TO THE PLAN AND AGREEMENT OF MERGER

                                 FIRST AMENDMENT

                                     TO THE

                          PLAN AND AGREEMENT OF MERGER

                                      OF

                           ESENJAY EXPLORATION, INC.

                                      AND

                             3DX TECHNOLOGIES INC.

                             DATED AS OF MAY 11, 1999



     Reference is hereby made to that certain Plan and Agreement of Merger of
Esenjay Exploration, Inc. and 3DX Technologies Inc. dated as of May 11, 1999
(the "Merger Agreement").  The parties agree that Paragraph 6.1.8 hereby
replaced in its entirety with the following:

     6.1.8   BY ESENJAY OR 3DX IF MERGER NOT EFFECTIVE BY OCTOBER 15, 1999. By
     either Esenjay or 3DX, if the merger shall not have become effective on
     or before October 15, 1999.

     Except as amended hereby, the Merger Agreement shall remain in full
force and effect, and the parties ratify, confirm and adopt the Merger
Agreement as amended hereby.

     IN WITNESS WHEREOF, the parties hereto have caused this First Amendment
to the Merger Agreement to be signed in their respective corporate names by
their respective duly authorized representatives, all as of August 20, 1999.


                                       3DX TECHNOLOGIES, INC.


                                       By: /s/ Xxxxxx X. Xxxxx
                                          -----------------------------------
                                               Xxxxxx X. Xxxxx, PRESIDENT


                                       ESENJAY EXPLORATION, INC.


                                       By: /s/ Xxxxxxx X. Xxxxxxx
                                          -----------------------------------
                                               Xxxxxxx X. Xxxxxxx, PRESIDENT