SUPPLEMENTAL OIL AND GAS DISCLOSURES (Unaudited)

12 Months Ended

Dec. 31, 2020

Extractive Industries [Abstract]

Supplemental Oil and Gas Disclosures (Unaudited)

SUPPLEMENTAL OIL AND GAS DISCLOSURES (Unaudited)

Oil and Gas Operations

The following table sets forth revenue and direct cost information relating to the Company’s oil and gas exploration and production activities. Apache has no long-term agreements to purchase oil or gas production from foreign governments or authorities.

	United States		Egypt(1)		North Sea		Other International		Total(1)
	(In millions, except per boe)
2020
Oil and gas production revenues	$	1,764	$	1,390	$	883	$	—	$	4,037
Operating cost:
Depreciation, depletion, and amortization(2)	726		540		377		—		1,643
Asset retirement obligation accretion	32		—		73		—		105
Lease operating expenses	400		424		305		—		1,129
Gathering, processing, and transmission	291		38		50		—		379
Exploration expenses	168		63		28		15		274
Impairments related to oil and gas properties	3,938		374		7		—		4,319
Production taxes(3)	106		—		—		—		106
Income tax	(818)		(22)		17		—		(823)
	4,843		1,417		857		15		7,132
Results of operations	$	(3,079)	$	(27)	$	26	$	(15)	$	(3,095)
2019
Oil and gas production revenues	$	2,763	$	2,276	$	1,276	$	—	$	6,315
Operating cost:
Depreciation, depletion, and amortization(2)	1,508		641		363		—		2,512
Asset retirement obligation accretion	29		—		76		—		105
Lease operating expenses	645		484		320		—		1,449
Gathering, processing, and transmission	299		40		45		—		384
Exploration expenses	688		100		2		15		805
Impairments related to oil and gas properties	1,633		—		—		—		1,633
Production taxes(3)	191		—		—		—		191
Income tax	(468)		455		188		—		175
	4,525		1,720		994		15		7,254
Results of operations	$	(1,762)	$	556	$	282	$	(15)	$	(939)
2018
Oil and gas production revenues	$	3,279	$	2,748	$	1,321	$	—	$	7,348
Operating cost:
Depreciation, depletion, and amortization(2)	1,206		688		371		—		2,265
Asset retirement obligation accretion	32		—		75		—		107
Lease operating expenses	670		428		341		—		1,439
Gathering, processing, and transmission	282		47		42		—		371
Exploration expenses	219		88		192		4		503
Impairments related to oil and gas properties	265		63		10		—		338
Production taxes(3)	203		—		—		—		203
Income tax	87		645		116		—		848
	2,964		1,959		1,147		4		6,074
Results of operations	$	315	$	789	$	174	$	(4)	$	1,274

(1)Includes a noncontrolling interest in Egypt.

(2)Reflects DD&A of capitalized costs of oil and gas properties and, therefore, does not agree with DD&A reflected on Note 17—Business Segment Information.

(3)Reflects only amounts directly related to oil and gas producing properties and, therefore, does not agree with taxes other than income reflected on Note 17—Business Segment Information.

Costs Incurred in Oil and Gas Property Acquisitions, Exploration, and Development Activities

	United States		Egypt(2)		North Sea		Other International		Total(2)
	(In millions)
2020
Acquisitions:
Proved	$	—	$	7	$	—	$	—	$	7
Unproved	4		—		—		—		4
Exploration	8		102		68		150		328
Development	332		378		162		—		872
Costs incurred(1)	$	344	$	487	$	230	$	150	$	1,211
(1) Includes capitalized interest and asset retirement costs as follows:
Capitalized interest	$	—	$	—	$	—	$	3	$	3
Asset retirement costs	9		—		29		—		38
2019
Acquisitions:
Proved	$	3	$	5	$	—	$	—	$	8
Unproved	47		10		—		—		57
Exploration	162		139		62		105		468
Development	1,500		374		119		3		1,996
Costs incurred(1)	$	1,712	$	528	$	181	$	108	$	2,529
(1) Includes capitalized interest and asset retirement costs as follows:
Capitalized interest	$	23	$	—	$	5	$	4	$	32
Asset retirement costs	14		—		(111)		—		(97)
2018
Acquisitions:
Proved	$	—	$	6	$	—	$	—	$	6
Unproved	111		16		—		—		127
Exploration	640		175		113		12		940
Development	1,791		457		133		—		2,381
Costs incurred(1)	$	2,542	$	654	$	246	$	12	$	3,454
(1) Includes capitalized interest and asset retirement costs as follows:
Capitalized interest	$	23	$	—	$	11	$	2	$	36
Asset retirement costs	93		—		(62)		—		31
(2) Includes a noncontrolling interest in Egypt.

Capitalized Costs

The following table sets forth the capitalized costs and associated accumulated depreciation, depletion, and amortization relating to the Company’s oil and gas acquisition, exploration, and development activities:

	United States		Egypt(1)		North Sea		Other International		Total(1)
	(In millions)
2020
Proved properties	$	20,343	$	12,069	$	8,805	$	—	$	41,217
Unproved properties	348		77		42		135		602
	20,691		12,146		8,847		135		41,819
Accumulated DD&A	(16,252)		(10,290)		(7,081)		—		(33,623)
	$	4,439	$	1,856	$	1,766	$	135	$	8,196
2019
Proved properties	$	20,291	$	11,614	$	8,635	$	—	$	40,540
Unproved properties	509		109		10		38		666
	20,800		11,723		8,645		38		41,206
Accumulated DD&A	(11,783)		(9,377)		(6,700)		—		(27,860)
	$	9,017	$	2,346	$	1,945	$	38	$	13,346

(1)Includes a noncontrolling interest in Egypt..

Oil and Gas Reserve Information

Proved oil and gas reserves are those quantities of natural gas, crude oil, condensate, and NGLs, which by analysis of geoscience and engineering data, can be estimated with reasonable certainty to be economically producible from a given date forward, from known reservoirs, and under existing economic conditions, operating methods, and government regulations. Estimated proved developed oil and gas reserves can be expected to be recovered through existing wells with existing equipment and operating methods. The Company reports all estimated proved reserves held under production-sharing arrangements utilizing the “economic interest” method, which excludes the host country’s share of reserves.

Estimated reserves that can be produced economically through application of improved recovery techniques are included in the “proved” classification when successful testing by a pilot project or the operation of an active, improved recovery program using reliable technology establishes the reasonable certainty for the engineering analysis on which the project or program is based. Economically producible means a resource that generates revenue that exceeds, or is reasonably expected to exceed, the costs of the operation. Reasonable certainty means a high degree of confidence that the quantities will be recovered. Reliable technology is a grouping of one or more technologies (including computational methods) that has been field-tested and has been demonstrated to provide reasonably certain results with consistency and repeatability in the formation being evaluated or in an analogous formation. In estimating its proved reserves, Apache uses several different traditional methods that can be classified in three general categories: (1) performance-based methods; (2) volumetric-based methods; and (3) analogy with similar properties. Apache will, at times, utilize additional technical analysis such as computer reservoir models, petrophysical techniques, and proprietary 3-D seismic interpretation methods to provide additional support for more complex reservoirs. Information from this additional analysis is combined with traditional methods outlined above to enhance the certainty of the Company’s reserve estimates.

There are numerous uncertainties inherent in estimating quantities of proved reserves and projecting future rates of production and timing of development expenditures. The reserve data in the following tables only represent estimates and should not be construed as being exact.

	Crude Oil and Condensate
	United States	Egypt(1)	North Sea	Total(1)
	(Thousands of barrels)
Proved developed reserves:
December 31, 2017	304,279	124,568	92,598	521,445
December 31, 2018	300,484	110,014	104,491	514,989
December 31, 2019	278,145	103,573	101,712	483,430
December 31, 2020	206,936	95,981	86,566	389,483
Proved undeveloped reserves:
December 31, 2017	31,904	16,198	14,013	62,115
December 31, 2018	45,182	9,484	11,278	65,944
December 31, 2019	46,716	10,831	10,049	67,596
December 31, 2020	25,516	11,228	7,273	44,017
Total proved reserves:
Balance December 31, 2017	336,183	140,766	106,611	583,560
Extensions, discoveries and other additions	61,976	22,473	15,682	100,131
Purchases of minerals in-place	140	—	—	140
Revisions of previous estimates	(14,334)	(9,556)	10,613	(13,277)
Production	(38,252)	(34,185)	(17,137)	(89,574)
Sales of minerals in-place	(47)	—	—	(47)
Balance December 31, 2018	345,666	119,498	115,769	580,933
Extensions, discoveries and other additions	52,297	21,039	9,017	82,353
Revisions of previous estimates	(16,446)	4,752	5,132	(6,562)
Production	(38,344)	(30,885)	(18,157)	(87,386)
Sales of minerals in-place	(18,312)	—	—	(18,312)
Balance December 31, 2019	324,861	114,404	111,761	551,026
Extensions, discoveries and other additions	17,858	17,855	5,275	40,988
Revisions of previous estimates	(69,247)	2,541	(4,756)	(71,462)
Production	(32,299)	(27,591)	(18,441)	(78,331)
Sales of minerals in-place	(8,721)	—	—	(8,721)
Balance December 31, 2020	232,452	107,209	93,839	433,500

(1)Includes proved reserves of 36 MMbbls, 38 MMbbls, 40 MMbbls, and 47 MMbbls as of December 31, 2020, 2019, 2018, and 2017, respectively, attributable to a noncontrolling interest in Egypt.

	Natural Gas Liquids
	United States	Egypt(1)	North Sea	Total(1)
	(Thousands of barrels)
Proved developed reserves:
December 31, 2017	171,005	685	2,025	173,715
December 31, 2018	197,574	502	1,938	200,014
December 31, 2019	158,794	667	2,317	161,778
December 31, 2020	150,599	716	2,053	153,368
Proved undeveloped reserves:
December 31, 2017	29,559	39	353	29,951
December 31, 2018	33,796	60	631	34,487
December 31, 2019	23,569	90	660	24,319
December 31, 2020	15,141	126	320	15,587
Total proved reserves:
Balance December 31, 2017	200,564	724	2,378	203,666
Extensions, discoveries and other additions	60,990	144	1,444	62,578
Purchases of minerals in-place	40	—	—	40
Revisions of previous estimates	(9,250)	31	(819)	(10,038)
Production	(20,969)	(337)	(434)	(21,740)
Sales of minerals in-place	(5)	—	—	(5)
Balance December 31, 2018	231,370	562	2,569	234,501
Extensions, discoveries and other additions	41,343	27	697	42,067
Revisions of previous estimates	(32,569)	508	345	(31,716)
Production	(24,959)	(340)	(634)	(25,933)
Sales of minerals in-place	(32,822)	—	—	(32,822)
Balance December 31, 2019	182,363	757	2,977	186,097
Extensions, discoveries and other additions	11,435	97	312	11,844
Revisions of previous estimates	(469)	264	(207)	(412)
Production	(27,133)	(276)	(709)	(28,118)
Sales of minerals in-place	(456)	—	—	(456)
Balance December 31, 2020	165,740	842	2,373	168,955

(1)  Includes proved reserves of 281 Mbbls, 252 Mbbls, 187 Mbbls, and 241 Mbbls as of December 31, 2020, 2019, 2018, and 2017, respectively, attributable to a noncontrolling interest in Egypt.

	Natural Gas
	United States	Egypt(1)	North Sea	Total(1)
	(Millions of cubic feet)
Proved developed reserves:
December 31, 2017	1,347,009	540,667	83,342	1,971,018
December 31, 2018	1,626,403	476,132	95,347	2,197,882
December 31, 2019	945,938	433,382	106,329	1,485,649
December 31, 2020	1,052,756	409,035	68,159	1,529,950
Proved undeveloped reserves:
December 31, 2017	297,226	47,255	11,063	355,544
December 31, 2018	267,090	33,006	15,804	315,900
December 31, 2019	115,040	24,704	16,604	156,348
December 31, 2020	76,504	12,572	8,341	97,417
Total proved reserves:
Balance December 31, 2017	1,644,235	587,922	94,405	2,326,562
Extensions, discoveries and other additions	704,135	79,394	55,274	838,803
Purchases of minerals in-place	906	—	—	906
Revisions of previous estimates	(239,204)	(38,892)	(21,933)	(300,029)
Production	(216,538)	(119,286)	(16,595)	(352,419)
Sales of minerals in-place	(41)	—	—	(41)
Balance December 31, 2018	1,893,493	509,138	111,151	2,513,782
Extensions, discoveries and other additions	249,205	34,758	27,711	311,674
Revisions of previous estimates	(509,753)	18,570	4,015	(487,168)
Production	(233,447)	(104,380)	(19,944)	(357,771)
Sales of minerals in-place	(338,520)	—	—	(338,520)
Balance December 31, 2019	1,060,978	458,086	122,933	1,641,997
Extensions, discoveries and other additions	60,965	83,718	8,140	152,823
Revisions of previous estimates	215,166	(19,849)	(33,541)	161,776
Production	(205,594)	(100,348)	(21,032)	(326,974)
Sales of minerals in-place	(2,255)	—	—	(2,255)
Balance December 31, 2020	1,129,260	421,607	76,500	1,627,367

(1) Includes proved reserves of 141 Bcf, 153 Bcf, 170 Bcf, and 196 Bcf as of December 31, 2020, 2019, 2018, and 2017, respectively, attributable to a noncontrolling interest in Egypt.

	Total Equivalent Reserves
	United States	Egypt(1)	North Sea	Total(1)
	(Thousands barrels of oil equivalent)
Proved developed reserves:
December 31, 2017	699,786	215,364	108,513	1,023,663
December 31, 2018	769,125	189,871	122,320	1,081,316
December 31, 2019	594,595	176,470	121,751	892,816
December 31, 2020	532,994	164,870	99,979	797,843
Proved undeveloped reserves:
December 31, 2017	111,001	24,112	16,210	151,323
December 31, 2018	123,493	15,045	14,543	153,081
December 31, 2019	89,458	15,038	13,476	117,972
December 31, 2020	53,408	13,449	8,983	75,840
Total proved reserves:
Balance December 31, 2017	810,787	239,476	124,723	1,174,986
Extensions, discoveries and other additions	240,322	35,849	26,338	302,509
Purchases of minerals in-place	331	—	—	331
Revisions of previous estimates	(63,451)	(16,007)	6,139	(73,319)
Production	(95,312)	(54,402)	(20,337)	(170,051)
Sales of minerals in-place	(59)	—	—	(59)
Balance December 31, 2018	892,618	204,916	136,863	1,234,397
Extensions, discoveries and other additions	135,174	26,859	14,333	176,366
Revisions of previous estimates	(133,974)	8,355	6,146	(119,473)
Production	(102,211)	(48,622)	(22,115)	(172,948)
Sales of minerals in-place	(107,554)	—	—	(107,554)
Balance December 31, 2019	684,053	191,508	135,227	1,010,788
Extensions, discoveries and other additions	39,454	31,905	6,944	78,303
Revisions of previous estimates	(33,854)	(502)	(10,554)	(44,910)
Production	(93,698)	(44,592)	(22,655)	(160,945)
Sales of minerals in-place	(9,553)	—	—	(9,553)
Balance December 31, 2020	586,402	178,319	108,962	873,683

(1) Includes include total proved reserves of 59 MMboe, 64 MMboe, 68 MMboe, and 80 MMboe as of December 31, 2020, 2019, 2018, and 2017, respectively, attributable to a noncontrolling interest in Egypt.

During 2020, Apache added approximately 78 MMboe from extensions, discoveries, and other additions. The Company recorded 39 MMboe of exploration and development adds in the U.S., primarily in the Southern Midland Basin (26 MMboe) associated with the Wolfcamp and Spraberry drilling programs and the remainder in the Delaware Basin and Austin Chalk. The international operations contributed 39 MMboe of exploration and development adds during 2020, with Egypt contributing 32 MMboe from onshore exploration and appraisal activity primarily in the Khalda Area and Umbarka Area concessions. The North Sea contributed 7 MMboe from drilling success, primarily in the Beryl Field. The Company had combined downward revisions of previously estimated reserves of 45 MMboe. Downward revisions related to changes in product prices accounted for 70 MMboe, engineering and performance upward revisions accounted for 27 MMboe, and downward interest revisions accounted for 2 MMboe. The Company also sold 10 MMboe of proved reserves associated with U.S. divestitures, primarily related to Eastern Shelf and Magnet Withers/Pickett Ridge.

During 2019, Apache added approximately 176 MMboe from extensions, discoveries, and other additions. The Company recorded 135 MMboe of exploration and development adds in the U.S., primarily associated with Woodford, Bone Springs, Spraberry, Barnett, and Wolfcamp drilling programs in the Permian Basin (129 MMboe) and various offset drilling activity in the Midcontinent region (6 MMboe). The Company’s international assets contributed 41 MMboe of exploration and development adds during 2019. Egypt contributed 27 MMboe from onshore exploration and appraisal activity in the Khalda Extension 2, Khalda, Khalda Extension 3, East Bahariya Extension 3, and West Kanayis concessions. The North Sea contributed 14 MMboe from drilling success in the Beryl and Forties fields. The Company had combined downward revisions of previously estimated reserves of 119 MMboe. Downward revisions related to changes in product prices accounted for 139 MMboe and engineering and performance upward revisions accounted for 20 MMboe. The Company also sold 107 MMboe of proved reserves associated with U.S. divestitures, primarily related to the sale of the Company’s Woodford-SCOOP and STACK plays and western Anadarko Basin assets.

During 2018, Apache added approximately 303 MMboe from extensions, discoveries, and other additions. The Company recorded 240 MMboe of exploration and development adds in the U.S., primarily associated with Woodford, Bone Springs, Yeso, Barnett, and Wolfcamp drilling programs in the Permian Basin (217 MMboe) and Woodford and Austin Chalk drilling activity in the Midcontinent region (20 MMboe). The Company’s international assets contributed 62 MMboe of exploration and development adds during 2018. Egypt contributed 36 MMboe from onshore exploration and appraisal activity in the Khalda Extension 2, Khalda, Khalda Extension 3, Matruh, and West Kalabsha concessions. The North Sea contributed 26 MMboe from drilling success in the Beryl and Forties fields. The Company had combined downward revisions of previously estimated reserves of 73 MMboe. Downward revisions related to changes in product prices accounted for 24 MMboe, interest revisions accounted for 5 MMboe, and engineering and performance downward revisions accounted for 44 MMboe.

Approximately 10 percent of the Company’s year-end 2020 estimated proved developed reserves are classified as proved not producing. These reserves relate to zones that are either behind pipe, or that have been completed but not yet produced, or zones that have been produced in the past, but are not now producing because of mechanical reasons. These reserves are considered to be a lower tier of reserves than producing reserves because they are frequently based on volumetric calculations rather than performance data. Future production associated with behind pipe reserves is scheduled to follow depletion of the currently producing zones in the same wellbores. Additional capital may have to be spent to access these reserves. The capital and economic impact of production timing are reflected in this Note 18, under “Future Net Cash Flows.”

Future Net Cash Flows

Future cash inflows as of December 31, 2020, 2019, and 2018 were calculated using an unweighted arithmetic average of oil and gas prices in effect on the first day of each month in the respective year, except where prices are defined by contractual arrangements. Operating costs, production and ad valorem taxes and future development costs are based on current costs with no escalation. Future development costs include abandonment and dismantlement costs.

The following table sets forth unaudited information concerning future net cash flows for proved oil and gas reserves, net of income tax expense. Income tax expense has been computed using expected future tax rates and giving effect to tax deductions and credits available, under current laws, and which relate to oil and gas producing activities. This information does not purport to present the fair market value of the Company’s oil and gas assets, but does present a standardized disclosure concerning possible future net cash flows that would result under the assumptions used.

	United States		Egypt(1)		North Sea		Total(1)
	(In millions)
2020
Cash inflows	$	12,537	$	5,560	$	4,122	$	22,219
Production costs	(6,244)		(1,704)		(2,388)		(10,336)
Development costs	(1,555)		(633)		(2,448)		(4,636)
Income tax expense	—		(1,096)		316		(780)
Net cash flows	4,738		2,127		(398)		6,467
10 percent discount rate	(1,829)		(437)		1,111		(1,155)
Discounted future net cash flows(2)	$	2,909	$	1,690	$	713	$	5,312
2019
Cash inflows	$	21,694	$	8,306	$	7,454	$	37,454
Production costs	(10,642)		(1,847)		(2,730)		(15,219)
Development costs	(1,740)		(707)		(2,651)		(5,098)
Income tax expense	(27)		(1,930)		(784)		(2,741)
Net cash flows	9,285		3,822		1,289		14,396
10 percent discount rate	(4,003)		(808)		297		(4,514)
Discounted future net cash flows(2)	$	5,282	$	3,014	$	1,586	$	9,882
2018
Cash inflows	$	29,906	$	9,866	$	9,206	$	48,978
Production costs	(13,699)		(1,799)		(2,588)		(18,086)
Development costs	(2,150)		(792)		(2,714)		(5,656)
Income tax expense	(19)		(2,455)		(1,352)		(3,826)
Net cash flows	14,038		4,820		2,552		21,410
10 percent discount rate	(6,516)		(1,066)		(107)		(7,689)
Discounted future net cash flows(2)	$	7,522	$	3,754	$	2,445	$	13,721

(1)Includes discounted future net cash flows of approximately $563 million, $1.0 billion, and $1.3 billion as of December 31, 2020, 2019, and 2018, respectively, attributable to a noncontrolling interest in Egypt.

(2)Estimated future net cash flows before income tax expense, discounted at 10 percent per annum, totaled approximately $7.1 billion, $12.4 billion, and $16.9 billion as of December 31, 2020, 2019, and 2018, respectively.

The following table sets forth the principal sources of change in the discounted future net cash flows:

	For the Year Ended December 31,
	2020		2019		2018
	(In millions)
Sales, net of production costs	$	(2,422)	$	(4,291)	$	(5,335)
Net change in prices and production costs	(5,753)		(3,034)		3,902
Discoveries and improved recovery, net of related costs	751		2,042		3,889
Change in future development costs	20		(75)		47
Previously estimated development costs incurred during the period	576		983		910
Revision of quantities	(418)		(741)		(648)
Purchases of minerals in-place	—		—		6
Accretion of discount	1,236		1,693		1,216
Change in income taxes	1,533		720		(1,125)
Sales of minerals in-place	(104)		(817)		(1)
Change in production rates and other	11		(319)		777
	$	(4,570)	$	(3,839)	$	3,638