1
                                                                   EXHIBIT 10.12

                                 FIRST AMENDMENT
                                       TO
                          AGREEMENT AND PLAN OF MERGER

         This First Amendment to the Agreement and Plan of Merger (this
"Amendment") is entered into as of January 30, 2001, (the "Effective Date"), by
and among Earl E. Rossman, Jr., as Shareholder Representative (the "Shareholder
Representative"), on behalf of the former shareholders of Texona Petroleum
Corporation, a Delaware corporation ("Texona"), Toreador Resources Corporation,
a Delaware corporation ("Toreador"), and Toreador Acquisition Corporation, a
Delaware corporation ("TAC").

                                    RECITALS

         A. Texona, Toreador and TAC entered into that certain Agreement and
Plan of Merger (the "Merger Agreement") dated as of September 11, 2000, and the
Merger Agreement authorizes Earl E. Rossman, Jr. to act as the Shareholder
Representative on behalf of the former shareholders of Texona.

         B. The Shareholder Representative on behalf of the former shareholders
of Texona, Toreador and TAC desire to amend the Merger Agreement.

         C. Capitalized terms used and not otherwise defined in this Amendment
shall have the meanings given to such terms in the Merger Agreement.

         D. Based on the recitals set forth above and the promises contained
herein, the parties agree as follows:

                                   AMENDMENTS

         1. Amendment to Section. Section 3.1(b) is replaced in its entirety and
amended to read as follows:

                             AMENDED SECTION 3.1(b)
                      CONSIDERATION FOR TEXONA COMMON STOCK

         Subject to the provisions of Section 3.1(c), each share of Texona
Common Stock issued and outstanding immediately prior to the Effective Time
(other than shares to be canceled in accordance with Section 3.1(a)) shall be
converted into the right to receive (i) at the Closing, a Proportionate Share of
the TRC Initial Shares, and (ii) on the Deferred Consideration Date, a
Proportionate Share of the TRC Deferred Shares, subject to the approval by a
majority vote of the TRC shareholders. TRC will use all reasonable efforts to
obtain approval by a majority vote of TRC shareholders to issue the TRC Deferred
Shares on or prior to June 1, 2001.

         2. Amendment to Other Sections. Any provisions of the Merger Agreement
that may be deemed to include reference to the $150,000 per month penalty
payment are


   2


hereby specifically amended to remove such reference to the $150,000 per month
penalty payment.


         3. Confirmation of Merger Agreement. The parties hereby confirm that,
except to the extent specifically amended hereby, the provisions of the Merger
Agreement shall remain unmodified and the Merger Agreement as so amended is
hereby confirmed as being in full force and effect.

         4. Miscellaneous. This Amendment and the Merger Agreement as amended
hereby shall be binding upon and shall inure to the benefit of the parties to
the Amendment and the Merger Agreement and their respective successors.


                                       2
   3



         IN WITNESS WHEREOF, this Amendment has been executed as of the date
first written above.


                                        ----------------------------------------
                                        Earl E. Rossman, Jr., as Shareholder
                                        Representative of the former
                                        shareholders of Texona Petroleum
                                        Corporation, a Delaware corporation

                                        TOREADOR RESOURCES CORPORATION,
                                        a Delaware corporation


                                        ----------------------------------------
                                        G. Thomas Graves III
                                        President and Chief Executive Officer


                                        TOREADOR ACQUISITION
                                        CORPORATION, a Delaware corporation


                                        ----------------------------------------
                                        G. Thomas Graves III
                                        President


                                       3