AGREEMENT MADE PURSUANT TO RULE 13d-1(f)(1)(iii) 2 JOINT FILING AGREEMENT

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                                  EXHIBIT 99.1

                           AGREEMENT MADE PURSUANT TO
                             RULE 13d-1(f)(1)(iii)
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                             JOINT FILING AGREEMENT

         The parties hereto agree that pursuant to Rule 13d-1(f)(1)(iii) of
Regulation 13D promulgated by the Securities and Exchange Commission pursuant
to the Securities Exchange Act of 1934, as amended, the Schedule 13D of which
this Agreement is made an exhibit is filed on behalf of it in the capacity set
forth below.


Date:  November 3, 1997                NATURAL GAS PARTNERS II, L.P.


                                        By: G.F.W. Energy II, L.P.,
                                            its Sole General Partner


                                            By: GFW II, L.L.C.,
                                                its Sole General Partner


                                            By: /s/ Xxxxxxx X. Xxxxx           
                                                -------------------------------
                                                Xxxxxxx X. Xxxxx,
                                                Authorized Member



Date:  November 3, 1997                G.F.W. ENERGY II, L.P.

                                        By: GFW II, L.L.C.,
                                            its Sole General Partner


                                        By: /s/ Xxxxxxx X. Xxxxx              
                                           ------------------------------------
                                           Xxxxxxx X. Xxxxx,
                                           Authorized Member



Date:  November 3, 1997                GFW II, L.L.C.

                                        
                                        By: /s/ Xxxxxxx X. Xxxxx              
                                           ------------------------------------
                                           Xxxxxxx X. Xxxxx,
                                           Authorized Member