SUPPLEMENTAL INFORMATION - NATURAL GAS AND CRUDE OIL PROPERTIES Supplemental Information on Natural Gas and Crude Oil Exploration, Development and Production Activities (Tables)

12 Months Ended

Dec. 31, 2019

Reserve Quantities [Line Items]

Index price for reserves, by commodity [Table Text Block]

The indicated index prices for our reserves, by commodity, are presented below.

	Average Benchmark Prices (1)
As of December 31,	Crude Oil (per Bbl) (2)		Natural Gas (per Mcf) (2)		NGLs (per Bbl) (3)
2019	$	55.69	$	2.58	$	55.69
2018	65.56		3.10		65.56
2017	51.34		2.98		51.34

Schedule of Prices Used to Estimate Natural Gas and Crude Oil Reserves [Table Text Block]

The netted back price used to estimate our reserves, by commodity, are presented below.

	Price Used to Estimate Reserves (4)
As of December 31,	Crude Oil (per Bbl)		Natural Gas (per Mcf)		NGLs (per Bbl)
2019	$	52.63	$	1.50	$	12.21
2018	61.14		2.15		23.04
2017	48.68		2.31		20.21

(1) Per SEC rules, the pricing used to prepare the proved reserves is based on the unweighted arithmetic average of the first of the month prices for the preceding 12 months.

(2) Our benchmark prices for crude oil and natural gas are WTI and Henry Hub, respectively.

(3) For NGLs, we use the NYMEX crude oil price as a reference for presentation purposes.

(4)

These prices are based on the index prices and are net of basin differentials, transportation fees, contractual adjustments and Btu adjustments we experienced for the respective commodity.

Schedule of Proved Developed and Undeveloped Oil and Gas Reserve Quantities [Table Text Block]

The following tables present the changes in our estimated quantities of proved reserves:

	Crude Oil, Condensate (MBbls)		Natural Gas (MMcf)		NGLs (MBbls)		Total (MBoe)
Proved reserves, January 1, 2017	118,169		833,697		84,288		341,407
Revisions of previous estimates	28,334		96,119		8,104		52,457
Extensions, discoveries and other additions	2,923		11,541		1,158		6,005
Acquisition of reserves	18,971		289,223		19,604		86,778
Dispositions	(653	)	(4,597	)	(481	)	(1,900	)
Production	(12,902	)	(71,689	)	(6,981	)	(31,830	)
Proved reserves, December 31, 2017	154,842		1,154,294		105,692		452,917
Revisions of previous estimates	26,548		94,738		12,674		55,011
Extensions, discoveries and other additions	8,786		61,750		8,868		27,946
Acquisition of reserves	19,644		148,674		15,936		60,360
Dispositions	(2,507	)	(35,750	)	(2,656	)	(11,121	)
Production	(16,964	)	(88,017	)	(8,527	)	(40,160	)
Proved reserves, December 31, 2018	190,349		1,335,689		131,987		544,953
Revisions of previous estimates	25,875		328,290		31,559		112,147
Extensions, discoveries and other additions	1,056		10,262		1,519		4,285
Acquisition of reserves	553		4,558		448		1,761
Dispositions	(1,412	)	(5,052	)	(614	)	(2,868	)
Production	(19,166	)	(115,950	)	(10,923	)	(49,414	)
Proved reserves, December 31, 2019	197,255		1,557,797		153,976		610,864

Proved developed reserves, as of:
December 31, 2017	46,862	365,332	35,220	142,971
December 31, 2018	61,821	443,151	43,856	179,535
December 31, 2019	66,211	554,234	55,411	213,994
Proved undeveloped reserves, as of:
December 31, 2017	107,980	788,962	70,472	309,946
December 31, 2018	128,528	892,538	88,131	365,418
December 31, 2019	131,044	1,003,563	98,565	396,870

	Developed		Undeveloped		Total
	(MBoe)
Proved reserves, January 1, 2017	98,285		243,122		341,407
Revisions of previous estimates	18,291		34,166		52,457
Extensions, discoveries and other additions	2,292		3,713		6,005
Acquisition of reserves	1,305		85,473		86,778
Dispositions	(20	)	(1,880	)	(1,900	)
Production	(31,830	)	—		(31,830	)
Undeveloped reserves converted to developed	54,648		(54,648	)	—
Proved reserves, December 31, 2017	142,971		309,946		452,917
Revisions of previous estimates	6,284		48,727		55,011
Extensions, discoveries and other additions	7,874		20,072		27,946
Acquisition of reserves	8,758		51,602		60,360
Dispositions	(4,486	)	(6,635	)	(11,121	)
Production	(40,160	)	—		(40,160	)
Undeveloped reserves converted to developed	58,294		(58,294	)	—
Proved reserves, December 31, 2018	179,535		365,418		544,953
Revisions of previous estimates	27,452		84,695		112,147
Extensions, discoveries and other additions	4,285		—		4,285
Acquisition of reserves	441		1,320		1,761
Dispositions	(474	)	(2,394	)	(2,868	)
Production	(49,414	)	—		(49,414	)
Undeveloped reserves converted to developed	52,169		(52,169	)	—
Proved reserves, December 31, 2019	213,994		396,870		610,864

Results of Operations for Oil and Gas Producing Activities Disclosure [Table Text Block]

The results of operations for crude oil and natural gas producing activities are presented below.

	Year Ended December 31,
	2019			2018			2017
	(in thousands)
Revenue:
Crude oil, natural gas and NGLs sales	$	1,307,275		$	1,389,961		$	913,084
Commodity price risk management gain (loss), net	(162,844		)	145,237			(3,936		)
	1,144,431			1,535,198			909,148
Expenses:
Lease operating expenses	142,248			130,957			89,641
Production taxes	80,754			90,357			60,717
Transportation, gathering and processing expenses	46,353			37,403			33,220
Exploration expense	4,054			6,204			47,334
Depreciation, depletion and amortization	638,499			551,265			462,482
Accretion of asset retirement obligations	6,117			5,075			6,306
Impairment of properties and equipment	38,536			458,397			285,887
(Gain) loss on sale of properties and equipment	9,734			394			(766		)
	966,295			1,280,052			984,821
Results of operations for crude oil and natural gas producing activities before income taxes	178,136			255,146			(75,673		)
Income tax (expense) benefit	(9,869		)	(185,667		)	47,247
Results of operations for crude oil and natural gas producing activities, excluding corporate overhead and interest costs	$	168,267		$	69,479		$	(28,426	)

Cost Incurred in Oil and Gas Property Acquisition, Exploration, and Development Activities Disclosure [Table Text Block]

Exploration Expenses. The following table presents the major components of exploration, geologic and geophysical expense:

	Year Ended December 31,
	2019		2018		2017
	(in thousands)
Exploratory dry hole costs	$	—	$	113	$	41,297
Geological and geophysical costs, including seismic purchases	3,017		3,401		3,881
Operating, personnel and other	1,037		2,690		2,156
Total exploration, geologic and geophysical expense	$	4,054	$	6,204	$	47,334

Costs incurred in crude oil and natural gas property acquisition, exploration and development are presented below.

	Year Ended December 31,
	2019		2018		2017
	(in thousands)
Acquisition of properties: (1)
Proved properties	$	16,007	$	205,253	$	172
Unproved properties	9,567		5,477		18,914
Development costs (2)	780,851		970,970		688,165
Exploration costs: (3)
Exploratory drilling	32,218		36,704		80,103
Geological and geophysical	3,017		3,401		3,881
Total costs incurred (4)	$	841,660	$	1,221,805	$	791,235

(1) Property acquisition costs represent costs incurred to purchase, lease or otherwise acquire a property.

(2) Development costs represent costs incurred to gain access to and prepare development well locations for drilling, drill and equip development wells, recomplete wells and provide facilities to extract, treat, gather and store crude oil, natural gas and NGLs. Of these costs incurred for the years ended December 31, 2019, 2018 and 2017, $308.9 million, $438.4 million and $463.4 million, respectively, were incurred to convert proved undeveloped reserves to proved developed reserves from the prior year end. These costs also include approximately $35.3 million, $74.6 million and $32.8 million of infrastructure and pipeline costs in 2019, 2018 and 2017 respectively.

(3) Exploration costs represent costs incurred in identifying areas that may warrant examination and in examining specific areas that are considered to have prospects of containing crude oil, natural gas and NGLs. These costs include, but are not limited to, dry hole contributions and costs of drilling and equipping exploratory wells.

(4) During 2017, we finalized our purchase price allocation for the 2016 Delaware Basin acquisition within the one year measurement period. The finalization included a reduction to our proved undeveloped and development costs of $24.6 million. We excluded this reduction from our 2017 costs incurred as it did not relate to any cash acquisitions in 2017.

Capitalized Costs Relating to Oil and Gas Producing Activities Disclosure [Table Text Block]

Aggregate capitalized costs related to crude oil and natural gas exploration and production activities with applicable accumulated DD&A are presented below:

	As of December 31,
	2019			2018
	(in thousands)
Proved crude oil and natural gas properties	$	6,241,780		$	5,452,613
Unproved crude oil and natural gas properties	403,379			492,594
Uncompleted wells, equipment and facilities	382,409			332,264
Capitalized costs	7,027,568			6,277,471
Less accumulated DD&A	(2,982,929		)	(2,341,897		)
Capitalized costs, net	$	4,044,639		$	3,935,574

Standardized Measure of Discounted Future Cash Flows Relating to Proved Reserves Disclosure [Table Text Block]

The following table presents information with respect to the standardized measure of discounted future net cash flows relating to proved reserves. Changes in the demand for crude oil, natural gas and NGLs, inflation and other factors make such estimates inherently imprecise and subject to substantial revision. This table should not be construed to be an estimate of the current market value of our proved reserves.

	As of December 31,
	2019			2018			2017
	(in thousands)
Future estimated cash flows	$	14,590,604		$	17,554,880		$	12,340,407
Future estimated production costs (1)	(4,530,173		)	(4,782,948		)	(3,245,627		)
Future estimated development costs	(3,257,106		)	(3,632,822		)	(2,893,335		)
Future estimated income tax expense	(907,382		)	(1,404,121		)	(748,494		)
Future net cash flows	5,895,943			7,734,989			5,452,951
10% annual discount for estimated timing of cash flows	(2,585,609		)	(3,287,273		)	(2,572,846		)
Standardized measure of discounted future estimated net cash flows	$	3,310,334		$	4,447,716		$	2,880,105

(1) Represents future estimated lease operating expenses, production taxes and transportation, gathering and processing expenses.

Schedule of Changes in Standardized Measure of Discounted Future Net Cash Flows [Table Text Block]

The following table presents the principal sources of change in the standardized measure of discounted future estimated net cash flows:

	Year Ended December 31,
	2019			2018			2017
	(in thousands)
Beginning of period	$	4,447,716		$	2,880,105		$	1,420,629
Sales of crude oil, natural gas and NGLs production, net of production costs	(1,037,920		)	(1,131,244		)	(729,506		)
Net changes in prices and production costs (1)	(2,122,538		)	936,077			841,713
Extensions, discoveries and improved recovery, less related costs	39,606			190,084			47,240
Sales of reserves	(14,533		)	(42,362		)	(2,613		)
Purchases of reserves	18,816			467,807			224,483
Development costs incurred during the period	605,753			462,088			419,047
Revisions of previous quantity estimates	538,242			631,198			484,431
Changes in estimated income taxes	346,826			(232,002		)	(138,560		)
Net changes in future development costs	206,003			(123,663		)	25,183
Accretion of discount	532,127			583,744			167,487
Timing and other	(249,764		)	(174,116		)	120,571
End of period	$	3,310,334		$	4,447,716		$	2,880,105

(1) Our weighted-average price, net of production costs per Boe, in our 2019 reserve report decreased to $16.18 as compared to $23.44 for 2018 and $20.08 for 2017.