FIRST AMENDMENT TO AMENDED AND RESTATED CREDIT AGREEMENT

Exhibit 10.22.5.2

FIRST AMENDMENT TO

AMENDED AND RESTATED CREDIT AGREEMENT

BETWEEN

PRIMEENERGY CORPORATION

PRIMEENERGY MANAGEMENT CORPORATION

PRIME OPERATING COMPANY

EASTERN OIL WELL SERVICE COMPANY

SOUTHWEST OILFIELD CONSTRUCTION COMPANY

EOWS MIDLAND COMPANY

AND

GUARANTY BANK, FSB

AS AGENT AND LETTER OF CREDIT ISSUER

AND

BNP PARIBAS,

AS CO-DOCUMENTATION AGENT

AND

JPMORGAN CHASE BANK, N.A.,

AS CO-DOCUMENTATION AGENT

AND

THE LENDERS SIGNATORY HERETO

JULY 17, 2007

REVOLVING LINE OF CREDIT OF UP TO $150,000,000

REVOLVING LINE OF CREDIT OF UP TO $10,000,000

TABLE OF CONTENTS

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FIRST AMENDMENT TO

AMENDED AND RESTATED CREDIT AGREEMENT

This FIRST AMENDMENT TO AMENDED AND RESTATED CREDIT AGREEMENT (this “ First Amendment ”) is made and entered into effective as of July 17, 2007, by and between PRIMEENERGY CORPORATION , a Delaware corporation (“ PEC ”), PRIMEENERGY MANAGEMENT CORPORATION , a New York corporation, PRIME OPERATING COMPANY , a Texas corporation, EASTERN OIL WELL SERVICE COMPANY , a West Virginia corporation, SOUTHWEST OILFIELD CONSTRUCTION COMPANY , an Oklahoma corporation, and EOWS MIDLAND COMPANY , a Texas corporation (collectively, the “ Borrower ”), with each other lender that is a signatory hereto or becomes a signatory hereto as provided in Section 9.1, (individually, together with its successors and assigns, a “ Lender ” and collectively together, with their respective successors and assigns, the “ Lenders ”) and GUARANTY BANK, FSB , a federal savings bank, as agent for the Lenders (in such capacity, together with its successors in such capacity pursuant to the terms hereof, the “ Agent ”) and Letter of Credit Issuer and BNP PARIBAS as Co-Documentation Agent and JPMORGAN CHASE BANK, N.A. as Co-Documentation Agent.

WITNESSETH

WHEREAS, the above named parties did execute and exchange counterparts of that certain Credit Agreement dated December 28, 2006 (the “ Agreement ”), to which reference is here made for all purposes;

WHEREAS, the parties subject to and bound by the Agreement are desirous of amending the Agreement in the particulars hereinafter set forth;

NOW, THEREFORE, in consideration of the mutual covenants and agreements of the parties to the Agreement, as set forth therein, and the mutual covenants and agreements of the parties hereto, as set forth in this First Amendment, the parties hereto agree as follows:

ARTICLE I

DEFINITIONS

1.01 Terms Defined Above . As used herein, each of the terms “ Agent ,” “ Agreement ,” “ Borrower ,” “ First Amendment ,” “ Lender ” and “ Lenders ” and shall have the meaning assigned to such term hereinabove.

1.02 Terms Defined in Agreement . As used herein, each term defined in the Agreement shall have the meaning assigned thereto in the Agreement, unless expressly provided herein to the contrary.

1.03 References . References in this First Amendment to Article or Section numbers shall be to Articles and Sections of this First Amendment, unless expressly stated herein to the contrary. References in this First Amendment to “hereby,” “herein,” hereinafter,” hereinabove,” “hereinbelow,” “hereof,” and “hereunder” shall be to this First Amendment in its entirety and not only to the particular Article or Section in which such reference appears.

1

1.04 Articles and Sections . This First Amendment, for convenience only, has been divided into Articles and Sections and it is understood that the rights, powers, privileges, duties, and other legal relations of the parties hereto shall be determined from this First Amendment as an entirety and without regard to such division into Articles and Sections and without regard to headings prefixed to such Articles and Sections.

1.05 Number and Gender . 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 and plural shall be equally applicable to the plural or singular, as the case may be.

ARTICLE II

AMENDMENTS

The Borrower and the Lender hereby amend the Agreement in the following particulars:

2.01 Amendment of Section 5.2 . Section 5.2 of the Agreement is hereby amended as follows:

“5.2 Quarterly Financial Statements; Compliance Certificates . Deliver to the Agent, (a) on or before the 45th day after the close of each of the first three quarterly periods of each fiscal year of the Borrower, a copy of the unaudited consolidated Financial Statements of PEC and its Subsidiaries and Affiliates as at the close of such quarterly period and from the beginning of such fiscal year to the end of such period, such Financial Statements to be certified by a Responsible Officer of the Borrower as having been prepared in accordance with GAAP consistently applied and as a fair presentation of the condition of the Borrower, subject to changes resulting from normal year-end audit adjustments, and (b) on or before the 60th day after the