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                                                                    EXHIBIT 10.7

                    PARTIAL CONVEYANCE OF PRODUCTION PAYMENT
                                       AND
               SEVENTH SUPPLEMENT TO PRODUCTION PAYMENT CONVEYANCE

     THIS PARTIAL CONVEYANCE OF PRODUCTION PAYMENT AND SEVENTH SUPPLEMENT TO
PRODUCTION PAYMENT CONVEYANCE (this "Supplement"), dated as of the date set out
at the end hereof, is made by TransTexas Gas Corporation, a Delaware corporation
("Grantor"), Mirant Americas Energy Capital, LP, formerly named Southern
Producer Services, L.P. ("SPS"), TCW DR VI Investment Partnership, L.P. ("Fund
VI"), and TCW Global Project Fund Ltd. ("GPF"). SPS, Fund VI, and GPF are herein
collectively called "Grantee".

                                    RECITALS:

A.   Effective as of March 1, 2000, Grantor executed in favor of TCW Portfolio
     No. 1555 DR V Sub-Custody Partnership, L.P. ("Fund V"), Fund VI, and SPS
     that certain Production Payment Conveyance dated as of March 14, 2000,
     which has been supplemented and amended by various supplements given prior
     to September 10, 2001 (as so supplemented and amended, the "Original
     Conveyance"). The Original Conveyance, including all such supplements, has
     been recorded as described on Schedule 1 to the Sixth Supplement to
     Production Payment Conveyance that is referred to below and attached
     hereto.

B.   Effective as of December 1, 2000, Fund V assigned all of its right, title,
     and interest under the PP Conveyance to SPS pursuant to a Conveyance of
     Interest in Production Payment.

C.   Effective as of the date hereof, Grantor, Fund VI, and SPS executed and
     delivered that certain Sixth Supplement to Production Payment Conveyance
     (the "Sixth Supplement"), a copy of which is attached hereto as Exhibit A
     and made a part hereof for all purposes. The Original Conveyance, as
     supplemented and amended by the Sixth Supplement and by this Supplement, is
     herein called the "PP Conveyance". By means of the Original Conveyance and
     the Sixth Supplement, a production payment (the "Production Payment") is
     now owned by Fund VI and SPS in undivided interests.

D.   SPS desires to convey to GPF an undivided 18.54493% interest in the
     Production Payment, upon and subject to the provisions hereof, in order
     that SPS, Fund VI, and GPF shall own the Production Payment in the
     percentages described below.

                                   CONVEYANCE:

     1. For a good and valuable consideration, the receipt and sufficiency of
which are hereby acknowledged, SPS does hereby convey to GPF, 18.54493% of the
entire 8/8ths interest in the Production Payment, such conveyance to be
effective as of the Effective Time, as hereafter defined, but subject to the
reservations and exceptions set out below (the "GPF Assignment").

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     2. As a result of this conveyance, and taking into account the percentage
interest in the Production Payment previously owned by SPS and Fund VI, SPS,
Fund VI, and GPF now own the following undivided percentage interests in the
Production Payment, and their "Percentage Shares", as defined in the PP
Conveyance, shall be deemed to be as follows:

            Fund VI  31.64025%
            SPS      49.81482%
            GPF      18.54493%

     3. SPS does hereby further assign to GPF such undivided interests in SPS's
accounts receivable from the sale of PP Hydrocarbons (as defined in the Original
Conveyance) - to the extent such accounts receivable exist and are unpaid at the
Effective Time and arise from the sale of PP Hydrocarbons before the Effective
Time - as are necessary in order to cause SPS and GPF to share in all
collections of such accounts receivable after the Effective Time in proportion
to their respective amended Percentage Shares as set out above.

     4. SPS expressly reserves to itself, and is not assigning to GPF, all of
its rights with respect to the Surviving Duties. As used herein, "Surviving
Duties" means (a) all indemnification obligations, reimbursement obligations and
other obligations of Grantor that are, as provided in the PP Conveyance (and/or
in any related documents or instruments), to survive any termination of the PP
Conveyance, and (b) without limitation of the foregoing, (i) the indemnification
obligations of Grantor under Section 4.1 of the PP Conveyance, (ii) Grantor's
obligations to pay all severance taxes in connection with all PP Hydrocarbons at
any time purchased by Grantor, and (iii) Grantor's obligations to pay all
royalties in connection with all PP Hydrocarbons at any time produced.

     5. Grantor hereby ratifies and confirms all of the Surviving Duties owed to
SPS and hereby agrees to pay and perform the same. Grantor further confirms that
it independently owes the Surviving Duties to Fund VI, as well as SPS, due to
Fund VI being a beneficiary of the PP Conveyance prior to this Conveyance from
SPS to Fund VI, and Grantor hereby ratifies and confirms the Surviving Duties
owed to Fund VI and agrees to pay and perform the same.

     6. SPS hereby represents and warrants to GPF that the interests assigned
herein have not been conveyed to any other person. Except for the foregoing
sentence, herein, this Partial Conveyance of Production Payment is given without
representation or warranty of any kind, express, implied or otherwise.

                           SUPPLEMENTS AND AGREEMENTS:

     7. In order to take into account the GPF Assignment, (a) all references to
"Grantee" in the Original Conveyance, as supplemented hereby, shall refer to
SPS, Fund VI, and GPF with respect to matters occurring after the date hereof
and (b) all references to "Fund V" in the Original Conveyance, as supplemented
hereby, shall refer to GPF with respect to matters occurring after the date
hereof.

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     8. The definition of "GPF", "Tamco", and "TCW London" are hereby added to
Section 1.1 of the Original Conveyance in appropriate alphabetical order to read
as follows:

          " 'GPF' means TCW Global Project Fund Ltd., a Bermuda-domiciled
     special purpose company, and, unless the context in which used shall
     otherwise require, such term shall also include any successor to it as
     owner at the time in question of any or all of the Production Payment."

          " 'Tamco' means TCW Asset Management Company, a California
     corporation."

          " 'TCW London' means TCW London International, Limited, a California
     corporation."

     9. The definitions of "Affiliate", "Funds Agent", and "TCW Beneficiary" in
Section 1.1 of the Original Conveyance are hereby amended in their entirety to
read as follows:

          " 'Affiliate' means, with respect to any Person: (a) any other Person
     directly or indirectly owning, controlling or holding with power to vote
     10% or more of the outstanding voting securities of such Person, (b) any
     other Person 10% or more of whose outstanding voting securities are
     directly or indirectly owned, controlled or held with power to vote by such
     Person, and (c) any other Person directly or indirectly controlling,
     controlled by or under common control with such Person; provided that,
     "Affiliate" also means, with respect to GPF, Fund V and Fund VI, (i) any of
     the TCW Beneficiaries, (ii) any trustee, general partner, investment
     manager, custodian, custodial agent, or other fiduciary of or for GPF, Fund
     V, Fund VI, or any TCW Beneficiary, (iii) Trust Company of the West, a
     California trust company, and (iv) Tamco and TCW London, in each case
     whether acting as Funds Agent or in any other capacity."

          " 'Funds Agent' means the Persons named as Funds Agent in Section 8.7,
     acting in such capacity, together with their successors and assigns in such
     capacity."

          " 'TCW Beneficiary' means (a) any Person that at any time is a general
     or limited partner in Fund V or in Fund VI or any Person for whom such a
     general or limited partner is acting as investment manager, custodian or
     custodial agent or in a similar capacity and (b) any Person that is a
     shareholder in GPF."

     10. Section 6.2 of the Original Conveyance is amended in its entirety to
read as follows:

          "Section 6.2. Assignments by Grantee. Grantee's interest in the
     Production Payment may not be transferred except in compliance with this
     section. Any Grantee and any Permitted Assign (as hereinafter defined)
     shall have the right to sell, assign, transfer or convey its interest in
     the Production Payment, in whole or in part (and either absolutely or by
     mortgage or other security instrument), at any time; provided that:

               (a) no change of ownership or right to receive payment of the
          Production Payment or of any part thereof, however accomplished, shall
          be effective or

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          binding until notice thereof, including the Percentage Share and
          address of the transferee, shall have been registered with Grantor by
          the transferor and by the transferee (which transferee must make to
          Grantor the representations and warranties in Section 4.2 of the
          Purchase Agreement), and then only with respect to production
          occurring after receipt of such notice, and

               (b) neither Grantee nor any Permitted Assign shall assign or
          convey any rights under or any interest in the Production Payment
          Documents or the Production Payment to any Restricted Assignee.

     Any Person to whom all or any interest in the Production Payment is
     assigned or conveyed in accordance with the foregoing requirements is
     herein called a "Permitted Assign". Grantor shall keep records of all
     Permitted Assigns, their Percentage Shares, and their addresses, and shall
     give notice thereof to the other Persons, if any, from time to time holding
     the interests of Grantee hereunder."

     11. Section 8.7 of the Original Conveyance is amended in its entirety to
read as follows:

          "Section 8.7. Funds Agent; Consents, Waivers, Supplements and
     Amendments.

          (a) Fund VI has, pursuant to the Purchase Agreement, appointed Tamco
     as its agent to administer the Production Payment and to act on its behalf
     (as a Person included in Grantee) in giving any consents or waivers under
     this Conveyance, in making any amendments or supplements hereto, and in
     arranging for the marketing of the PP Hydrocarbons. GPF has, pursuant to
     other agreements, appointed TCW London as its agent to administer the
     Production Payment and to act on its behalf (as a Person included in
     Grantee) in giving any consents or waivers under this Conveyance, in making
     any amendments or supplements hereto, and in arranging for the marketing of
     the PP Hydrocarbons. Accordingly, as used herein, "Funds Agent" refers
     collectively to Tamco, acting on behalf of Fund VI, and to TCW London,
     acting on behalf of GPF. Unless and until this Conveyance is supplemented
     to reflect the termination of such agency or the appointment of a
     replacement or successor Funds Agent (which supplement may be executed by
     Fund VI and GPF without the joinder of Grantor or SPS), all Persons dealing
     with Grantor or Grantee in connection with the Production Payment shall be
     entitled to rely upon the authority of (i) Tamco to act as Funds Agent for
     Fund VI in connection herewith and (ii) TCW London to act as Funds Agent
     for GPF in connection herewith.

          (b) No consent, waiver, supplement or amendment given by Grantee in
     connection with this Conveyance or the Production Payment shall be valid or
     effective unless given be in writing and signed by each Person included in
     Grantee (provided that Tamco may sign the same on behalf of Fund VI and TCW
     London may sign the same on behalf of GPF but neither may sign on behalf of
     SPS)."

     12. Grantor and Grantee acknowledge to each other that concurrently
herewith SPS, GPF Fund V, and Fund VI are entering into an agreement which
supplements the Production Sales

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Agreements to provide that SPS, as Marketer, will be the purchaser of the PP
Hydrocarbons belonging to GPF.

     13. All of the terms and provisions of the Original Conveyance, as the same
is amended and supplemented hereby, are ratified, adopted, affirmed and renewed,
and remain in full force and effect for the benefit of Grantee, the
Beneficiaries, Funds Agent, and their respective successors and assigns.

     14. This Supplement may be executed in multiple counterparts, all of which
are identical.

     15. This Supplement shall be binding upon and shall inure to the benefit of
the parties hereto, and their respective successors and assigns, and all of the
covenants and agreements contained in the Original Conveyance, as amended
hereby, shall be deemed to be covenants and agreements running with the lands
affected thereby.

     16. This Supplement shall be governed by and construed in accordance with
the laws of the State of Texas, without regard to principles of conflicts of
laws.

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     IN WITNESS WHEREOF, this instrument is executed by the parties hereto on
the dates of their respective acknowledgments, effective as to deliveries of
oil, gas and other hydrocarbons as of 9:01 a.m., Texas time, on September 10,
2001 (the "Effective Time").

                                       TRANSTEXAS GAS CORPORATION

                                       By:
                                           -------------------------------------
                                           Simon Ward
                                           Vice President and Treasurer

Grantor's address:                     1300 North Sam Houston Parkway East
                                       Suite 310
                                       Houston, Texas 77032-2949
                                       Attention: Ed Donahue, Vice President
                                       Telephone: 281/987-8600
                                       Telecopy: 281/986-8865


                                       MIRANT AMERICAS ENERGY CAPITAL, LP

                                       By: Mirant Americas Development, Inc.,
                                           its general partner

                                           By:
                                               ---------------------------------
                                               John A. Rigas
                                               Attorney-in-Fact

SPS's address:                         1200 Smith Street
                                       Suite 2890
                                       Houston, Texas 77002
                                       Attention: David W. Stewart
                                       Telephone: 713/276-1902
                                       Telecopy: 713/276-1990

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                                       TCW DR VI INVESTMENT PARTNERSHIP, L.P.

                                       By: TCW ASSET MANAGEMENT COMPANY, as
                                           Agent

                                           By:
                                               ---------------------------------
                                               Kurt A. Talbot
                                               Senior Vice President


Fund VI's address:                     c/o Trust Company of the West
                                       865 South Figueroa
                                       Los Angeles, California  90017
                                       Attention: Thomas F. Mehlberg
                                       Telephone: 213/244-0702
                                       Telecopy: 213/244-0604


                                       TCW GLOBAL PROJECT FUND LTD.

                                       By: TCW LONDON INTERNATIONAL, LIMITED, as
                                           Investment Advisor

                                           By:
                                               ---------------------------------
                                               Randall S. Wade
                                               Vice President


                                               By:
                                                   -----------------------------
                                                   George R. Hutchinson
                                                   Managing Director


GPF's address:                         TCW Global Project Fund Ltd.
                                       c/o Conyers, Dill & Pearman
                                       Clarendon House
                                       Church Street
                                       Hamilton, Bermuda
                                       Attention: Kevin Butler
                                       Telephone: 441/299-4993
                                       Telecopy: 441/292-4720

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                  with a copy to:      TCW London International, Limited
                                       865 South Figueroa
                                       Los Angeles, California  90017
                                       Attention: Arthur Carlson
                                       Telephone: 213/244-0053
                                       Telecopy: 213/244-0604

This document prepared by:

John W. Rain
Thompson & Knight L.L.P.
1700 Pacific Avenue, Suite 3300
Dallas, Texas 75201

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STATE OF TEXAS                      )
                                    )
COUNTY OF HARRIS                    )

     The foregoing instrument was acknowledged before me on this 10th day of
September, 2001, by Simon Ward, the Vice President and Treasurer of TransTexas
Gas Corporation, a Delaware corporation, on behalf of such corporation.


                                       -----------------------------------------
        [SEAL]                         Notary Public, State of Texas

STATE OF TEXAS                      )
                                    )
COUNTY OF HARRIS                    )

     The foregoing instrument was acknowledged before me on this 10th day of
September, 2001, by John A. Rigas, the Attorney-in-Fact of Mirant Americas
Development, Inc., a Georgia corporation, on behalf of such corporation acting
as general partner of Mirant Americas Energy Capital, LP, a Delaware limited
partnership, and on behalf of such limited partnership.


                                       -----------------------------------------
        [SEAL]                         Notary Public, State of Texas

STATE OF TEXAS                      )
                                    )
COUNTY OF HARRIS                    )

         The foregoing instrument was acknowledged before me on this 10th day of
September, 2001, by Kurt A. Talbot, the Senior Vice President of TCW Asset
Management Company, a California corporation, on behalf of such corporation
acting as agent as aforesaid.


                                       -----------------------------------------
        [SEAL]                         Notary Public, State of Texas

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STATE OF TEXAS                    )
                                  )
COUNTY OF HARRIS                  )

         The foregoing instrument was acknowledged before me on this 10th day of
September, 2001, by George R. Hutchinson, a Managing Director of TCW London
International, Limited, a California corporation, on behalf of such corporation
acting as investment advisor as aforesaid.


                                       -----------------------------------------
        [SEAL]                         Notary Public, State of Texas

STATE OF TEXAS                    )
                                  )
COUNTY OF HARRIS                  )

         The foregoing instrument was acknowledged before me on this 10th day of
September, 2001, by Randall S. Wade, a Vice President of TCW London
International, Limited, a California corporation, on behalf of such corporation
acting as investment advisor as aforesaid.


                                       -----------------------------------------
        [SEAL]                         Notary Public, State of Texas

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                                    EXHIBIT A

                         SIXTH SUPPLEMENT TO PRODUCTION
                               PAYMENT CONVEYANCE