EXHIBIT 10.7.1 -------------- December 20, 1999 To the Banks and Financial Institutions Listed on Schedule 1 Hereto Re: Credit Agreement dated as of June 24, 1999 (as amended to date, the "Credit Agreement") among Titan Exploration, Inc. as Borrower ("Borrower"), Chase Bank of Texas, National Association, as Agent and the Lenders Signatory Thereto Ladies and Gentlemen: Reference is made to the Credit Agreement for the meanings of terms defined therein which, unless otherwise defined in this letter, shall have the same meanings when used herein. As you know, Unocal Corporation ("Unocal") and Borrower have agreed to merge Unocal's oil and gas exploration and production assets in the Permian and San Juan basins with Titan into a new publicly traded company to be named Pure Energy Resources, Inc. ("Pure"). Pure will form a wholly owned subsidiary, TRH, Inc. ("TRH"), which will be merged into Borrower, with Borrower to be the surviving corporation. As part of the merger, Borrower's existing shareholders will receive approximately thirty-five percent of the common stock of Pure, and Unocal will retain approximately sixty-five percent of the common stock of Pure. This transaction (the "Merger") is more fully described in the Agreement and Plan of Merger dated December 13, 1999 (the "Merger Agreement") among Union Oil Company of California, Titan Resources Holdings, Inc., TRH, and Borrower, a copy of which is enclosed with this letter. As a result of the Merger, Borrower will be a wholly owned subsidiary of Pure. Pure will initially have one or more other subsidiaries (the "Other Subsidiaries") that will not be owned by Borrower or any of Borrower's Subsidiaries. The Permian and San Juan assets to be contributed to Pure by Unocal will initially be held in the Other Subsidiaries. The Merger and the other transactions contemplated in the Merger Agreement (collectively, the "Transactions") may violate the following provisions of the Credit Agreement: Section 5.03(c) restricting mergers, Section 5.03(k), restricting certain transactions with Affiliates, and Section 6.13, providing for a Change in Control to constitute an Event of Default. As a result of the Transactions, Unocal and its Subsidiaries may also become ERISA Affiliates of Borrower and its Subsidiaries. Borrower hereby requests Lenders' and Agent's consent to the Transactions and their waiver of the provisions of Sections 5.03(c), 5.03(k), and 6.13 of the Credit Agreement (and any similar provisions of the Financing Documents) which would be violated by the Transactions. Borrower further requests Lenders' and Agent's agreement that (a) the term "ERISA Affiliate" in the Credit Agreement will hereafter refer only to Borrower and its own Subsidiaries and (b) the term "Maturity Date" in the Credit Agreement will hereafter refer to April 1, 2001 rather than January 1, 2001. Please execute a copy of this letter in the space provided below to evidence this requested consent, waiver, and agreement: Thank you very much for your cooperation. Yours truly, TITAN EXPLORATION, INC. By: /s/ John L. Benfatti ----------------------------------------------- Name: John L. Benfatti ---------------------------------------- Title: Vice President - Accounting & Controller ---------------------------------------- CONSENTED TO AND AGREED and WAIVED as of the date first written above: CHASE BANK OF TEXAS, NATIONAL ASSOCIATION Individually, as Issuing Bank, and as Administrative Agent By: /s/ Robert C. Mertensotto ----------------------------------------------- Name: Robert C. Mertensotto ---------------------------------------- Title: Managing Director ---------------------------------------- FIRST UNION NATIONAL BANK, Individually and as Documentation Agent By: /s/ Robert R. Wetteroff ----------------------------------------------- Name: Robert R. Wetteroff ---------------------------------------- Title: Senior Vice President ---------------------------------------- MORGAN GUARANTY TRUST COMPANY OF NEW YORK, Individually and as Syndication Agent By: /s/ John Kowalczuk ----------------------------------------------- Name: John Kowalczuk ---------------------------------------- Title: Vice President ---------------------------------------- CREDIT LYONNAIS NEW YORK BRANCH By: /s/ Philippe Soustra ----------------------------------------------- Name: Philippe Soustra ---------------------------------------- Title: Senior Vice President ---------------------------------------- BANK ONE, TEXAS, N.A. By: /s/ Wm. Mark Cranmer ------------------------------------------- Name: Wm. Mark Cranmer ------------------------------------ Title: Vice President ------------------------------------ PARIBAS By: /s/ Marian Livingston ------------------------------------------- Name: Marian Livingston ------------------------------------ Title: Vice President ------------------------------------ UNION BANK OF CALIFORNIA, N.A. By: /s/ Gary Shekerjian ------------------------------------------- Name: Gary Shekerjian ------------------------------------ Title: Assistant Vice President ------------------------------------ SCHEDULE 1 Chase Bank of Texas, N.A. One Chase Manhattan Plaza, 8th Floor New York, NY 10081 Attention: Muniram Appanna Agency Services First Union National Bank c/o First Union Corporation 1001 Fannin Street, Suite 2255 Houston, Texas 77002-6709 Attention: Ms. Vicki Crispens Morgan Guaranty Trust Company of New York 60 Wall Street New York, New York 10260 Attention: Phillip McNeal Credit Lyonnais New York Branch c/o Credit Lyonnais Houston Representative Office 1000 Louisiana, Suite 5360 Houston, Texas 77002 Attention: John M. Falbo Bank One, Texas, N.A. 1717 Main Street Dallas, Texas 75201 Attention: Mark Cranmer Paribas 1200 Smith Street, Suite 3100 Houston, Texas 77002 Attention: Brian Malone Union Bank of California, N.A. 4200 Lincoln Plaza 500 North Akard Dallas, Texas 75201 Attention: Gary Shekerjian cc: Chase Securities, Inc. 707 Travis Street, 5N86 Houston, Texas 77002 Attention: Robert C. Mertensotto