EXHIBIT 4.11 ================================================================================ WESTPORT RESOURCES CORPORATION, a Nevada corporation, as Issuer, Each Subsidiary of the Issuer listed on the signatory pages hereto, as Subsidiary Guarantors, and THE BANK OF NEW YORK, as Trustee THIRD SUPPLEMENTAL INDENTURE Dated as of April 3, 2003 to INDENTURE Dated as of November 5, 2001 8 1/4% Senior Subordinated Notes Due 2011 ================================================================================ THIRD SUPPLEMENTAL INDENTURE THIRD SUPPLEMENTAL INDENTURE (this "SUPPLEMENTAL INDENTURE"), dated as of April 3, 2003, among Westport Resources Corporation, a Nevada corporation (the "COMPANY"), the Subsidiary Guarantors under the indenture referred to below and The Bank of New York, as trustee under the indenture referred to below (the "TRUSTEE"). WITNESSETH: WHEREAS, the Company, the Subsidiary Guarantors and the Trustee are parties to that certain Indenture, dated as of November 5, 2001 (the "ORIGINAL INDENTURE"), as amended by the First Supplemental Indenture thereto, dated as of December 31, 2001, and by the Second Supplemental Indenture thereto, dated as of December 17, 2002 (together with the Original Indenture, the "INDENTURE") providing for the issuance of 8 1/4% Senior Subordinated Notes due 2011 (the "SECURITIES"); WHEREAS, the Company is issuing $125,000,000 of Additional Securities as permitted by Sections 2.13 and 4.03(a) of the Indenture (the "ADDITIONAL SECURITIES"); and WHEREAS, pursuant to Section 9.01 of the Indenture, the Trustee, the Company and the Subsidiary Guarantors are authorized to execute and deliver this Supplemental Indenture. NOW, THEREFORE, in consideration of the foregoing and for other good and valuable consideration, the receipt of which is hereby acknowledged, the Company, the Subsidiary Guarantors and the Trustee mutually covenant and agree for the equal and ratable benefit of the holders of the Securities as follows: 1. DEFINITIONS. (a) Capitalized terms used herein without definition shall have the meanings assigned to them in the Indenture. (b) For all purposes of this Supplemental Indenture, except as otherwise herein expressly provided or unless the context otherwise requires: (i) the terms and expressions used herein shall have the same meanings as corresponding terms and expressions used in the Indenture; and (ii) the words "herein," "hereof" and "hereby" and other words of similar import used in this Supplemental Indenture refer to this Supplemental Indenture as a whole and not to any particular section hereof. 2. ADDITIONAL SECURITIES. Attached hereto as Annex 1 is a copy of the form of Officers' Certificate required by Section 2.13 of the Indenture in connection with the issuance of the Additional Securities. The definition of the term "ADDITIONAL SECURITIES" set forth in the Indenture is hereby supplemented by adding the following sentence at the end of such definition: "On April 3, 2003, the Company issued $125,000,000 of Additional Securities, as more particularly described in the Third Supplemental Indenture hereto, dated as of such date." 3. GOVERNING LAW. THIS SUPPLEMENTAL INDENTURE SHALL BE GOVERNED BY, AND CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK BUT WITHOUT GIVING EFFECT TO APPLICABLE PRINCIPLES OF CONFLICTS OF LAW TO THE EXTENT THAT THE APPLICATION OF THE LAWS OF ANOTHER JURISDICTION WOULD BE REQUIRED THEREBY. 4. TRUSTEE MAKES NO REPRESENTATION. The recitals herein contained are made by the Company and the Subsidiary Guarantors and not by the Trustee, and the Trustee assumes no responsibility for the correctness thereof. The Trustee makes no representation as to the validity or sufficiency of this Supplemental Indenture. 5. COUNTERPARTS. The parties may sign any number of copies of this Supplemental Indenture. Each signed copy shall be an original, but all of them together represent the same agreement. 6. EFFECT OF HEADINGS. The Section headings herein are for convenience only and shall not effect the construction thereof. [SIGNATURE PAGE FOLLOWS] 2 IN WITNESS WHEREOF, the parties hereto have caused this Supplemental Indenture to be duly executed as of the date first above written. WESTPORT RESOURCES CORPORATION By: /s/ LON MCCAIN ----------------------------------------------- Lon McCain, Vice President, Treasurer and Chief Financial Officer SUBSIDIARY GUARANTORS: --------------------- WESTPORT CANADA LLC By: WESTPORT OIL AND GAS COMPANY, L.P. By: WHG, INC. By: /s/ LON MCCAIN ------------------------------------- Lon McCain, Vice President, Treasurer and Chief Financial Officer JERRY CHAMBERS EXPLORATION COMPANY By: WESTPORT OIL AND GAS COMPANY, L.P. By: WHG, INC. By: /s/ LON MCCAIN ------------------------------------- Lon McCain, Vice President, Treasurer and Chief Financial Officer WESTPORT FINANCE CO. By: /s/ LON MCCAIN --------------------- Lon McCain, Treasurer S-1 WESTPORT ARGENTINA LLC By: WESTPORT OIL AND GAS COMPANY, L.P., its member, a Delaware limited partnership By: WHG, INC., its general partner, a Delaware corporation By: /s/ LON MCCAIN ------------------------------------- Lon McCain, Vice President, Treasurer and Chief Financial Officer WESTPORT OVERRIDING ROYALTY LLC By: WESTPORT OIL AND GAS COMPANY, L.P. By: WHG, INC. By: /s/ LON MCCAIN ------------------------------------- Lon McCain, Vice President, Treasurer and Chief Financial Officer WESTPORT OIL AND GAS COMPANY, L.P. By: WHG, INC. By: /s/ LON MCCAIN ------------------------------------------- Lon McCain, Vice President, Treasurer and Chief Financial Officer WHG, INC. By: /s/ LON MCCAIN ----------------------------------------------- Lon McCain, Vice President, Treasurer and Chief Financial Officer S-2 WHL, INC. By: /s/ LON MCCAIN ----------------------------------------------- Lon McCain, Vice President, Treasurer and Chief Financial Officer HORSE CREEK TRADING & COMPRESSION COMPANY LLC By: WESTPORT OIL AND GAS COMPANY, L.P. By: WHG, INC. By: /s/ LON MCCAIN ------------------------------------- Lon McCain, Vice President, Treasurer and Chief Financial Officer WESTPORT FIELD SERVICES, LLC By: WESTPORT RESOURCES CORPORATION By: /s/ LON MCCAIN ----------------------------------------- Lon McCain, Vice President, Treasurer and Chief Financial Officer THE BANK OF NEW YORK, as Trustee By: /s/ VAN BROWN ------------------------------------ Name: Van Brown ------------------------------------ Title: Vice President ------------------------------------ S-3 ANNEX 1 FORM OF OFFICERS' CERTIFICATE