FOURTH AMENDMENT TO SEVENTH AMENDED AND RESTATED CREDIT AGREEMENT

Exhibit 4.4.1

FOURTH AMENDMENT

TO

SEVENTH AMENDED AND RESTATED CREDIT AGREEMENT

THIS FOURTH AMENDMENT TO SEVENTH AMENDED AND RESTATED CREDIT AGREEMENT (this “Amendment”) is dated as of March 31, 2009 (but effective on the Effective Date, defined below in Section 3.1) by and among Chesapeake Energy Corporation (the “Company”), Chesapeake Exploration, L.L.C. (“Chesapeake Exploration”) and Chesapeake Appalachia, L.L.C. (“Chesapeake Appalachia”, and together with Chesapeake Exploration, collectively, “Co-Borrowers”), Union Bank, N.A., as Administrative Agent (“Agent”), the other agents named therein and the Lenders from time to time parties thereto (“Lenders”).

W I T N E S S E T H:

WHEREAS, Co-Borrowers, the Company, Agent and Lenders entered into that certain Seventh Amended and Restated Credit Agreement dated as of November 2, 2007 (as amended from time to time prior to the date hereof, the “Original Agreement”), for the purpose and consideration therein expressed, whereby Lenders became obligated to make loans and extend credit to Co-Borrowers as therein provided;

WHEREAS, Co-Borrowers, the Company, Agent and Lenders party hereto desire to amend the Original Agreement as set forth herein;

NOW, THEREFORE, in consideration of the premises and the mutual covenants and agreements contained herein and in the Original Agreement, in consideration of the loans and extensions of credit that may hereafter be made by Lenders and the Issuing Lenders to Co-Borrowers, and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties hereto do hereby agree as follows:

ARTICLE I.

DEFINITIONS AND REFERENCES

Section 1.1. Terms Defined in the Original Agreement. Unless the context otherwise requires or unless otherwise expressly defined herein, the terms defined in the Original Agreement shall have the same meanings whenever used in this Amendment.

Section 1.2. Other Defined Terms. Unless the context otherwise requires, the following terms when used in this Amendment shall have the meanings assigned to them in this Section 1.2.

“Amendment” means this Fourth Amendment to Seventh Amended and Restated Credit Agreement.

“Credit Agreement” means the Original Agreement as amended hereby.

“Effective Date” has the meaning given to such term in Section 3.1.

ARTICLE II.

AMENDMENTS

Section 2.1. Defined Terms.

(a) The definition of “Applicable Margin” in Section 1.1 of the Original Agreement is hereby amended in its entirety to read as follows:

““Applicable Margin”: for each Type of Revolving Loan, on any day, the rate per annum set forth at the appropriate intersection at the relevant column heading below based on the Applicable Rating Level as of the close of business on the immediately preceding Business Day:

(b) The definition of “Commitment Fee Rate” in Section 1.1 of the Original Agreement is hereby amended in its entirety to read as follows:

““Commitment Fee Rate”: on any day, a rate per annum equal to 0.500%.”

(c) The definition of “Consolidated Total Capitalization” in Section 1.1 of the Original Agreement is hereby amended in its entirety to read as follows:

““Consolidated Total Capitalization”: Consolidated Indebtedness plus stockholders’ equity of the Group Members as determined on a consolidated basis in accordance with GAAP; excluding, however, the stockholder’s equity of any Group Member attributable to such Group Member’s ownership of equity interests in any Unrestricted Subsidiary; provided, however, that all calculations of Consolidated Total Capitalization beginning December 31, 2008 shall exclude the effects of any write down of oil or gas assets which is required under Rule 4-10 (Financial Accounting and Reporting for Oil and Gas Producing Activities Pursuant to the Federal Securities Laws and the Energy Policy and Conservation Act of 1975) of Regulation S-X, promulgated by SEC regulation, or by the equivalent write down required by GAAP.”

Section 2.2. Financial Condition Covenants. Section 7.1(a) of the Original Agreement is hereby amended in its entirety to read as follows:

“(a) Consolidated Indebtedness to Total Capitalization Ratio. Permit the ratio of (i) Consolidated Indebtedness to (ii) Consolidated Total Capitalization at any time (x) prior to the Collateral Release Date, to be greater than 0.70 to 1.0 or (y) after the Collateral Release Date, to be greater than 0.65 to 1.0. The portion of any reduction in Consolidated Total Capitalization that results from non-cash write downs of assets related to changes in accounting practices (whether or not required under GAAP), shall not be effective for purposes of this Section 7.1(a) until 60 days after such non-cash write down is reflected on financial statements delivered pursuant to Section 6.1(a) or (b).”

ARTICLE III.

CONDITIONS OF EFFECTIVENESS; CLOSING

Section 3.1. Effective Date. This Amendment shall become effective on the date (the “Effective Date”) when Agent shall have received:

(a) duly executed and delivered in form and substance satisfactory to Agent, all of the following:

(i) this Amendment duly executed by Co-Borrowers, the Company, Agent, and Majority Lenders;

(ii) the Consent Agreement attached hereto duly executed by all Subsidiary Guarantors;

(iii) such other supporting documents as the Agent may reasonably request.

(b) for the account of each Lender (other than a Defaulting Lender) who executes this Amendment on or before the Effective Date, an amendment fee equal to 0.10% of such Lender’s Revolving Percentage of the current Total Revolving Commitments.

ARTICLE IV.

REPRESENTATIONS AND WARRANTIES

Section 4.1. Representations and Warranties of Co-Borrowers. In order to induce each Lender to enter into this Amendment, the Company and Co-Borrowers represent and warrant to Agent and to each Lender that:

(a) The representations and warranties contained in Section 4 of the Original Agreement are true and correct at and as of the time of the effectiveness hereof, except to the extent such representations and warranties specifically relate to an earlier date, in which case such representations and warranties are true and correct as of such earlier date.

(b) The Company and Co-Borrowers are duly authorized to execute and deliver this Amendment and are and will continue to be duly authorized to borrow monies and to perform their respective obligations under the Credit Agreement. The Company and Co-Borrowers

have duly taken all corporate or limited liability company action necessary to authorize the execution and delivery of this Amendment and to authorize the performance of the obligations of the Company and Co-Borrowers hereunder.

(c) The execution and delivery by each of the Company and Co-Borrowers of this Amendment, the performance by each of the Company and Co-Borrowers of its obligations hereunder and the consummation of the transactions contemplated hereby do not and will not conflict with any provision of law, statute, rule or regulation or of the certificate of incorporation or organization, bylaws, or agreement of limited liability company of the Company or either of the Co-Borrowers (as applicable), or of any material agreement, judgment, license, order or permit applicable to or binding upon the Company or either of the Co-Borrowers, or result in the creation of any lien, charge or encumbrance upon any assets or properties of the Company or either of the Co-Borrowers. Except for those which have been obtained, no consent, approval, authorization or order of any court or governmental authority or third party is required in connection with the execution and delivery by the Company and Co-Borrowers of this Amendment or to consummate the transactions contemplated hereby.

(d) When duly executed and delivered, each of this Amendment and the Credit Agreement will be a legal and binding obligation of the Company and Co-Borrowers, enforceable in accordance with its terms, except as limited by bankruptcy, insolvency or similar laws of general application relating to the enforcement of creditors’ rights and by equitable principles of general application.

(e) The audited annual consolidated financial statements of the Company dated as of December 31, 2008 fairly present the consolidated financial position at such date and the consolidated statement of operations and the changes in consolidated financial position for the period ending on such date for the Company. Copies of such financial statements have heretofore been delivered to each Lender. Since such date no material adverse change has occurred in the financial condition or businesses or in the consolidated financial condition or businesses of the Company.

ARTICLE V.

MISCELLANEOUS

Section 5.1. Ratification of Agreements. The Original Agreement as hereby amended and each of the Security Documents is hereby ratified and confirmed in all respects. Each Loan Party affirms that the terms of the Security Documents secure, and shall continue to secure, all of the Obligations, after giving effect to this Amendment. Any reference to the Credit Agreement in any Loan Document shall be deemed to be a reference to the Original Agreement as hereby amended. The execution, delivery and effectiveness of this Amendment shall not, except as expressly provided herein, operate as a waiver of any right, power or remedy of Lenders under the Credit Agreement, the Notes, or any other Loan Document nor constitute a waiver of any provision of the Credit Agreement, the Notes or any other Loan Document.

Section 5.2. Survival of Agreements. All representations, warranties, covenants and agreements of the Company and Co-Borrowers herein shall survive the execution and delivery of

this Amendment and the performance hereof, including without limitation the making or granting of the Loans, and shall further survive until all of the Obligations are paid in full. All statements and agreements contained in any certificate or instrument delivered by the Company, Co-Borrowers or any Subsidiary Guarantor hereunder or under the Credit Agreement to any Lender shall be deemed to constitute representations and warranties by, and/or agreements and covenants of, such Loan Party under this Amendment and under the Credit Agreement.

Section 5.3. Loan Documents. This Amendment is a Loan Document, and all provisions in the Credit Agreement pertaining to Loan Documents apply hereto.

Section 5.4. Governing Law. This Amendment shall be governed by and construed in accordance with the laws of the State of Texas and any applicable laws of the United States of America in all respects, including construction, validity and performance.

Section 5.5. Counterparts; Fax. This Amendment may be separately executed in counterparts and by the different parties hereto in separate counterparts, each of which when so executed shall be deemed to constitute one and the same Amendment. This Amendment may be validly executed by facsimile or other electronic transmission.

THIS AMENDMENT AND THE OTHER LOAN DOCUMENTS REPRESENT THE FINAL AGREEMENT BETWEEN THE PARTIES AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS, OR SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES. THERE ARE NO UNWRITTEN ORAL AGREEMENTS OF THE PARTIES.

[The remainder of this page intentionally left blank. Signature pages follow.]

IN WITNESS WHEREOF, this Amendment is executed as of the date first above written.

Section 2.1. (a) Applicable Margin amendment

Section 2.1. (b) Commitment Fee Rate amendment

Arvest Bank acknowledges the Majority Lenders’ decision regarding

Section 2.1. (c) amended definition of Consolidated Total Capitalization and

Section 2.2 Financial Condition Covenants amended Consolidated Indebtedness to Total Capitalization Ratio.

CONSENT AND AGREEMENT

By its execution below, each of the undersigned hereby (i) consents to the provisions of this Amendment and the transactions contemplated herein, (ii) ratifies and confirms the Fifth Amended and Restated Guarantee Agreement dated as of November 2, 2007 made by it for the benefit of Administrative Agent and Lenders (as modified by certain Assumption Agreements, if any) and the other Loan Documents executed by it pursuant to the Credit Agreement (or any prior amendment or supplement to the Credit Agreement), (iii) agrees that all of its respective obligations and covenants thereunder shall remain unimpaired by the execution and delivery of this Amendment and the other documents and instruments executed in connection herewith, and (iv) agrees that the Fifth Amended and Restated Guarantee Agreement and such other Loan Documents shall remain in full force and effect.