*Execution Copy*  Exhibit 4.A**FIFTH SUPPLEMENTAL INDENTURE****among****EL PASO EXPLORATION & PRODUCTION COMPANY,****as Issuer,****MBOW FOUR STAR CORPORATION,****EL PASO EXPLORATION & PRODUCTION MANAGEMENT, INC.,****EL PASO E&P HOLDINGS, INC.,****EL PASO E&P COMPANY, L.P.,****EL PASO PRODUCTION RESALE COMPANY,****EL PASO ENERGY OIL TRANSMISSION, L.L.C.****and****EL PASO PRODUCTION OIL & GAS GATHERING, L.P.,****as Subsidiary Guarantors,****and****WILMINGTON TRUST COMPANY****as Trustee** **June 30, 2006** **73/4% Senior Notes due 2013**  
 

 
**FIFTH SUPPLEMENTAL INDENTURE**     This Fifth Supplemental Indenture, dated as of June 30, 2006 (this “Fifth SupplementalIndenture”), is entered into by and among (i) El Paso Exploration & Production Company (the“Company”), formerly known as El Paso Production Holding Company, (ii) MBOW Four StarCorporation, El Paso Exploration & Production Management, Inc., formerly known as El PasoProduction Oil & Gas Company (“El Paso Management”), El Paso E&P Holdings, Inc., formerlyknown as El Paso Production Oil & Gas Holdings, Inc. (“El Paso Holdings”), El Paso E&PCompany, L.P., formerly known as El Paso Production Oil & Gas USA, L.P. (“El Paso E&P”), ElPaso Production Resale Company (“El Paso Resale”), El Paso Energy Oil Transmission, L.L.C.(“El Paso Transmission”) and El Paso Production Oil & Gas Gathering, L.P. (“El PasoGathering”) (collectively, the “Subsidiary Guarantors”), and (iii) Wilmington TrustCompany, as trustee (the “Trustee”). Capitalized terms used but not defined herein havethe meanings ascribed to them in the Indenture (as defined below).**W I T N E S S E T H:**     WHEREAS, the Company, El Paso Production Company (“El Paso Production”), El PasoProduction GOM Inc. (“GOM”), Vermejo Minerals Corporation (“Vermejo”) and El PasoEnergy Raton, L.L.C. (“Raton”) heretofore executed and delivered to the Trustee thatcertain Indenture, dated as of May 23, 2003 (the “Original Indenture”), providing for theissuance of $1,200,000,000 aggregate principal amount of the Company’s 73/4% Senior Notes due 2013(the “Notes”);     WHEREAS, as set forth in the First Supplemental Indenture (as defined below), Raton andVermejo entered into an Agreement of Merger dated January 31, 2003, pursuant to which (i) Raton wasmerged with and into Vermejo, (ii) Vermejo was the surviving corporation of the merger contemplatedby such agreement, and (iii) Vermejo’s name was changed to “El Paso Energy Raton Corporation”(“Raton Corporation”);     WHEREAS, the Company, El Paso Production, GOM, Vermejo and the Trustee entered into thatcertain First Supplemental Indenture, dated as of January 31, 2004 (the “First SupplementalIndenture”), pursuant to which the Original Indenture was amended and Vermejo expressly assumedthe obligations of Raton under its Subsidiary Guarantee;     WHEREAS, the Company, El Paso Production, GOM, Raton Corporation and the Trustee entered intothat certain Second Supplemental Indenture, dated as of July 26, 2004 (the “Second SupplementalIndenture”), pursuant to which the Original Indenture was further amended and certaincovenants were added for the benefit of the Holders pursuant to Section 9.01(6) of the OriginalIndenture;     WHEREAS, the Company, El Paso Production, GOM, Raton Corporation, Medicine Bow EnergyCorporation (“Medicine Bow”), Medicine Bow Operating Company (“MBOW Operating”) andMBOW Four Star Corporation (“MBOW Four Star”) entered into that certain Third SupplementalIndenture, dated as of August 31, 2005 (the “Third Supplemental Indenture”), pursuant towhich the Original Indenture was further amended and Medicine Bow,
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MBOW Operating and MBOW Four Star each expressly assumed the obligations of a SubsidiaryGuarantor under the Original Indenture;     WHEREAS, the Company, El Paso Production, Medicine Bow, MBOW Operating, MBOW Four Star, ElPaso Management, El Paso Holdings, El Paso E&P, El Paso Resale, El Paso Transmission and El PasoGathering entered into that certain Fourth Supplemental Indenture, dated as of December 31, 2005(the “Fourth Supplemental Indenture”), pursuant to which the Original Indenture wasfurther amended and (i) El Paso Management, El Paso Holdings, El Paso E&P, El Paso Resale, El PasoTransmission and El Paso Gathering each expressly assumed the obligations of a Subsidiary Guarantorunder the Original Indenture and (ii) El Paso E&P, in connection with the merger of GOM and RatonCorporation with and into El Paso E&P, expressly assumed the obligations of GOM and RatonCorporation under their respective Subsidiary Guarantees;     WHEREAS, as of the date hereof, in connection with the reorganization of certain subsidiariesof the Company, (i) El Paso Production, MBOW Operating, and El Paso E&P entered into andconsummated an Agreement of Merger pursuant to which (a) El Paso Production and MBOW Operatingmerged with and into El Paso E&P and (b) El Paso E&P is the surviving entity of the merger and (ii)the Company and Medicine Bow entered into and consummated an Agreement of Merger pursuant to which(a) Medicine Bow merged with and into the Company and (b) the Company is the surviving entity ofthe merger;     WHEREAS, Section 5.01(b) of the Original Indenture (as supplemented by the First SupplementalIndenture, the Second Supplemental Indenture, the Third Supplemental Indenture and the FourthSupplemental Indenture, and as so supplemented, the “Indenture”) provides that, inconnection with a merger of any Subsidiary Guarantor with or into any Person, such Person shallexpressly assume the obligations of such Subsidiary Guarantor under its Subsidiary Guarantee;     WHEREAS, El Paso E&P desires to expressly assume the obligations of El Paso Production andMBOW Operating under their respective Subsidiary Guarantees, and the Company desires to expresslyassume the obligations of Medicine Bow under its Subsidiary Guarantee; and     WHEREAS, the Trustee, upon satisfaction of all actions and conditions on the part of theCompany and the Subsidiary Guarantors necessary for the execution, delivery and performance of thisFifth Supplemental Indenture (including, without limitation, the receipt of an Officers’Certificate and an Opinion of Counsel) is willing to amend the Indenture as hereinafter set forth;     NOW, THEREFORE, the Company, the Subsidiary Guarantors and the Trustee mutually covenant andagree for the equal and proportionate benefit of all Holders of the Notes as follows:**ARTICLE 1**     Section 1.01 This Fifth Supplemental Indenture is supplemental to the Indenture, anddoes and shall be deemed to form a part of, and shall be construed in connection with and as a partof, the Indenture, for any and all purposes.
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     Section 1.02 This Fifth Supplemental Indenture shall become effective immediately uponits execution and delivery by each of the Company, the Subsidiary Guarantors and the Trustee.**ARTICLE 2**     Section 2.01 El Paso E&P hereby assumes all of the obligations of El Paso Productionand MBOW Operating under the Indenture, including all their obligations under their respectiveSubsidiary Guarantees, and the Company hereby assumes the obligations of Medicine Bow under theIndenture, including all its obligations under its Subsidiary Guarantee.**ARTICLE 3**     Section 3.01 Except as specifically modified herein, the Notes and the Indenture arein all respects ratified and confirmed and shall remain in full force and effect in accordance withtheir terms. This Fifth Supplemental Indenture shall form a part of the Indenture for allpurposes, and every Holder of Notes heretofore or hereafter authenticated and delivered shall bebound hereby. The Trustee shall not be responsible in any manner whatsoever for or in respect ofthe validity or sufficiency of this Fifth Supplemental Indenture or for or in respect of therecitals contained herein, all of which are made solely by the Company and the SubsidiaryGuarantors.     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 byreason of this Fifth Supplemental Indenture. This Fifth Supplemental Indenture is executed andaccepted by the Trustee subject to all the terms and conditions set forth in the Indenture with thesame force and effect as if those terms and conditions were repeated at length herein and madeapplicable to the Trustee with respect hereto. In entering into this Fifth Supplemental Indenture,the Trustee shall be entitled to the benefit of every provision of the Indenture relating to theconduct or affecting the liability or affording protection to the Trustee, regardless of whetherelsewhere herein so provided, including indemnification pursuant to Section 7.07 of the OriginalIndenture, and the Company acknowledges that the Trustee shall be entitled to indemnificationpursuant to Section 7.07 of the Original Indenture against any and all loss, liability or expense(including attorney’s fees) in connection with the Trustee’s signing this Fifth SupplementalIndenture.     Section 3.03**THIS FIFTH SUPPLEMENTAL INDENTURE SHALL BE GOVERNED BY, AND CONSTRUED INACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK.**     Section 3.04 This Fifth Supplemental Indenture may be executed in any number ofcounterparts, each of which when so executed and delivered shall be deemed an original, but allsuch counterparts together shall constitute but one and the same instrument.     Section 3.05 All notices and other communications to the New Subsidiary Guarantorsshall be given as provided in Section 11.02 of the Original Indenture for notices to SubsidiaryGuarantors.[Signature page follows.]
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     IN WITNESS WHEREOF, the parties hereto have caused this Fifth Supplemental Indenture to beduly executed as of the date first written above.      Issuer: