EXHIBIT 4.3.1 ================================================================================ CHESAPEAKE ENERGY CORPORATION and the Guarantors named herein ---------------------------------- 8 1/8% SENIOR NOTES DUE 2011 ---------------------------------- ---------- SECOND SUPPLEMENTAL INDENTURE DATED AS OF September 12, 2001 ---------- BANK OF NEW YORK Trustee ------------------- ================================================================================ THIS SECOND SUPPLEMENTAL INDENTURE, dated as of September 12, 2001, is among Chesapeake Energy Corporation, an Oklahoma corporation (the "Company"), each of the parties identified under the caption "Guarantors" on the signature page hereto (the "Guarantors") and Bank of New York, successor to United States Trust Company of New York, as Trustee. RECITALS WHEREAS, the Company, the Subsidiary Guarantors a party thereto and the Trustee entered into an Indenture, dated as of April 6, 2001, as supplemented by that certain Supplemental Indenture dated May 14, 2001 (the "Indenture"), pursuant to which the Company has originally issued $800,000,000 in principal amount of 8 1/8% Senior Notes due 2011 (the "Notes"); and WHEREAS, Section 9.01(3) of the Indenture provides that the Company, the Subsidiary Guarantors and the Trustee may amend or supplement the Indenture in order to execute and deliver a guarantee to comply with Section 10.03 thereof without the consent of the Holders of the Notes; and WHEREAS, all acts and things prescribed by the Indenture, by law and by the charter and the bylaws (or comparable constituent documents) of the Company, of the Guarantors and of the Trustee necessary to make this Second Supplemental Indenture a valid instrument legally binding on the Company, the Guarantors and the Trustee, in accordance with its terms, have been duly done and performed; NOW, THEREFORE, to comply with the provisions of the Indenture and in consideration of the above premises, the Company, the Guarantors and the Trustee covenant and agree for the equal and proportionate benefit of the respective Holders of the Notes as follows: ARTICLE 1 Section 1.01. This Second Supplemental Indenture is supplemental to the Indenture and does and shall be deemed to form a part of, and shall be construed in connection with and as part of, the Indenture for any and all purposes. Section 1.02. This Second Supplemental Indenture shall become effective immediately upon its execution and delivery by each of the Company, the Guarantors and the Trustee. ARTICLE 2 From this date, in accordance with Section 10.03 and by executing this Second Supplemental Indenture, each of Chesapeake Mountain Front Corp., an Oklahoma corporation, and Chesapeake- Staghorn Acquisition L.P., an Oklahoma limited partnership, are subject to the provisions of the Indenture as Subsidiary Guarantors to the extent provided for in Article 10 thereunder. ARTICLE 3 Section 3.01. Except as specifically modified herein, the Indenture and the Notes are in all respects ratified and confirmed (mutatis mutandis) and shall remain in full force and effect in accordance with their terms with all capitalized terms used herein without definition having the same respective meanings ascribed to them as in the Indenture. Section 3.02. Except as otherwise expressly provided herein, no duties, responsibilities or liabilities are assumed, or shall be construed to be assumed, by the Trustee by reason of this Second Supplemental Indenture. This Second Supplemental Indenture is executed and accepted by the Trustee subject to all the terms and conditions set forth in the Indenture with the same force and effect as if those terms and conditions were repeated at length herein and made applicable to the Trustee with respect hereto. Section 3.03. The Company hereby notifies the Trustee that each of Chesapeake Mountain Front Corp. and Chesapeake-Staghorn Acquisition L.P. have been designated by the Board of Directors of the Company as Restricted Subsidiaries pursuant to Section 10.03 (a) of the Indenture. Section 3.04. THE LAW OF THE STATE OF NEW YORK SHALL GOVERN AND BE USED TO CONSTRUE AND ENFORCE THIS SECOND SUPPLEMENTAL INDENTURE. Section 3.05. The parties may sign any number of copies of this Second Supplemental Indenture. Each signed copy shall be an original, but all of such executed copies together shall represent the same agreement. [NEXT PAGE IS SIGNATURE PAGE] IN WITNESS WHEREOF, the parties hereto have caused this Second Supplemental Indenture to be duly executed, all as of the date first written above. COMPANY: CHESAPEAKE ENERGY CORPORATION By /s/ AUBREY K. MCCLENDON ----------------------------------------- Name: Aubrey K. McClendon --------------------------------------- Title: Chief Executive Officer -------------------------------------- GUARANTORS: THE AMES COMPANY, INC. CHESAPEAKE ACQUISITION CORPORATION CHESAPEAKE ROYALTY COMPANY NOMAC DRILLING CORPORATION CHESAPEAKE ENERGY LOUISIANA CORPORATION CHESAPEAKE CANADA CORPORATION CHESAPEAKE OPERATING, INC. CHESAPEAKE MOUNTAIN FRONT CORP. GOTHIC ENERGY CORPORATION GOTHIC PRODUCTION CORPORATION By /s/ AUBREY K. MCCLENDON ----------------------------------------- Name: Aubrey K. McClendon --------------------------------------- Title: Chief Executive Officer -------------------------------------- CHESAPEAKE EXPLORATION LIMITED PARTNERSHIP CHESAPEAKE LOUISIANA, L.P. CHESAPEAKE PANHANDLE LIMITED PARTNERSHIP CHESAPEAKE-STAGHORN ACQUISITION L.P. By: Chesapeake Operating, Inc. as general partner of each representative entity By /s/ AUBREY K. MCCLENDON -------------------------------------- Name: Aubrey K. McClendon ------------------------------------ Title: Chief Executive Officer ----------------------------------- ARKOMA PITTSBURG HOLDING CORPORATION By /s/ HENRY J. HOOD ------------------------------------------ Name: Henry J. Hood --------------------------------------- Title: President -------------------------------------- TRUSTEE: BANK OF NEW YORK, successor to United States Trust Company of New York, as Trustee By /s/ LOUIS P. YOUNG ------------------------------------------ Name: Louis P. Young --------------------------------------- Title: Authorized Signer --------------------------------------