Document:

<PAGE>
                                                                    EXHIBIT 10.3

                     NINTH SUPPLEMENT TO PURCHASE AGREEMENT

         THIS NINTH SUPPLEMENT TO PURCHASE AGREEMENT dated as of June 7, 2002
(this "Supplement"), is made by:

         o        TransTexas Gas Corporation, a Delaware corporation (herein
                  called "Grantor"),

         o        Mirant Americas Energy Capital Assets, LLC ("Mirant"),

         o        TCW DR VI Investment Partnership, L.P. ("Fund VI"), acting
                  through its agent, TCW Asset Management Company,

         o        TCW Global Project Fund Ltd. ("GPF"), acting through its
                  agent, TCW London International, Limited (Mirant, Fund VI, and
                  GPF are herein collectively called, "Grantee"), and

         o        TCW London International, Limited ("TCW London"), as Agent on
                  behalf of GPF, and TCW Asset Management Company ("Tamco"), as
                  Agent on behalf of Fund VI (TCW London and Tamco are in such
                  capacities herein collectively called "Funds Agent").

                                    RECITALS

         1. Grantor, Mirant Americas Energy Capital, LP, formerly named Southern
Producer Services, L.P. ("SPS"), TCW Portfolio No. 1555 DR V Sub-Custody
Partnership, L.P. ("Fund V"), Fund VI and Funds Agent have heretofore entered
into that certain Purchase Agreement dated as of March 14, 2000 (herein, as
heretofore amended or supplemented, called the "Original Purchase Agreement"),
and, as contemplated therein, Grantor has, by means of a Production Payment
Conveyance dated as of the same date (herein, as heretofore amended or
supplemented, called the "Original Conveyance"), conveyed to SPS, Fund V and
Fund VI the "Production Payment" as therein defined, burdening interests of
Grantor in certain oil and gas properties.

         2. Effective as of December 1, 2000, Fund V assigned all of its right,
title, and interest under the Original Conveyance to SPS pursuant to that
certain Conveyance of Interest in Production Payment dated as of February 7,
2001.

         3. Effective as of September 10, 2001, SPS assigned to GPF an undivided
interest in the Production Payment pursuant to that certain Partial Conveyance
of Production Payment and Seventh Supplement to Production Payment Conveyance
dated as of September 10, 2001.

         4. On March 4, 2002, SPS assigned all of its right, title, and interest
under the Original Conveyance to Mirant (the "Mirant Assignment").

         5. In consideration of the payment by GPF of the Current Purchase Price
Payment to Grantor, as more fully described below, Grantor and Grantee now
desire to supplement and amend the Original Conveyance to (a) increase the
amount of the unliquidated balance of the Primary Sum, (b) adjust the relative
Percentage Shares of each Person included in Grantee to

<PAGE>

account for such additional Purchase Price Payment, and (c) provide for the
conveyance by Grantor to Grantee of additional Subject Interests to be subject
to the Production Payment.

         6. Grantor has requested that Grantee reconvey a portion of the
Production Payment by reducing the Dedication Percentage, and, in consideration
of the payment of the Partial Reconveyance Price (defined below), Grantee is
willing to do so.

         NOW, THEREFORE, in consideration of the premises and the mutual
covenants and agreements contained herein, Grantor, Mirant, Fund VI, GPF, and
Funds Agent hereby agree as follows:

                     I ARTICLE - Definitions and References

1. Section 1. Defined Terms and References. As used herein, the terms "Original
Conveyance", "Original Purchase Agreement", "Grantor", "Mirant", "SPS", "Fund
V", "Fund VI", "GPF", "Grantee", "Tamco", "TCW London", "Mirant Assignment", and
"Funds Agent" have the meanings given them above. Reference is also made to the
Original Purchase Agreement and to the Original Conveyance for the meaning of
various terms defined therein, all of which shall when used herein (unless
otherwise expressly defined herein) have the same meanings. For purposes of this
Supplement, unless the context otherwise requires, the following additional
terms shall have the following meanings:

         "Current Closing Date" has the meaning given such term in Section 2.6.

         "Current Conveyance Supplement" means the Ninth Supplement to
Production Payment Conveyance executed by Grantor and Grantee substantially in
the form of Exhibit A hereto.

         "Current Purchase Price Payment" means a Purchase Price Payment in the
amount of $13,000,000.

         "Current Supplement Documents" means this Supplement, the Current
Conveyance Supplement, and all other Production Payment Documents delivered
substantially contemporaneously herewith.

         "Mirant Effective Time" has the meaning given such term in Section 2.5.

         "Partial Reconveyance Price" means a partial reconveyance payment to
Grantee in the amount of $1,500,000.

         "Production Payment" has the meaning given such term in the Production
Payment Conveyance.

         "Production Payment Conveyance" means the Original Conveyance as
amended and supplemented by the Current Conveyance Supplement.

         "Purchase Agreement" means the Original Purchase Agreement as
supplemented and amended hereby.

                                       2
<PAGE>

2. Section 1. Rules of Construction. All references in this Supplement to
articles, sections, subsections and other subdivisions refer to corresponding
articles, sections, subsections and other subdivisions of this Supplement unless
expressly provided otherwise. Titles appearing at the beginning of any of such
subdivisions are for convenience only and shall not constitute part of such
subdivisions and shall be disregarded in construing the language contained in
such subdivisions. The words "this Supplement, "this instrument", "herein",
"hereof", "hereby", "hereunder" and words of similar import refer to this
Supplement as a whole and not to any particular subdivision unless expressly so
limited. Unless the context otherwise requires: "including" (and its grammatical
variations) means "including without limitation"; "or" is not exclusive; words
in the singular form shall be construed to include the plural and vice versa;
words in any gender include all other genders; references herein to any
instrument or agreement refer to such instrument or agreement as it may be from
time to time supplemented or amended; and references herein to any Person
include such Person's successors and assigns. All references in this Supplement
to exhibits and schedules refer to the exhibits and schedules to this Supplement
unless expressly provided otherwise, and all such exhibits and schedules are
hereby incorporated herein by reference and made a part hereof for all purposes.

                            II ARTICLE - Amendments

1. Section 2. Agreement to Amend Conveyance. Upon the terms and conditions of
this Supplement and the Purchase Agreement, Grantor and Grantee agree to amend
and supplement the Original Conveyance by executing and delivering the Current
Conveyance Supplement.

2. Section 2. Amendments to Purchase Agreement. The definition of Program
Period in Section 1.1 of the Original Purchase Agreement is hereby amended in
its entirety to read as follows:

         " 'Program Period' means the period beginning on the Initial Closing
         Date through and including June 7, 2002."

         In addition, although the provisions of the Original Purchase Agreement
contemplated that Purchase Price Payments would be paid only by SPS, Grantor and
Grantee acknowledge and agree that Purchase Price Payments may be paid by any
Person included within Grantee at the time in question, and that the Purchase
Agreement shall be construed accordingly.

         Section 2.3. Closing. On the Current Closing Date, Grantor shall
deliver the Current Conveyance Supplement to Grantee, and Grantor shall satisfy
all of the conditions set out in Sections 3.4 and 3.5 of the Purchase Agreement
(other than the conditions in Section 3.4(e) and (f) of the Purchase Agreement,
which are hereby waived without prejudice to the rights of Mirant, GPF and Fund
VI to request and receive the same in connection with any subsequent supplement
to the Purchase Agreement). On the Current Closing Date, GPF shall pay all of
the Current Purchase Price Payment to Grantor in accordance with the terms and
procedures of the Purchase Agreement.

         Section 2.4. Partial Reconveyance Price. On the Current Closing Date,
Grantor shall pay all of the Partial Reconveyance Price to Mirant, Fund VI and
GPF in accordance with their "amended Percentage Shares" (as defined in the
Current Conveyance Supplement) in accordance with Section 2.7 of the Purchase
Agreement.

                                       3
<PAGE>

         Section 2.5 Grantee. In order to take into account the Mirant
Assignment, (a) all references to "Grantee" in the Original Purchase Agreement,
as supplemented hereby, shall refer to Mirant, Fund VI, and GPF with respect to
matters occurring after 9:00 a.m. Houston, Texas time on March 4, 2002 (the
"Mirant Effective Time"), and (b) all references to "SPS" in the Original
Purchase Agreement, as supplemented hereby, shall refer to Mirant with respect
to matters occurring after the Mirant Effective Time.

         Section 2.6. Time and Place of Closing. The closing for the
consummation of the transactions contemplated herein shall take place on June 7,
2002 or on such other date as may be agreed to by Grantor and Grantee (herein
called the "Current Closing Date").

         Section 2.7 Winnie Guaranty. Grantor hereby confirms that Mirant, as a
transferee and assign of SPS, is a "Guaranteed Party", as such term is defined
in the Winnie Guaranty, and the Winnie Guaranty shall apply to and inure to the
benefit of Mirant.

                  III ARTICLE - Representations and Covenants

1. Section 3. Representations and Warranties of Grantor. To induce Grantee to
enter into the Current Supplement Documents and to pay the Current Purchase
Price Payment, Grantor hereby represents and warrants and covenants to Grantee
that:

         (a) All representations and warranties made by Grantor or any other
TransTexas Company in any Production Payment Document now or previously
delivered are true and correct as of the Current Closing Date (unless such
representations and warranties are expressly limited to an earlier date, in
which case such representations and warranties are true and correct as of such
earlier date), provided that the representations and warranties confirmed in the
Omnibus Certificates heretofore delivered are true and correct as such
Certificates are amended and updated through the date hereof. Without limitation
of the foregoing, no Senior Notes Event of Default exists.

         (b) Each TransTexas Company has performed all agreements, covenants,
and conditions which it is required by any Production Payment Document to
perform on or prior to the Current Closing Date.

         (c) The consummation on the Current Closing Date of the transactions
contemplated in the Current Supplement Documents: (i) is not prohibited by any
law or any regulation or order of any court or governmental agency or authority
applicable to Grantor or any other TransTexas Company, and (ii) does not subject
any of them to any penalty or other onerous condition under or pursuant to any
such law, regulation or order.

2. Section 3. Covenants. To induce Grantee to enter into the Current Supplement
Documents and to pay the Current Purchase Price Payment, Grantor hereby
covenants with Grantee that Grantor will perform all of its covenants and duties
under the Production Payment Documents, all as fully as if they were set out in
full herein.

                                       4
<PAGE>

3. Section 3. Representations and Warranties of Grantee. Each Person included
within Grantee hereby represents and warrants to Grantor that: (a) such Person
has incurred no obligation or liability, contingent or otherwise, for broker's
or finder's fees in respect of any of the matters provided for in this
Supplement for which fees Grantor might be liable; (b) the Purchase Agreement
constitutes the legal, valid and binding act and obligation of such Person,
enforceable against such Person in accordance with its terms except as such
enforcement may be limited by bankruptcy, insolvency, moratorium and other
similar laws applicable to creditors' rights generally or by general principles
of equity; (c) no bankruptcy or insolvency proceeding is presently pending (or,
to such Person's best knowledge, threatened) by or against such Person under any
applicable bankruptcy, insolvency or other similar law of any jurisdiction; (d)
such Person has not made a general assignment for the benefit of creditors; and
(e) such Person is acquiring the Production Payment for its own account and not
with any intention to transfer all or any part of the Production Payment to
others in violation of the Securities Act of 1933, as amended, or any other
applicable securities laws. Fund VI further represents and warrants that in
connection with the transactions contemplated herein and in the Purchase
Agreement (i) it is represented by Tamco, an investment manager that qualifies
as a "qualified professional asset manager" as defined in Department of Labor
Prohibited Transaction Exemption 84-14 (the "QPAM Exemption") and (ii) each of
the conditions of the QPAM Exemption are satisfied and will, throughout the term
of the Purchase Agreement (as hereby supplemented and amended), be satisfied.

                           IV ARTICLE - Miscellaneous

1. Section 4. Ratification of Production Payment Documents. The Original
Purchase Agreement as hereby supplemented and amended is hereby ratified and
confirmed in all respects. The other Production Payment Documents, as they may
be supplemented, amended or affected by the Current Supplement Documents, are
hereby ratified and confirmed in all respects. Any reference to the Purchase
Agreement in any Production Payment Document shall be deemed to refer to this
Supplement also, and any reference in any Production Payment Document to any
other document or instrument amended, renewed, extended or otherwise affected by
any Current Supplement Document shall also refer to such Current Supplement
Document. The execution, delivery and effectiveness of this Supplement and the
other Current Supplement Documents shall not, except as expressly provided
herein or therein, operate as a waiver of any right, power or remedy of Grantee
or Funds Agent under the Purchase Agreement or any other Production Payment
Document nor constitute a waiver of any provision of the Purchase Agreement or
any other Production Payment Document.

2. Section 4. Survival of Agreements. All representations, warranties, covenants
and agreements of Grantor herein shall survive the execution and delivery of
this Supplement and the other Current Supplement Documents and shall further
survive until terminated in accordance with the Purchase Agreement.

3. Section 4. Production Payment Documents. This Supplement and the other
Current Supplement Documents are Production Payment Documents, and all
provisions in the Purchase Agreement pertaining to Production Payment Documents
(including the arbitration provisions of Section 6.9 of the Purchase Agreement)
apply hereto and thereto.

                                       5
<PAGE>

         THIS WRITTEN AGREEMENT AND THE OTHER PRODUCTION PAYMENT DOCUMENTS
REPRESENT THE FINAL AGREEMENT BETWEEN THE PARTIES AND MAY NOT BE CONTRADICTED BY
EVIDENCE OF PRIOR, CONTEMPORANEOUS, OR SUBSEQUENT ORAL AGREEMENTS OF THE
PARTIES.

         THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

         Section 4.4. New Address. The address of Mirant for all purposes under
the Production Payment Documents shall be as set forth on its signature page to
the Current Conveyance Supplement.

         Section 4.5. Governing Law. This Supplement shall be deemed a contract
and instrument made under the laws of the State of Texas and shall be construed
and enforced in accordance with and governed by the laws of the State of Texas
and the laws of the United States of America, without regard to principles of
conflicts of law.

         Section 4.6. Counterparts. This Supplement may be separately executed
in counterparts and by the different parties hereto in separate counterparts,
each of which when so executed shall be deemed to constitute one and the same
Supplement.

            [THE REMAINDER OF THIS PAGE IS INTENTIONALLY LEFT BLANK]

                                       6
<PAGE>

         IN WITNESS WHEREOF, this Supplement is executed as of the date first
written above.

                                     TRANSTEXAS GAS CORPORATION

                                     By:
                                         ---------------------------------------
                                         Ed Donahue
                                         Vice President

                                     MIRANT AMERICAS ENERGY CAPITAL ASSETS, LLC

                                     By:   Mirant Americas Energy Capital, LP,
                                           its manager

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

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

                                     TCW DR VI INVESTMENT PARTNERSHIP, L.P.

                                     By:   TCW ASSET MANAGEMENT COMPANY, as
                                           its Agent

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

                                     TCW GLOBAL PROJECT FUND LTD.

                                     By:
                                         ---------------------------------------
                                         David J. Doyle
                                         Director

                                       7

<PAGE>

                                     TCW ASSET MANAGEMENT COMPANY, as Agent

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

                                       8
<PAGE>

                                 ACKNOWLEDGMENT

         To induce Grantee to enter into the above Supplement, the undersigned
Galveston Bay Pipeline Company and Galveston Bay Processing Company each hereby
ratify and confirm their various agreements made in connection with the
Production Payment Documents referred to above and acknowledge and agree that
such agreements remain in full force and effect after taking into account the
Current Supplement Documents referred to above.

EXECUTED as of the date of the above supplement.

GALVESTON BAY PIPELINE COMPANY

By:
         ------------------------------
         Ed Donahue
         Vice President

GALVESTON BAY PROCESSING COMPANY

By:
         ------------------------------
         Ed Donahue
         Vice President

                                       9
<PAGE>
                                                                       EXHIBIT A

                         NINTH SUPPLEMENT TO PRODUCTION
                               PAYMENT CONVEYANCE

                                       10<PAGE>
                                                                    EXHIBIT 10.4

                         NINTH SUPPLEMENT TO PRODUCTION
                               PAYMENT CONVEYANCE

         THIS NINTH SUPPLEMENT TO PRODUCTION PAYMENT CONVEYANCE (this
"Supplement"), dated as June 7, 2002, is made by TransTexas Gas Corporation, a
Delaware corporation ("Grantor"), Mirant Americas Energy Capital Assets, LLC
("Mirant"), TCW DR VI Investment Partnership, L.P. ("Fund VI"), and TCW Global
Project Fund Ltd. ("GPF"). Mirant, 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 Mirant Americas Energy Capital, LP, formerly named Southern
         Producer Services, L.P. ("SPS"), that certain Production Payment
         Conveyance dated as of March 14, 2000 (the "3/14/2000 Conveyance"). The
         3/14/2000 Conveyance has previously been supplemented and amended by
         various supplements and, as so supplemented and amended, is herein
         called the "Original Conveyance". The 3/14/2000 Conveyance and such
         supplements have been recorded as set forth in Schedule 1 hereto (the
         "Recording Schedule"); all capitalized terms used but not defined
         herein shall have the meanings assigned to them in the Original
         Conveyance.

B.       Effective as of December 1, 2000, Fund V assigned all of its right,
         title, and interest under the Original Conveyance to SPS pursuant to a
         Conveyance of Interest in Production Payment dated as of February 7,
         2001.

C.       Effective as of September 10, 2001, SPS conveyed an undivided interest
         in the Production Payment to GPF pursuant to a Partial Conveyance of
         Production Payment and Seventh Supplement to Production Payment
         Conveyance dated as of September 10, 2001.

D.       On March 4, 2002, SPS assigned all of its right, title, and interest
         under the Original Conveyance to Mirant pursuant to that certain
         Assignment dated as of March 4, 2002 (the "Mirant Assignment"). The
         Production Payment is now owned by Fund VI, Mirant, and GPF in
         undivided interests. The Mirant Assignment covered, and was subject to
         the terms of, all of the instruments listed on the Recording Schedule
         (collectively, the "Recording Schedule Instruments"), and Mirant hereby
         ratifies and confirms each of the Recording Schedule Instruments
         (including without limitation the Eighth Supplement to Production
         Payment Conveyance effective March 7, 2002 and the Partial Conveyance
         of Production Payment effective March 7, 2002 from SPS to GPF).

E.       Grantee and Grantor desire to supplement and amend the Original
         Conveyance, as set forth herein, to account for (a) an increase in the
         unliquidated balance of the Primary Sum in consideration of the payment
         by GPF of additional funds to Grantor, (b) the conveyance by Grantor to
         Grantee of Additional Subject Interests (defined below) to be subject
         to the Production Payment, and (c) the reconveyance by Grantee to
         Grantor of a portion of the Production Payment by means of certain
         amendments to the Dedication Percentage.

<PAGE>

F.       As described in Section 8.7 of the Original Conveyance, Fund VI has
         appointed TCW Asset Management Company and GPF has appointed TCW London
         International, Limited to act as their respective agents in connection
         with supplements and amendments to the Original Conveyance.

                           SUPPLEMENTS AND AGREEMENTS:

         FOR A GOOD AND VALUABLE CONSIDERATION, the receipt and sufficiency of
which are hereby acknowledged, Grantor and Grantee do hereby agree, act and
covenant as follows:

         1. Effective as of 9:00 a.m. Houston, Texas time, on June 7, 2002 (the
"Effective Time"), the Original Conveyance is amended in order to add the amount
of Thirteen Million Dollars ($13,000,000) to the unliquidated balance of the
Primary Sum, as such unliquidated balance stood as of the Effective Time after
giving effect to all applications of PP Proceeds made before the Effective Time.
After giving effect to such amendment (and to such application of PP Proceeds),
the unliquidated balance of the Primary Sum as of the Effective Time is
$38,215,737. (Any PP Proceeds received after the Effective Time on June 7, 2002
shall be deemed to have been received on the next following Business Day.)

         2. 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.

         3. The definition of "Percentage Share" in Section 1.1 of the Original
Conveyance is hereby amended in its entirety to read as follows:

         " 'Percentage Share' means, with respect to each Person included in
         Grantee, the fractional undivided interest which it owns in the
         Production Payment at the time in question. From the initial grant of
         the Production Payment until June 7, 2000, the Percentage Share of each
         Person included in Grantee was as follows:

                  Fund V       42.859594%
                  Fund VI      21.429797%
                  SPS          35.710609%

         From and after June 7, 2000, until September 8, 2000, the Percentage
         Share of each Person included in Grantee was as follows:

                  Fund V       33.048697%
                  Fund VI      16.524349%
                  SPS          50.426954%

                                       2
<PAGE>

         From and after September 8, 2000, until November 7, 2000, the
         Percentage Share of each Person included in Grantee was as follows:

                  Fund V       22.863142%
                  Fund VI      11.431571%
                  SPS          65.705287%

         From and after November 7, 2000, until December 1, 2000, the Percentage
         Share of each Person included in Grantee was as follows:

                  Fund V       19.08294%
                  Fund VI       9.54147%
                  SPS          71.37559%

         From and after December 1, 2000, until February 7, 2001, the Percentage
         Share of each Person included in Grantee was as follows:

                  Fund VI       9.54147%
                  SPS          90.45853%

         From and after February 7, 2001, until July 9, 2001, the Percentage
         Share of each Person included in Grantee was as follows:

                  Fund VI      49.82233%
                  SPS          51.17767%

         From and after July 9, 2001, until September 10, 2001, the Percentage
         Share of each Person included in Grantee was as follows:

                  Fund VI      43.83362%
                  SPS          56.16638%

         From and after September 10, 2001, until March 7, 2002, the Percentage
         Share of each Person included in Grantee was as follows:

                  Fund VI      31.64025%
                  SPS (or      49.81482%
                  Mirant)
                  GPF          18.54493%

         From and after March 7, 2002, until June 7, 2002, the Percentage Share
         of each Person included in Grantee was as follows:

                  Fund VI      19.36125%
                  Mirant       30.48260%
                  GPF          50.15615%

         As of 9:00 a.m. Houston, Texas time, on June 7, 2002, the Percentage
         Share of each Person included in Grantee is as follows:

                  Fund VI      12.77506%
                  Mirant       20.11321%
                  GPF          67.11173%

                                       3
<PAGE>

The foregoing Percentage Shares of Fund VI, Mirant, and GPF, respectively,
taking effect as of 9:00 a.m., Houston, Texas time on June 7, 2002, are in this
Supplement called their "amended Percentage Shares".

         4. The definition of "Dedication Percentage" in Section 1.1 of the
Original Conveyance is hereby amended in its entirety to read as follows (and to
the extent that the reductions in the Dedication Percentage set out in clauses
(g) and (h) below cause a reduction in Grantee's ownership interest in the
Subject Interests, Grantee hereby makes a corresponding reconveyance to
Grantor):

         " 'Dedication Percentage' means:

         (a) fifty percent (50%) from the Initial Time until 9:00 a.m., Texas
         time, on September 1, 2000;

         (b) sixty-two percent (62%) from 9:00 a.m., Texas time, on September 1,
         2000 until 9:00 a.m., Texas time, on December 1, 2000;

         (c) thirty percent (30%) from and after 9:00 a.m., Texas time, on
         December 1, 2000 until 9:00 a.m., Texas time, on August 1, 2001;

         (d) fifty percent (50%) from and after 9:00 a.m., Texas time, on August
         1, 2001 until 9:00 a.m., Texas time, on September 1, 2001;

         (e) ninety percent (90%) from and after 9:00 a.m., Texas time, on
         September 1, 2001 until 9:00 a.m., Texas time, on February 1, 2002;

         (f) eighty-five percent (85%) from and after 9:00 a.m., Texas time, on
         February 1, 2002 until 9:00 a.m., Texas time, on April 1, 2002;

         (g) sixty percent (60%) from and after 9:00 a.m., Texas time, on April
         1, 2002 until 9:00 a.m., Texas time, on June 1, 2002; and

         (h) seventy percent (70%) from and after 9:00 a.m., Texas time, on June
         1, 2002."

Notwithstanding the foregoing clause (g), the Dedication Percentage in effect
from 9:00 a.m., Texas time, on April 1, 2002 until 9:00 a.m., Texas time, on May
1, 2002, shall be increased or decreased above or below 60% to the extent, if
any, that is necessary to cause the PP Proceeds to be received by Grantee on
June 7, 2002, to be exactly $3,650,000.

         5. In consideration of the additional purchase price payment made by
GPF to Grantor and the foregoing increase in the unliquidated balance of the
Primary Sum:

         (a) Fund VI and Mirant do hereby GRANT, BARGAIN, SELL, CONVEY, ASSIGN,
         TRANSFER, SET OVER and DELIVER unto GPF such additional undivided
         interests in the Production Payment as are necessary in order to cause
         Mirant, GPF and Fund VI to

                                       4
<PAGE>

         own the Production Payment, at and after the Effective Time, in
         undivided interests in proportion to their respective amended
         Percentage Shares, and

         (b) Fund VI and Mirant do further assign unto GPF such undivided
         interests in Fund VI's and GPF's accounts receivable from the sale of
         PP Hydrocarbons - 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 Mirant,
         GPF and Fund VI to share in all collections of such accounts receivable
         after the Effective Time in proportion to their respective amended
         Percentage Shares.

         TO HAVE AND TO HOLD the same, upon and subject to the terms of the
Original Conveyance, as amended hereby, unto GPF and its successors and
Permitted Assigns, until the Termination Time.

         6. Exhibit A to the Original Conveyance is hereby amended and
supplemented, effective as of the Effective Time, to include at the end thereof
Exhibit A hereto (herein called "Additional Exhibit A").

         7. The terms "NRI Percentage," "PP Hydrocarbons," "Subject
Hydrocarbons," "Subject Interests," "Subject Lands," and "Subject Wells," as
such terms are defined and used in the Original Conveyance, are hereby amended,
effective as of the Effective Time, in order to take into account and recognize
the addition of Additional Exhibit A hereto to the end of Exhibit A as attached
to the Original Conveyance, and all other direct or indirect references in the
Original Conveyance shall likewise be considered amended in order to take into
account and recognize such Supplement and the addition of Additional Exhibit A
hereto to the end of Exhibit A as attached to the Original Conveyance.

         8. In consideration of the additional purchase price payment made by
GPF to Grantor, Grantor does hereby, in order to more fully effectuate the
amendments and other provisions herein contained, GRANT, BARGAIN, SELL, CONVEY,
ASSIGN, TRANSFER, SET OVER and DELIVER unto Grantee, as a production payment, to
be held in undivided interests in proportion to their Percentage Shares, a term
overriding royalty interest carved out of and burdening the Subject Interests
(including the "Additional Subject Interests," as defined below) equal to and
measured by all "Additional PP Hydrocarbons," as defined below, in, under and
that may be produced from (or, to the extent pooled or unitized, allocated to)
the Subject Lands (including the "Additional Subject Lands," as defined below),
with such production payment to be effective as to deliveries of Additional PP
Hydrocarbons as of the Effective Time, and to terminate as of the Termination
Time.

         TO HAVE AND TO HOLD the above-described production payment, upon and
subject to the terms of the Original Conveyance, as amended hereby, unto
Grantee, and its successors and Permitted Assigns, until the Termination Time.

         As used herein, the following terms have the following meanings:

         (a)      "Additional PP Hydrocarbons" means the Dedication Percentage
                  of the NRI Percentage (as the definitions of such terms are
                  amended herein) of:

                                       5
<PAGE>

                  (i)      all Hydrocarbons in, under or that may be produced
                           from (or, to the extent pooled or unitized, allocated
                           to) any Additional Subject Lands prior to the
                           Termination Time (as determined after giving effect
                           to this Supplement); and

                  (ii)     all other Hydrocarbons in, under or that may be
                           produced from (or, to the extent pooled or unitized,
                           allocated to) the Subject Lands prior to the
                           Termination Time, as determined after giving effect
                           to this Supplement and the Recording Schedule
                           Instruments, to the extent such Hydrocarbons are
                           included within the PP Hydrocarbons as a result of
                           the Termination Time being changed because of this
                           Supplement and the Recording Schedule Instruments.

         (b)      "Additional Subject Interests" means:

                  (i)      All of the leasehold interests and other property
                           interests described in Additional Exhibit A; and

                  (ii)     Without limitation of the foregoing, all other right,
                           title and interest (of whatever kind or character,
                           whether legal or equitable and whether vested or
                           contingent) of Grantor in and to the oil, gas and
                           other minerals in and under or that may be produced
                           from the Additional Subject Lands (including
                           interests in oil, gas or mineral leases to the extent
                           the same cover such lands, overriding royalties,
                           production payments and net profits interests in such
                           lands or such leases, and fee mineral interests, fee
                           royalty interests and other interests in such oil,
                           gas and other minerals) even though Grantor's
                           interest in such oil, gas and other minerals may be
                           incorrectly described in, or omitted from, Additional
                           Exhibit A; and

                  (iii)    All rights, titles and interests of Grantor in and
                           to, or otherwise derived from, all presently existing
                           and valid oil, gas or mineral unitization, pooling,
                           or communitization agreements, declarations or orders
                           and in and to the properties covered and the units
                           created thereby (including all units formed under
                           orders, rules, regulations, or other official acts of
                           any federal, state, or other authority having
                           jurisdiction, voluntary unitization agreements,
                           designations or declarations, and so-called "working
                           interest units" created under operating agreements or
                           otherwise) relating to the properties described in
                           subsections (i) or (ii) above in this definition.

         (c)      "Additional Subject Lands" means the lands and depths
                  described in Additional Exhibit A hereto (where no depth limit
                  is specified, Additional Subject Lands shall include all
                  depths).

         Without limitation of the generality of the provisions of Section 7,
above, or of the foregoing provisions of this Section 8, effective as to
deliveries of Additional PP Hydrocarbons at and after the Effective Time, the
definition of PP Hydrocarbons as found in the Original Conveyance is hereby
amended to include all Additional PP Hydrocarbons, as defined herein, the
definition of Subject Lands as found in the Original Conveyance is hereby
amended to include all Additional Subject Lands, as defined herein, and the
definition of Subject Interests as found in the Original Conveyance is hereby
amended to

                                       6
<PAGE>

include all Additional Subject Interests, as defined herein; the term "Initial
Time", as found in the definition of "Subject Hydrocarbons" in the Original
Conveyance, shall be deemed to refer to the Effective Time, as such term is
defined herein, but only as to Additional PP Hydrocarbons, and the Original
Conveyance is amended to so provide.

         9. In order to take into account the Mirant Assignment, (a) all
references to "Grantee" in the Original Conveyance, as supplemented hereby,
shall refer to Mirant, Fund VI, and GPF with respect to matters occurring after
9:00 a.m. Houston, Texas time on March 4, 2002 (the "Mirant Effective Time") and
(b) all references to "SPS" in the Original Conveyance, as supplemented hereby,
shall refer to Mirant with respect to matters occurring after the Mirant
Effective Time.

         10. 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.

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

         12. 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.

         13. 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.

         IN WITNESS WHEREOF, this Supplement is executed by the parties hereto
on the dates set out below in their respective acknowledgments, dated for
purposes of reference as of June 7, 2002, and effective as of the Effective
Time.

                                           TRANSTEXAS GAS CORPORATION

                                           By:
                                                --------------------------------
                                                Ed Donahue
                                                Vice President

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

                                       7
<PAGE>

                                    MIRANT AMERICAS ENERGY CAPITAL ASSETS, LLC

                                    By:  Mirant Americas Energy Capital, LP, its
                                         manager

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

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

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

                                    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:
                                        ----------------------------------------
                                        David J. Doyle
                                        Director

                                       8
<PAGE>

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

                  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

                                       9
<PAGE>

STATE OF TEXAS       )
                     )
COUNTY OF HARRIS     )

        The foregoing instrument was acknowledged before me on this ____ day of
June, 2002, by Ed Donahue, the Vice President of TransTexas Gas Corporation, a
Delaware corporation, on behalf of such corporation.

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

STATE OF TEXAS            )
                          )
COUNTY OF                 )
          ----------
         The foregoing instrument was acknowledged before me on this ____ day of
June, 2002, 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, on behalf of such limited partnership acting as manager of Mirant
Americas Energy Capital Assets, LLC, a Delaware limited liability company, and
on behalf of such limited liability company.

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

STATE OF TEXAS            )
                          )
COUNTY OF HARRIS          )

         The foregoing instrument was acknowledged before me on this ____ day of
June, 2002, 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

                                       10
\
<PAGE>

COLONY OF BERMUDA           )
CITY OF HAMILTON            )
CONSULATE GENERAL OF THE    )
UNITED STATES OF AMERICA    )

         The foregoing instrument was acknowledged before me on this ____ day of
June, 2002, by David J. Doyle, a Director of TCW Global Project Fund Ltd., a
Bermuda company, on behalf of such company.

                                         ---------------------------------------
         [SEAL]                          Consul of the United States of America

                                       11
<PAGE>

                                   SCHEDULE 1

                               RECORDING SCHEDULE

                                 TCW/TransTexas
                                  (83611.09854)

1.       Production Payment Conveyance among TCW Portfolio No. 1555 DR V
         Sub-Custody Partnership, L.P., TCW DR VI Investment Partnership, L.P.,
         Southern Producer Services, L.P. and TransTexas Gas Corporation.

<Table>
<Caption>

         Recording Jurisdiction                                   Recording Data
         ----------------------                                   --------------
<S>                                                               <C>

         Calhoun County, TX                                       Volume 262, Page 33
                                                                  Filed 9/19/00

         Chambers County, TX                                      Document No. 00-448-604,
                                                                  Filed 3/17/2000

         Galveston County, TX                                     Film Code #014-39-0178,
                                                                  Filed 3/17/2000

         Jim Hogg County, TX                                      Volume 17, Page 362,
                                                                  Filed 3/20/2000

         Live Oak County, TX                                      Volume 449, Page 135,
                                                                  Filed 3/20/2000

         Wharton County, TX                                       Volume 360, Page 596,
                                                                  Filed 3/17/2000

         Zapata County, TX                                        Volume 629, Page 471,
                                                                  Filed 3/17/2000

         General Land Office of Texas                             Filed
</Table>

                                       1
<PAGE>
2.       First Supplement to Production Payment Conveyance among TransTexas Gas
         Corporation, Southern Producer Services, L.P., TCW Portfolio No. 1555
         DR V Sub-Custody Partnership, L.P. and TCW DR VI Investment
         Partnership, L.P.

<Table>
<Caption>

         Recording Jurisdiction                                   Recording Data
         ----------------------                                   --------------
<S>                                                               <C>

         Calhoun County, TX                                       Volume 262, Page 114
                                                                  Filed 9/19/00

         Chambers County, TX                                      Document No. 00-459-630
                                                                  Filed 6/9/2000

         Galveston County, TX                                     Film Code 014-62-1617
                                                                  Filed 6/9/2000

         Jim Hogg County, TX                                      Volume 19, Page 526,
                                                                  Filed 6/9/2000

         Live Oak County, TX                                      Volume 450, Page 428,
                                                                  Filed 6/12/2000

         Wharton County, TX                                       Volume 371, Page 458,
                                                                  Filed 6/9/2000

         Zapata County, TX                                        Volume 634, Page 110,
                                                                  Filed 6/9/2000

         General Land Office of Texas                             Filed
</Table>

                                       2
<PAGE>

3.       Second Supplement to Production Payment Conveyance among TransTexas Gas
         Corporation, Southern Producer Services, L.P., TCW Portfolio No. 1555
         DR V Sub-Custody Partnership, L.P. and TCW DR VI Investment
         Partnership, L.P.

<Table>
<Caption>

         Recording Jurisdiction                                   Recording Data
         ----------------------                                   --------------
<S>                                                               <C>

         Calhoun County, TX                                       Volume 262, Page 132
                                                                  Filed 9/19/00

         Chambers County, TX                                      Document No. 00-470-562
                                                                  Filed 9/18/00

         Galveston County, TX                                     Film Code 014-90-1272
                                                                  Filed 9/15/00

         Jim Hogg County, TX                                      Volume 21, Page 370
                                                                  Filed 9/22/00

         Live Oak County, TX                                      Volume 387, Page 279
                                                                  Filed 9/19/00

         Wharton County, TX                                       Volume 383, Page 740,
                                                                  Filed 9/19/00

         Zapata County, TX                                        Volume 638, Page 642,
                                                                  Filed 9/22/00

         General Land Office of Texas                             Filed
</Table>

                                       3
<PAGE>

4.       Third Supplement to Production Payment Conveyance among TransTexas Gas
         Corporation, Southern Producer Services, L.P., TCW Portfolio No. 1555
         DR V Sub-Custody Partnership, L.P. and TCW DR VI Investment
         Partnership, L.P.

<Table>
<Caption>

         Recording Jurisdiction                                   Recording Data
         ----------------------                                   --------------
<S>                                                               <C>

         Calhoun County, TX                                       Volume 266, Page 205,
                                                                  Filed 11/13/00

         Chambers County, TX                                      Document No. 00-477-116,
                                                                  Filed 11/14/00

         Galveston County, TX                                     Film Code 015-08-1029
                                                                  Filed 11/13/00

         Jim Hogg County, TX                                      Volume 22, Page 256,
                                                                  Filed 11/13/00

         Live Oak County, TX                                      Volume 454, Page 239,
                                                                  Filed 11/14/00

         Wharton County, TX                                       Volume 390, Page 480,
                                                                  Filed 11/13/00

         Zapata County, TX                                        Volume 641, Page 169,
                                                                  Filed 11/13/00

         General Land Office of Texas                             Filed
</Table>

                                       4
<PAGE>

5.       Fourth Supplement to Production Payment Conveyance among TransTexas Gas
         Corporation, Mirant Americas Energy Capital, LP, and TCW DR VI
         Investment Partnership, L.P.

<Table>
<Caption>

         Recording Jurisdiction                                   Recording Data
         ----------------------                                   --------------
<S>                                                               <C>

         Calhoun County, TX                                       Volume 272, Page 114,
                                                                  Filed 2/12/01

         Chambers County, TX                                      Document No. 01-486-620
                                                                  Filed 2/12/01

         Galveston County, TX                                     Film Code 015-31-0563
                                                                  Filed 2/12/01

         Jim Hogg County, TX                                      Volume 23, Page 769,
                                                                  Filed 2/12/01

         Live Oak County, TX                                      Volume 456, Page 400,
                                                                  Filed 2/12/01

         Wharton County, TX                                       Volume 400, Page 418,
                                                                  Filed 2/12/01

         Zapata County, TX                                        Volume 645, Page 328,
                                                                  Filed 2/12/01

         General Land Office of Texas                             Filed
</Table>

                                       5
<PAGE>

6.       Fifth Supplement to Production Payment Conveyance among TransTexas Gas
         Corporation, Mirant Americas Energy Capital, LP and TCW DR VI
         Investment Partnership, L.P.

<Table>
<Caption>

         Recording Jurisdiction                                   Recording Data
         ----------------------                                   --------------
<S>                                                               <C>

         Calhoun County, TX                                       Volume 282, Page 226,
                                                                  Filed 7/18/01

         Chambers County, TX                                      Document No. 01-507-508
                                                                  Filed 7/18/01

         Galveston County, TX                                     Film Code 015-83-1832
                                                                  Filed 7/17/01

         Jim Hogg County, TX                                      Volume 26, Page 417,
                                                                  Filed 7/18/01

         Live Oak County, TX                                      Volume 461, Page 1,
                                                                  Filed 7/23/01

         Wharton County, TX                                       Volume 419, Page 909,
                                                                  Filed 7/17/01

         Zapata County, TX                                        Volume 652, Page 504,
                                                                  Filed 7/20/01

         General Land Office of Texas                             Filed
</Table>

                                       6
<PAGE>

7.       Sixth Supplement to Production Payment Conveyance among TransTexas Gas
         Corporation, Mirant Americas Energy Capital, LP and TCW DR VI
         Investment Partnership, L.P.

<Table>
<Caption>

         Recording Jurisdiction                                   Recording Data
         ----------------------                                   --------------

<S>                                                               <C>
         Calhoun County, TX                                       Volume 287, Page 102,
                                                                  Filed 9/19/01

         Chambers County, TX                                      Document No. 01-517-188
                                                                  Filed 9/21/01

         Galveston County, TX                                     Film Code 016-06-0472
                                                                  Filed 9/18/01

         Jim Hogg County, TX                                      Volume 27, Page 668,
                                                                  Filed 9/19/01

         Live Oak County, TX                                      Volume 462, Page 251,
                                                                  Filed 9/19/01

         Wharton County, TX                                       Volume 427, Page 346,
                                                                  Filed 9/18/01

         Zapata County, TX                                        Volume 655, Page 437,
                                                                  Filed 9/18/01

         General Land Office of Texas                             Filed
</Table>

                                       7
<PAGE>

8.       Partial Conveyance of Production Payment and Seventh Supplement to
         Production Payment Conveyance among TransTexas Gas Corporation, Mirant
         Americas Energy Capital, LP, TCW DR VI Investment Partnership, L.P. and
         TCW Global Project Fund Ltd.

<Table>
<Caption>

         Recording Jurisdiction                                   Recording Data
         ----------------------                                   --------------
<S>                                                               <C>

         Calhoun County, TX                                       Volume 287, Page 114,
                                                                  Filed 9/19/01

         Chambers County, TX                                      Document No. 01-517-199
                                                                  Filed 9/21/01

         Galveston County, TX                                     Film Code 016-06-0483
                                                                  Filed 9/18/01

         Jim Hogg County, TX                                      Volume 27, Page 679,
                                                                  Filed 9/19/01

         Live Oak County, TX                                      Volume 462, Page 263,
                                                                  Filed 9/19/01

         Wharton County, TX                                       Volume 427, Page 358,
                                                                  Filed 9/18/01

         Zapata County, TX                                        Volume 655, Page 448,
                                                                  Filed 9/18/01

         General Land Office of Texas                             Filed
</Table>

                                       8
<PAGE>

9.       Partial Reconveyance of Production Payment and Amendment to Production
         Payment Conveyance dated as of October 1, 2001 among TransTexas Gas
         Corporation, Mirant Americas Energy Capital, LP, TCW DR VI Investment
         Partnership, L.P. and TCW Global Project Fund Ltd.

<Table>
<Caption>

         Recording Jurisdiction                                   Recording Data
         ----------------------                                   --------------
<S>                                                               <C>

         Calhoun County, TX                                       Volume 289, Page 350,
                                                                  Filed 10/19/01

         Chambers County, TX                                      Document No. 01-520-788
                                                                  Filed 10/19/01

         Galveston County, TX                                     Film Code 016-16-1828
                                                                  Filed 10/18/01

         Jim Hogg County, TX                                      Volume 28, Page 613,
                                                                  Filed 10/19/01

         Live Oak County, TX                                      Volume 464, Page 74,
                                                                  Filed 10/19/01

         Wharton County, TX                                       Volume 430, Page 902,
                                                                  Filed 10/18/01

         Zapata County, TX                                        Volume ____, Page ____,
                                                                  Filed _______

         General Land Office of Texas                             Filed
</Table>

10.      Eighth Supplement to Production Payment Conveyance effective March 7,
         2002 among TransTexas Gas Corporation, Mirant Americas Energy Capital,
         LP, TCW DR VI Investment Partnership, L.P. and TCW Global Project Fund
         Ltd.

<Table>
<Caption>

         Recording Jurisdiction                                   Recording Data
         ----------------------                                   --------------
<S>                                                               <C>

         Calhoun County, TX                                       Volume 300, Page 91,
                                                                  Filed 3/12/02

         Chambers County, TX                                      Document No. 02-546-654
                                                                  Filed 3/12/02

         Galveston County, TX                                     Film Code 016-67-0330
                                                                  Filed 3/11/02

         Jim Hogg County, TX                                      Volume 31, Page 802,
                                                                  Filed 3/12/02

         Live Oak County, TX                                      Volume 467, Page 282,
                                                                  Filed 3/12/02

         Wharton County, TX                                       Volume 450, Page 770,
                                                                  Filed 3/12/02

         Zapata County, TX                                        Volume 664, Page 845,
                                                                  Filed 3/13/02

         Texas General Land Office                                Filed
</Table>

                                       9
<PAGE>

11.      Partial Conveyance of Production Payment effective March 7, 2002 from
         TransTexas Gas Corporation, Mirant Americas Energy Capital, LP, TCW DR
         VI Investment Partnership, L.P. and TCW Global Project Fund Ltd.

<Table>
<Caption>

         Recording Jurisdiction                                   Recording Data
         ----------------------                                   --------------
<S>                                                               <C>

         Calhoun County, TX                                       Volume 300, Page 107,
                                                                  Filed 3/12/02

         Chambers County, TX                                      Document No. 02-546-669
                                                                  Filed 3/12/02

         Galveston County, TX                                     Film Code 016-67-0345
                                                                  Filed 3/11/02

         Jim Hogg County, TX                                      Volume 31, Page 817,
                                                                  Filed 3/12/02

         Live Oak County, TX                                      Volume 467, Page 297,
                                                                  Filed 3/12/02

         Wharton County, TX                                       Volume 450, Page 785,
                                                                  Filed 3/12/02

         Zapata County, TX                                        Volume 664, Page 860,
                                                                  Filed 3/13/02

         Texas General Land Office                                Filed
</Table>

                                       10
<PAGE>

                                    EXHIBIT A
                                       TO
                               NINTH SUPPLEMENT TO
                          PRODUCTION PAYMENT CONVEYANCE

                          ADDITIONAL SUBJECT INTERESTS

                              WHARTON COUNTY, TEXAS

Lease A:

Lessor:           W. E. Schweinle, Elfrieda E. Schweinle, William E. Schweinle,
                  Jr., Frieda Schweinle, Joyce Schweinle Franklin, Melba
                  Schweinle Beken, William E. Schweinle and Elfrieda E.
                  Schweinle, Trustees of the W. E. & E. E. Schweinle Living
                  Trust and WJMF Investments.
Lessee:           Adobe Energy, Inc.
Date:             July 15, 1996.
Recorded:         Volume 202, Page 167, Official Records of Wharton County,
                  Texas.

Lease B:

Lessor:           Lou Anne Hancock Kellman, Nancy Hancock Sanders, Essie Hancock
                  Leslie, Mary Hancock Post, Joshua Ryan Hancock and Joe Bruce
                  Hancock, Individually and as Independent Co-Executors of the
                  Estate of Virginia Lou Hancock, Deceased, William Robert
                  Suggs, Jr., and Bruce Carlton Suggs.
Lessee:           Adobe Energy, Inc.
Date:             June 27, 1996.
Recorded:         Memorandum at Volume 202, Page 522, Official Records of
                  Wharton County, Texas.

Extension and Ratification of Lease B:

Lessor:           Lou Anne Hancock Kellman, Nancy Hancock Sanders, Essie Hancock
                  Leslie, Mary Hancock Post, Joshua Ryan Hancock and Joe Bruce
                  Hancock, Individually and as Independent Co-Executors of the
                  Estate of Virginia Lou Hancock, Deceased, William Robert
                  Suggs, Jr., and Bruce Carlton Suggs.
Lessee:           Adobe Energy, Inc.
Date:             June 26, 1998.
Recorded:         Volume 332, Page 754, Official Records of Wharton County,
                  Texas.

Lease C:

Lessor:           Joe Bruce Hancock, Trustee of the Clements Northington Trust
Lessee:           Adobe Energy, Inc.
Date:             June 27, 1996.
Recorded:         Memorandum at Volume 202, Page 520, Official Records of
                  Wharton County, Texas.

                                       11

<PAGE>

Extension and Ratification of Lease C:

Lessor:           Joe Bruce Hancock, Trustee of the Clements Northington Trust
Lessee:           Adobe Energy, Inc.
Date:             June 26, 1998.
Recorded:         Volume 288, Page 34, Official Records of Wharton County, Texas

Lease D:

Lessor:           Joe Bruce Hancock, Guardian of the Estate of William Andrew
                  Northington, Jr., N. C. M.
Lessee:           Adobe Energy, Inc.
Date:             June 27, 1996.
Recorded:         Memorandum at Volume 202, Page 518, Official Records of
                  Wharton County, Texas.

Extension and Ratification of Lease D:

Lessor:           Joe Bruce Hancock, Trustee of the Clements Heard Northington
                  Trust, Nancy Hancock Sanders, Essie Lynn Hancock Leslie, Mary
                  Hancock Post, Joe Bruce Hancock, Jr., Joshua Ryan Hancock,
                  William Robert Suggs, Jr., Bruce Carlton Suggs.
Lessee:           Adobe Energy, Inc.
Date:             June 26, 1998.
Recorded:         Volume 332, Page 764, Official Records of Wharton County,
                  Texas.

Amendment of Leases B, C, and D

Lessors:          Lou Anne Hancock Kellman, Individually and as Independent
                  Co-Executor of the Estate of Virginia Lou Hancock, Deceased,
                  Nancy Hancock Sanders, Individually and as Independent
                  Co-Executor of the Estate of Virginia Lou Hancock, Deceased,
                  Essie Hancock Leslie, Individually and as Independent
                  Co-Executor of the Estate of Virginia Lou Hancock, Deceased,
                  Mary Hancock Post, Individually and as Independent Co-Executor
                  of the Estate of Virginia Lou Hancock, Deceased, Joe Bruce
                  Hancock, Individually and as Independent Co-Executor of the
                  Estate of Virginia Lou Hancock, Deceased, Joshua Ryan Hancock,
                  Individually and as Independent Co-Executor of the Estate of
                  Virginia Lou Hancock, Deceased, William Robert Suggs, Jr.,
                  Bruce Carlton Suggs, Joe Bruce Hancock, Co-Trustee of the
                  Joseph Craig Sanders 1997 Trust, Jack Frost Sanders,
                  Co-Trustee of the Joseph Craig Sanders 1997 Trust, and Gary
                  Dean Post, Co-Trustee of the Joseph Craig Sanders 1997 Trust,
                  Joe Bruce Hancock, Co-Trustee of the Jeremy J. Sanders 1997
                  Trust, Jeremy J. Sanders, Co-Trustee of the Jeremy J. Sanders
                  1997 Trust, and Gary Dean Post, Co-Trustee of the Jeremy J.
                  Sanders 1997 Trust.

                                       12

<PAGE>

Lessees:          TransTexas Gas Corporation and Adobe Energy, Inc.
Date:             June 30, 1999.
Recorded:         Volume 354, Page 386, Official Records of Wharton County,
                  Texas.

Amendment of Leases B, C, and D

Lessors:          Lou Anne Hancock Kellman, Individually and as Independent
                  Co-Executor of the Estate of Virginia Lou Hancock, Deceased,
                  Nancy Hancock Sanders, Individually and as Independent
                  Co-Executor of the Estate of Virginia Lou Hancock, Deceased,
                  Essie Hancock Leslie, Individually and as Independent
                  Co-Executor of the Estate of Virginia Lou Hancock, Deceased,
                  Mary Hancock Post, Individually and as Independent Co-Executor
                  of the Estate of Virginia Lou Hancock, Deceased, Joe Bruce
                  Hancock, Individually and as Independent Co-Executor of the
                  Estate of Virginia Lou Hancock, Deceased, Joshua Ryan Hancock,
                  Individually and as Independent Co-Executor of the Estate of
                  Virginia Lou Hancock, Deceased, William Robert Suggs, Jr.,
                  Bruce Carlton Suggs, Joe Bruce Hancock, Co-Trustee of the
                  Joseph Craig Sanders 1997 Trust, Jack Frost Sanders,
                  Co-Trustee of the Joseph Craig Sanders 1997 Trust, and Gary
                  Dean Post, Co-Trustee of the Joseph Craig Sanders 1997 Trust,
                  Joe Bruce Hancock, Co-Trustee of the Jeremy J. Sanders 1997
                  Trust, Jeremy J. Sanders, Co-Trustee of the Jeremy J. Sanders
                  1997 Trust, and Gary Dean Post, Co-Trustee of the Jeremy J.
                  Sanders 1997 Trust.
Lessees:          TransTexas Gas Corporation and Adobe Energy, Inc.
Date:             January 10, 2001.
Recorded:         Volume 414, Page 257, Official Records of Wharton County,
                  Texas.

INSOFAR AND ONLY INSOFAR AS SAID LEASES, AS RATIFIED, EXTENDED AND AMENDED,
COVER AND INCLUDE ZONES, STRATA AND HORIZONS OCCURRING BELOW 8,021 FEET
SUBSURFACE IN THE FOLLOWING DESCRIBED LAND (said land and depths being
hereinafter referred to as the "Subject Tract"):

         228.92 acres of land, more or less, located in the John P. Borden
         Survey, A-9, and the James W. Jones Survey, A-35, Wharton County,
         Texas, being a portion of Tract 1 (called 452.618 acres) and Tract 2
         (called 5.477 acres) of that certain Warranty Deed from John Harborth
         et ux. to W.E. & E.E. Schweinle, recorded in Volume 151, Page 773 of
         the Official Records of Wharton County, Texas, and being more
         particularly described as follows:

         COMMENCING at a 5/8 inch iron rod found in the southwest right of way
         line of State Hwy 102 and the northwest corner of said called 5.477
         acre tract and northwest corner of said Schweinle lease;

         THENCE, S 18(degrees) 00' 14" W along a fence and the west line of said
         lease, a distance of 4000.00 feet to the POINT OF BEGINNING of herein
         described tract;

         THENCE, S 18(degrees) 00' 14" W along a fence and the west line of said
         lease, a distance of 3215.06 feet to a point, said point being the
         southwest corner of herein described tract;

                                       13
<PAGE>

         THENCE, S 69(degrees) 50' 08" E crossing said lease, a distance of
         2101.46 feet to a point in the east line of said lease and the
         southeast corner of herein described tract;

         THENCE, N 17(degrees) 20' 23" E with the east line of said lease, a
         distance of 6040.93 feet to a fence corner found in the southwest right
         of way line of said Hwy 102;

         THENCE, N 40(degrees) 17' 43" W with said right of way line and north
         line of said lease, a distance of 1210.58 feet to a point;

         THENCE, S 18(degrees) 00' 14" W a distance of 3382.36 feet to a point
         for corner;

         THENCE, N 71(degrees) 59' 47" W a distance of 1000.00 feet to the POINT
         OF BEGINNING.

As to the entirety of the Subject Tract:

     TransTexas Gas Corporation                  100.00% Working Interest

As to production from depths above 11,868 feet (TVD) in the Schweinle No. 1
wellbore (API No. 42-481-34124):

         TransTexas Gas Corporation               80.00% Net Revenue Interest

As to the entirety of the Subject Tract less and except production from depths
above 11,868 feet (TVD) in the Schweinle No. 1 wellbore (API No. 42-481-34124),
including the TransTexas Gas Corporation - Schweinle Nos. 2, 5, 6, 7 and 8
wells:

         TransTexas Gas Corporation               76.50% Net Revenue Interest

                                       15

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