CONTACTS:
(Media):		Bill Mintz		(713) 296-7276
		Bob Dye		(713) 296-6662
(Investors):		Tom Chambers		(713) 296-6685
		Rob Rayphole		(713) 296-6160
(Web site):		www.apachecorp.com

APACHE’S PRODUCTION RISES 10 PERCENT TO RECORD 646,866 BOE PER DAY
FUELING SECOND-QUARTER EARNINGS OF $860 MILLION OR $2.53 PER SHARE

     Houston, July 20, 2010 — Apache Corporation (NYSE, Nasdaq: APA) today reported that higher oil output from international operations fueled record production in the second quarter as net income climbed to $860 million or $2.53 per diluted common share, nearly double the net income of $443 million or $1.31 per share in the prior-year period.

     Production totaled 646,866 barrels of oil equivalent (boe) per day, up 10 percent from the prior-year period. Liquid hydrocarbon production climbed to 348,272 barrels per day, up 19 percent from the prior-year period and 16 percent from the first quarter of 2010. Natural gas production increased to 1.79 billion cubic feet per day, a 1-percent increase from the year-earlier period and up 5 percent from the first quarter.

     Apache’s increased oil production was the result of a nearly sixfold increase in output in Australia, including a full quarter of production from the Van Gogh and Pyrenees oil developments, and higher output from the Faghur Basin in Egypt’s Western Desert. Natural gas production was higher in Australia, Gulf Coast, Egypt and the Anadarko Basin of western Oklahoma.

     Cash from operations before changes in operating assets and liabilities* totaled $1.8 billion in the second quarter, up 46 percent from $1.3 billion in the year-earlier period. At the end of the quarter, Apache’s cash balance was $1.8 billion.

     Apache’s second-quarter adjusted earnings*, which exclude certain items that impact the comparability of operating results, totaled $829 million or $2.44 per diluted share, up from $474 million or $1.41 per share in the prior-year period.

     “Apache’s second-quarter results illustrate the benefit of our focus on long-term growth,” said G. Steven Farris, chairman and chief executive officer. “We are realizing the benefit of significant discoveries and the investments Apache made to bring them on production. Apache’s financial results also benefitted from our balanced commodity mix at a time when oil prices remain strong relative to North American natural gas prices.”

     Apache’s international operations accounted for 56 percent of worldwide production. Liquids sales were 54 percent of worldwide production and 78 percent of revenue. Apache realized an average of $74.89 per barrel of oil, essentially unchanged from the first quarter, and $4.01 per thousand cubic feet (Mcf) of natural gas, down from $4.60 per Mcf in the first quarter.

     Apache’s second-quarter results include production from June 9 on Gulf Shelf assets acquired on that date from Devon Energy Corp. for $1.05 billion. The acquisition brought year-end 2009 estimated proved and probable reserves of 83 million boe across approximately 150 blocks.

     Apache also expects to close its previously announced merger with Mariner Energy upon approval of regulators and Mariner’s shareholders. Mariner is an independent producer with operations in the Gulf of Mexico, the Gulf Coast and the Permian Basin with year-end 2009 estimated proved reserves of 181 million boe (47 percent liquid hydrocarbons) as well as unbooked resource potential of 2 billion boe. Approval is projected for the third quarter.

     Apache Corporation is an oil and gas exploration and production company with operations in the United States, Canada, Egypt, the United Kingdom North Sea, Australia and Argentina. From time to time, Apache posts announcements, updates and investor information, in addition to copies of all press releases, on its Web site, www.apachecorp.com.

     *Adjusted earnings and cash from operations before changes in operating assets and liabilities are non-GAAP measures. Please see reconciliations below. For supplemental and non-GAAP information, please go to www.apachecorp.com/financialinfo.

Additional Information

     This communication does not constitute an offer to sell or the solicitation of an offer to buy any securities or a solicitation of any vote or approval. Apache has filed with the Securities and Exchange Commission (“SEC”) a registration statement on Form S-4 containing a preliminary proxy statement of Mariner Energy that also constitutes a preliminary prospectus of Apache. A definitive proxy statement/prospectus will be mailed to stockholders of Mariner. Apache and Mariner also plan to file other documents with the SEC regarding the proposed transaction. INVESTORS AND SECURITY HOLDERS OF MARINER ARE URGED TO READ THE DEFINITIVE PROXY STATEMENT/PROSPECTUS AND OTHER DOCUMENTS FILED WITH THE SEC CAREFULLY AND IN THEIR ENTIRETY WHEN THEY BECOME AVAILABLE BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION ABOUT THE PROPOSED TRANSACTION. Investors and security holders will be able to obtain the documents (when available) free of charge at the SEC’s web site, www.sec.gov. Copies of the documents filed with the SEC by Apache will be available free of charge on Apache’s website at www.apachecorp.com under the tab “Investors” or by contacting Apache’s Investor Relations Department at 713-296-6000. Copies of the documents filed with the SEC by Mariner will be available free of charge on Mariner’s website at www.mariner-energy.com under the tab “Investor Information” or by contacting Mariner’s Investor Relations Department at 713-954-5558. You may also read and copy any reports, statements and other information filed with the SEC at the SEC public reference room at 100 F Street N.E., Room 1580, Washington, D.C. 20549. Please call the SEC at (800) 732-0330 or visit the SEC’s website for further information on its public reference room.

     Apache, Mariner, their respective directors and executive officers and other persons may be deemed, under SEC rules, to be participants in the solicitation of proxies from stockholders of Mariner in connection with the proposed transaction. Information regarding Apache’s directors and officers can be found in its proxy statement filed with the SEC on March 31, 2010, and information regarding Mariner’s directors and officers can be found in its proxy statement filed with the SEC on April 1, 2010. Additional information regarding the participants in the proxy solicitation and a description of their direct and indirect interests in the transaction, by security holdings or otherwise, will be contained in the definitive proxy statement/prospectus and other relevant materials to be filed with the SEC when they become available.

Forward-Looking Statements

     Statements in this document include “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. The opinions, forecasts, projections, future plans or other statements other than statements of historical fact, are forward-looking statements. We can give no assurance that such expectations will prove to have been correct. Actual results could differ materially as a result of a variety of risks and uncertainties, including: the timing to consummate the proposed transaction; the risk that a condition to closing of the proposed transaction may not be satisfied; the risk that a regulatory approval that may be required for the proposed transaction is not obtained or is obtained subject to conditions that are not anticipated; negative effects from the pendency of the merger; our ability to achieve the synergies and value creation contemplated by the proposed transaction; our ability to promptly and effectively integrate the merged businesses; and the diversion of management time on transaction-related issues. Other factors that could materially affect actual results are discussed in Apache’s and Mariner’s most recent Forms 10-K as well as each company’s other filings with the SEC available at the SEC’s website at www.sec.gov. Actual results may differ materially from those expected, estimated or projected. Forward-looking statements speak only as of the date they are made, and we undertake no obligation to publicly update or revise any of them in light of new information, future events or otherwise.

APACHE CORPORATION
FINANCIAL INFORMATION
(In thousands, except per share data)

		For the Quarter								For the Six Months
		Ended June 30,								Ended June 30,
		2010				2009				2010				2009
REVENUES AND OTHER:
Oil and gas production revenues		$	2,968,765			$	2,074,344			$	5,662,390			$	3,677,958
Other			3,145				19,034				(17,229	)			49,245
			2,971,910				2,093,378				5,645,161				3,727,203
COSTS AND EXPENSES:
Depreciation, depletion and amortization
Recurring			729,751				573,359				1,368,249				1,153,976
Additional			—				—				—				2,818,161
Asset retirement obligation accretion			24,760				26,483				48,762				53,221
Lease operating expenses			445,949				405,273				886,195				802,762
Gathering and transportation			43,038				33,479				83,403				66,818
Taxes other than income			186,833				115,941				363,771				203,280
General and administrative			91,829				90,905				178,979				175,951
Financing costs, net			55,757				61,155				115,024				119,742
			1,577,917				1,306,595				3,044,383				5,393,911
INCOME (LOSS) BEFORE INCOME TAXES			1,393,993				786,783				2,600,778				(1,666,708	)
Current income tax provision			339,151				218,247				682,125				220,741
Deferred income tax provision (benefit)			194,619				123,816				353,449				(575,229	)
NET INCOME (LOSS)			860,223				444,720				1,565,204				(1,312,220	)
Preferred stock dividends			—				1,420				—				2,840
INCOME (LOSS) ATTRIBUTABLE TO COMMON STOCK		$	860,223			$	443,300			$	1,565,204			$	(1,315,060	)
NET INCOME (LOSS) PER COMMON SHARE:
Basic		$	2.55			$	1.32			$	4.64			$	(3.92	)
Diluted		$	2.53			$	1.31			$	4.61			$	(3.92	)
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING			337,618				335,637				337,273				335,372
DILUTED SHARES OUTSTANDING			339,377				337,365				339,282				335,372

APACHE CORPORATION
FINANCIAL INFORMATION
(In thousands)

		For the Quarter								For the Six Months
		Ended June 30,								Ended June 30,
		2010				2009				2010				2009
COSTS INCURRED: (1)
North America exploration and development		$	782,103			$	381,782			$	1,310,492			$	887,098
International exploration and development			475,016				506,229				956,787				993,011
Oil and gas property acquisitions			1,028,724				183,195				1,033,394				243,220
		$	2,285,843			$	1,071,206			$	3,300,673			$	2,123,329

Capitalized interest		$	15,747			$	14,972			$	31,676			$	30,981
Asset retirement costs		$	292,373			$	34,098			$	314,607			$	93,703

		June 30,				December 31,
		2010				2009
BALANCE SHEET DATA:
Cash and Cash Equivalents		$	1,805,347			$	2,048,117
Other Current Assets			2,701,593				2,537,732
Property and Equipment, net			25,123,455				22,900,615
Goodwill			189,252				189,252
Other Assets			612,760				510,027
Total Assets		$	30,432,407			$	28,185,743
Short-Term Debt		$	116,205			$	117,326
Other Current Liabilities			2,086,630				2,275,232
Long-Term Debt			4,896,127				4,950,390
Deferred Credits and Other Noncurrent Liabilities			5,657,685				5,064,174
Shareholders’ Equity			17,675,760				15,778,621
Total Liabilities and Shareholders’ Equity		$	30,432,407			$	28,185,743
Common shares outstanding at end of period			337,799				336,437

APACHE CORPORATION
FINANCIAL INFORMATION

		For the Quarter								For the Six Months
		Ended June 30,								Ended June 30,
		2010				2009				2010				2009
PRODUCTION DATA:
OIL VOLUME — Barrels per day
Gulf Coast			50,788				52,054				50,649				50,441
Central			2,929				2,212				2,652				2,242
Permian			35,812				34,264				35,843				34,959
United States			89,529				88,530				89,144				87,642
Canada			14,561				15,833				14,447				16,090
North America			104,090				104,363				103,591				103,732
Egypt			98,495				95,359				94,642				89,475
Australia			60,680				10,478				43,978				9,164
North Sea			58,141				59,688				57,995				60,089
Argentina			9,874				11,948				9,897				12,192
International			227,190				177,473				206,512				170,920
Total			331,280				281,836				310,103				274,652
NATURAL GAS VOLUME — Mcf per day
Gulf Coast			382,550				364,961				381,636				338,792
Central			206,386				202,594				198,478				206,697
Permian			85,950				95,279				93,247				92,405
United States			674,886				662,834				673,361				637,894
Canada			339,611				373,796				326,646				365,551
North America			1,014,497				1,036,630				1,000,007				1,003,445
Egypt			388,367				376,737				375,249				347,443
Australia			203,147				161,069				205,209				151,607
North Sea			2,516				2,645				2,540				2,663
Argentina			183,028				192,542				168,953				192,250
International			777,058				732,993				751,951				693,963
Total			1,791,555				1,769,623				1,751,958				1,697,408
NGL VOLUME — Barrels per day
Gulf Coast			4,903				3,935				4,901				3,614
Central			500				201				496				279
Permian			6,475				1,347				3,977				1,305
United States			11,878				5,483				9,374				5,198
Canada			1,996				2,052				1,866				2,082
North America			13,874				7,535				11,240				7,280
Argentina			3,118				3,091				3,204				3,114
Total			16,992				10,626				14,444				10,394
BOE per day
Gulf Coast			119,450				116,816				119,156				110,520
Central			37,827				36,178				36,228				36,971
Permian			56,612				51,491				55,362				51,665
United States			213,889				204,485				210,746				199,156
Canada			73,159				80,185				70,753				79,097
North America			287,048				284,670				281,499				278,253
Egypt			163,223				158,148				157,184				147,382
Australia			94,538				37,323				78,179				34,431
North Sea			58,560				60,129				58,418				60,533
Argentina			43,497				47,130				41,260				47,348
International			359,818				302,730				335,041				289,694
Total			646,866				587,400				616,540				567,947

APACHE CORPORATION
FINANCIAL INFORMATION

		For the Quarter								For the Six Months
		Ended June 30,								Ended June 30,
		2010				2009				2010				2009
PRICING DATA:
AVERAGE OIL PRICE PER BARREL
Gulf Coast		$	76.95			$	57.40			$	76.94			$	49.05
Central			74.20				56.07				74.66				45.94
Permian			73.95				52.23				74.50				43.36
United States (1)			74.20				57.00				74.26				49.95
Canada			70.87				55.17				73.10				46.49
North America (1)			73.73				56.72				74.10				49.41
Egypt			76.08				60.30				76.27				51.90
Australia			74.42				63.01				74.58				49.74
North Sea			78.78				58.77				76.58				51.51
Argentina			55.41				46.17				56.60				46.73
International			75.43				58.99				75.05				51.28
Total (1)			74.89				58.15				74.74				50.57
AVERAGE NATURAL GAS PRICE PER MCF
Gulf Coast		$	4.45			$	3.76			$	5.07			$	4.29
Central			4.23				2.96				4.95				3.38
Permian			4.76				4.08				6.03				3.94
United States (1)			5.11				3.88				5.58				4.21
Canada (1)			4.51				3.86				4.88				4.26
North America (1)			4.91				3.88				5.35				4.23
Egypt			3.51				3.85				3.54				3.73
Australia			2.22				1.82				2.22				1.71
North Sea			17.15				12.24				17.73				9.82
Argentina			1.88				1.89				2.01				1.94
International			2.83				2.92				2.88				2.82
Total (1)			4.01				3.48				4.29				3.65
AVERAGE NGL PRICE PER BARREL
Gulf Coast		$	44.27			$	27.13			$	49.25			$	26.33
Central			38.87				27.28				44.40				23.21
Permian			37.73				28.04				38.96				25.30
United States			40.48				27.36				44.63				25.90
Canada			35.76				24.23				37.97				22.40
North America			39.80				26.50				43.52				24.90
Argentina			25.68				15.91				30.23				16.51
Total			37.21				23.42				40.58				22.39

APACHE CORPORATION
FINANCIAL INFORMATION
(In thousands, except per share data)

NON-GAAP FINANCIAL MEASURES:

Reconciliation of income attributable to common stock to adjusted earnings:

The press release discusses Apache’s adjusted earnings. Adjusted earnings exclude certain items that management believes affect the comparability of operating results and are meaningful for the following reasons:

Ÿ		Management uses adjusted earnings to evaluate the company’s operational trends and performance relative to other oil and gas producing companies.

Ÿ		Management believes this presentation may be useful to investors who follow the practice of some industry analysts who adjust reported company earnings for items that may obscure underlying fundamentals and trends.

Ÿ		The reconciling items below are the types of items management believes are frequently excluded by analysts when evaluating the operating trends and comparability of the company’s results.

		For the Quarter								For the Six Months
		Ended June 30,								Ended June 30,
		2010				2009				2010				2009
Income (Loss) Attributable to Common Stock (GAAP)		$	860,223			$	443,300			$	1,565,204			$	(1,315,060	)
Adjustments:
Foreign currency fluctuation impact on deferred tax expense			(31,511	)			31,164				(24,927	)			26,350
Additional depletion, net of tax			—				—				—				1,981,398
Adjusted Earnings (Non-GAAP)		$	828,712			$	474,464			$	1,540,277			$	692,688
Adjusted Earnings Per Share (Non-GAAP)
Basic		$	2.45			$	1.41			$	4.57			$	2.07
Diluted		$	2.44			$	1.41			$	4.54			$	2.05
Average Number of Common Shares
Basic			337,618				335,637				337,273				335,372
Diluted			339,377				337,365				339,282				337,198

Reconciliation of net cash provided by operating activities to cash from operations before changes in operating assets and liabilities:

The press release discusses Apache’s cash from operations before changes in operating assets and liabilities. It is presented because management believes the information is useful for investors because it is used internally and widely accepted by those following the oil and gas industry as a financial indicator of a company’s ability to generate cash to internally fund exploration and development activities, fund dividend programs, and service debt. It is also used by research analysts to value and compare oil and gas exploration and production companies, and is frequently included in published research when providing investment recommendations. Cash from operations before changes in operating assets and liabilities, therefore, is an additional measure of liquidity, but is not a measure of financial performance under GAAP and should not be considered as an alternative to cash flows from operating, investing, or financing activities.

The following table reconciles net cash provided by operating activities to cash from operations before changes in operating assets and liabilities.

		For the Quarter								For the Six Months
		Ended June 30,								Ended June 30,
		2010				2009				2010				2009
Net cash provided by operating activities		$	1,932,012			$	823,513			$	3,085,441			$	1,366,729
Changes in operating assets and liabilities			(97,289	)			436,071				317,162				875,914
Cash from operations before changes in operating assets and liabilities		$	1,834,723			$	1,259,584			$	3,402,603			$	2,242,643