
<PAGE>


                       SECURITIES AND EXCHANGE COMMISSION

                              WASHINGTON, DC 20549



                                    FORM 8-K

                                 CURRENT REPORT
                     PURSUANT TO SECTION 13 OR 15(D) OF THE
                         SECURITIES EXCHANGE ACT OF 1934



               Date of report (Date of earliest event reported): May 12, 1999


                                3DX TECHNOLOGIES INC.
                 (Exact Name of Registrant as Specified in Charter)


         Delaware                      0-21841                   76-0386601
(State or Other Juisdiction          (Commission               (IRS Employer
     of Incorporation)               File Number)            Identification No.)


         12012 Wickchester, Suite 250, Houston, Texas               77079
           (Address of Principal Executive Offices)               (Zip Code)
                              


       Registrant's telephone number, including area code: (281) 579-3398


<PAGE>



ITEM 5.     OTHER EVENTS.

            On May 12, 1999, 3DX  Technologies  Inc. (the  "Company")  announced
that it has signed a Plan and Agreement of Merger with Esenjay Exploration, Inc.
(Esenjay) (NASDAQ:  ESNJ) which provides for the merger of 3DX into Esenjay. The
Boards of both  companies  have  approved  the  transaction,  and closing of the
merger is conditioned  upon approval from the shareholders of both companies and
satisfaction of certain other  conditions set forth in the Plan and Agreement of
Merger.

            The  terms of the  merger  provide  for 3DX  shareholders  to select
either the issuance of Esenjay  common stock at a ratio of 1:3.25  shares of 3DX
common stock or the issuance of a new Esenjay  convertible  preferred stock at a
ratio of 1:2.75  shares of 3DX common stock.  The preferred  stock is limited to
50% of the total 3DX shares converted and may be redeemed at Esenjay's option at
any time during the first twelve months after the merger at $1.925 per share. If
not redeemed  during the first year,  the preferred will  automatically  convert
into one share of Esenjay  common stock if the average  closing price of Esenjay
common is greater than $1.875  during a predefined  measurement  period.  If the
Esenjay  common is less than $1.875 the preferred  holder has the right to "put"
the shares to Esenjay. Esenjay will then have the right to pay for this "put" in
cash  or  common  shares.   Esenjay   currently  has  15,784,834  common  shares
outstanding and 3DX currently has 9,685,761 shares outstanding.


ITEM 7.     FINANCIAL STATEMENTS, PRO FORMA FINANCIAL INFORMATION AND EXHIBITS.

            (a)   Financial Statements of Businesses Acquired.

                        Not Applicable.

            (b)   Pro Forma Financial Information.

                        Not Applicable.

            (c)   Exhibits.

                        The following exhibit is filed with this Report.

EXHIBIT NO.       DESCRIPTION

99                      Press Release of the Company, dated May 12, 1999.



<PAGE>



                                   SIGNATURES


            Pursuant to the requirements of the Securities Exchange Act of 1934,
the  Registrant  has duly  caused  this report to be signed on its behalf by the
undersigned hereunto duly authorized.


                                          3DX TECHNOLOGIES INC.



Dated: May 14, 1999                       By: /s/ Russell L. Allen 
                                              Russell L. Allen
                                              Chief Financial Officer



<PAGE>



                                  EXHIBIT INDEX


EXHIBIT NO.       DESCRIPTION

99                Press Release of the Company, dated May 12, 1999.





