UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

(Amendment No.    )

Under the Securities Exchange Act of 1934

NGL Energy Partners LP

(Name of Issuer)

Common units representing limited partnership interests

(Title of Class of Securities)

62913M107

(CUSIP Number)

Candice L. Cheeseman

General Counsel and Secretary

Two Warren Place

6120 S. Yale Avenue, Suite 700

Tulsa, OK 74136-4216

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

November 1, 2011

(Date of Event Which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.   ¨

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See Rule 13d-7 for other parties to whom copies are to be sent.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

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This Schedule 13D relates to common units (“Common Units”) representing limited partner interests in NGL Energy Partners LP (the “Issuer”). The Issuer is a Delaware limited partnership with its principal executive offices located at 6120 South Yale Avenue, Suite 805, Tulsa, Oklahoma 74136.

This Schedule 13D is filed jointly, pursuant to a Joint Filing Agreement attached hereto as Exhibit 1, by the following persons (collectively, the “Reporting Persons”):

SemOperating is the sole general partner of SemStream. SemGroup is the sole limited partner of SemStream and is the sole member of SemOperating. SemGroup is a New York Stock Exchange (“NYSE”) listed company, whose common stock trades on the NYSE under the symbol “SEMG”.

The principal business and office address of each of the Reporting Persons is Two Warren Place, 6120 S. Yale Avenue, Suite 700, Tulsa, OK 74136-4216.

The name and present principal occupation of each director and executive officer of SemGroup (collectively, the “SemGroup Directors and Officers”, and together with the Reporting Persons, the “Covered Persons”) are set forth below. All executive officers and directors listed are United States citizens.

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The Common Units disclosed on this Schedule 13D were issued to SemStream pursuant to that certain Contribution Agreement dated as of August 31, 2011 (the “Contribution Agreement”), by and among SemStream, NGL Supply Terminal Company LLC, a Delaware limited liability company (“NGL Subsidiary”), the Issuer, and NGL Energy Holdings LLC, a Delaware limited liability company (“Holdings”). The transactions contemplated by the Contribution Agreement were consummated on November 1, 2011.

Pursuant to the Contribution Agreement, SemStream sold substantially all of its assets to NGL Subsidiary in exchange for: 8,932,031 Common Units (the “NGL Common Units”) and $93,054,011.04 in cash consideration, which is subject to a customary working capital adjustment (the “Transaction”). As part of the Transaction, SemStream waived ordinary course cash distributions from the Issuer on 3,932,031 of the NGL Common Units (the “Distribution Waiver Units”) until August 30, 2012. In addition, SemStream acquired 7.5% of the equity securities of Holdings (the “Holdings Interests”), NGL’s general partner and holder of its incentive distribution rights, for a purchase price of $22,500. The assets of SemStream’s wholly-owned subsidiary, SemStream Arizona Propane, L.L.C. were excluded from the Transaction. The NGL Common Units and the Holdings Interests have been pledged as collateral to secure all indebtedness and obligations of SemGroup arising under SemGroup’s senior credit facility.

Pursuant to the Contribution Agreement, SemStream may not transfer or sell any of the NGL Common Units until the Issuer has made its quarterly distribution for the Issuer’s quarter ending December 31, 2011. In addition, pursuant to the Contribution Agreement, SemStream may not transfer or sell any of the Distribution Waiver Units prior to September 30, 2012, unless the purchaser of any such Distribution Waiver Units enters into a forbearance agreement with the Issuer relating to the Distribution Waiver Units purchased. The Contribution Agreement also prohibits SemStream from acquiring any additional equity interests of the Issuer or Holdings without the consent of the Issuer or Holdings, respectively.

In connection with the consummation of the Transaction, SemStream entered into a Second Amended and Restated Limited Liability Company Agreement of Holdings (the “Second Amended and Restated Limited Liability Company Agreement”). Pursuant to the Second Amended and Restated Limited Liability Company Agreement, SemStream received the right to appoint two directors to the board of directors of Holdings (the “Board”). SemStream has appointed Norman J. Szydlowski and Kevin Clement to the Board.

Further, in connection with the Contribution Agreement, the parties to the agreement contemplated entering into a registration rights agreement with respect to the NGL Common Units. On October 3, 2011, such registration rights agreement was amended and restated by NGL and other parties (the “Amended and Restated Registration Rights Agreement”). On November 1, 2011, SemStream and Holdings entered into an amendment and joinder to the Amended and Restated Registration Rights Agreement with respect to the NGL Common Units (“Joinder to Registration Rights Agreement”), pursuant to which SemStream received demand registration rights with respect to the NGL Common Units.

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The descriptions of the Contribution Agreement, the Second Amended and Restated Limited Liability Company Agreement, the Amended and Restated Registration Rights Agreement and the Joinder to Registration Rights Agreement are qualified in their entirety by reference to the full text of the agreements, which are filed as Exhibits 2, 3, 4 and 5 to this Schedule 13D, respectively, and each is incorporated herein by reference.

The information contained in Item 3 above is incorporated herein by reference.

The Common Units described herein were acquired for investment purposes. The Covered Persons will continuously evaluate their investment in the Common Units, alternative investment opportunities and all other factors deemed relevant in determining whether additional Common Units will be acquired by any of the Covered Persons or by other affiliated persons or whether any of the Reporting Persons or any such other affiliated persons will dispose of Common Units. At any time, but subject to the restrictions set forth in the Contribution Agreement, additional Common Units may be acquired or some or all of the Common Units beneficially owned by the Covered Persons may be sold, in either case in the open market, in privately negotiated transactions or otherwise.

Except as described herein, none of the Covered Persons has any current plans or proposals that would be related to or would result in any of the matters described in Items 4(a)-(j) of Schedule 13D; however, as part of their ongoing evaluation of this investment and investment alternatives, the Covered Persons may consider such matters in the future and, subject to applicable law, may formulate a plan with respect to such matters, and, from time to time, the Covered Persons may hold discussions with or make formal proposals to management or the Board, other holders of Common Units or other third parties regarding such matters.

(a)(b) The information contained on the cover pages and in Items 2 and 3 of this Schedule 13D is incorporated herein by reference.

SemStream is the beneficial owner of the number and percentage of Common Units stated in rows (11) and (13) on the corresponding cover page hereto.

The NGL Common Units are also reported as beneficially owned by SemOperating, the general partner of SemStream, and SemGroup, the limited partner of SemStream and the sole member of SemOperating. By reason of these relationships, each of the Reporting Persons are reported as having shared power to vote, or to direct the vote, and shared power to dispose, or direct the disposition of, the NGL Common Units.

The ownership percentages included in this Schedule 13D for the Reporting Persons are based on 21,796,253 Common Units outstanding as of November 1, 2011, consisting of (a) 8,864,222 Common Units outstanding as of August 12, 2011, per the Issuer’s Form 10-Q filed with the Securities and Exchange Commission (the “SEC”) on August 15, 2011, (b) 4,000,000 Common Units issued by the Issuer to certain individuals and entities pursuant to that certain contribution agreement dated as of August 12, 2011, as further described in the Issuer’s Current Report on Form 8-K filed with the SEC on October 7, 2011, and (c) 8,932,031 Common Units issued to SemStream pursuant to the Contribution Agreement. Outstanding units do not include 5,919,346 subordinated units of Issuer issued and outstanding, of which the Covered Persons own none.

Neither the filing of this Schedule 13D nor any of its contents shall be deemed to constitute an admission by any of the Covered Persons (other than by SemStream, solely with respect to the NGL Common Units) that they are the beneficial owner of any of the Common Units referred to herein for the purposes of Section 13(d) of the Act, or for any other purpose, and such beneficial ownership is expressly disclaimed by each Covered Person (other than by SemStream, solely with respect to the NGL Common Units) except to the extent of such Covered Person’s pecuniary interest, if any, in the Common Units.

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(c) Except as described above, the Covered Persons have not engaged in any transactions in any equity securities of the Issuer during the past 60 days.

(d)(e) Not applicable.

The information contained in Items 2 and 3 of this Schedule 13D is incorporated herein by reference.

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SIGNATURES

After reasonable inquiry and to the best of our knowledge and belief, the undersigned certify that the information set forth in this statement is true, complete and correct.

Dated: November 14, 2011

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EXHIBIT INDEX

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Exhibit 1

JOINT FILING AGREEMENT

This JOINT FILING AGREEMENT is entered into as of November 14, 2011, by and among the signatories hereto. The undersigned hereby agree that the Statement on Schedule 13D with respect to the common units representing limited partnership interests in NGL Energy Partners LP, a Delaware limited partnership, is, and any amendment thereafter signed by each of the undersigned shall be, filed on behalf of each of the undersigned pursuant to and in accordance with the provisions of Rule 13d-1(k)(1) under the Securities Exchange Act of 1934, as amended. The undersigned further agree to the filing of this Joint Filing Agreement as an exhibit to such joint filing.

IN WITNESS WHEREOF, the undersigned hereby execute this Joint Filing Agreement as of the date first above written.