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                                                                     EXHIBIT 4.9

                              CERTIFICATE OF MERGER
                             OF BARGO ENERGY COMPANY
                  WITH AND INTO BELLWETHER EXPLORATION COMPANY

Pursuant to the provisions of Section 252 of the Delaware General Corporation
Law, the undersigned adopt the following Certificate of Merger for the purpose
of merging them into one of such corporation and certify as follows:

1.       The name and state of incorporation of each corporation which is a
         party to the merger is:

                           NAME                                  STATE
                           ----                                  -----

               Bellwether Exploration Company                   Delaware
               Bargo Energy Company                              Texas


2.       The surviving corporation of the merger is Bellwether Exploration
         Company.

3.       The Agreement and Plan of Merger has been approved, adopted,
         certified, executed and acknowledged by the directors and shareholders
         of Bargo Energy Company and the directors and stockholders of
         Bellwether Exploration Company.

4.       The following amendment to the Certificate of Incorporation of the
         surviving corporation shall be effected in connection with the merger.

         Article One of the Certificate of Incorporation of the surviving
         corporation shall be deleted and replaced in its entirety as follows:

                                  "ARTICLE ONE

         The name of the corporation is Mission Resources Corporation."

5.       An executed copy of the Agreement and Plan of Merger is on file
         at the principal place of business of the surviving corporation, which
         place of business is located at Bellwether Exploration Company, 1331
         Lamar, Suite 1455, Houston, Texas 77010.

6.       A copy of the Agreement and Plan of Merger will be furnished by
         the surviving corporation on written request and without cost to the
         shareholders of Bargo Energy Company and the stockholders of Bellwether
         Exploration Company.

7.       As to Bargo Energy Company, the Texas corporation, the Agreement and
         Plan of Merger was duly authorized and approved by all action required
         by the laws of the State of Texas and by its constituent documents.

8.       As to Bellwether Exploration Company, the Delaware corporation,
         the Agreement and Plan of Merger was duly authorized and approved by
         all action required by the laws of the State of Delaware and by its
         constituent documents. The total number of shares outstanding, voted
         for and against the Agreement and Plan of Merger, and as to each class
         entitled to vote thereon as a class, the number of shares voted for and
         against the Agreement and Plan of Merger:


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<TABLE>
<CAPTION>

                                                                              ENTITLED TO VOTE AS A CLASS
                                                                         ------------------------------------
                                               TOTAL      TOTAL
                                   TOTAL       VOTED      VOTED                   TOTAL      VOTED    VOTED
   NAME OF CORPORATION             SHARES       FOR      AGAINST         CLASS    SHARES      FOR     AGAINST
   -------------------             ------       ---      -------         -----    ------      ---     -------

<S>                                <C>         <C>       <C>             <C>       <C>        <C>      <C>
   Bellwether Exploration                                                 N/A       N/A        N/A      N/A
   Company
</TABLE>

9.       The surviving corporation will be responsible for the payment of all
         fees and franchise taxes and will be obligated to pay such fees and
         franchise taxes if the same are not timely paid.

         IN WITNESS WHEREOF, these Certificate of Merger have been duly executed
and delivered on this 16th day of May, 2001.


                                    BELLWETHER EXPLORATION COMPANY

                                    /s/ Douglas G. Manner
                                    --------------------------------------------
                                    Name:  Douglas G. Manner
                                    Title: Chief Executive Officer and President



                                    BARGO ENERGY COMPANY

                                    /s/ Jonathan M. Clarkson
                                    --------------------------------------------
                                    Name:  Jonathan M. Clarkson
                                    Title: President and Chief Operating Officer