AMENDMENT NO. 1 AND CONSENT

Exhibit 4.1

AMENDMENT NO. 1 AND CONSENT

     This Amendment No. 1 and Consent (“Agreement”) dated as of April 7, 2006 (“Effective Date”) is among Mariner Energy, Inc., a Delaware corporation (the “Parent”), Mariner Energy Resources, Inc., a Delaware corporation (together with the Parent, the “Borrowers”, each a “Borrower”), the Lenders (as defined in the Credit Agreement described below), and Union Bank of California, N.A., as administrative agent for such Lenders (in such capacity, the “Administrative Agent”) and as issuing lender for such Lenders (in such capacity, the “Issuing Lender”).

RECITALS

     A. The Borrowers, the Lenders, the Issuing Lender and the Administrative Agent are parties to the Amended and Restated Credit Agreement dated as of March 2, 2006 (as amended, restated, supplemented or otherwise modified from time to time, the “Credit Agreement”).

     B. At the request of the Borrowers, the Administrative Agent and the Lenders wish to, subject to the terms and conditions of this Agreement, (i) consent to an increase in the Borrowing Base and (ii) amend certain provisions of the Credit Agreement relating to Bond Issuances (as defined in the Credit Agreement) as set forth herein.

     THEREFORE, the Borrowers, the subsidiaries of the Borrowers signatory hereto (the “Guarantors”), the Lenders, the Issuing Lender and the Administrative Agent hereby agree as follows:

ARTICLE I.
DEFINITIONS

     Section 1.01 Terms Defined Above. As used in this Agreement, each of the terms defined in the opening paragraph and the Recitals above shall have the meanings assigned to such terms therein.

     Section 1.02 Terms Defined in the Credit Agreement. Each term defined in the Credit Agreement and used herein without definition shall have the meaning assigned to such term in the Credit Agreement, unless expressly provided to the contrary.

     Section 1.03 Other Definitional Provisions. The words “hereby”, “herein”, “hereinafter”, “hereof”, “hereto” and “hereunder” when used in this Agreement shall refer to this Agreement as a whole and not to any particular Article, Section, subsection or provision of this Agreement. Article, Section, subsection and Exhibit references herein are to such Articles, Sections, subsections and Exhibits of this Agreement unless otherwise specified. All titles or headings to Articles, Sections, subsections or other divisions of this Agreement or the exhibits hereto, if any, are only for the convenience of the parties and shall not be construed to have any effect or meaning with respect to the other content of such Articles, Sections, subsections, other divisions or exhibits, such other content being controlling as the agreement among the parties hereto. Whenever the context requires, reference herein made to the single number shall be understood to include the plural; and likewise, the plural shall be understood to include the singular. Words denoting sex shall be construed to include the masculine, feminine and neuter, when such construction is appropriate; and specific enumeration shall not exclude the general but

shall be construed as cumulative. Definitions of terms defined in the singular or plural shall be equally applicable to the plural or singular, as the case may be, unless otherwise indicated.

ARTICLE II.
CONSENTS

     Section 2.01 Consent and Acknowledgment. Subject to the terms of this Agreement, the Administrative Agent and the Lenders hereby consent to the Borrowing Base being increased to $430,000,000, and the Administrative Agent, the Lenders and the Borrowers hereby acknowledge that new $430,000,000 Borrowing Base amount shall remain in effect until the next redetermination or adjustment of the Borrowing Base is made pursuant to Section 2.02 of the Credit Agreement.

ARTICLE III.
AMENDMENT TO CREDIT AGREEMENT

     Section 3.01 Restatement of Section 2.02(e) — Reduction and Redetermination for Bond Issuance. The first sentence of Section 2.02(e) is hereby amended and restated in its entirety with the following:

     “Notwithstanding the foregoing provisions of this Section 2.02, the Borrowing Base then in effect on the date of the closing of a Bond Issuance shall automatically reduce by an amount equal to (a) $55,000,000 with respect to the first such Bond Issuance occurring after the date of this Agreement that is $250,000,000 or less in aggregate principal amount, (or if such Bond Issuance has an aggregate principal amount of more than $250,000,000, an amount equal to $55,000,000 plus 25% of the aggregate principal amount of such Bond Issuance that exceeds $250,000,000), or (b) 25% of the aggregate principal amount of any other Bond Issuance; provided that, to the extent any other Bond Issuance refinances or replaces Debt owing in connection with a then-existing Bond Issuance, then only the principal amount issued in excess of the principal amount being so refinanced shall be included in the calculation described in this clause (b).

ARTICLE IV.
REPRESENTATIONS AND WARRANTIES

     Section 4.01 Borrowers Representations and Warranties. Each of the Borrowers represents and warrants that: (a) its representations and warranties contained in Article IV of the Credit Agreement and its representations and warranties contained in the Security Instruments, the Guaranties, and each of the other Loan Documents to which it is a party are true and correct in all material respects on and as of the Effective Date, after giving effect to the terms of this Agreement, as though made on and as of such date, except those representations and warranties that speak of a certain date, which representations and warranties were true and correct as of such date; (b) after giving effect to the terms of this Agreement, no Default has occurred and is continuing; (c) the execution, delivery and performance of this Agreement is within the corporate power and authority of each of the Borrowers and have been duly authorized by appropriate corporate action and proceedings; (d) this Agreement constitutes a legal, valid, and binding

obligation of each of the Borrowers enforceable in accordance with its terms, except as limited by applicable bankruptcy, insolvency, reorganization, moratorium, or similar laws affecting the rights of creditors generally and general principles of equity; (e) there are no governmental or other third party consents, licenses and approvals required in connection with the execution, delivery, performance, validity and enforceability of this Agreement; and (f) the Liens under the Security Instruments are valid and subsisting and secure each of the Borrowers’ obligations under the Loan Documents.

     Section 4.02 Guarantors Representations and Warranties. Each Guarantor represents and warrants that: (a) its representations and warranties contained in Article IV of the Credit Agreement and its representations and warranties contained in the Security Instruments, the Guaranties, and each of the other Loan Documents to which it is a party are true and correct in all material respects on and as of the Effective Date, as though made on and as of such date, except those representations and warranties that speak of a certain date, which representations and warranties were true and correct as of such date; (b) after giving effect to the terms of this Agreement, no Default has occurred and is continuing; (c) the execution, delivery and performance of this Agreement are within the corporate power and authority of such Guarantor and have been duly authorized by appropriate corporate action and proceedings; (d) this Agreement constitutes a legal, valid, and binding obligation of such Guarantor enforceable in accordance with its terms, except as limited by applicable bankruptcy, insolvency, reorganization, moratorium, or similar laws affecting the rights of creditors generally and general principles of equity; (e) there are no governmental or other third party consents, licenses and approvals required in connection with the execution, delivery, performance, validity and enforceability of this Agreement; (f) it has no defenses to the enforcement of its Guaranty; and (g) the Liens under the Security Instruments are valid and subsisting and secure such Guarantor’s obligations under the Loan Documents.

ARTICLE V.
CONDITIONS

     This Agreement and the consents contained herein shall become effective and enforceable against the parties hereto, and the Credit Agreement shall be amended as provided herein, upon the occurrence of the following conditions precedent:

     Section 5.01 Documents; Certificates. The Administrative Agent shall have received multiple original counterparts, as requested by the Administrative Agent, of (a) this Agreement duly and validly executed and delivered by duly authorized officers of the Borrowers, the Guarantors, the Administrative Agent, and the Lenders, and (b) such other instruments, documents and amendments or supplements as the Administrative Agent may reasonably request.

     Section 5.02 No Default. No Default shall have occurred and be continuing as of the Effective Date.

     Section 5.03 Representations. The representations and warranties in this Agreement shall be true and correct in all material respects.

     Section 5.04 Fees. The Borrower shall have paid (a) to the Administrative Agent for the benefit of the Lenders a borrowing base increase fee equal to $75,000, and (b) all reasonable fees and expenses of the Administrative Agent under the Credit Agreement that have been invoiced and are then due and owing.

ARTICLE VI.
MISCELLANEOUS

     Section 6.01 Effect on Loan Documents; Acknowledgments.

     (a) Each of the Borrowers acknowledges that on the date hereof all Obligations are payable without defense, offset, counterclaim or recoupment.

     (b) The Administrative Agent, the Issuing Lender, and the Lenders hereby expressly reserve all of their rights, remedies, and claims under the Loan Documents. Nothing in this Agreement shall constitute a waiver or relinquishment of (i) any Default or Event of Default under any of the Loan Documents other than as expressly set forth above, (ii) any of the agreements, terms or conditions contained in any of the Loan Documents other than as expressly set forth above, (iii) any rights or remedies of the Administrative Agent, the Issuing Lender or any Lender with respect to the Loan Documents, or (iv) the rights of the Administrative Agent, any Issuing Lender or any Lender to collect the full amounts owing to them under the Loan Documents.

     (c) Each of the Borrowers, the Guarantors, Administrative Agent, Issuing Lender, and Lenders does hereby adopt, ratify, and confirm the Credit Agreement, as amended hereby, and acknowledges and agrees that the Credit Agreement, as amended hereby, and all other Loan Documents are and remain in full force and effect, and each of the Borrowers and the Guarantors acknowledges and agrees that its liabilities under the Credit Agreement and the other Loan Documents are not impaired in any respect by this Agreement or the consents granted hereunder.

     (d) From and after the Effective Date, all references to the Credit Agreement and the Loan Documents shall mean such Credit Agreement and such Loan Documents as amended by this Agreement.

     (e) This Agreement is a Loan Document for the purposes of the provisions of the other Loan Documents. Without limiting the foregoing, any breach of representations, warranties, and covenants under this Agreement shall be a Default or Event of Default, as applicable, under the Credit Agreement.

     Section 6.02 Reaffirmation of the Guaranty. Each Guarantor hereby ratifies, confirms, acknowledges and agrees that its obligations under its Guaranty are in full force and effect and that such Guarantor continues to unconditionally and irrevocably guarantee the full and punctual payment, when due, whether at stated maturity or earlier by acceleration or otherwise, all of the Guaranteed Obligations (as defined in its Guaranty), as such Guaranteed Obligations may have been amended by this Agreement, and its execution and deliver of this Agreement does not indicate or establish an approval or consent requirement by such Guarantor under its Guaranty in connection with the execution and delivery of amendments to the Credit Agreement, the Notes or any of the other Loan Documents.

     Section 6.03 Counterparts. This Agreement may be signed in any number of counterparts, each of which shall be an original and all of which, taken together, constitute a single instrument. This Agreement may be executed by facsimile signature and all such signatures shall be effective as originals.

     Section 6.04 Successors and Assigns. This Agreement shall be binding upon and inure to the benefit of the Lenders, the Borrowers and the Administrative Agent hereto and their respective successors and assigns permitted pursuant to the Credit Agreement.

     Section 6.05 Invalidity. In the event that any one or more of the provisions contained in this Agreement shall for any reason be held invalid, illegal or unenforceable in any respect, such invalidity, illegality or unenforceability shall not affect any other provision of this Agreement.

     Section 6.06 Governing Law. This Agreement shall be deemed to be a contract made under and shall be governed by and construed in accordance with the laws of the State of Texas.

     Section 6.07 Entire Agreement. THIS AGREEMENT, THE CREDIT AGREEMENT AS AMENDED BY THIS AGREEMENT, THE NOTES, AND THE OTHER LOAN DOCUMENTS CONSTITUTE THE ENTIRE UNDERSTANDING AMONG THE PARTIES HERETO WITH RESPECT TO THE SUBJECT MATTER HEREOF AND SUPERSEDE ANY PRIOR AGREEMENTS, WRITTEN OR ORAL, WITH RESPECT THERETO.

     THERE ARE NO UNWRITTEN ORAL AGREEMENTS AMONG THE PARTIES.

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     EXECUTED effective as of the date first above written.

Signature Page to Amendment No. 1 and Consent
(Mariner Energy, Inc. and Mariner Energy Resources, Inc.)

Signature Page to Amendment No. 1 and Consent
(Mariner Energy, Inc. and Mariner Energy Resources, Inc.)

Signature Page to Amendment No. 1 and Consent
(Mariner Energy, Inc. and Mariner Energy Resources, Inc.)

Signature Page to Amendment No. 1 and Consent
(Mariner Energy, Inc. and Mariner Energy Resources, Inc.)

Signature Page to Amendment No. 1 and Consent
(Mariner Energy, Inc. and Mariner Energy Resources, Inc.)

Signature Page to Amendment No. 1 and Consent
(Mariner Energy, Inc. and Mariner Energy Resources, Inc.)

Signature Page to Amendment No. 1 and Consent
(Mariner Energy, Inc. and Mariner Energy Resources, Inc.)

Signature Page to Amendment No. 1 and Consent
(Mariner Energy, Inc. and Mariner Energy Resources, Inc.)

Signature Page to Amendment No. 1 and Consent
(Mariner Energy, Inc. and Mariner Energy Resources, Inc.)

Signature Page to Amendment No. 1 and Consent
(Mariner Energy, Inc. and Mariner Energy Resources, Inc.)

Signature Page to Amendment No. 1 and Consent
(Mariner Energy, Inc. and Mariner Energy Resources, Inc.)

Signature Page to Amendment No. 1 and Consent
(Mariner Energy, Inc. and Mariner Energy Resources, Inc.)