Document:

<PAGE>
                                                                     EXHIBIT 4.9

================================================================================
                         WESTPORT RESOURCES CORPORATION,
                              a Nevada corporation,
                                   as Issuer,

                             Each Subsidiary of the
                              Issuer listed on the
                             signatory pages hereto,
                            as Subsidiary Guarantors,

                                       and
                              THE BANK OF NEW YORK,
                                   as Trustee

                          SECOND SUPPLEMENTAL INDENTURE

                          Dated as of December 17, 2002

                                       to

                                    INDENTURE

                          Dated as of November 5, 2001

                    8 1/4% Senior Subordinated Notes due 2011

================================================================================

<PAGE>

                          SECOND SUPPLEMENTAL INDENTURE

         SECOND SUPPLEMENTAL INDENTURE (this "SUPPLEMENTAL INDENTURE"), dated as
of December 17, 2002, among Westport Resources Corporation, a Nevada corporation
(the "COMPANY"), the existing Subsidiary Guarantors under the indenture referred
to below (the "EXISTING SUBSIDIARY GUARANTORS"), the parties identified as New
Subsidiary Guarantors on the signature page hereto (the "NEW SUBSIDIARY
GUARANTORS") and The Bank of New York, as trustee under the indenture referred
to below (the "TRUSTEE").

                                   WITNESSETH:

         WHEREAS, the Company and the Existing Subsidiary Guarantors have
heretofore executed and delivered to the Trustee an indenture, dated as of
November 5, 2001 (the "ORIGINAL INDENTURE"), as amended by the First
Supplemental Indenture thereto, dated as of December 31, 2001 (together with the
Original Indenture, the "INDENTURE") providing for the issuance of 8 1/4% Senior
Subordinated Notes due 2011 (the "SECURITIES");

         WHEREAS, on November 5, 2001, the Company issued $275,000,000 in
principal amount of Securities; and

         WHEREAS, the Company has entered into that certain Purchase Agreement,
dated December 11, 2002, by and among the Company, the Subsidiary Guarantors,
Credit Suisse First Boston Corporation, J.P. Morgan Securities Inc., and Lehman
Brothers Inc., acting on behalf of themselves and as representatives of other
purchasers, pursuant to which, on this date, the Company is issuing $300,000,000
of Additional Securities as permitted by Sections 2.13 and 4.03(a) of the
Indenture (the "DECEMBER 2002 ADDITIONAL SECURITIES");

         WHEREAS, through the indirect acquisition of all of the membership
interests of Horse Creek Trading & Compression LLC and the formation of Westport
Field Services, LLC, the Company has acquired two new Subsidiaries;

         WHEREAS, Section 4.10 of the Indenture provides that, under certain
circumstances, the Company is required to cause its Subsidiaries to execute and
deliver to the Trustee a Guaranty Agreement pursuant to which such Subsidiaries
shall unconditionally guarantee all of the Company's obligations under the
Securities and the Indenture on the terms and conditions set forth herein; and

         WHEREAS, pursuant to Section 9.01 of the Indenture, the Trustee, the
Company and the Existing Subsidiary Guarantors are authorized to execute and
deliver this Supplemental Indenture.

         NOW, THEREFORE, in consideration of the foregoing and for other good
and valuable consideration, the receipt of which is hereby acknowledged, the
Company, the Existing Subsidiary Guarantors, the New Subsidiary Guarantors and
the Trustee mutually covenant and agree for the equal and ratable benefit of the
holders of the Securities as follows:

         1. DEFINITIONS. (a) Capitalized terms used herein without definition
shall have the meanings assigned to them in the Indenture.

<PAGE>

         (b) For all purposes of this Supplemental Indenture, except as
otherwise herein expressly provided or unless the context otherwise requires:
(i) the terms and expressions used herein shall have the same meanings as
corresponding terms and expressions used in the Indenture; and (ii) the words
"herein," "hereof" and "hereby" and other words of similar import used in this
Supplemental Indenture refer to this Supplemental Indenture as a whole and not
to any particular section hereof.

         2. AGREEMENT TO GUARANTEE. The New Subsidiary Guarantors hereby agree,
jointly and severally with all other Subsidiary Guarantors, to guarantee the
Company's obligations under the Securities and the Indenture on the same terms
and conditions as set forth in Articles 11 and 12 of the Indenture and to be
bound by all other applicable provisions of the Indenture. Except as expressly
amended hereby, the Indenture is in all respects ratified and confirmed and all
the terms, conditions and provisions thereof shall remain in full force and
effect. This Supplemental Indenture is a "GUARANTY AGREEMENT" as contemplated by
Section 4.10 of the Indenture and shall form a part of the Indenture for all
purposes, and every holder of Securities heretofore or hereafter authenticated
and delivered shall be bound hereby.

         3. EXISTING SUBSIDIARY GUARANTORS. Each Existing Subsidiary Guarantor
executes this Supplemental Indenture to: (i) ratify and confirm its existing
Subsidiary Guaranty as continuing to be in full force and effect; and (ii)
evidence its agreement to the terms of this Supplemental Indenture.

         4. DECEMBER 2002 ADDITIONAL SECURITIES. Attached hereto as Annex 1 is a
true and correct copy of the resolutions of the Board of Directors and the
Officers' Certificate required by Section 2.13 of the Indenture in connection
with the issuance of the December 2002 Additional Securities. The definition of
the term "ADDITIONAL SECURITIES" set forth in the Indenture is hereby
supplemented by adding the following sentence at the end of such definition: "On
December 17, 2002, the Company issued $300,000,000 of Additional Securities, as
more particularly described in the Second Supplemental Indenture hereto, dated
as of December 17, 2002."

         5. GOVERNING LAW. THIS SUPPLEMENTAL INDENTURE SHALL BE GOVERNED BY, AND
CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK BUT WITHOUT
GIVING EFFECT TO APPLICABLE PRINCIPLES OF CONFLICTS OF LAW TO THE EXTENT THAT
THE APPLICATION OF THE LAWS OF ANOTHER JURISDICTION WOULD BE REQUIRED THEREBY.

         6. TRUSTEE MAKES NO REPRESENTATION. The recitals herein contained are
made by the Company and the Subsidiary Guarantors and not by the Trustee, and
the Trustee assumes no responsibility for the correctness thereof. The Trustee
makes no representation as to the validity or sufficiency of this Supplemental
Indenture.

         7. COUNTERPARTS. The parties may sign any number of copies of this
Supplemental Indenture. Each signed copy shall be an original, but all of them
together represent the same agreement.

         8. EFFECT OF HEADINGS. The Section headings herein are for convenience
only and shall not effect the construction thereof.

                                       2

<PAGE>

                            [SIGNATURE PAGE FOLLOWS]

                                       3

<PAGE>

         IN WITNESS WHEREOF, the parties hereto have caused this Supplemental
Indenture to be duly executed as of the date first above written.

                                   WESTPORT RESOURCES CORPORATION

                                   By:  /s/ LON MCCAIN
                                        ----------------------------------------
                                        Lon McCain, Vice President, Treasurer
                                        and Chief Financial Officer

                                   EXISTING SUBSIDIARY GUARANTORS:

                                   WESTPORT CANADA LLC

                                   By:   WESTPORT OIL AND GAS COMPANY, L.P.

                                         By: WHG, INC.

                                              By:  /s/ LON MCCAIN
                                                  ------------------------------
                                                  Lon McCain, Vice President,
                                                  Treasurer and Chief Financial
                                                  Officer

                                   JERRY CHAMBERS EXPLORATION COMPANY

                                   By:   WESTPORT OIL AND GAS COMPANY, L.P.

                                         By: WHG, INC.

                                              By: /s/ LON MCCAIN
                                                  ------------------------------
                                                  Lon McCain, Vice President,
                                                  Treasurer and Chief Financial
                                                  Officer

                                   WESTPORT FINANCE CO.

                                   By:   /s/ LON MCCAIN
                                         ---------------------------------------
                                         Lon McCain, Treasurer

                                   WESTPORT ARGENTINA LLC

                                   By:   /s/ DONALD D. WOLF
                                         ---------------------------------------
                                         Donald D. Wolf, Manager

                                       S-1

<PAGE>

                                   WESTPORT OVERRIDING ROYALTY LLC

                                   By:   WESTPORT OIL AND GAS COMPANY, L.P.

                                         By: WHG, INC.

                                               By:  /s/ LON MCCAIN
                                                    ----------------------------
                                                    Lon McCain, Vice President,
                                                    Treasurer and Chief
                                                    Financial Officer

                                  WESTPORT OIL AND GAS COMPANY, L.P.

                                  By: WHG, INC.

                                       By:  /s/ LON MCCAIN
                                            ------------------------------------
                                            Lon McCain, Vice President,
                                            Treasurer and Chief Financial
                                            Officer

                                  WHG, INC.

                                  By:  /s/ LON MCCAIN
                                       -----------------------------------------
                                       Lon McCain, Vice President, Treasurer and
                                       Chief Financial Officer

                                  WHL, INC.

                                  By:  /s/ LON MCCAIN
                                       -----------------------------------------
                                       Lon McCain, Vice President, Treasurer and
                                       Chief Financial Officer

                                      S-2

<PAGE>

                                  NEW SUBSIDIARY GUARANTORS:

                                  HORSE CREEK TRADING & COMPRESSION LLC

                                  By:   WESTPORT OIL AND GAS COMPANY, L.P.

                                        By:   WHG, INC.

                                              By:   /s/ LON MCCAIN
                                                    ----------------------------
                                                    Lon McCain, Vice President,
                                                    Treasurer and Chief
                                                    Financial Officer

                                  WESTPORT FIELD SERVICES, LLC

                                  By:   WESTPORT RESOURCES CORPORATION

                                        By:   /s/ LON MCCAIN
                                              ----------------------------------
                                              Lon McCain, Vice President,
                                              Treasurer and Chief Financial
                                              Officer

                                  THE BANK OF NEW YORK,
                                  as Trustee

                                  By:    /s/ VAN K. BROWN
                                         ---------------------------------------
                                  Name:  Van K. Brown
                                  Title: Vice President

                                      S-3

<PAGE>

                                     ANNEX A

                      RESOLUTIONS OF THE BOARD OF DIRECTORS

                                       AND

                              OFFICERS' CERTIFICATE<PAGE>
                                                                    EXHIBIT 4.14

                          FOURTH SUPPLEMENTAL INDENTURE

         FOURTH SUPPLEMENTAL INDENTURE (this "SUPPLEMENTAL INDENTURE"), dated as
of December 17, 2002, among Westport Resources Corporation, a company
incorporated under the laws of the State of Nevada, formerly known as Belco Oil
& Gas Corp. (the "COMPANY"), the existing Subsidiary Guarantors under the
indenture referred to below (the "EXISTING SUBSIDIARY GUARANTORS"), the parties
identified as New Subsidiary Guarantors on the signature page hereto (the "NEW
SUBSIDIARY GUARANTORS"), and The Bank of New York, a New York banking
corporation, as trustee under the indenture referred to below (the "TRUSTEE").

                                   WITNESSETH

         WHEREAS, the Company and the Existing Subsidiary Guarantors have
heretofore executed and delivered to the Trustee a certain Indenture (as
previously amended, the "INDENTURE"), dated as of September 23, 1997, providing
for the issuance of an aggregate principal amount at maturity of $150,000,000 of
8-7/8% Senior Subordinated Notes due 2007 (the "NOTES");

         WHEREAS, through the indirect acquisition of all of the membership
interests of Horse Creek Trading & Compression LLC and the formation of Westport
Field Services, LLC, the Company has acquired two new Subsidiaries;

         WHEREAS, Section 4.16 of the Indenture provides that, under certain
circumstances, the Company is required to cause Subsidiaries to execute and
deliver to the Trustee a Subsidiary Guarantee on the terms and conditions set
forth herein; and

         WHEREAS, pursuant to Section 9.1 of the Indenture, the Company, each
Subsidiary Guarantor and the Trustee are authorized to execute and deliver this
Supplemental Indenture.

         NOW, THEREFORE, in consideration of the foregoing and for other good
and valuable consideration, the receipt of which is hereby acknowledged, the
Company, the Existing Subsidiary Guarantors, the New Subsidiary Guarantors and
the Trustee mutually covenant and agree for the equal and ratable benefit of the
Holders as follows:

         1. CAPITALIZED TERMS.

         Capitalized terms used herein without definition shall have the
meanings assigned to them in the Indenture.

         2. INDENTURE PROVISIONS PURSUANT TO WHICH GUARANTEE IS GIVEN.

         This Supplemental Indenture is being executed and delivered pursuant to
Sections 4.16 and 9.1 of the Indenture.

         3. AGREEMENTS TO GUARANTEE.

         The New Subsidiary Guarantors hereby agree as follows:

<PAGE>

         The New Subsidiary Guarantors, jointly and severally with all other
Subsidiary Guarantors, if any, unconditionally guarantee to each Holder of a
Note authenticated and delivered by the Trustee and to the Trustee and its
successors and assigns, regardless of the validity and enforceability of the
Indenture, the Notes and the obligations of the Company under the Indenture and
the Notes, that:

                  (i) the principal of, premium, if any, and interest on the
Notes shall be promptly paid in full when due, whether at maturity, by
acceleration, redemption or otherwise, and interest on the overdue principal of,
premium, if any, and interest on the Notes, to the extent lawful, and all other
obligations of the Company to the Holders or the Trustee thereunder shall be
promptly paid in full, all in accordance with the terms thereof; and

                  (ii) in case of any extension of time for payment or renewal
of any Notes or any of such other obligations, that the same shall be promptly
paid in full when due in accordance with the terms of the extension or renewal,
whether at maturity, by acceleration or otherwise.

                  Notwithstanding the foregoing, in the event that the
Subsidiary Guarantee of any New Subsidiary Guarantor would constitute or result
in a violation of any applicable fraudulent conveyance or similar law of any
relevant jurisdiction, the liability of such New Subsidiary Guarantor under this
Supplemental Indenture and its Subsidiary Guarantee shall be limited to such
amount as will not, after giving effect thereto, and to all other liabilities of
such New Subsidiary Guarantor, result in such amount constituting a fraudulent
transfer or conveyance.

         4. SUBORDINATION.

                  Each Subsidiary Guarantor agrees, and each Holder by accepting
a Note agrees, that: (a) the obligations of each Subsidiary Guarantor under its
Subsidiary Guarantee are subordinated in right of payment to the prior payment
in full (when due) of all existing and future Guarantor Senior Indebtedness of
such Subsidiary Guarantor, including without limitation any guarantee by such
Subsidiary Guarantor of any Senior Debt of the Company or of any Guarantor
Senior Indebtedness of any other Subsidiary Guarantor, to the extent and in the
matter provided in Article 10 (including, without limitation, Section 10.12) of
the Indenture (as if the Subsidiary Guarantor were the Company for purposes of
such Article 10 and all defined terms used therein, and the Guarantor Senior
Indebtedness of the Guarantor were Senior Debt), and this Subsidiary Guarantee
is made subject to such provisions (which are hereby incorporated herein by
reference); and (b) such subordination is for the benefit of and enforceable by
the holders of Guarantor Senior Indebtedness of the Subsidiary Guarantor.

         5. EXECUTION AND DELIVERY OF SUBSIDIARY GUARANTEE.

                  (a) To evidence its Subsidiary Guarantee set forth in this
Supplemental Indenture, each New Subsidiary Guarantor hereby agrees that a
notation of such Subsidiary Guarantee substantially in the form of Annex A
hereto shall be endorsed by an officer of such New Subsidiary Guarantor on each
Note authenticated and delivered by the Trustee after the date hereof.

                                       2

<PAGE>

                  (b) Notwithstanding the foregoing, each New Subsidiary
Guarantor hereby agrees that its Subsidiary Guarantee set forth herein shall
remain in full force and effect notwithstanding any failure to endorse on each
Note a notation of such Subsidiary Guarantee.

                  (c) If an officer whose signature is on this Supplemental
Indenture or on the Subsidiary Guarantee no longer holds that office at the time
the Trustee authenticates the Note on which a Subsidiary Guarantee is endorsed,
the Subsidiary Guarantee shall be valid nevertheless.

                  (d) The delivery of a Note by the Trustee, after the
authentication thereof under the Indenture, shall constitute due delivery of the
Subsidiary Guarantee set forth in this Supplemental Indenture on behalf of each
New Subsidiary Guarantor.

                  (e) Each New Subsidiary Guarantor hereby agrees that its
obligations hereunder shall be unconditional, regardless of the validity,
regularity or enforceability of the Notes or the Indenture, the absence of any
action to enforce the same, any waiver or consent by any Holder of the Notes
with respect to any provisions hereof or thereof, the recovery of any judgment
against the Company, any action to enforce the same or any other circumstance
which might otherwise constitute a legal or equitable discharge or defense of a
guarantor.

                  (f) Each New Subsidiary Guarantor hereby waives diligence,
presentment, demand of payment, filing of claims with a court in the event of
insolvency or bankruptcy of the Company, any right to require a proceeding first
against the Company, protest, notice and all demands whatsoever and covenants
that its Subsidiary Guarantee made pursuant to this Supplemental Indenture will
not be discharged except by complete performance of the obligations contained in
the Notes and the Indenture or pursuant to Section 6(b) of this Supplemental
Indenture.

                  (g) If the Trustee or any Holder has instituted any proceeding
to enforce any right or remedy under this Supplemental Indenture or under the
Subsidiary Guarantee made pursuant to this Supplemental Indenture and such
proceeding has been discontinued or abandoned for any reason, or has been
determined adversely to the Trustee or to such Holder, then, and in every such
case, subject to any determination in such proceeding, the Subsidiary Guarantor,
the Trustee and the Holders shall be restored severally and respectively to
their former positions hereunder and thereafter all rights and remedies of each
Subsidiary Guarantor, the Trustee and the Holders shall continue as though no
such proceeding had been instituted.

                  (h) Each New Subsidiary Guarantor hereby waives and will not
in any manner whatsoever claim or take the benefit or advantage of, any rights
of reimbursement, indemnity or subrogation or any other rights against the
Company or any other Subsidiary Guarantor as a result of any payment by such
Subsidiary Guarantor under its Subsidiary Guarantee. Each Subsidiary Guarantor
further agrees that, as between the Subsidiary Guarantors, on the one hand, and
the Holders and the Trustee, on the other hand:

                           (i) the maturity of the obligations guaranteed hereby
may be accelerated as provided in Article 6 of the Indenture for the purposes of
the Subsidiary Guarantee

                                       3

<PAGE>

made pursuant to this Supplemental Indenture, notwithstanding any stay,
injunction or other prohibition preventing such acceleration in respect of the
obligations guaranteed hereby; and

                           (ii) in the event of any declaration of acceleration
of such obligations as provided in such Article 6, such obligations (whether or
not due and payable) shall forthwith become due and payable by each Subsidiary
Guarantor for the purpose of the Subsidiary Guarantee made pursuant to this
Supplemental Indenture.

                  (i) Each Subsidiary Guarantor shall have the right to seek
contribution from any other non-paying Subsidiary Guarantor, if any, so long as
the exercise of such right does not impair the rights of the Holders under the
Subsidiary Guarantee made pursuant to this Supplemental Indenture.

                  (j) Each New Subsidiary Guarantor covenants (to the extent
that it may lawfully do so) that it will not at any time insist upon, or plead,
or in any manner whatsoever claim or take the benefit or advantage of, any stay,
extension or usury law wherever enacted, now or at any time hereafter in force,
which may affect the covenants or the performance of the Indenture or this
Subsidiary Guarantee; and each New Subsidiary Guarantor (to the extent that it
may lawfully do so) hereby expressly waives all benefit or advantage of any such
law, and covenants that it will not hinder, delay or impede the execution of any
power herein granted to the Trustee, but will suffer and permit the execution of
every such power as though no such law had been enacted.

         6. SUBSIDIARY GUARANTORS MAY CONSOLIDATE, ETC. ON CERTAIN TERMS.

                  (a) Except as set forth in Articles 4 and 5 of the Indenture,
nothing contained in the Indenture, this Supplemental Indenture or in the Notes
shall prevent any consolidation or merger of a Subsidiary Guarantor with or into
the Company or any other Subsidiary Guarantor or shall prevent any transfer,
sale or conveyance of the property of the Subsidiary Guarantor as an entirety or
substantially as an entirety, to the Company or any other Subsidiary Guarantor.

                  (b) Except as set forth in Article 5 of the Indenture, upon
the sale or disposition of all of the Capital Stock of a Subsidiary Guarantor by
the Company or the Subsidiary of the Company, or upon the consolidation or
merger of a Subsidiary Guarantor with or into any Person, or the sale of all or
substantially all of the assets of a Subsidiary Guarantor (in each case, other
than to an Affiliate of the Company), such Subsidiary Guarantor shall be deemed
automatically and unconditionally released and discharged from all obligations
under this Subsidiary Guarantee without any further action required on the part
of the Trustee or any Holder if no Default shall have occurred and be
continuing; provided, that in the event of an Asset Sale, the Net Proceeds
therefrom are treated in accordance with Section 4.10 of the Indenture. Except
with respect to transactions set forth in the preceding sentence, the Company
and each Subsidiary Guarantor covenant and agree that upon any such
consolidation, merger or transfer of assets, the performance of all covenants
and conditions of this Supplemental Indenture to be performed by such Subsidiary
Guarantor shall be expressly assumed by supplemental indenture satisfactory in
form to the Trustee, by the corporation formed by such consolidation, or into
which the Subsidiary Guarantor shall have merged, or by the corporation

                                       4

<PAGE>

which shall have acquired such property. Upon receipt of an Officers'
Certificate of the Company or any Subsidiary Guarantor, as the case may be, to
the effect that the Company or such Subsidiary Guarantor has complied with the
first sentence of this Section 6(b), the Trustee shall execute any documents
reasonably requested by the Company or such Subsidiary Guarantor, at the cost of
the Company or such Subsidiary Guarantor, as the case may be, in order to
evidence the release of such Subsidiary Guarantor from its obligations under its
Guarantee endorsed on the Notes and under the Indenture and this Supplemental
Indenture.

         7. RELEASES UPON RELEASE OF GUARANTEE OF GUARANTEED INDEBTEDNESS.

                  Concurrently with the release or discharge of any Subsidiary
Guarantor's guarantee of the payment of: (i) the notes and other obligations
under that certain Indenture, dated as of November 5, 2001, by and among the
Company, the subsidiary guarantors from time to time parties thereto, and the
Trustee as trustee, as supplemented to the date hereof and from time to time
hereafter; and (ii) obligations under that certain Credit Agreement, dated as of
December 17, 2002, among the Company, the several lenders and agents party
thereto and JPMorgan Chase Bank, as issuing bank and administrative agent, as
such may be amended, supplemented, or refinanced from time to time (other than a
release or discharge by or as a result of payment under such guarantee of
Guaranteed Indebtedness), the Subsidiary Guarantor shall be automatically and
unconditionally released and relieved of its obligations under this Supplemental
Indenture and its Subsidiary Guarantee made pursuant to Section 5 of this
Supplemental Indenture. Upon delivery by the Company to the Trustee of an
Officers' Certificate to the effect that such release or discharge has occurred,
the Trustee shall execute any documents reasonably required in order to evidence
the release of the relevant Subsidiary Guarantor from its obligations under this
Supplemental Indenture and such Subsidiary Guarantor's Subsidiary Guarantee made
pursuant hereto; provided, that such documents shall not affect or impair the
rights of the Trustee and Paying Agent under Section 7.7 of the Indenture.

         8. EXISTING SUBSIDIARY GUARANTORS.

                  Each Existing Subsidiary Guarantor executes this Supplemental
Indenture to: (i) ratify and confirm its existing Subsidiary Guarantee as
continuing to be in full force and effect; and (ii) evidence its agreement to
the terms of this Supplemental Indenture.

         9. NEW YORK LAW TO GOVERN.

                  The substantive law of the State of New York shall govern and
be used to construe this Supplemental Indenture.

         10. COUNTERPARTS.

                  The parties may sign any number of copies of this Supplemental
Indenture. Each signed copy shall be an original, but all of them together
represent the same agreement.

                                       5

<PAGE>

         11. RECITALS, ETC.

                  The recitals herein contained are made by the Company and the
Subsidiary Guarantors and not by the Trustee, and the Trustee assumes no
responsibility for the correctness thereof. The Trustee makes no representations
as to the validity or sufficiency of this Supplemental Indenture.

         12. EFFECT OF HEADINGS.

                  The Section headings herein are for convenience only and shall
not effect the construction hereof.

                            [SIGNATURE PAGE FOLLOWS]

                                       6

<PAGE>
         IN WITNESS WHEREOF, the parties hereto have caused this Supplemental
Indenture to be duly executed and attested, all as of the date first above
written.

                         WESTPORT RESOURCES CORPORATION

                         By:  /s/ LON MCCAIN
                             ---------------------------------------------------
                             Lon McCain, Vice President, Treasurer and Chief
                             Financial Officer

                         EXISTING SUBSIDIARY GUARANTORS:

                         WESTPORT CANADA LLC

                         By:      WESTPORT OIL AND GAS COMPANY, L.P.

                                  By: WHG, INC.

                                        By:      /s/ LON MCCAIN
                                                 -------------------------------
                                                 Lon McCain, Vice President,
                                                 Treasurer and Chief Financial
                                                 Officer

                         JERRY CHAMBERS EXPLORATION COMPANY

                         By:      WESTPORT OIL AND GAS COMPANY, L.P.

                                  By: WHG, INC.

                                        By:      /s/ LON MCCAIN
                                                 -------------------------------
                                                 Lon McCain, Vice President,
                                                 Treasurer and Chief Financial
                                                 Officer

                         WESTPORT FINANCE CO.

                         By:      /s/ LON MCCAIN
                                  ----------------------------------------------
                                  Lon McCain, Treasurer

                         WESTPORT ARGENTINA LLC

                         By:      /s/ DONALD D. WOLF
                                  ----------------------------------------------
                                  Donald D. Wolf, Manager

                                      S-1

<PAGE>
                         WESTPORT OVERRIDING ROYALTY LLC

                         By:      WESTPORT OIL AND GAS COMPANY, L.P.

                                  By: WHG, INC.

                                        By:      /s/ LON MCCAIN
                                                 -------------------------------
                                                 Lon McCain, Vice President,
                                                 Treasurer and Chief Financial
                                                 Officer

                         WESTPORT OIL AND GAS COMPANY, L.P.

                         By: WHG, INC.

                               By:      /s/ LON MCCAIN
                                        -------------------------------
                                        Lon McCain, Vice President,
                                        Treasurer and Chief Financial
                                        Officer

                         WHG, INC.

                         By:      /s/ LON MCCAIN
                                  -------------------------------------
                                  Lon McCain, Vice President, Treasurer
                                  and Chief Financial Officer

                         WHL, INC.

                         By:      /s/ LON MCCAIN
                                  -------------------------------------
                                  Lon McCain, Vice President, Treasurer
                                  and Chief Financial Officer

                                      S-2

<PAGE>
                                  NEW SUBSIDIARY GUARANTORS:

                                  HORSE CREEK TRADING & COMPRESSION LLC

                                  By:      WESTPORT OIL AND GAS COMPANY, L.P.

                                           By:      WHG, INC.

                                                    By:   /s/ LON MCCAIN
                                                          ----------------------
                                                          Lon McCain, Vice
                                                          President, Treasurer
                                                          and Chief Financial
                                                          Officer

                                  WESTPORT FIELD SERVICES, LLC

                                  By:      WESTPORT RESOURCES CORPORATION

                                           By:      /s/ LON MCCAIN
                                                    ----------------------------
                                                    Lon McCain, Vice President,
                                                    Treasurer and Chief
                                                    Financial Officer

                                  THE BANK OF NEW YORK,
                                  as Trustee

                                  By:    /s/ VAN K. BROWN
                                         ---------------------------------------
                                  Name:  Van K. Brown
                                  Title: Vice President

                                      S-3

<PAGE>

                        ANNEX A TO SUPPLEMENTAL INDENTURE

                FORM OF NOTATION OF SUBSIDIARY GUARANTEE ON NOTE

         Each Subsidiary Guarantor (as defined in the Indenture) has jointly and
severally unconditionally guaranteed: (a) the due and punctual payment of the
principal of, premium, if any, and interest on the Notes, whether at Stated
Maturity or an Interest Payment Date, by acceleration, call for redemption or
otherwise; (b) the due and punctual payment of interest on the overdue principal
and premium of, and interest, to the extent lawful, on the Notes; and (c) that
in case of any extension of time of payment or renewal of any Notes or any of
such other obligations, the same will be promptly paid in full when due in
accordance with the terms of the extension of renewal, whether at stated
maturity, by acceleration or otherwise.

         Notwithstanding the foregoing, in the event that the Subsidiary
Guarantee would constitute or result in a violation of any applicable fraudulent
conveyance or similar law of any relevant jurisdiction, the liability of the
Subsidiary Guarantor under its Subsidiary Guarantee shall be limited to such
amount as will not, after giving effect thereto, and to all other liabilities of
the Subsidiary Guarantor, result in such amount constituting a fraudulent
transfer or conveyance.

         This Subsidiary Guarantee shall not be valid or obligatory for any
purpose until the certificate of authentication on the Note upon which the
Subsidiary Guarantee is noted shall have been executed by the Trustee under the
Indenture by the manual signature of one of its authorized signatories.

Dated:                   , 200 .
       ------------------     -

                                            [SUBSIDIARY GUARANTOR]

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

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00046-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00046-of-00352.parquet"}]]