SUPPLEMENTAL OIL AND GAS DISCLOSURES (Unaudited)

12 Months Ended

Dec. 31, 2013

Extractive Industries [Abstract]

SUPPLEMENTAL OIL AND GAS DISCLOSURES (Unaudited)

14. 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.

On March 12, 2014, Apache’s subsidiaries completed the sale of all of the Company’s operations in Argentina and as such the results of Argentina have been classified as discontinued operations.

	United States		Canada			Egypt(3)		Australia		North Sea		Other International			Total(3)(4)
	(In millions, except per boe)
2013
Oil and gas production revenues	$	6,902	$	1,224		$	3,917	$	1,140	$	2,728	$	—		$	15,911
Operating cost:
Depreciation, depletion, and amortization
Recurring(1)		2,227		426			881		361		999		—			4,894
Additional		552		—			—		—		367		76			995
Asset retirement obligation accretion		94		49			—		27		68		—			238
Lease operating expenses		1,320		459			471		214		400		—			2,864
Gathering and transportation		84		155			42		—		7		—			288
Production taxes(2)		324		40			—		14		382		—			760
Income tax		817		24			1,161		157		313		—			2,472
		5,418		1,153			2,555		773		2,536		76			12,511
Results of operation	$	1,484	$	71		$	1,362	$	367	$	192	$	(76	)	$	3,400
Amortization rate per boe	$	18.39	$	10.89		$	16.21	$	17.47	$	37.25	$	—		$	18.67
2012
Oil and gas production revenues	$	6,226	$	1,322		$	4,554	$	1,575	$	2,751	$	—		$	16,428
Operating cost:
Depreciation, depletion, and amortization
Recurring(1)		1,984		580			924		460		912		—			4,860
Additional		—		1,883			—		—		—		43			1,926
Asset retirement obligation accretion		112		41			—		17		58		—			228
Lease operating expenses		1,386		458			410		215		315		—			2,784
Gathering and transportation		69		163			39		—		24		—			295
Production taxes(2)		279		42			—		11		451		—			783
Income tax		851		(466	)		1,527		262		614		—			2,788
		4,681		2,701			2,900		965		2,374		43			13,664
Results of operation	$	1,545	$	(1,379	)	$	1,654	$	610	$	377	$	(43	)	$	2,764
Amortization rate per boe	$	17.24	$	11.66		$	13.81	$	17.67	$	32.65	$	—		$	17.18
2011
Oil and gas production revenues	$	6,104	$	1,617		$	4,791	$	1,734	$	2,091	$	—		$	16,337
Operating cost:
Depreciation, depletion, and amortization
Recurring(1)		1,634		537			818		435		405		—			3,829
Additional		—		—			—		—		—		109			109
Asset retirement obligation accretion		97		26			—		10		17		—			150
Lease operating expenses		1,167		470			398		197		208		—			2,440
Gathering and transportation		64		165			35		—		25		—			289
Production taxes(2)		255		44			—		9		538		—			846
Income tax		1,025		95			1,699		325		557		—			3,701
		4,242		1,337			2,950		976		1,750		109			11,364
Results of operation	$	1,862	$	280		$	1,841	$	758	$	341	$	(109	)	$	4,973
Amortization rate per boe	$	15.55	$	10.44		$	11.63	$	16.59	$	20.21	$	—		$	14.18

⁽¹⁾  This amount only reflects DD&A of capitalized costs of oil and gas proved properties and, therefore, does not agree with DD&A reflected on Note 13—Business Segment Information.

⁽²⁾  Only reflects amounts directly related to oil and gas producing properties and, therefore, does not agree with taxes other than income reflected on Note 13—Business Segment Information.

⁽³⁾  2013 includes a noncontrolling interest in Egypt.

⁽⁴⁾  Amounts have been recast to exclude discontinued operations.

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

	United States		Canada		Egypt(2)			Australia			North Sea		Argentina		Other International		Total(2)
	(In millions)
2013
Acquisitions:
Proved	$	17	$	—	$	35		$	—		$	125	$	—	$	—	$	177
Unproved		—		137		11			—			17		—		—		165
Exploration		757		50		563			169			278		53		22		1,892
Development		5,435		722		618			996			635		142		—		8,548
Costs incurred(1)	$	6,209	$	909	$	1,227		$	1,165		$	1,055	$	195	$	22	$	10,782
(1)      Includes capitalized interest and asset retirement costs as follows:
Capitalized interest	$	239	$	35	$	15		$	16		$	25	$	10	$	—	$	340
Asset retirement costs		480		17		—			(30	)		67		3		—		537
(2)       Includes a noncontrolling interest in Egypt.
2012
Acquisitions:
Proved	$	1,076	$	5	$	28		$	32		$	110	$	—	$	—	$	1,251
Unproved		2,329		—		—			—			26		—		—		2,355
Exploration		1,369		111		696			149			111		157		96		2,689
Development		4,465		762		394			915			837		161		2		7,536
Costs incurred(1)	$	9,239	$	878	$	1,118		$	1,096		$	1,084	$	318	$	98	$	13,831
(1)       Includes capitalized interest and asset retirement costs as follows:
Capitalized interest	$	215	$	38	$	16		$	12		$	24	$	11	$	—	$	316
Asset retirement costs		473		245		—			207			89		18		—		1,032
2011
Acquisitions:
Proved	$	368	$	—	$	(12	)	$	—		$	2,399	$	—	$	—	$	2,755
Unproved		116		33		2			48			476		—		13		688
Exploration		418		209		570			286			18		202		59		1,762
Development		2,832		883		344			429			941		156		2		5,587
Costs incurred(1)	$	3,734	$	1,125	$	904		$	763		$	3,834	$	358	$	74	$	10,792
(1)      Includes capitalized interest and asset retirement costs as follows:
Capitalized interest	$	152	$	47	$	18		$	14		$	—	$	12	$	—	$	243
Asset retirement costs		380		228		—			125			678		—		—		1,411

Capitalized Costs

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

	United States			Canada			Egypt(1)			Australia			North Sea			Argentina			Other International			Total(1)
	(In millions)
2013
Proved properties	$	41,904		$	13,231		$	8,418		$	7,298		$	9,378		$	2,933		$	228		$	83,390
Unproved properties		5,042			1,116			660			471			702			349			23			8,363
		46,946			14,347			9,078			7,769			10,080			3,282			251			91,753
Accumulated DD&A		(20,745	)		(9,310	)		(5,356	)		(2,839	)		(4,811	)		(1,964	)		(228	)		(45,253	)
	$	26,201		$	5,037		$	3,722		$	4,930		$	5,269		$	1,318		$	23		$	46,500
(1)       Includes a noncontrolling interest in Egypt.
2012
Proved properties	$	40,163		$	13,477		$	7,165		$	6,319		$	8,401		$	2,706		$	152		$	78,383
Unproved properties		5,641			1,059			686			284			626			382			76			8,754
		45,804			14,536			7,851			6,603			9,027			3,088			228			87,137
Accumulated DD&A		(17,968	)		(8,899	)		(4,474	)		(2,478	)		(3,445	)		(1,562	)		(152	)		(38,978	)
	$	27,836		$	5,637		$	3,377		$	4,125		$	5,582		$	1,526		$	76		$	48,159

Costs Not Being Amortized

The following table sets forth a summary of oil and gas property costs not being amortized at December 31, 2013, by the year in which such costs were incurred. There are no individually significant properties or significant development projects included in costs not being amortized. The majority of the evaluation activities are expected to be completed within five to ten years.

	Total		2013		2012		2011		2010 and Prior
	(In millions)
Property acquisition costs	$	6,437	$	466	$	3,391	$	899	$	1,681
Exploration and development		1,666		1,138		388		88		52
Capitalized interest		260		48		48		30		134
Total	$	8,363	$	1,652	$	3,827	$	1,017	$	1,867

Oil and Gas Reserve Information

Proved oil and gas reserves are the estimated quantities of natural gas, crude oil, condensate, and natural gas liquids (NGLs) that geological and engineering data demonstrate with reasonable certainty to be recoverable in future years from known reservoirs under existing conditions, operating conditions, 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 which 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 our 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
	(Thousands of barrels)
	United States			Canada			Egypt(1)			Australia			North Sea			Argentina			Total(1)
Proved developed reserves:
December 31, 2010		422,737			90,292			109,657			48,072			115,705			16,583			803,046
December 31, 2011		428,251			81,846			105,840			35,725			136,990			16,001			804,653
December 31, 2012		474,837			79,695			106,746			29,053			119,635			15,845			825,811
December 31, 2013		457,981			80,526			119,242			22,524			100,327			14,195			794,795
Proved undeveloped reserves:
December 31, 2010		214,117			56,855			17,470			18,064			38,663			4,062			349,231
December 31, 2011		205,763			59,746			22,195			32,220			32,415			4,585			356,924
December 31, 2012		203,068			70,650			17,288			34,808			28,019			2,981			356,814
December 31, 2013		195,835			56,366			16,302			36,703			29,253			2,231			336,690
Total proved reserves:
Balance December 31, 2010		636,855			147,146			127,127			66,136			154,368			20,645			1,152,277
Extensions, discoveries and other additions		45,676			16,712			45,021			15,762			332			3,230			126,733
Purchase of minerals in-place		5,097			705			—			—			34,612			—			40,414
Revisions of previous estimates		(8,904	)		(17,117	)		(6,185	)		—			—			215			(31,991	)
Production		(43,587	)		(5,202	)		(37,928	)		(13,953	)		(19,907	)		(3,503	)		(124,080	)
Sale of properties		(1,123	)		(653	)		—			—			—			—			(1,776	)
Balance December 31, 2011		634,014			141,591			128,035			67,945			169,405			20,587			1,161,577
Extensions, discoveries and other additions		84,656			18,935			36,188			6,277			346			1,133			147,535
Purchase of minerals in-place		15,942			188			—			276			2,143			—			18,549
Revisions of previous estimates		(7,474	)		(4,577	)		(3,678	)		(66	)		(928	)		671			(16,052	)
Production		(49,089	)		(5,792	)		(36,511	)		(10,571	)		(23,312	)		(3,565	)		(128,840	)
Sale of properties		(144	)		—			—			—			—			—			(144	)
Balance December 31, 2012		677,905			150,345			124,034			63,861			147,654			18,826			1,182,625
Extensions, discoveries and other additions		133,227			10,177			43,738			2,539			1,543			998			192,222
Purchase of minerals in-place		85			—			5			—			3,623			—			3,713
Revisions of previous estimates		1,683			(531	)		457			(118	)		18			24			1,533
Production		(53,621	)		(6,469	)		(32,690	)		(7,055	)		(23,258	)		(3,422	)		(126,515	)
Sale of properties		(105,463	)		(16,630	)		—			—			—			—			(122,093	)
Balance December 31, 2013		653,816			136,892			135,544			59,227			129,580			16,426			1,131,485

⁽¹⁾  2013 includes proved reserves of 45 MMbbls as of December 31, 2013 attributable to a noncontrolling interest in Egypt.

	Natural Gas Liquids
	(Thousands of barrels)
	United States			Canada			Egypt			Australia		North Sea			Argentina			Total
Proved developed reserves:
December 31, 2010		91,800			23,701			—			—		—			5,875			121,376
December 31, 2011		107,490			23,256			—			—		8,753			5,939			145,438
December 31, 2012		154,508			21,996			—			—		2,438			5,007			183,949
December 31, 2013		184,485			26,099			—			—		2,435			4,110			217,129
Proved undeveloped reserves:
December 31, 2010		30,361			4,142			—			—		—			579			35,082
December 31, 2011		52,543			8,193			—			—		509			1,215			62,460
December 31, 2012		60,889			12,258			—			—		380			876			74,403
December 31, 2013		63,538			9,970			—			—		215			1,009			74,732
Total proved reserves:
Balance December 31, 2010		122,160			27,844			—			—		—			6,454			156,458
Extensions, discoveries and other additions		43,915			5,890			18			—		72			1,784			51,679
Purchase of minerals in-place		586			47			—			—		9,191			—			9,824
Revisions of previous estimates		1,713			774			—			—		—			17			2,504
Production		(8,071	)		(2,174	)		(18	)		—		(1	)		(1,102	)		(11,366	)
Sale of properties		(270	)		(931	)		—			—		—			—			(1,201	)
Balance December 31, 2011		160,033			31,450			—			—		9,262			7,153			207,898
Extensions, discoveries and other additions		71,965			7,655			—			—		246			—			79,866
Purchase of minerals in-place		230			9			—			—		231			—			470
Revisions of previous estimates		(4,559	)		(2,569	)		—			—		(6,329	)		(169	)		(13,626	)
Production		(12,272	)		(2,291	)		—			—		(592	)		(1,101	)		(16,256	)
Sale of properties		—			—			—			—		—			—			—
Balance December 31, 2012		215,397			34,254			—			—		2,818			5,883			258,352
Extensions, discoveries and other additions		69,231			4,014			—			—		—			—			73,245
Purchase of minerals in-place		45			—			—			—		295			—			340
Revisions of previous estimates		1,591			546			—			—		1			3			2,141
Production		(19,922	)		(2,442	)		—			—		(464	)		(767	)		(23,595	)
Sale of properties		(18,319	)		(303	)		—			—		—			—			(18,622	)
Balance December 31, 2013		248,023			36,069			—			—		2,650			5,119			291,861

	Natural Gas
	(Millions of cubic feet)
	United States			Canada			Egypt(1)			Australia			North Sea			Argentina			Total(1)
Proved developed reserves:
December 31, 2010		2,284,116			2,181,615			748,573			682,763			4,144			462,206			6,363,417
December 31, 2011		2,215,973			2,108,801			700,866			675,618			105,028			447,132			6,253,418
December 31, 2012		2,353,587			1,734,657			690,436			596,052			93,319			365,054			5,833,105
December 31, 2013		2,005,966			1,294,420			621,825			626,543			88,177			289,133			4,926,064
Proved undeveloped reserves:
December 31, 2010		988,869			1,310,352			328,344			805,735			—			70,465			3,503,765
December 31, 2011		760,238			1,438,710			282,100			893,966			3,414			90,427			3,468,855
December 31, 2012		832,320			403,227			205,055			1,074,018			18,985			97,496			2,631,101
December 31, 2013		667,160			439,037			190,355			975,224			18,988			121,584			2,412,348
Total proved reserves:
Balance December 31, 2010		3,272,985			3,491,967			1,076,917			1,488,498			4,144			532,671			9,867,182
Extensions, discoveries and other additions		169,506			505,049			77,049			148,640			475			81,274			981,993
Purchase of minerals in-place		67,595			8,838			—			—			104,658			—			181,091
Revisions of previous estimates		(7,716	)		(133,359	)		(37,623	)		—			—			1,107			(177,591	)
Production		(315,631	)		(230,880	)		(133,377	)		(67,554	)		(835	)		(77,493	)		(825,770	)
Sale of properties		(210,528	)		(94,104	)		—			—			—			—			(304,632	)
Balance December 31, 2011		2,976,211			3,547,511			982,966			1,569,584			108,442			537,559			9,722,273
Extensions, discoveries and other additions		365,863			252,130			55,967			176,969			16,397			2,623			869,949
Purchase of minerals in-place		313,885			2,503			—			1,745			8,494			—			326,627
Revisions of previous estimates		(156,840	)		(1,443,989	)		(13,974	)		101			—			496			(1,614,206	)
Production		(312,600	)		(219,849	)		(129,468	)		(78,329	)		(21,029	)		(78,128	)		(839,403	)
Sale of properties		(612	)		(422	)		—			—			—			—			(1,034	)
Balance December 31, 2012		3,185,907			2,137,884			895,491			1,670,070			112,304			462,550			8,464,206
Extensions, discoveries and other additions		306,721			359,493			44,382			13,351			2,750			16,515			743,212
Purchase of minerals in-place		855			—			—			—			10,680			—			11,535
Revisions of previous estimates		61,247			109,551			2,413			(101	)		32			49			173,191
Production		(285,187	)		(181,593	)		(130,106	)		(81,553	)		(18,601	)		(68,397	)		(765,437	)
Sale of properties		(596,417	)		(691,878	)		—			—			—			—			(1,288,295	)
Balance December 31, 2013		2,673,126			1,733,457			812,180			1,601,767			107,165			410,717			7,338,412

⁽¹⁾  2013 includes proved reserves of 271 Bcf as of December 31, 2013 attributable to a noncontrolling interest in Egypt.

	Total Equivalent Reserves
	(Thousands barrels of oil equivalent)
	United States			Canada			Egypt(1)			Australia			North Sea			Argentina			Total(1)
Proved developed reserves:
December 31, 2010		895,223			477,594			234,419			161,866			116,396			99,493			1,984,991
December 31, 2011		905,069			456,569			222,651			148,328			163,248			96,462			1,992,327
December 31, 2012		1,021,610			390,800			221,819			128,395			137,626			81,695			1,981,945
December 31, 2013		976,795			322,362			222,880			126,948			117,457			66,494			1,832,936
Proved undeveloped reserves:
December 31, 2010		409,290			279,389			72,194			152,353			38,663			16,385			968,274
December 31, 2011		385,013			307,724			69,212			181,214			33,493			20,871			997,527
December 31, 2012		402,677			150,113			51,464			213,811			31,563			20,106			869,734
December 31, 2013		370,566			139,509			48,028			199,240			32,633			23,504			813,480
Total proved reserves:
Balance December 31, 2010		1,304,512			756,984			306,613			314,219			155,059			115,878			2,953,265
Extensions, discoveries and other additions		117,842			106,778			57,882			40,534			483			18,559			342,078
Purchase of minerals in-place		16,949			2,225			—			—			61,246			—			80,420
Revisions of previous estimates		(8,477	)		(38,570	)		(12,456	)		—			—			417			(59,086	)
Production		(104,263	)		(45,856	)		(60,176	)		(25,211	)		(20,047	)		(17,521	)		(273,074	)
Sale of properties		(36,481	)		(17,268	)		—			—			—			—			(53,749	)
Balance December 31, 2011		1,290,082			764,293			291,863			329,542			196,741			117,333			2,989,854
Extensions, discoveries and other additions		217,598			68,612			45,516			35,772			3,325			1,570			372,393
Purchase of minerals in-place		68,486			614			—			567			3,790			—			73,457
Revisions of previous estimates		(38,172	)		(247,811	)		(6,007	)		(49	)		(7,258	)		585			(298,712	)
Production		(113,461	)		(44,725	)		(58,089	)		(23,626	)		(27,409	)		(17,687	)		(284,997	)
Sale of properties		(246	)		(70	)		—			—			—			—			(316	)
Balance December 31, 2012		1,424,287			540,913			273,283			342,206			169,189			101,801			2,851,679
Extensions, discoveries and other additions		253,578			74,107			51,135			4,764			2,001			3,751			389,336
Purchase of minerals in-place		273			—			5			—			5,698			—			5,976
Revisions of previous estimates		13,482			18,274			859			(135	)		24			35			32,539
Production		(121,074	)		(39,177	)		(54,374	)		(20,647	)		(26,822	)		(15,589	)		(277,683	)
Sale of properties		(223,185	)		(132,246	)		—			—			—			—			(355,431	)
Balance December 31, 2013		1,347,361			461,871			270,908			326,188			150,090			89,998			2,646,416

⁽¹⁾  2013 includes total proved reserves of 90 MMboe attributable to a noncontrolling interest in Egypt.

During 2013, Apache added 6 MMboe of estimated proved reserves through purchases of minerals in-place. We sold 355 MMboe through several divestiture transactions which included the majority of our Gulf of Mexico Shelf properties and certain fields in Canada. During 2013, Apache also added 389 MMboe from extensions, discoveries and other additions. In the U.S., the Company recorded 254 MMboe primarily associated with drilling successes in the Permian and Anadarko basins, which added 150 MMboe and 65 MMboe, respectively; 20 MMboe from appraisal drilling in the deepwater Gulf of Mexico; and 19 MMboe from various drilling programs in other U.S. regions. In Canada, additions of 74 MMboe were primarily a result of drilling activity for liquids-rich gas targets in the Kaybob field area, horizontal drilling in our House Mountain waterflood units, extensions of the Glauconitic trend in our West 5 area and shallow oil drilling in Brownfield and Consort field areas. Egypt contributed 51 MMboe from exploration and appraisal activity in the West Kalabsha, Shushan, Khalda and Ras Kanayes concessions along with continued development of the Razzak, Abu Gharadig and Meghar fields. Australia, Argentina and North Sea regions contributed 11 MMboe from their combined drilling programs.

Approximately 10 percent of Apache’s year-end 2013 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 14, under “Future Net Cash Flows.”

Future Net Cash Flows

Future cash inflows as of December 31, 2013 and 2012 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.

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			Canada			Egypt(2)			Australia			North Sea			Argentina			Total(2)
	(In millions)
2013
Cash inflows	$	79,654		$	19,260		$	16,864		$	20,637		$	15,359		$	2,824		$	154,598
Production costs		(26,032	)		(8,105	)		(2,590	)		(4,494	)		(8,147	)		(1,176	)		(50,544	)
Development costs		(4,834	)		(2,458	)		(1,899	)		(2,283	)		(3,284	)		(397	)		(15,155	)
Income tax expense		(12,832	)		(678	)		(4,328	)		(3,072	)		(2,376	)		(142	)		(23,428	)
Net cash flows		35,956			8,019			8,047			10,788			1,552			1,109			65,471
10 percent discount rate		(20,117	)		(3,987	)		(2,193	)		(6,423	)		85			(242	)		(32,877	)
Discounted future net cash flows(1)	$	15,839		$	4,032		$	5,854		$	4,365		$	1,637		$	867		$	32,594
2012
Cash inflows	$	84,060		$	20,512		$	16,210		$	20,823		$	16,732		$	3,010		$	161,347
Production costs		(27,230	)		(8,543	)		(2,126	)		(4,896	)		(8,451	)		(1,162	)		(52,408	)
Development costs		(6,768	)		(2,916	)		(1,756	)		(2,484	)		(3,053	)		(248	)		(17,225	)
Income tax expense		(12,740	)		(754	)		(4,246	)		(3,172	)		(3,163	)		(141	)		(24,216	)
Net cash flows		37,322			8,299			8,082			10,271			2,065			1,459			67,498
10 percent discount rate		(19,464	)		(4,472	)		(2,107	)		(6,361	)		(98	)		(443	)		(32,945	)
Discounted future net cash flows(1)	$	17,858		$	3,827		$	5,975		$	3,910		$	1,967		$	1,016		$	34,553

⁽¹⁾  Estimated future net cash flows before income tax expense, discounted at 10 percent per annum, totaled approximately $45.4 billion and $48.2 billion as of December 31, 2013 and 2012, respectively.

⁽²⁾  Includes discounted future net cash flows of approximately $1.95 billion in 2013 attributable to a noncontrolling interest in Egypt.

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

	For the Year Ended December 31,
	2013			2012			2011
	(In millions)
Sales, net of production costs	$	(12,271	)	$	(12,589	)	$	(13,152	)
Net change in prices and production costs		1,438			(1,941	)		12,167
Discoveries and improved recovery, net of related costs		6,892			6,742			6,751
Change in future development costs		(2,017	)		(935	)		(2,250	)
Previously estimated development costs incurred during the period		4,654			4,359			2,479
Revision of quantities		500			(4,065	)		(1,475	)
Purchases of minerals in-place		227			1,181			2,139
Accretion of discount		4,823			5,234			4,161
Change in income taxes		855			2,711			(4,303	)
Sales of properties		(6,232	)		(3	)		(1,285	)
Change in production rates and other		(828	)		(2,088	)		273
	$	(1,959	)	$	(1,394	)	$	5,505