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                                                                   EXHIBIT 10.13

                              SECOND AMENDMENT TO
                         REGISTRATION RIGHTS AGREEMENT

          THIS SECOND AMENDMENT (this "Amendment") is entered into as of the
day of August, 1996, between Flores & Rucks, Inc., a Delaware corporation
("FRI"), Flores & Rucks, Inc., a Louisiana corporation ("FRI Louisiana"), Enron
Finance Corp. ("Enron") and Merrill Lynch Capital Markets plc ("Merrill").
Capitalized terms used but not defined herein shall have the meanings ascribed
to them in the Registration Rights Agreement dated as of December 7, 1994 (the
"Agreement"), among FRI, FRI Louisiana and Enron (collectively, the "Original
Parties").

          WHEREAS, the Original Parties entered into the Agreement for the
purpose of granting the Rights to Enron; and

          WHEREAS, the Original Parties executed a Waiver and Amendment, dated
January 19, 1996 (the "Waiver and Amendment"), for the purpose of waiving or
amending certain provisions of the Agreement; and

          WHEREAS, in connection with the transfer of a portion of the
Registrable Shares from Enron to Merrill, the Original Parties wish to further
amend the Agreement in order to include Merrill as a party to the Agreement and
the Waiver and Amendment and to transfer to Merrill Enron's Rights under 
Section 2(a) of the Agreement;

          NOW, THEREFORE, in consideration of the premises and the mutual
covenants contained herein, and other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, the parties hereto
agree to amend the Agreement and the Waiver and Amendment as follows:

          1.  Merrill is hereby made a party to the Agreement and the Waiver and
Amendment and, except with respect to, and as limited by, the definition of
"Holder" as amended by Paragraph 2 of this Amendment, all references to the
rights, powers, obligations and limitations of Enron in the Agreement or the
Waiver and Amendment shall be deemed to refer to each of Enron and Merrill.  By
executing this Amendment, (i) Merrill agrees to be bound by the terms of, and to
assume the rights, powers, obligations and limitations under, the Agreement and
the Waiver and Amendment, (ii) FRI and FRI Louisiana agree to grant all of the
rights, powers and other benefits under the Agreement and the Waiver and
Amendment to Merrill and (iii) Enron consents to this Amendment and to Merrill
being made a party to the Agreement.

          2. Section 1 of the Agreement is hereby amended such that the
definition of "Holder" reads in its entirety as follows:

          " "Holder" means Enron, Merrill Lynch Capital Markets plc and any
          other Person holding Registrable Shares; provided, that such Person
          acquired such Registrable Shares in accordance with Section 7 of this
          Agreement; and provided further, that Enron shall not have any Rights
          under Section 2(a) hereof."
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          3.  Section 2 of the Agreement is hereby amended such that the second
paragraph of Section 2(b) shall read in its entirety as follows:

          "Upon the written request of a Holder or Holders delivered to FRI
          within two business days after receipt of any such notice, FRI shall
          use its best efforts (subject to the provisions of this Section 2(b))
          to cause all Registrable Shares, the Holders of which shall have so
          requested registration thereof, to be registered under the Securities
          Act, all to the extent requisite to permit the sale or other
          disposition by the Holder or Holders of such Registrable Shares;
          provided however, FRI may elect not to file a registration statement
          pursuant to this Section 2(b) or may withdraw any registration
          statement filed pursuant to this Section 2(b) at any time prior to the
          effective date thereof."

          4. The address and facsimile number for communications to Merrill
under the Agreement shall be:

             Merrill Lynch Capital Markets plc  
             c/o Merrill Lynch & Co. 
             One Houston Center 
             1221 McKinney 
             Suite 2700 
             Houston, Texas 77010
             Facsimile: (713) 759-2588 
             Attention: Greg Pipkin

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          IN WITNESS WHEREOF, the parties hereto have executed and delivered
this Amendment as of the date first above written.


                              FLORES & RUCKS, INC., a Delaware corporation



                              By:
                                 -----------------------------------------------
                                 Name:
                                      ------------------------------------------
                                 Title:
                                       -----------------------------------------


                              FLORES & RUCKS, INC., a Louisiana corporation



                              By:
                                 -----------------------------------------------
                                 Name:
                                      ------------------------------------------
                                 Title:
                                       -----------------------------------------


                              ENRON FINANCE CORP.



                              By:
                                 -----------------------------------------------
                                 Name:
                                      ------------------------------------------
                                 Title:
                                       -----------------------------------------


                              MERRILL LYNCH CAPITAL MARKETS PLC



                              By:
                                 -----------------------------------------------
                                 Name:
                                      ------------------------------------------
                                 Title:
                                       -----------------------------------------

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