6)
Settlements	5		3
Fair value at end of period	(99)		(66)
The amount of total gain/(loss) for the period included in earnings attributable to the change in unrealized gain/(loss) relating to liabilities still held at end of period	$	5	$	(5)

(1)     Gain/(loss) on derivatives embedded in commodity contracts are recorded in “Purchased product costs” on the Consolidated Statements of Income.

Fair Values – Reported

MPLX’s primary financial instruments are cash and cash equivalents, receivables, receivables from related parties, lease receivables from related parties, accounts payable, payables to related parties and debt. MPLX’s fair value assessment incorporates a variety of considerations, including (1) the duration of the instruments, (2) MPC’s investment-grade credit rating and (3) the historical incurrence of and expected future insignificance of bad debt expense, which includes an evaluation of counterparty credit risk. MPLX believes the carrying values of its current assets and liabilities approximate fair value. The recorded value of the amounts outstanding under the bank revolving credit facility, if any, approximates fair value due to the variable interest rate that approximate current market rates. Derivative instruments are recorded at fair value, based on available market information (see Note 10).

The fair value of MPLX’s debt is estimated based on recent market non-binding indicative quotes. The debt fair values are considered Level 3 measurements. The following table summarizes the fair value and carrying value of our third-party debt, excluding finance leases and unamortized debt issuance costs:

	March 31, 2022				December 31, 2021
(In millions)	Fair Value		Carrying Value		Fair Value		Carrying Value
Outstanding debt(1)	$	20,392	$	19,864	$	20,779	$	18,664

(1)    Amounts outstanding under the MPC Loan Agreement are not included in the table above, as the carrying value approximates fair value. This balance is reflected in “Current liabilities - related parties” on the Consolidated Balance Sheets.

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Derivative Financial Instruments

3 Months Ended

Mar. 31, 2022

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivative Instruments and Hedging Activities Disclosure [Text Block]

Derivative Financial Instruments

As of March 31, 2022, MPLX had no commodity contracts beyond the embedded derivative discussed below.

Embedded Derivative - MPLX has a natural gas purchase commitment embedded in a keep-whole processing agreement with a producer customer in the Southern Appalachian region expiring in December 2027. The customer has the unilateral option to extend the agreement for one five-year term through December 2032. For accounting purposes, the natural gas purchase commitment and the term extending option has been aggregated into a single compound embedded derivative. The probability of the customer exercising its option is determined based on assumptions about the customer’s potential business strategy decision points that may exist at the time they would elect whether to renew the contract. The changes in fair value of this compound embedded derivative are based on the difference between the contractual and index pricing, the probability of the producer customer exercising its option to extend and the estimated favorability of these contracts compared to current market conditions. The changes in fair value are recorded in earnings through “Purchased product costs” on the Consolidated Statements of Income. For further information regarding the fair value measurement of derivative instruments, see Note 9. As of March 31, 2022 and December 31, 2021, the estimated fair value of this contract was a liability of $99 million and $108 million, respectively.

Certain derivative positions are subject to master netting agreements, therefore, MPLX has elected to offset derivative assets and liabilities that are legally permissible to be offset. As of March 31, 2022 and December 31, 2021, there were no derivative assets or liabilities that were offset on the Consolidated Balance Sheets. The impact of MPLX’s derivative instruments on its Consolidated Balance Sheets is summarized below:

(In millions)	March 31, 2022				December 31, 2021
Derivative contracts not designated as hedging instruments and their balance sheet location	Asset		Liability		Asset		Liability
Commodity contracts(1)
Other current assets / Other current liabilities	$	—	$	(16)	$	—	$	(15)
Other noncurrent assets / Deferred credits and other liabilities	—		(83)		—		(93)
Total	$	—	$	(99)	$	—	$	(108)

(1)     Includes the embedded derivative in the commodity contract discussed above.

We make a distinction between realized or unrealized gains and losses on derivatives. During the period when a derivative contract is outstanding, changes in the fair value of the derivative are recorded as an unrealized gain or loss. When a derivative contract matures or is settled, the previously recorded unrealized gain or loss is reversed and the realized gain or loss of the contract is recorded. The impact of MPLX’s derivative contracts not designated as hedging instruments and the location of gains and losses recognized on the Consolidated Statements of Income is summarized below:

	Three Months Ended March 31,
(In millions)	2022		2021
Purchased product costs
Realized loss	$	(5)	$	(3)
Unrealized gain/(loss)	9		(3)
Purchased product cost derivative gain/(loss)	$	4	$	(6)

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Debt

3 Months Ended

Mar. 31, 2022

Debt Disclosure [Abstract]

Debt

Debt

MPLX’s outstanding borrowings consist of the following:

(In millions)	March 31, 2022		December 31, 2021
MPLX LP:
MPLX Credit Agreement	$	—	$	300
Fixed rate senior notes	20,032		18,532
Consolidated subsidiaries:
MarkWest	23		23
ANDX	45		45
Financing lease obligations	8		9
Total	20,108		18,909
Unamortized debt issuance costs	(116)		(102)
Unamortized discount/premium	(236)		(236)
Amounts due within one year	(999)		(499)
Total long-term debt due after one year	$	18,757	$	18,072

Credit Agreement

MPLX’s amended and restated credit agreement (as amended, the “MPLX Credit Agreement”), provides for borrowings up to $3.5 billion and a term that extends to July 2024. During the three months ended March 31, 2022, MPLX borrowed $900 million under the MPLX Credit Agreement, at an average interest rate of 1.451 percent, and repaid $1,200 million. At March 31, 2022, MPLX had no outstanding borrowings and less than $1 million in letters of credit outstanding under the MPLX Credit Agreement, resulting in total availability of $3.5 billion, or 100 percent of the borrowing capacity.

Fixed Rate Senior Notes

MPLX’s senior notes, including those issued by consolidated subsidiaries, consist of various series of senior notes maturing between 2022 and 2058 with interest rates ranging from 1.750 percent to 5.500 percent. Interest on each series of notes is payable semi-annually in arrears on various dates depending on the series of the notes.

On March 14, 2022, MPLX issued $1.5 billion aggregate principal amount of 4.950 percent senior notes due March 2052 (the “2052 Senior Notes”) in an underwritten public offering. The 2052 Senior Notes were offered at a price to the public of 98.982 percent with interest payable semi-annually in arrears, commencing on September 14, 2022. The net proceeds were used to repay amounts outstanding under the MPC Intercompany Loan Agreement and the MPLX Credit Agreement.

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Revenue

3 Months Ended

Mar. 31, 2022

Revenue from Contract with Customer [Abstract]

Revenue from Contract with Customer [Text Block]

Revenue

Disaggregation of Revenue

The following tables represent a disaggregation of revenue for each reportable segment for the three months ended March 31, 2022 and 2021:

	Three Months Ended March 31, 2022
(In millions)	L&S		G&P		Total
Revenues and other income:
Service revenue	$	72	$	482	$	554
Service revenue - related parties	911		4		915
Service revenue - product related	—		123		123
Product sales	1		496		497
Product sales - related parties	3		42		45
Total revenues from contracts with customers	$	987	$	1,147	2,134
Non-ASC 606 revenue(1)					476
Total revenues and other income					$	2,610

	Three Months Ended March 31, 2021
(In millions)	L&S		G&P		Total
Revenues and other income:
Service revenue	$	84	$	505	$	589
Service revenue - related parties	869		3		872
Service revenue - product related	—		77		77
Product sales	1		281		282
Product sales - related parties	3		39		42
Total revenues from contracts with customers	$	957	$	905	1,862
Non-ASC 606 revenue(1)					477
Total revenues and other income					$	2,339

(1)    Non-ASC 606 Revenue includes rental income, sales-type lease revenue, income from equity method investments, and other income.

Contract Balances

Contract assets typically relate to deficiency payments related to minimum volume commitments and aid in construction agreements where the revenue recognized and MPLX’s rights to consideration for work completed exceeds the amount billed to the customer. Contract assets are included in “Other current assets” and “Other noncurrent assets” on the Consolidated Balance Sheets.

Contract liabilities, which we refer to as “Deferred revenue” and “Long-term deferred revenue,” typically relate to advance payments for aid in construction agreements and deferred customer credits associated with makeup rights and minimum volume commitments. Related to minimum volume commitments, breakage is estimated and recognized into service revenue in

instances where it is probable the customer will not use the credit in future periods. We classify contract liabilities as current or long-term based on the timing of when we expect to recognize revenue.

“Receivables, net” primarily relate to our commodity sales. Portions of the “Receivables, net” balance are attributed to the sale of commodity product controlled by MPLX prior to sale while a significant portion of the balance relates to the sale of commodity product on behalf of our producer customers. The sales and related “Receivables, net” are commingled and excluded from the table below. MPLX remits the net sales price back to our producer customers upon completion of the sale. Each period end, certain amounts within accounts payable relate to our payments to producer customers. Such amounts are not deemed material at period end as a result of when we settle with each producer.

The tables below reflect the changes in our contract balances for the three-month periods ended March 31, 2022 and 2021:

(In millions)	Balance at December 31, 2021(1)		Additions/ (Deletions)		Revenue Recognized(2)		Balance at March 31, 2022
Contract assets	$	25	$	(18)	$	—	$	7
Long-term contract assets	2		—		—		2
Deferred revenue	56		11		(9)		58
Deferred revenue - related parties	60		34		(26)		68
Long-term deferred revenue	135		2		—		137
Long-term deferred revenue - related parties	31		—		—		31
Long-term contract liabilities	$	5	$	—	$	—	$	5

(In millions)	Balance at December 31, 2020(1)		Additions/ (Deletions)		Revenue Recognized(2)		Balance at March 31, 2021
Contract assets	$	40	$	(27)	$	—	$	13
Long-term contract assets	2		—		—		2
Deferred revenue	37		7		(1)		43
Deferred revenue - related parties	91		21		(20)		92
Long-term deferred revenue	119		4		—		123
Long-term deferred revenue - related parties	48		(4)		—		44
Long-term contract liabilities	$	6	$	—	$	—	$	6

(1)    Balance represents ASC 606 portion of each respective line item.

(2)     No significant revenue was recognized related to past performance obligations in the current periods.

Remaining Performance Obligations

The table below includes estimated revenue expected to be recognized in the future related to performance obligations that are unsatisfied (or partially unsatisfied) at the end of the reporting period.

As of March 31, 2022, the amounts allocated to contract assets and contract liabilities on the Consolidated Balance Sheets are $293 million and are reflected in the amounts below. This will be recognized as revenue as the obligations are satisfied, which is expected to occur over the next 22 years. Further, MPLX does not disclose variable consideration due to volume variability in the table below.

(In millions)
2022	$	1,432
2023	1,771
2024	1,633
2025	1,560
2026 and thereafter	3,362
Total revenue on remaining performance obligations(1)(2)(3)	$	9,758

(1)    All fixed consideration from contracts with customers is included in the amounts presented above. Variable consideration that is constrained or not required to be estimated as it reflects our efforts to perform is excluded.

(2)    Arrangements deemed implicit leases and sales-type leases are excluded from this table.

(3)    Only minimum volume commitments that are deemed fixed are included in the table above. MPLX has various minimum volume commitments in processing arrangements that vary based on the actual Btu content of the gas received. These amounts are deemed variable consideration and are excluded from the table above.

We do not disclose information on the future performance obligations for any contract with an original expected duration of one year or less.

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Supplemental Cash Flow Information

3 Months Ended

Mar. 31, 2022

Supplemental Cash Flow Elements [Abstract]

Supplemental Cash Flow Information [Text Block]

Supplemental Cash Flow Information

	Three Months Ended March 31,
(In millions)	2022		2021
Net cash provided by operating activities included:
Interest paid (net of amounts capitalized)	$	213	$	231

The Consolidated Statements of Cash Flows exclude changes to the Consolidated Balance Sheets that do not affect cash. The following is the change of additions to property, plant and equipment related to capital accruals:

	Three Months Ended March 31,
(In millions)	2022		2021
Increase/(decrease) in capital accruals	$	3	$	(37)

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Commitments and Contingencies

3 Months Ended

Mar. 31, 2022

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies Disclosure [Text Block]

Commitments and Contingencies

MPLX is the subject of, or a party to, a number of pending or threatened legal actions, contingencies and commitments involving a variety of matters, including laws and regulations relating to the environment. Some of these matters are discussed below. For matters for which MPLX has not recorded a liability, MPLX is unable to estimate a range of possible loss because the issues involved have not been fully developed through pleadings, discovery or court proceedings. However, the ultimate resolution of some of these contingencies could, individually or in the aggregate, be material.

Environmental Matters

MPLX is subject to federal, state and local laws and regulations relating to the environment. These laws generally provide for control of pollutants released into the environment and require responsible parties to undertake remediation of hazardous waste disposal sites. Penalties may be imposed for non-compliance.

At March 31, 2022 and December 31, 2021, accrued liabilities for remediation totaled $42 million and $23 million, respectively. It is not presently possible to estimate the ultimate amount of all remediation costs that might be incurred or the penalties, if any, that may be imposed.

MPLX is involved in environmental enforcement matters arising in the ordinary course of business. While the outcome and impact to MPLX cannot be predicted with certainty, management believes the resolution of these environmental matters will not, individually or collectively, have a material adverse effect on its consolidated results of operations, financial position or cash flows.

MPLX is also a party to a number of other lawsuits and other proceedings arising in the ordinary course of business. While the ultimate outcome and impact to MPLX cannot be predicted with certainty, management believes the resolution of these other lawsuits and proceedings will not, individually or collectively, have a material adverse effect on its consolidated financial position, results of operations or cash flows.

Guarantees

Over the years, MPLX has sold various assets in the normal course of its business. Certain of the related agreements contain performance and general guarantees, including guarantees regarding inaccuracies in representations, warranties, covenants and agreements, and environmental and general indemnifications that require MPLX to perform upon the occurrence of a triggering event or condition. These guarantees and indemnifications are part of the normal course of selling assets. MPLX is typically not able to calculate the maximum potential amount of future payments that could be made under such contractual provisions because of the variability inherent in the guarantees and indemnities. Most often, the nature of the guarantees and indemnities is such that there is no appropriate method for quantifying the exposure because the underlying triggering event has little or no past experience upon which a reasonable prediction of the outcome can be based.

We hold a 9.19 percent indirect interest in a joint venture (“Dakota Access”) that owns and operates the Dakota Access Pipeline and Energy Transfer Crude Oil Pipeline projects, collectively referred to as the Bakken Pipeline system or DAPL. In 2020, the

U.S. District Court for the District of Columbia (the “D.D.C.”) ordered the U.S. Army Corps of Engineers (“Army Corps”), which granted permits and an easement for the Bakken Pipeline system, to prepare an environmental impact statement (“EIS”) relating to an easement under Lake Oahe in North Dakota. The D.D.C. later vacated the easement. The EIS is currently expected to be completed in the second half of 2022.

In May 2021, the D.D.C. denied a renewed request for an injunction to shut down the pipeline while the EIS is being prepared. In June 2021, the D.D.C. issued an order dismissing without prejudice the tribes’ claims against the Dakota Access Pipeline. The litigation could be reopened or new litigation challenging the EIS, once completed, could be filed. The pipeline remains operational.

We have entered into a Contingent Equity Contribution Agreement whereby MPLX LP, along with the other joint venture owners in the Bakken Pipeline system, has agreed to make equity contributions to the joint venture upon certain events occurring to allow the entities that own and operate the Bakken Pipeline system to satisfy their senior note payment obligations. The senior notes were issued to repay amounts owed by the pipeline companies to fund the cost of construction of the Bakken Pipeline system. If the pipeline were temporarily shut down, MPLX would have to contribute its 9.19 percent pro rata share of funds required to pay interest accruing on the notes and any portion of the principal that matures while the pipeline is shutdown. MPLX also expects to contribute its 9.19 percent pro rata share of any costs to remediate any deficiencies to reinstate the permit and/or return the pipeline into operation. If the vacatur of the easement permit results in a permanent shutdown of the pipeline, MPLX would have to contribute its 9.19 percent pro rata share of the cost to redeem the bonds (including the one percent redemption premium required pursuant to the indenture governing the notes) and any accrued and unpaid interest. As of March 31, 2022, our maximum potential undiscounted payments under the Contingent Equity Contribution Agreement were approximately $170 million.

Other Legal Proceedings

In July 2020, Tesoro High Plains Pipeline Company, LLC (“THPP”), a subsidiary of MPLX, received a Notification of Trespass Determination from the Bureau of Indian Affairs (“BIA”) relating to a portion of the Tesoro High Plains Pipeline that crosses the Fort Berthold Reservation in North Dakota. The notification demanded the immediate cessation of pipeline operations and assessed trespass damages of approximately $187 million. On appeal, the Assistant Secretary - Indian Affairs issued an order vacating the BIA’s trespass order and remanded to the Regional Director for the BIA Great Plains Region to issue a new decision based on specific criteria. On December 15, 2020, the Regional Director of the BIA issued a new trespass notice to THPP, finding that THPP was in trespass and assessing trespass damages of approximately $4 million (including interest), which has been paid. The order also required that THPP immediately cease and desist use of the portion of the pipeline that crosses the property at issue. THPP has complied with the Regional Director’s December 15, 2020 notice. In March 2021, THPP received a copy of an order purporting to vacate all orders related to THPP’s alleged trespass issued by the BIA between July 2, 2020 and January 14, 2021. The order directs the Regional Director of the BIA to reconsider the issue of THPP’s alleged trespass and issue a new order, if necessary, after all interested parties have had an opportunity to be heard. Subsequently, landowners voluntarily dismissed the suit filed in the District of North Dakota. On April 23, 2021, THPP filed a lawsuit in the District of North Dakota against the United States of America, the U.S. Department of the Interior and the BIA (together, the “U.S. Government Parties”) challenging the March order purporting to vacate all previous orders related to THPP’s alleged trespass.

On February 8, 2022, the U.S. Government Parties filed their answer to THPP’s suit, asserting counterclaims for trespass and ejectment. The U.S. Government Parties claim THPP is in continued trespass with respect to the pipeline and seek disgorgement of pipeline profits from June 1, 2013 to present, removal of the pipeline and remediation. We intend to vigorously defend ourselves against these counterclaims. We continue to work towards a settlement of this matter with holders of the property rights at issue.

Contractual Commitments and Contingencies

From time to time and in the ordinary course of business, MPLX and its affiliates provide guarantees of MPLX’s subsidiaries payment and performance obligations in the G&P segment. Certain natural gas processing and gathering arrangements require MPLX to construct new natural gas processing plants, natural gas gathering pipelines and NGL pipelines and contain certain fees and charges if specified construction milestones are not achieved for reasons other than force majeure. In certain cases, certain producers may have the right to cancel the processing arrangements if there are significant delays that are not due to force majeure. As of March 31, 2022, management does not believe there are any indications that MPLX will not be able to meet the construction milestones, that force majeure does not apply or that such fees and charges will otherwise be triggered.

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Description of the Business and Basis of Presentation Accounting Policies (Policies)

3 Months Ended

Mar. 31, 2022

Accounting Policies [Abstract]

Business Description and Basis of Presentation [Text Block]

Description of the Business and Basis of Presentation

Description of the Business

MPLX LP is a diversified, large-cap master limited partnership formed by Marathon Petroleum Corporation that owns and operates midstream energy infrastructure and logistics assets, and provides fuels distribution services. References in this report to “MPLX LP,” “MPLX,” “the Partnership,” “we,” “ours,” “us,” or like terms refer to MPLX LP and its subsidiaries. References to “MPC” refer collectively to Marathon Petroleum Corporation as our sponsor and its subsidiaries, other than the Partnership. We are engaged in the gathering, transportation, storage and distribution of crude oil, refined products and other hydrocarbon-based products; the gathering, processing and transportation of natural gas; and the gathering, transportation, fractionation, storage and marketing of NGLs. MPLX’s principal executive office is located in Findlay, Ohio.

MPLX’s business consists of two segments based on the nature of services it offers: Logistics and Storage (“L&S”), which relates primarily to crude oil, refined products and other hydrocarbon-based products; and Gathering and Processing (“G&P”), which relates primarily to natural gas and NGLs. See Note 7 for additional information regarding the operations and results of these segments.

Basis of Presentation

The accompanying interim consolidated financial statements are unaudited; however, in the opinion of MPLX’s management, these statements reflect all adjustments necessary for a fair statement of the results for the periods reported. All such adjustments are of a normal, recurring nature unless otherwise disclosed. These interim consolidated financial statements, including the notes, have been prepared in accordance with the rules and regulations of the SEC applicable to interim period financial statements and do not include all of the information and disclosures required by GAAP for complete financial statements. Certain information derived from our audited annual financial statements, prepared in accordance with GAAP, has been condensed or omitted from these interim financial statements.

These interim consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2021. The results of operations for the three months ended March 31, 2022 are not necessarily indicative of the results to be expected for the full year.

MPLX’s consolidated financial statements include all majority-owned and controlled subsidiaries. For non-wholly owned consolidated subsidiaries, the interests owned by third parties have been recorded as “Noncontrolling interests” on the accompanying Consolidated Balance Sheets. Intercompany investments, accounts and transactions have been eliminated. MPLX’s investments in which MPLX exercises significant influence but does not control and does not have a controlling financial interest are accounted for using the equity method. MPLX’s investments in VIEs in which MPLX exercises significant influence but does not control and is not the primary beneficiary are also accounted for using the equity method.

Certain prior period financial statement amounts have been reclassified to conform to current period presentation.

Use of Estimates, Policy [Policy Text Block]

The accompanying interim consolidated financial statements are unaudited; however, in the opinion of MPLX’s management, these statements reflect all adjustments necessary for a fair statement of the results for the periods reported. All such adjustments are of a normal, recurring nature unless otherwise disclosed. These interim consolidated financial statements, including the notes, have been prepared in accordance with the rules and regulations of the SEC applicable to interim period financial statements and do not include all of the information and disclosures required by GAAP for complete financial statements. Certain information derived from our audited annual financial statements, prepared in accordance with GAAP, has been condensed or omitted from these interim financial statements.

Consolidation, Subsidiaries or Other Investments, Consolidated Entities, Policy [Policy Text Block]

MPLX’s consolidated financial statements include all majority-owned and controlled subsidiaries. For non-wholly owned consolidated subsidiaries, the interests owned by third parties have been recorded as “Noncontrolling interests” on the accompanying Consolidated Balance Sheets. Intercompany investments, accounts and transactions have been eliminated. MPLX’s investments in which MPLX exercises significant influence but does not control and does not have a controlling financial interest are accounted for using the equity method. MPLX’s investments in VIEs in which MPLX exercises significant influence but does not control and is not the primary beneficiary are also accounted for using the equity method.Certain prior period financial statement amounts have been reclassified to conform to current period presentation.

Nature of Operations

We are engaged in the gathering, transportation, storage and distribution of crude oil, refined products and other hydrocarbon-based products; the gathering, processing and transportation of natural gas; and the gathering, transportation, fractionation, storage and marketing of NGLs. MPLX’s principal executive office is located in Findlay, Ohio.MPLX’s business consists of two segments based on the nature of services it offers: Logistics and Storage (“L&S”), which relates primarily to crude oil, refined products and other hydrocarbon-based products; and Gathering and Processing (“G&P”), which relates primarily to natural gas and NGLs. See Note 7 for additional information regarding the operations and results of these segments.

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Net Income Per Limited Partner Unit Accounting Policy (Policies)	3 Months Ended
	Mar. 31, 2022
Accounting Policies [Abstract]
Earnings Per Share, Policy [Policy Text Block]	Net income/(loss) per unit applicable to common units is computed by dividing net income attributable to MPLX LP less income allocated to participating securities by the weighted average number of common units outstanding.

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Investments and Noncontrolling Interests (Tables)

3 Months Ended

Mar. 31, 2022

Equity Method Investments and Joint Ventures [Abstract]

Equity Method Investments [Table Text Block]

The following table presents MPLX’s equity method investments at the dates indicated:

	Ownership as of	Carrying value at
	March 31,	March 31,		December 31,
(In millions, except ownership percentages)	2022	2022		2021
L&S
MarEn Bakken Company LLC(1)	25%	$	502	$	449
Illinois Extension Pipeline Company, L.L.C.	35%	249		243
LOOP LLC	41%	274		265
Andeavor Logistics Rio Pipeline LLC(2)	67%	181		183
Minnesota Pipe Line Company, LLC	17%	182		183
Whistler Pipeline LLC(2)	38%	166		155
Explorer Pipeline Company	25%	65		66
W2W Holdings LLC(2)	50%	56		58
Other(2)		125		116
Total L&S		1,800		1,718
G&P
MarkWest Utica EMG, L.L.C.(2)	57%	681		680
Sherwood Midstream LLC(2)	50%	539		544
MarkWest EMG Jefferson Dry Gas Gathering Company, L.L.C.(2)	67%	336		332
MarkWest Torñado GP, L.L.C.(2)	60%	266		246
Rendezvous Gas Services, L.L.C.(2)	78%	145		147
Sherwood Midstream Holdings LLC(2)	51%	133		136
Centrahoma Processing LLC	40%	133		133
Other(2)		46		45
Total G&P		2,279		2,263
Total		$	4,079	$	3,981

(1)    The investment in MarEn Bakken Company LLC includes our 9.19 percent indirect interest in a joint venture (“Dakota Access”) that owns and operates the Dakota Access Pipeline and Energy Transfer Crude Oil Pipeline projects, collectively referred to as the Bakken Pipeline system or DAPL.    

(2)    Investments deemed to be VIEs. Some investments included within “Other” have also been deemed to be VIEs.

Summarized Financial Information For Equity Method Investees Table [Table Text Block]

Summarized financial information for MPLX’s equity method investments for the three months ended March 31, 2022 and 2021 is as follows:

	Three Months Ended March 31, 2022
(In millions)	VIEs		Non-VIEs		Total
Revenues and other income	$	249	$	308	$	557
Costs and expenses	137		129		266
Income from operations	112		179		291
Net income	103		166		269
Income from equity method investments	$	55	$	44	$	99

	Three Months Ended March 31, 2021
(In millions)	VIEs		Non-VIEs		Total
Revenues and other income	$	163	$	284	$	447
Costs and expenses	107		131		238
Income from operations	56		153		209
Net income	64		140		204
Income from equity method investments	$	39	$	31	$	70

Summarized balance sheet information for MPLX’s equity method investments as of March 31, 2022 and December 31, 2021 is as follows:

	March 31, 2022
(In millions)	VIEs		Non-VIEs		Total
Current assets	$	386	$	370	$	756
Noncurrent assets	7,482		4,875		12,357
Current liabilities	773		259		1,032
Noncurrent liabilities	$	1,929	$	789	$	2,718

	December 31, 2021
(In millions)	VIEs		Non-VIEs		Total
Current assets	$	335	$	411	$	746
Noncurrent assets	7,439		4,895		12,334
Current liabilities	217		310		527
Noncurrent liabilities	$	2,461	$	788	$	3,249

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Related Party Agreements and Transactions (Tables)

3 Months Ended

Mar. 31, 2022

Related Party Transactions [Abstract]

Schedule of Short-term Debt

Activity on the MPC Loan Agreement was as follows:

	Three Months Ended March 31,
(In millions)	2022			2021
Borrowings	$	1,849		$	2,241
Average interest rate of borrowings	1.400		%	1.371		%
Repayments	$	2,976		$	2,241
Outstanding balance at end of period	$	323		$	—

Schedule of Related Party Transactions [Table Text Block]

(In millions)	March 31, 2022		December 31, 2021
Current assets - related parties
Receivables	$	707	$	555
Prepaid	17		4
Other	3		3
Lease receivables	86		82
Total	813		644
Noncurrent assets - related parties
Long-term receivables	30		31
Right of use assets	229		229
Long-term lease receivables	828		854
Unguaranteed residual asset	64		47
Total	1,151		1,161
Current liabilities - related parties
MPC loan agreement and other payables(1)	606		1,702
Operating lease liabilities	1		1
Deferred revenue - Minimum volume deficiencies	38		35
Deferred revenue - Project reimbursements	42		42
Total	687		1,780
Long-term liabilities - related parties
Long-term operating lease liabilities	228		228
Long-term deferred revenue - Project reimbursements	77		74
Total	$	305	$	302

(1) Includes $323 million as of March 31, 2022 and $1,450 million as of December 31, 2021 related to outstanding borrowings on the intercompany loan with MPC, which are included in “Current liabilities - related parties” on the Consolidated Balance Sheets.

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Equity (Tables)

3 Months Ended

Mar. 31, 2022

Equity [Abstract]

Schedule of Stockholders Equity [Table Text Block]

The changes in the number of common units during the three months ended March 31, 2022 are summarized below:

(In units)	Common
Balance at December 31, 2021	1,016,178,378
Unit-based compensation awards	148,951
Units redeemed in unit repurchase program	(3,119,522)
Balance at March 31, 2022	1,013,207,807

Distributions Made to Limited Partner, by Distribution [Table Text Block]

The allocation of total quarterly cash distributions to limited and preferred unitholders is as follows for the three months ended March 31, 2022 and 2021. Distributions, although earned, are not accrued until declared. MPLX’s distributions are declared subsequent to quarter end; therefore, the following table represents total cash distributions applicable to the period in which the distributions were earned.

	Three Months Ended March 31,
(In millions)	2022		2021
Common and preferred unit distributions:
Common unitholders, includes common units of general partner	$	713	$	707
Series A preferred unit distributions	21		20
Series B preferred unit distributions	11		11
Total cash distributions declared	$	745	$	738

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Net Income Per Limited Partner Unit (Tables)

3 Months Ended

Mar. 31, 2022

Earnings Per Share [Abstract]

Schedule of Distributions By Partner By Class [Table Text Block]

During the three months ended March 31, 2022 and 2021, MPLX had participating securities consisting of common units, certain equity-based compensation awards, Series A preferred units and Series B preferred units and had dilutive potential common units consisting of certain equity-based compensation awards. Potential common units omitted from the diluted earnings per unit calculation for the three months ended March 31, 2022 and 2021 were less than 1 million.

	Three Months Ended March 31,
(In millions)	2022		2021
Net income attributable to MPLX LP	$	825	$	739
Less: Distributions declared on Series A preferred units	21		20
Distributions declared on Series B preferred units	11		11
Limited partners’ distributions declared on MPLX common units (including common units of general partner)	713		707
Undistributed net gain attributable to MPLX LP	$	80	$	1

Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]

	Three Months Ended March 31, 2022
(In millions, except per unit data)	Limited Partners’ Common Units		Series A Preferred Units		Series B Preferred Units		Total
Basic and diluted net income attributable to MPLX LP per unit
Net income attributable to MPLX LP:
Distributions declared	$	713	$	21	$	11	$	745
Undistributed net gain attributable to MPLX LP	78		2		—		80
Net income attributable to MPLX LP(1)	$	791	$	23	$	11	$	825
Weighted average units outstanding:
Basic	1,015
Diluted	1,015
Net income attributable to MPLX LP per limited partner unit:
Basic	$	0.78
Diluted	$	0.78

(1)    Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.

	Three Months Ended March 31, 2021
(In millions, except per unit data)	Limited Partners’ Common Units		Series A Preferred Units		Series B Preferred Units		Total
Basic and diluted net income attributable to MPLX LP per unit
Net income attributable to MPLX LP:
Distributions declared	$	707	$	20	$	11	$	738
Undistributed net gain attributable to MPLX LP	1		—		—		1
Net income attributable to MPLX LP(1)	$	708	$	20	$	11	$	739
Weighted average units outstanding:
Basic	1,037
Diluted	1,037
Net income attributable to MPLX LP per limited partner unit:
Basic	$	0.68
Diluted	$	0.68

(1)    Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.

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Segment Information (Tables)

3 Months Ended

Mar. 31, 2022

Segment Reporting [Abstract]

Schedule of Segment Reporting Information, by Segment [Table Text Block]

The tables below present information about revenues and other income, Segment Adjusted EBITDA, restructuring expenses, capital expenditures and investments in unconsolidated affiliates for our reportable segments:

	Three Months Ended March 31,
(In millions)	2022		2021
L&S
Service revenue	$	983	$	953
Rental income	175		249
Product related revenue	4		4
Sales-type lease revenue	111		37
Income from equity method investments	52		36
Other income	12		15
Total segment revenues and other income(1)	1,337		1,294
Segment Adjusted EBITDA(2)	904		896
Capital expenditures	77		59
Investments in unconsolidated affiliates	68		9
G&P
Service revenue	486		508
Rental income	81		92
Product related revenue	661		397
Income from equity method investments	47		34
Other income/(loss)	(2)		14
Total segment revenues and other income(1)	1,273		1,045
Segment Adjusted EBITDA(2)	489		456
Capital expenditures	95		30
Investments in unconsolidated affiliates	$	42	$	26

(1)    Within the total segment revenues and other income amounts presented above, third party revenues for the L&S segment were $135 million and $129 million for the three months ended March 31, 2022 and March 31, 2021, respectively. Third party revenues for the G&P segment were $1,212 million and $989 million for the three months ended March 31, 2022 and March 31, 2021, respectively.

(2)    See below for the reconciliation from Segment Adjusted EBITDA to “Net income.”

Reconciliation of Other Significant Reconciling Items from Segments to Consolidated [Table Text Block]

The table below provides a reconciliation between “Net income” and Segment Adjusted EBITDA.

	Three Months Ended March 31,
(In millions)	2022		2021
Reconciliation to Net income:
L&S Segment Adjusted EBITDA	$	904	$	896
G&P Segment Adjusted EBITDA	489		456
Total reportable segments	1,393		1,352
Depreciation and amortization(1)	(313)		(329)
Interest and other financial costs	(222)		(225)
Income from equity method investments	99		70
Distributions/adjustments related to equity method investments	(132)		(121)
Other	(1)		(9)
Adjusted EBITDA attributable to noncontrolling interests	9		10
Net income	$	833	$	748

(1)    Depreciation and amortization attributable to L&S was $130 million and $147 million for the three months ended March 31, 2022 and March 31, 2021, respectively. Depreciation and amortization attributable to G&P was $183 million and $182 million for the three months ended March 31, 2022 and March 31, 2021, respectively.

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Property, Plant and Equipment (Tables)

3 Months Ended

Mar. 31, 2022

Property, Plant and Equipment [Abstract]

Summary of Property, Plant and Equipment

Property, plant and equipment with associated accumulated depreciation is shown below:

	March 31, 2022						December 31, 2021
(In millions)	Gross PP&E		Accumulated Depreciation		Net PP&E		Gross PP&E		Accumulated Depreciation		Net PP&E
L&S	$	12,438	$	3,347	$	9,091	$	12,371	$	3,227	$	9,144
G&P	14,253		3,432		10,821		14,175		3,277		10,898
Total	$	26,691	$	6,779	$	19,912	$	26,546	$	6,504	$	20,042

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Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2022

Fair Value Disclosures [Abstract]

Fair Value Inputs Assets and Liabilities Quantitative Information [Table Text Block]

Level 3 instruments relate to an embedded derivative liability for a natural gas purchase commitment embedded in a keep-whole processing agreement. The fair value calculation for these Level 3 instruments used significant unobservable inputs including: (1) NGL prices interpolated and extrapolated due to inactive markets ranging from $0.73 to $2.38 per gallon with a weighted average of $0.97 per gallon and (2) the probability of renewal of 100 percent for the five-year renewal term of the gas purchase commitment and related keep-whole processing agreement. Increases or decreases in the fractionation spread result in an increase or decrease in the fair value of the embedded derivative liability, respectively. Beyond the embedded derivative discussed above, we had no outstanding commodity derivative contracts as of March 31, 2022 or December 31, 2021.

Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]

The following table is a reconciliation of the net beginning and ending balances recorded for net assets and liabilities classified as Level 3 in the fair value hierarchy.

	Three Months Ended March 31,
	2022		2021
(In millions)	Embedded Derivatives in Commodity Contracts (net)		Embedded Derivatives in Commodity Contracts (net)
Fair value at beginning of period	$	(108)	$	(63)
Total gain/(loss) (realized and unrealized) included in earnings(1)	4		(6)
Settlements	5		3
Fair value at end of period	(99)		(66)
The amount of total gain/(loss) for the period included in earnings attributable to the change in unrealized gain/(loss) relating to liabilities still held at end of period	$	5	$	(5)

(1)     Gain/(loss) on derivatives embedded in commodity contracts are recorded in “Purchased product costs” on the Consolidated Statements of Income.

Fair Value Carrying Value by Balance Sheet Grouping [Table Text Block]

The following table summarizes the fair value and carrying value of our third-party debt, excluding finance leases and unamortized debt issuance costs:

	March 31, 2022				December 31, 2021
(In millions)	Fair Value		Carrying Value		Fair Value		Carrying Value
Outstanding debt(1)	$	20,392	$	19,864	$	20,779	$	18,664

(1)    Amounts outstanding under the MPC Loan Agreement are not included in the table above, as the carrying value approximates fair value. This balance is reflected in “Current liabilities - related parties” on the Consolidated Balance Sheets.

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Derivative Financial Instruments (Tables)

3 Months Ended

Mar. 31, 2022

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block]

The impact of MPLX’s derivative instruments on its Consolidated Balance Sheets is summarized below:

(In millions)	March 31, 2022				December 31, 2021
Derivative contracts not designated as hedging instruments and their balance sheet location	Asset		Liability		Asset		Liability
Commodity contracts(1)
Other current assets / Other current liabilities	$	—	$	(16)	$	—	$	(15)
Other noncurrent assets / Deferred credits and other liabilities	—		(83)		—		(93)
Total	$	—	$	(99)	$	—	$	(108)

(1)     Includes the embedded derivative in the commodity contract discussed above.

Derivative Instruments, Gain (Loss) [Table Text Block]

The impact of MPLX’s derivative contracts not designated as hedging instruments and the location of gains and losses recognized on the Consolidated Statements of Income is summarized below:

	Three Months Ended March 31,
(In millions)	2022		2021
Purchased product costs
Realized loss	$	(5)	$	(3)
Unrealized gain/(loss)	9		(3)
Purchased product cost derivative gain/(loss)	$	4	$	(6)

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Debt (Tables)

3 Months Ended

Mar. 31, 2022

Debt Disclosure [Abstract]

Schedule of Debt [Table Text Block]

MPLX’s outstanding borrowings consist of the following:

(In millions)	March 31, 2022		December 31, 2021
MPLX LP:
MPLX Credit Agreement	$	—	$	300
Fixed rate senior notes	20,032		18,532
Consolidated subsidiaries:
MarkWest	23		23
ANDX	45		45
Financing lease obligations	8		9
Total	20,108		18,909
Unamortized debt issuance costs	(116)		(102)
Unamortized discount/premium	(236)		(236)
Amounts due within one year	(999)		(499)
Total long-term debt due after one year	$	18,757	$	18,072

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Revenue (Tables)

3 Months Ended

Mar. 31, 2022

Revenue from Contract with Customer [Abstract]

Disaggregation of Revenue [Table Text Block]

The following tables represent a disaggregation of revenue for each reportable segment for the three months ended March 31, 2022 and 2021:

	Three Months Ended March 31, 2022
(In millions)	L&S		G&P		Total
Revenues and other income:
Service revenue	$	72	$	482	$	554
Service revenue - related parties	911		4		915
Service revenue - product related	—		123		123
Product sales	1		496		497
Product sales - related parties	3		42		45
Total revenues from contracts with customers	$	987	$	1,147	2,134
Non-ASC 606 revenue(1)					476
Total revenues and other income					$	2,610

	Three Months Ended March 31, 2021
(In millions)	L&S		G&P		Total
Revenues and other income:
Service revenue	$	84	$	505	$	589
Service revenue - related parties	869		3		872
Service revenue - product related	—		77		77
Product sales	1		281		282
Product sales - related parties	3		39		42
Total revenues from contracts with customers	$	957	$	905	1,862
Non-ASC 606 revenue(1)					477
Total revenues and other income					$	2,339

(1)    Non-ASC 606 Revenue includes rental income, sales-type lease revenue, income from equity method investments, and other income.

Contract with Customer, Contract Asset, Contract Liability, and Receivable [Table Text Block]

The tables below reflect the changes in our contract balances for the three-month periods ended March 31, 2022 and 2021:

(In millions)	Balance at December 31, 2021(1)		Additions/ (Deletions)		Revenue Recognized(2)		Balance at March 31, 2022
Contract assets	$	25	$	(18)	$	—	$	7
Long-term contract assets	2		—		—		2
Deferred revenue	56		11		(9)		58
Deferred revenue - related parties	60		34		(26)		68
Long-term deferred revenue	135		2		—		137
Long-term deferred revenue - related parties	31		—		—		31
Long-term contract liabilities	$	5	$	—	$	—	$	5

(In millions)	Balance at December 31, 2020(1)		Additions/ (Deletions)		Revenue Recognized(2)		Balance at March 31, 2021
Contract assets	$	40	$	(27)	$	—	$	13
Long-term contract assets	2		—		—		2
Deferred revenue	37		7		(1)		43
Deferred revenue - related parties	91		21		(20)		92
Long-term deferred revenue	119		4		—		123
Long-term deferred revenue - related parties	48		(4)		—		44
Long-term contract liabilities	$	6	$	—	$	—	$	6

(1)    Balance represents ASC 606 portion of each respective line item.

(2)     No significant revenue was recognized related to past performance obligations in the current periods.

Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table Text Block]

As of March 31, 2022, the amounts allocated to contract assets and contract liabilities on the Consolidated Balance Sheets are $293 million and are reflected in the amounts below. This will be recognized as revenue as the obligations are satisfied, which is expected to occur over the next 22 years. Further, MPLX does not disclose variable consideration due to volume variability in the table below.

(In millions)
2022	$	1,432
2023	1,771
2024	1,633
2025	1,560
2026 and thereafter	3,362
Total revenue on remaining performance obligations(1)(2)(3)	$	9,758

(1)    All fixed consideration from contracts with customers is included in the amounts presented above. Variable consideration that is constrained or not required to be estimated as it reflects our efforts to perform is excluded.

(2)    Arrangements deemed implicit leases and sales-type leases are excluded from this table.

(3)    Only minimum volume commitments that are deemed fixed are included in the table above. MPLX has various minimum volume commitments in processing arrangements that vary based on the actual Btu content of the gas received. These amounts are deemed variable consideration and are excluded from the table above.

We do not disclose information on the future performance obligations for any contract with an original expected duration of one year or less.

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Supplemental Cash Flow Information (Tables)

3 Months Ended

Mar. 31, 2022

Supplemental Cash Flow Elements [Abstract]

Summary of Supplemental Cash Flow Information [Table Text Block]

	Three Months Ended March 31,
(In millions)	2022		2021
Net cash provided by operating activities included:
Interest paid (net of amounts capitalized)	$	213	$	231

Summary of Reconciliation of Additions to Property, Plant and Equipment to Total Capital Expenditures [Table Text Block]

The Consolidated Statements of Cash Flows exclude changes to the Consolidated Balance Sheets that do not affect cash. The following is the change of additions to property, plant and equipment related to capital accruals:

	Three Months Ended March 31,
(In millions)	2022		2021
Increase/(decrease) in capital accruals	$	3	$	(37)

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Description of Business and Basis of Presentation - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2022
Accounting Policies [Abstract]
Number of reportable segments	2

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Investments and Noncontrolling Interests (Summary of Equity Method Investment Financial Information) (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Schedule of Equity Method Investments [Line Items]
Equity method investments		$ 4,079		$ 3,981
Revenues		2,610	$ 2,339
Costs and Expenses		1,550	1,365
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		833	748
Income from equity method investments		99	70
Assets, Current		1,798		1,507
Liabilities, Current		$ 2,858		3,348
MarEn Bakken Company LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		25.00%
Illinois Extension
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		35.00%
LOOP
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		41.00%
Andeavor Logistics Rio Pipeline [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		67.00%
Minnesota Pipe Line Company, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		17.00%
Whistler Pipeline LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		38.00%
Explorer
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		25.00%
W2W Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		50.00%
MarkWest Utica EMG
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		57.00%
Sherwood Midstream
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		50.00%
MarkWest EMG Jefferson Dry Gas Gathering Company, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		67.00%
MarkWest Tornado GP, L.L.C.
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		60.00%
Rendezvous Gas Services, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		78.00%
Centrahoma Processing LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		40.00%
Indirect Ownership Interest [Member] | Bakken Pipeline System [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		9.19%
Indirect Ownership Interest [Member] | Sherwood Midstream Holdings
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		24.55%
Direct Ownership Interest [Member] | Sherwood Midstream Holdings
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		51.00%
G&P | MarkWest Utica EMG
Schedule of Equity Method Investments [Line Items]
Equity method investments	[1]	$ 681		680
G&P | Sherwood Midstream
Schedule of Equity Method Investments [Line Items]
Equity method investments	[1]	539		544
G&P | MarkWest EMG Jefferson Dry Gas Gathering Company, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[1]	336		332
G&P | MarkWest Tornado GP, L.L.C.
Schedule of Equity Method Investments [Line Items]
Equity method investments	[1]	266		246
G&P | Rendezvous Gas Services, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[1]	145		147
G&P | Sherwood Midstream Holdings
Schedule of Equity Method Investments [Line Items]
Equity method investments	[1]	133		136
G&P | Centrahoma Processing LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments		133		133
G&P | Other VIEs and Non-VIEs [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[1]	46		45
L&S | MarEn Bakken Company LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[2]	502		449
L&S | Illinois Extension
Schedule of Equity Method Investments [Line Items]
Equity method investments		249		243
L&S | LOOP
Schedule of Equity Method Investments [Line Items]
Equity method investments		274		265
L&S | Andeavor Logistics Rio Pipeline [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[1]	181		183
L&S | Minnesota Pipe Line Company, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments		182		183
L&S | Whistler Pipeline LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[1]	166		155
L&S | Explorer
Schedule of Equity Method Investments [Line Items]
Equity method investments		65		66
L&S | W2W Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[1]	56		58
L&S | Other VIEs and Non-VIEs [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[1]	125		116
Operating Segments | G&P
Schedule of Equity Method Investments [Line Items]
Equity method investments		2,279		2,263
Revenues	[3]	1,273	1,045
Income from equity method investments		47	34
Operating Segments | L&S
Schedule of Equity Method Investments [Line Items]
Equity method investments		1,800		1,718
Revenues	[3]	1,337	1,294
Income from equity method investments		52	36
Other VIEs and Non-VIEs [Member]
Schedule of Equity Method Investments [Line Items]
Revenues		557	447
Costs and Expenses		266	238
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest		291	209
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		269	204
Assets, Current		756		746
Assets, Noncurrent		12,357		12,334
Liabilities, Current		1,032		527
Liabilities, Noncurrent		2,718		3,249
Non-VIEs [Member]
Schedule of Equity Method Investments [Line Items]
Revenues		308	284
Costs and Expenses		129	131
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest		179	153
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		166	140
Income from equity method investments		44	31
Assets, Current		370		411
Assets, Noncurrent		4,875		4,895
Liabilities, Current		259		310
Liabilities, Noncurrent		789		788
Other VIEs [Member]
Schedule of Equity Method Investments [Line Items]
Revenues		249	163
Costs and Expenses		137	107
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest		112	56
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		103	64
Income from equity method investments		55	$ 39
Assets, Current		386		335
Assets, Noncurrent		7,482		7,439
Liabilities, Current		773		217
Liabilities, Noncurrent		$ 1,929		$ 2,461

[1] Investments deemed to be VIEs. Some investments included within “Other” have also been deemed to be VIEs.

[2] The investment in MarEn Bakken Company LLC includes our 9.19 percent indirect interest in a joint venture (“Dakota Access”) that owns and operates the Dakota Access Pipeline and Energy Transfer Crude Oil Pipeline projects, collectively referred to as the Bakken Pipeline system or DAPL.

[3] Within the total segment revenues and other income amounts presented above, third party revenues for the L&S segment were $135 million and $129 million for the three months ended March 31, 2022 and March 31, 2021, respectively. Third party revenues for the G&P segment were $1,212 million and $989 million for the three months ended March 31, 2022 and March 31, 2021, respectively.

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Related Party Agreements and Transactions MPC Loan Agreement (Details) - Related Party Revolving Credit Agreement [Member] - MPC Investment [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Related Party Transaction [Line Items]
Line of Credit Facility, Current Borrowing Capacity	$ 1,500
Debt Instrument, Description of Variable Rate Basis	LIBOR plus 1.25 percent
Related party debt - borrowings	$ 1,849	$ 2,241
Line of Credit Facility, Interest Rate During Period	1.40%	1.371%
Repayments of Lines of Credit	$ 2,976	$ 2,241
Line of Credit, Current	$ 323	$ 0	$ 1,450

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Related Party Disclosures (Details) - Marathon Petroleum Corporation [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Related Party Transaction [Line Items]
Sales Revenue, Goods, Related Party, Net Zero	$ 293	$ 168
Asset under Construction [Member]
Related Party Transaction [Line Items]
Property, Plant and Equipment, Additions	$ 19	$ 12

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Summary of Charges for Employee Services and Omnibus Agreements (Details) - Marathon Petroleum Corporation [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Related Party Transaction [Line Items]
General and Administrative Expense	$ 55	$ 57
Asset under Construction [Member]
Related Party Transaction [Line Items]
Property, Plant and Equipment, Additions	$ 19	$ 12

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Other Assets and Liabilities from Related Parties (Details) - USD ($) $ in Millions		Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021
Affiliated Entity
Related Party Transaction [Line Items]
Accounts Receivable, Related Parties, Current		$ 707	$ 555
Prepaid Insurance		17	4
Other current assets		3	3
Sales-type Lease, Interest Income		86	82
Current Assets, Related Parties		813	644
Accounts Receivable, Related Parties, Noncurrent		30	31
Due from Related Parties, Noncurrent		1,151	1,161
Accounts Payable, Related Parties, Current	[1]	606	1,702
Operating Lease, Right-of-Use Asset		229	229
Net Investment in Lease, Noncurrent		828	854
Sales-type Lease, Unguaranteed Residual Asset		64	47
Due to Related Parties, Current		687	1,780
Operating Lease, Liability, Current		1	1
Operating Lease, Liability, Noncurrent		228	228
Liabilities, Related Parties, Noncurrent		305	302
MPC Investment [Member] | Related Party Revolving Credit Agreement [Member]
Related Party Transaction [Line Items]
Line of Credit, Current		323	1,450	$ 0
Minimum Committed Volume Contracts [Member] | Affiliated Entity
Related Party Transaction [Line Items]
Deferred Revenue Related Parties		38	35
Reimbursable Projects [Member] | Affiliated Entity
Related Party Transaction [Line Items]
Deferred Revenue Related Parties		42	42
Deferred Revenue, Noncurrent, Related Parties		$ 77	$ 74

[1] Includes $323 million as of March 31, 2022 and $1,450 million as of December 31, 2021 related to outstanding borrowings on the intercompany loan with MPC, which are included in “Current liabilities - related parties” on the Consolidated Balance Sheets.

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Equity - Changes in Partners Capital, Unit Rollforward (Details) - USD ($) $ / shares in Units, $ in Millions				3 Months Ended		11 Months Ended
	Apr. 26, 2022	Feb. 15, 2022	Apr. 27, 2021	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2023	Dec. 31, 2021	Nov. 02, 2020
Stockholders Equity [Line Items]
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders				$ (746)	$ (745)
Distribution Made to Limited Partner, Cash Distributions Declared				$ 745	738
Stock Repurchase Program, Authorized Amount								$ 1,000
Treasury Stock Acquired, Average Cost Per Share				$ 32.06
Stock Repurchase Program, Remaining Authorized Repurchase Amount				$ 237
Cash distributions declared per limited partner common unit			$ 0.6875
Payments for Repurchase of Common Stock				$ 100	155
Limited Partners Common Units [Member]
Stockholders Equity [Line Items]
Balance at December 31, 2021				1,016,178,378
Unit-based compensation awards				148,951
Stock Repurchased and Retired During Period, Shares				3,119,522
Balance at March 31, 2022				1,013,207,807
Distribution Made to Limited Partner, Cash Distributions Declared				$ 713	707
Series B Preferred Stock [Member]
Stockholders Equity [Line Items]
Preferred Units, Outstanding				600,000			600,000
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders				$ (21)	(21)
Subsequent Event
Stockholders Equity [Line Items]
Cash distributions declared per limited partner common unit	$ 0.7050
Series B Preferred Stock [Member]
Stockholders Equity [Line Items]
Preferred Units, Outstanding				600,000
Dividend rate, percentage				6.875%
Price per share				$ 1,000
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders		$ (21)
Preferred Stock, Redemption Terms				MPLX has the right to redeem some or all of the Series B preferred units, at any time, on or after February 15, 2023 at the Series B preferred unit redemption price of $1,000 per unit, plus any accumulated and unpaid distributions up to the redemption date.
Series B Preferred Stock [Member] | Preferred Partner [Member]
Stockholders Equity [Line Items]
Distribution Made to Limited Partner, Cash Distributions Declared				$ 11	$ 11
Cash distributions declared per limited partner common unit				$ 68.75
Series B Preferred Stock [Member] | Subsequent Event
Stockholders Equity [Line Items]
Dividend rate, percentage						4.652%
Preferred Stock, Dividend Payment Rate, Variable						LIBOR plus

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Equity - Cash Distributions (Details) - USD ($) $ / shares in Units, $ in Millions						3 Months Ended		11 Months Ended
	May 13, 2022	May 06, 2022	Apr. 26, 2022	Feb. 15, 2022	Apr. 27, 2021	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2023
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Distribution Made to Limited Partner, Cash Distributions Declared						$ 745	$ 738
Cash distributions declared per limited partner common unit					$ 0.6875
Partners' Capital Account, Distributions						$ 746	745
Series B Preferred Stock [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Preferred Units, Outstanding						600,000
Distribution date				Feb. 15, 2022
Partners' Capital Account, Distributions				$ 21
Preferred Stock, Dividend Rate, Percentage						6.875%
Subsequent Event
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Distribution Made to Limited Partner, Declaration Date			Apr. 26, 2022
Cash distributions declared per limited partner common unit			$ 0.7050
Distribution date	May 13, 2022
Date of record		May 06, 2022
Subsequent Event | Series B Preferred Stock [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Preferred Stock, Dividend Payment Rate, Variable								LIBOR plus
Preferred Stock, Dividend Rate, Percentage								4.652%
Limited Partners Common Units [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Distribution Made to Limited Partner, Cash Distributions Declared						$ 713	707
Series A Preferred Stock [Member] | Series B Preferred Stock [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Distribution Made to Limited Partner, Cash Distributions Declared						$ 11	11
Cash distributions declared per limited partner common unit						$ 68.75
Series A Preferred Stock [Member] | Series A Preferred Stock [Member]
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Distribution Made to Limited Partner, Cash Distributions Declared						$ 21	$ 20

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Net Income Per Limited Partner Unit - Schedule of Distributions by Partner by Class (Details) - USD ($) shares in Millions, $ in Millions		3 Months Ended
		Mar. 31, 2022	Mar. 31, 2021
Net Income Per Share [Line Items]
Potentially dilutive units		1	1
Net Income (Loss) Attributable to Parent	[1]	$ 825	$ 739
Distribution Made to Limited Partner, Cash Distributions Declared		745	738
Undistributed net income (loss) attributable to MPLX LP		80	1
Limited Partners Common Units [Member]
Net Income Per Share [Line Items]
Distribution Made to Limited Partner, Cash Distributions Declared		713	707
Undistributed net income (loss) attributable to MPLX LP		78	1
Series A Preferred Stock [Member] | Series A Preferred Stock [Member]
Net Income Per Share [Line Items]
Net Income (Loss) Attributable to Parent	[1]	23	20
Distribution Made to Limited Partner, Cash Distributions Declared		21	20
Undistributed net income (loss) attributable to MPLX LP		2	0
Series B Preferred Stock [Member] | Series A Preferred Stock [Member]
Net Income Per Share [Line Items]
Net Income (Loss) Attributable to Parent	[1]	11	11
Distribution Made to Limited Partner, Cash Distributions Declared		11	11
Undistributed net income (loss) attributable to MPLX LP		0	0
Common Stock | Limited Partners Common Units [Member]
Net Income Per Share [Line Items]
Net Income (Loss) Attributable to Parent	[1]	$ 791	$ 708

[1] Allocation of net income attributable to MPLX LP assumes all earnings for the period had been distributed based on the distribution priorities applicable to the period.

XML

Net Income Per Limited Partner Unit - Basic and Diluted Earnings Per Unit (Details) - Limited Partners Common Units [Member] - $ / shares shares in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Weighted average units outstanding:
Common - basic (in shares)	1,015	1,037
Common - diluted (in shares)	1,015	1,037
Net Income (Loss), Per Outstanding Limited Partnership Unit, Basic, Net of Tax	$ 0.78	$ 0.68
Common - diluted (in USD per unit)	$ 0.78	$ 0.68

XML

Segment Information (Details)	3 Months Ended
	Mar. 31, 2022
Segment Reporting [Abstract]
Number of reportable segments	2

XML

Segment Information - Segment Adjusted EBITDA (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2022	Mar. 31, 2021
Segment Reporting Information [Line Items]
Income from equity method investments		$ 99	$ 70
Total segment revenues and other income		(2,610)	(2,339)
Payments to Acquire Equity Method Investments		(110)	(35)
L&S
Segment Reporting Information [Line Items]
Total revenues from contracts with customers		987	957
Payments to Acquire Equity Method Investments		(68)	(9)
L&S | Marathon Petroleum Corporation [Member]
Segment Reporting Information [Line Items]
Sales-type Lease, Revenue		111	37
G&P
Segment Reporting Information [Line Items]
Total revenues from contracts with customers		1,147	905
Payments to Acquire Equity Method Investments		(42)	(26)
Operating Segments
Segment Reporting Information [Line Items]
Total revenues from contracts with customers		2,134	1,862
Adjusted EBITDA		1,393	1,352
Operating Segments | L&S
Segment Reporting Information [Line Items]
Operating Lease, Lease Income		175	249
Income from equity method investments		52	36
Other income		12	15
Total segment revenues and other income	[1]	(1,337)	(1,294)
Adjusted EBITDA	[2]	904	896
Capital Expenditure		77	59
Operating Segments | G&P
Segment Reporting Information [Line Items]
Operating Lease, Lease Income		81	92
Income from equity method investments		47	34
Other income		(2)	14
Total segment revenues and other income	[1]	(1,273)	(1,045)
Adjusted EBITDA	[2]	489	456
Capital Expenditure		95	30
Service [Member]
Segment Reporting Information [Line Items]
Total revenues from contracts with customers		554	589
Service [Member] | L&S
Segment Reporting Information [Line Items]
Total revenues from contracts with customers		72	84
Service [Member] | G&P
Segment Reporting Information [Line Items]
Total revenues from contracts with customers		482	505
Service [Member] | Operating Segments | L&S
Segment Reporting Information [Line Items]
Total revenues from contracts with customers		983	953
Service [Member] | Operating Segments | G&P
Segment Reporting Information [Line Items]
Total revenues from contracts with customers		486	508
Product [Member]
Segment Reporting Information [Line Items]
Total revenues from contracts with customers		497	282
Product [Member] | L&S
Segment Reporting Information [Line Items]
Total revenues from contracts with customers		1	1
Product [Member] | G&P
Segment Reporting Information [Line Items]
Total revenues from contracts with customers		496	281
Product [Member] | Operating Segments | L&S
Segment Reporting Information [Line Items]
Total revenues from contracts with customers		4	4
Product [Member] | Operating Segments | G&P
Segment Reporting Information [Line Items]
Total revenues from contracts with customers		661	397
Third Party [Member] | L&S
Segment Reporting Information [Line Items]
Total segment revenues and other income		(135)	(129)
Third Party [Member] | G&P
Segment Reporting Information [Line Items]
Total segment revenues and other income		$ (1,212)	$ (989)

[1] Within the total segment revenues and other income amounts presented above, third party revenues for the L&S segment were $135 million and $129 million for the three months ended March 31, 2022 and March 31, 2021, respectively. Third party revenues for the G&P segment were $1,212 million and $989 million for the three months ended March 31, 2022 and March 31, 2021, respectively.

[2] See below for the reconciliation from Segment Adjusted EBITDA to “Net income.”

XML

Segment Information - Reconciliation to Net Income (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2022	Mar. 31, 2021
Segment Reporting, Revenue Reconciling Item [Line Items]
Cost, Depreciation and Amortization	[1]	$ (313)	$ (329)
Interest and Other Financial Costs		(222)	(225)
Income from equity method investments		99	70
Proceeds from Equity Method Investment, Distribution		(120)	(119)
Other Cost and Expense, Operating		(1)	(9)
Net income		833	748
Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Adjusted EBITDA		1,393	1,352
Segment Reconciling Items [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Proceeds from Equity Method Investment, Distribution		(132)	(121)
Adjusted EBITDA attributable to noncontrolling interests		9	10
L&S
Segment Reporting, Revenue Reconciling Item [Line Items]
Cost, Depreciation and Amortization		(130)	(147)
L&S | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Adjusted EBITDA	[2]	904	896
Income from equity method investments		52	36
G&P
Segment Reporting, Revenue Reconciling Item [Line Items]
Cost, Depreciation and Amortization		(183)	(182)
G&P | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Adjusted EBITDA	[2]	489	456
Income from equity method investments		$ 47	$ 34

[1] Depreciation and amortization attributable to L&S was $130 million and $147 million for the three months ended March 31, 2022 and March 31, 2021, respectively. Depreciation and amortization attributable to G&P was $183 million and $182 million for the three months ended March 31, 2022 and March 31, 2021, respectively.

[2] See below for the reconciliation from Segment Adjusted EBITDA to “Net income.”

XML

Property, Plant and Equipment (Summary of Property, Plant and Equipment) (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 26,691	$ 26,546
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	6,779	6,504
Property, Plant and Equipment, Net, Total	19,912	20,042
L&S
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	12,438	12,371
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	3,347	3,227
Property, Plant and Equipment, Net, Total	9,091	9,144
G&P
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	14,253	14,175
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	3,432	3,277
Property, Plant and Equipment, Net, Total	$ 10,821	$ 10,898

XML

Fair Value Measurements - Recurring - Financial Instruments by Valuation Hierarchy (Details) - USD ($) $ in Millions		Mar. 31, 2022	Dec. 31, 2021
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset	[1]	$ 0	$ 0
Derivative Liability, Fair Value, Gross Liability	[1]	(99)	(108)
Embedded Derivative Financial Instruments [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability		$ 99	$ 108

[1] Includes the embedded derivative in the commodity contract discussed above.

XML

Fair Value Measurments - Recurring - Significant Unobservable Inputs in Level 3 Valuation (Details)	3 Months Ended
	Mar. 31, 2022 USD ($) $ / gal
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivative, Average Forward Price | $ / gal	0.97
Embedded Derivative Financial Instruments [Member] | Natural Gas [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Embedded Derivative Renewal Term	5 years
Fair Value, Inputs, Level 3 [Member] | Embedded Derivative Financial Instruments [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs Probability of Renewal	100.00%
Minimum [Member] | Fair Value, Inputs, Level 3 [Member] | Commodity Contract [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs Forward Commodity Price	$ 0.73
Maximum [Member] | Fair Value, Inputs, Level 3 [Member] | Commodity Contract [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Fair Value Inputs Forward Commodity Price	$ 2.38

XML

Fair Value Measurements - Recurring - Changes in Level 3 Measurements (Details) - Embedded Derivatives in Commodity Contracts (net) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2022	Mar. 31, 2021
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value at beginning of period		$ (108)	$ (63)
Total gains (losses) (realized and unrealized) included in earnings	[1]	4	(6)
Settlements		5	3
Fair value at end of period		(99)	(66)
The amount of total gains (losses) for the period included in earnings attributable to the change in unrealized losses relating to liabilities still held at end of period		$ 5	$ (5)

[1] Gain/(loss) on derivatives embedded in commodity contracts are recorded in “Purchased product costs” on the Consolidated Statements of Income.

XML

Fair Value Measurements - Reported (Details) - USD ($) $ in Millions		Mar. 31, 2022	Dec. 31, 2021
Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	[1]	$ 19,864	$ 18,664
Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	[1]	$ 20,392	$ 20,779

[1] Amounts outstanding under the MPC Loan Agreement are not included in the table above, as the carrying value approximates fair value. This balance is reflected in “Current liabilities - related parties” on the Consolidated Balance Sheets.

XML

Derivative Financial Instruments - Embedded Derivatives in Commodity Contracts (Details) - Embedded Derivative Financial Instruments [Member] $ in Millions	3 Months Ended
	Mar. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Fair Value, Inputs, Level 3 [Member] | Fair Value, Recurring [Member]
Derivative [Line Items]
Derivative Liability	$ (99)	$ (108)
Natural Gas [Member]
Derivative [Line Items]
Number of Renewals	1
Embedded Derivative Renewal Term	5 years

XML

Derivative Financial Instruments - Derivatives Balance Sheet Location (Details) - Not Designated as Hedging Instrument [Member] - Commodity Contract [Member] - USD ($) $ in Millions		Mar. 31, 2022	Dec. 31, 2021
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	[1]	$ 0	$ 0
Derivative Liability, Fair Value, Gross Liability	[1]	99	108
Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	[1]	0	0
Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	[1]	16	15
Other noncurrent assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	[1]	0	0
Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	[1]	$ 83	$ 93

[1] Includes the embedded derivative in the commodity contract discussed above.

XML

Derivatives Financial Instruments - Derivative Income Statement Location (Details) - Purchased product costs - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Derivative [Line Items]
Realized gain (loss)	$ (5)	$ (3)
Total gain (loss)	4	(6)
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Unrealized Gain (Loss) on Derivatives and Commodity Contracts	$ 9	$ (3)

XML

Debt - Summary of Outstanding Borrowings (Detail) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Total	$ 20,108	$ 18,909
Unamortized debt issuance costs	(116)	(102)
Unamortized discount/premium	(236)	(236)
Long-term Debt and Lease Obligation, Current	999	499
Total long-term debt due after one year	18,757	18,072
Fixed Rate Senior Notes [Member] | MPLX LP [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	20,032	18,532
Fixed Rate Senior Notes [Member] | MarkWest [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	23	23
Fixed Rate Senior Notes [Member] | ANDX LP [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	45	45
Finance Lease [Member] | MPLX LP [Member]
Debt Instrument [Line Items]
Financing lease obligations	8	9
MPLX Revolving Credit Facility due July 2024 [Member]
Debt Instrument [Line Items]
Long-term Line of Credit	$ 0	$ 300
Senior Note Due March 2052 [Domain] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	4.95%
Percent of Par	98.982%
Minimum [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	1.75%
Maximum [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.50%

XML

Debt - Additional Information (Detail) - USD ($) $ in Millions		3 Months Ended
	Mar. 14, 2022	Mar. 31, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Debt and Lease Obligation		$ 20,108	$ 18,909
Unamortized Debt Issuance Expense		116	102
Debt Instrument, Unamortized Discount		236	236
Long-term debt		18,757	18,072
MPLX Revolving Credit Facility due July 2024 [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Current Borrowing Capacity		3,500
Long-term Line of Credit		0	300
MPLX Revolving Credit Facility due July 2024 [Member] | MPLX LP [Member]
Debt Instrument [Line Items]
Proceeds from Lines of Credit		$ 900
Debt Instrument, Interest Rate, Effective Percentage		1.451%
Repayments of Long-term Lines of Credit		$ 1,200
Letters of Credit Outstanding		1
Line of Credit Facility, Remaining Borrowing Capacity		$ 3,500
Line of Credit Facility, Remaining Borrowing Capacity, Percentage		100.00%
Fixed Rate Senior Notes [Member] | MPLX LP [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 20,032	18,532
Fixed Rate Senior Notes [Member] | ANDX LP [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		45	45
Fixed Rate Senior Notes [Member] | MarkWest [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		23	23
Finance Lease [Member] | MPLX LP [Member]
Debt Instrument [Line Items]
Finance Lease, Liability		$ 8	$ 9
Senior Notes [Member] | Senior Note Due March 2052 [Domain]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		4.95%
Percent of Par		98.982%
Debt Instrument, Face Amount		$ 1,500
Debt Instrument, Issuance Date	Mar. 14, 2022
Minimum [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		1.75%
Maximum [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		5.50%

XML

Revenue Disaggregation of Revenue (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2022	Mar. 31, 2021
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Product and Service [Extensible Enumeration]		Product and Service, Other [Member]	Product and Service, Other [Member]
Revenue Not from Contract with Customer, Other	[1]	$ 476	$ 477
Revenues		2,610	2,339
Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		2,134	1,862
L&S
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		$ 987	$ 957
Revenue from Contract with Customer, Product and Service [Extensible Enumeration]		Product and Service, Other [Member]	Product and Service, Other [Member]
L&S | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	[2]	$ 1,337	$ 1,294
G&P
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		$ 1,147	$ 905
Revenue from Contract with Customer, Product and Service [Extensible Enumeration]		Product and Service, Other [Member]	Product and Service, Other [Member]
G&P | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues	[2]	$ 1,273	$ 1,045
Service [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		554	589
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		915	872
Service [Member] | L&S
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		72	84
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		911	869
Service [Member] | L&S | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		983	953
Service [Member] | G&P
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		482	505
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		4	3
Service [Member] | G&P | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		486	508
Service, Other [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		123	77
Service, Other [Member] | L&S
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		0	0
Service, Other [Member] | G&P
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		123	77
Product [Member]
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		497	282
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		45	42
Product [Member] | L&S
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		1	1
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		3	3
Product [Member] | L&S | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		4	4
Product [Member] | G&P
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		496	281
Revenue from Contract with Customer, Excluding Assessed Tax, Related Parties		42	39
Product [Member] | G&P | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenues from contracts with customers		$ 661	$ 397

[1] Non-ASC 606 Revenue includes rental income, sales-type lease revenue, income from equity method investments, and other income.

[2] Within the total segment revenues and other income amounts presented above, third party revenues for the L&S segment were $135 million and $129 million for the three months ended March 31, 2022 and March 31, 2021, respectively. Third party revenues for the G&P segment were $1,212 million and $989 million for the three months ended March 31, 2022 and March 31, 2021, respectively.

XML

Revenue Contract Balances (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021	[1]	Dec. 31, 2020
Long-term deferred revenue, beginning balance		$ 383
Long-term deferred revenue, ending balance		405
Liability, change in timeframe, performance obligation satisfied, revenue recognized		0	$ 0
Contract Liability, Noncurrent, Period Increase (Decrease)		0	0
ASC 606
Contract assets, beginning balance	[1]	25	40
Contract assets, additions/(deletions)		(18)	(27)
Contract assets, revenue recognized	[2]	0	0
Contract assets, ending balance		7	13
Contract With Customer Non Current Asset Reclassified To Receivable [Line Items]		0	0
Contract with Customer, Asset, before Allowance for Credit Loss, Noncurrent		2	2	$ 2		$ 2
Deferred revenue, beginning balance	[1]	56	37
Deferred revenue, additions/(deletions)		11	7
Deferred revenue, revenue recognized	[2]	(9)	(1)
Deferred revenue, ending balance		58	43
Deferred revenue - related parties, beginning balance	[1]	60	91
Deferred revenue - related party, additions/(deletions)		34	21
Deferred revenue - related parties, revenue recognized	[2]	(26)	(20)
Deferred revenue - related parties, ending balance		68	92
Long-term deferred revenue, beginning balance	[1]	135	119
Long-term deferred revenue, additions/(deletions)		2	4
Long-term deferred revenue, revenue recognized	[2]	0	0
Long-term deferred revenue, ending balance		137	123
Long-term deferred revenue - related parties, beginning balance	[1]	31	48
Long-term deferred revenue - related party, additions/(deletions)		0	(4)
Long-term deferred revenue - related parties, revenue recognized	[2]	0	0
Long-term deferred revenue - related parties, ending balance		31	44
Contract Liability, Noncurrent, Revenue Recognized		0	0
Contract with Customer, Liability, Noncurrent		5	6	$ 5		$ 6
Contract with Customer, Asset Increase (Decrease), Noncurrent		$ 0	$ 0

[1] Balance represents ASC 606 portion of each respective line item.

[2] No significant revenue was recognized related to past performance obligations in the current periods.

XML

Revenue Remaining Performance Obligations (Details) $ in Millions	Mar. 31, 2022 USD ($)
Revenue from Contract with Customer [Abstract]
Contract with customer, liability	$ 293
Revenue, Remaining Performance Obligation, Amount	9,758	[1],[2],[3]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-04-01
Revenue from Contract with Customer [Abstract]
Revenue, Remaining Performance Obligation, Amount	$ 1,432
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, expected timing of satisfaction, years	9 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue from Contract with Customer [Abstract]
Revenue, Remaining Performance Obligation, Amount	$ 1,771
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, expected timing of satisfaction, years	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue from Contract with Customer [Abstract]
Revenue, Remaining Performance Obligation, Amount	$ 1,633
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, expected timing of satisfaction, years	2 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Revenue from Contract with Customer [Abstract]
Revenue, Remaining Performance Obligation, Amount	$ 1,560
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, expected timing of satisfaction, years	3 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01
Revenue from Contract with Customer [Abstract]
Revenue, Remaining Performance Obligation, Amount	$ 3,362
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, expected timing of satisfaction, years	4 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2043-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, expected timing of satisfaction, years	22 years

[1] All fixed consideration from contracts with customers is included in the amounts presented above. Variable consideration that is constrained or not required to be estimated as it reflects our efforts to perform is excluded.

[2] Arrangements deemed implicit leases and sales-type leases are excluded from this table.

[3] Only minimum volume commitments that are deemed fixed are included in the table above. MPLX has various minimum volume commitments in processing arrangements that vary based on the actual Btu content of the gas received. These amounts are deemed variable consideration and are excluded from the table above.

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Supplemental Cash Flow Information - Summary of Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Supplemental Cash Flow Information [Abstract]
Interest Paid, Excluding Capitalized Interest, Operating Activities	$ 213	$ 231

XML

Supplemental Cash Flow Information - Summary of Reconciliation of Additions to Property, Plant and Equipment to Total Capital Expenditures (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Supplemental Cash Flow Elements [Abstract]
Increase/(decrease) in capital accruals	$ 3	$ (37)

XML

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2021
Commitments And Contingencies [Line Items]
Accrued liabilities for environmental remediation	$ 42			$ 23
Loss Contingency, Damages Sought, Value			$ 187
Loss Contingency, Damages Paid, Value		$ 4
Guarantor Obligations, Origin and Purpose	GuaranteesOver the years, MPLX has sold various assets in the normal course of its business. Certain of the related agreements contain performance and general guarantees, including guarantees regarding inaccuracies in representations, warranties, covenants and agreements, and environmental and general indemnifications that require MPLX to perform upon the occurrence of a triggering event or condition. These guarantees and indemnifications are part of the normal course of selling assets. MPLX is typically not able to calculate the maximum potential amount of future payments that could be made under such contractual provisions because of the variability inherent in the guarantees and indemnities. Most often, the nature of the guarantees and indemnities is such that there is no appropriate method for quantifying the exposure because the underlying triggering event has little or no past experience upon which a reasonable prediction of the outcome can be based.We hold a 9.19 percent indirect interest in a joint venture (“Dakota Access”) that owns and operates the Dakota Access Pipeline and Energy Transfer Crude Oil Pipeline projects, collectively referred to as the Bakken Pipeline system or DAPL. In 2020, the U.S. District Court for the District of Columbia (the “D.D.C.”) ordered the U.S. Army Corps of Engineers (“Army Corps”), which granted permits and an easement for the Bakken Pipeline system, to prepare an environmental impact statement (“EIS”) relating to an easement under Lake Oahe in North Dakota. The D.D.C. later vacated the easement. The EIS is currently expected to be completed in the second half of 2022.In May 2021, the D.D.C. denied a renewed request for an injunction to shut down the pipeline while the EIS is being prepared. In June 2021, the D.D.C. issued an order dismissing without prejudice the tribes’ claims against the Dakota Access Pipeline. The litigation could be reopened or new litigation challenging the EIS, once completed, could be filed. The pipeline remains operational.We have entered into a Contingent Equity Contribution Agreement whereby MPLX LP, along with the other joint venture owners in the Bakken Pipeline system, has agreed to make equity contributions to the joint venture upon certain events occurring to allow the entities that own and operate the Bakken Pipeline system to satisfy their senior note payment obligations. The senior notes were issued to repay amounts owed by the pipeline companies to fund the cost of construction of the Bakken Pipeline system. If the pipeline were temporarily shut down, MPLX would have to contribute its 9.19 percent pro rata share of funds required to pay interest accruing on the notes and any portion of the principal that matures while the pipeline is shutdown. MPLX also expects to contribute its 9.19 percent pro rata share of any costs to remediate any deficiencies to reinstate the permit and/or return the pipeline into operation. If the vacatur of the easement permit results in a permanent shutdown of the pipeline, MPLX would have to contribute its 9.19 percent pro rata share of the cost to redeem the bonds (including the one percent redemption premium required pursuant to the indenture governing the notes) and any accrued and unpaid interest. As of March 31, 2022, our maximum potential undiscounted payments under the Contingent Equity Contribution Agreement were approximately $170 million.
Indirect Ownership Interest [Member] | Bakken Pipeline System [Member]
Commitments And Contingencies [Line Items]
Equity method investment, ownership percentage	9.19%
Guarantee Type, Other [Member]
Commitments And Contingencies [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	$ 170