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UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): August 2, 2010

Apache Corporation

(Exact name of registrant as specified in charter)

Delaware	1-4300	41-0747868
(State of Incorporation)	(Commission File No.)	(I.R.S. Employer Identification No.)

2000 Post Oak Boulevard, Suite 100,	77056-4400
Houston, Texas	(Zip Code)
(Address of Principal Executive Offices)

Registrant’s telephone number, including area code: (713) 296-6000

(former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

þ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

o Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

o Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

o Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Item 1.01 Entry into a Material Definitive Agreement

     On August 2, 2010, Apache Corporation, a Delaware corporation (“Apache”), Mariner Energy, Inc., a Delaware corporation (“Mariner”), and ZMZ Acquisitions LLC, a Delaware limited liability company and wholly owned subsidiary of Apache (“Merger Sub”), entered into Amendment No. 1 (the “Amendment”) to the Agreement and Plan of Merger dated as of April 14, 2010 (the “Merger Agreement”), by and among Apache, Mariner and Merger Sub. The Amendment was effected by the parties in connection with the proposed settlement of two stockholder lawsuits filed in Delaware and Texas as a result of Apache’s proposed acquisition of Mariner. The Amendment eliminated the requirement for Mariner to pay to Apache a termination fee of $67 million if the Merger Agreement is terminated by Mariner (prior to Mariner stockholder approval) as a result of a change in Mariner’s recommendation due to a superior proposal for which Mariner’s board of directors has authorized a definitive agreement. No other changes were included in the Amendment.

     A copy of the Amendment is filed as Exhibit 2.1 to this report and is incorporated herein by reference. The foregoing description of the Amendment does not purport to be complete and is qualified in its entirety by reference to the Amendment.

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 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 THAT WILL BE 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.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits

Number		Description
	2.1	Amendment No. 1 dated as of August 2, 2010 to the Agreement and Plan of Merger dated as of April 14, 2010 by and among Apache Corporation, ZMZ Acquisitions LLC and Mariner Energy, Inc.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

	APACHE CORPORATION
Dated: August 3, 2010	By:	/s/ John A. Crum
		Name:	John A. Crum
		Title:	Co-Chief Operating Officer and President - North America

INDEX TO EXHIBITS

Number		Description
	2.1	Amendment No. 1 dated as of August 2, 2010 to the Agreement and Plan of Merger dated as of April 14, 2010 by and among Apache Corporation, ZMZ Acquisitions LLC and Mariner Energy, Inc.

EX-2.1

EXECUTION COPY

AMENDMENT NO. 1

TO THE

AGREEMENT AND PLAN OF MERGER

     THIS AMENDMENT NO. 1 (this “Amendment”) dated as of August 2, 2010 to the Agreement and Plan of Merger (the “Merger Agreement” or the “Agreement”) dated as of April 14, 2010 by and among APACHE CORPORATION, a Delaware corporation (“Parent”), ZMZ ACQUISITIONS LLC, a Delaware limited liability company and a wholly owned subsidiary of Parent (“Merger Sub”), and MARINER ENERGY, INC., a Delaware corporation (the “Company”).

AGREEMENT:

     In consideration of the mutual promises contained herein, the benefits to be derived by each party hereunder and other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, Parent, Merger Sub and the Company agree as follows:

ARTICLE I

DEFINITIONS

     Section 1.1 Definitions; References. Unless otherwise specifically defined herein, each term used herein shall have the meaning assigned to such term in the Merger Agreement. Each reference to “hereof,” “herein” and “hereunder” and words of similar import when used in the Merger Agreement shall, from and after the date hereof, refer to the Merger Agreement, as amended by this Amendment. Notwithstanding the foregoing, references to the date of the Agreement, as amended hereby, shall in all instances continue to refer to April 14, 2010, references to “the date hereof” and “the date of this Agreement” shall continue to refer to April 14, 2010 and references to the date of the Amendment and “as of the date of the Amendment” shall refer to August 2, 2010.

ARTICLE II

AMENDMENTS TO MERGER AGREEMENT

     Section 2.1 Amendment to Section 7.3(a). In order to amend Section 7.3(a) of the Merger Agreement to delete the reference to “or
7.1(d)(ii)”, Section 7.3(a) of the Merger Agreement is hereby amended and restated in its entirety to read as follows:

     (a) If this Agreement is terminated pursuant to Section 7.1(c)(ii) then, in such event, the Company shall pay Parent a fee in a cash amount equal to $67,000,000, less the amount of any Expenses of Parent reimbursed by Company pursuant to Section 7.3(d) (the “Company Termination Fee”). Such amount shall be paid in cash by wire transfer

in immediately available funds not later than two business days after the occurrence of such termination.

     Section 2.2 Amendment to Section 7.1(d)(ii). In order to amend Section 7.1(d)(ii) of the Merger Agreement to delete the reference to “provided, however, that such termination under this clause (d)(ii) shall not be effective until the Company has made payment to Parent of the Company Termination Fee pursuant to Section 7.3(a)”, Section 7.1(d)(ii) of the Merger Agreement is hereby amended and restated in its entirety to read as follows:

     (ii) prior to obtaining the Company Stockholder Approval, the Company Board of Directors shall have effected a Change in the Company Recommendation pursuant to Section 5.3(b)(ii)(B) and authorized the Company to enter into a binding definitive agreement in respect of such Superior Proposal;

ARTICLE III

GENERAL PROVISIONS

     Section 3.1 No Further Amendment. Except as expressly amended hereby, the Merger Agreement is in all respects ratified and confirmed and all the terms, conditions, and provisions thereof shall remain in full force and effect. This Amendment is limited precisely as written and shall not be deemed to be an amendment to any other term or condition of the Merger Agreement.

     Section 3.2. Effect of Amendment. This Amendment shall form a part of the Merger Agreement for all purposes, and each party thereto and hereto shall be bound hereby. From and after the execution of this Amendment by the parties hereto, any reference to the Merger Agreement shall be deemed a reference to the Merger Agreement as amended hereby. This Amendment shall be deemed to be in full force and effect from and after the execution of this Amendment by the parties hereto.

     Section 3.3 Headings. The descriptive headings contained in this Amendment are included for convenience of reference only and shall not affect in any way the meaning or interpretation of this Amendment.

     Section 3.4 Counterparts. This Amendment may be executed in one or more counterparts, and by the different parties hereto in separate counterparts, each of which when executed shall be deemed to be an original but all of which taken together shall constitute one and the same agreement.

     Section 3.5 Governing Law; Jurisdiction and Venue. This Amendment shall be governed by, and construed in accordance with, the laws of the State of Delaware applicable to contracts executed in and to be performed in that state. All actions and proceedings arising out of or relating to this Amendment shall be heard and determined in the Delaware Court of Chancery. Each of the Company, Parent and Merger Sub hereby irrevocably and unconditionally consents to submit to the exclusive jurisdiction of the Delaware Court of Chancery for any litigation arising out of or relating to this Amendment and the transactions contemplated hereby (and agrees not to commence any litigation relating thereto except in such

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court), waives any objection to the laying of venue of any such litigation in the Delaware Court of Chancery and agrees not to plead or claim that such litigation brought therein has been brought in any inconvenient forum.

     Section 3.6 Severability. If any term or other provision of this Amendment is invalid, illegal or incapable of being enforced by any rule of law, or public policy, all other conditions and provisions of this Amendment shall nevertheless remain in full force and effect so long as the economic or legal substance of the transactions contemplated hereby are not affected in any manner materially adverse to any party. Upon such determination that any term or other provision is invalid, illegal or incapable of being enforced, the parties hereto shall negotiate in good faith to modify this Amendment so as to effect the original intent of the parties as closely as possible in a mutually acceptable manner in order that the transactions contemplated hereby are consummated as originally contemplated to the fullest extent possible.

[signature page follows]

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IN WITNESS WHEREOF, Parent, Merger Sub and the Company have caused this Amendment to be executed as of the date first written above by their respective officers thereunto duly authorized.

APACHE CORPORATION
By:	/s/ John A. Crum
	Name:	John A. Crum
	Title:	Co-Chief Operating Officer and President - North America
ZMZ ACQUISITIONS LLC
By:	/s/ John A. Crum
	Name:	John A. Crum
	Title:	Chief Operating Officer and President
MARINER ENERGY, INC.
By:	/s/ Jesus G. Melendrez
	Name:	Jesus G. Melendrez
	Title:	Senior Vice President, Chief Commercial Officer, Acting Chief Financial Officer and Treasurer

[Signature Page to Amendment No. 1 to the Merger Agreement]

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