<PAGE>   1
================================================================================

                                                                EXHIBIT 10.2


                              AMENDED AND RESTATED


                             SHAREHOLDERS AGREEMENT


                                  BY AND AMONG


                         WESTPORT RESOURCES CORPORATION

                              BELCO OIL & GAS CORP.

                              ERI INVESTMENTS, INC.

                               WESTPORT ENERGY LLC

                                       AND

                        CERTAIN STOCKHOLDERS NAMED HEREIN



                            DATED AS OF JUNE 8, 2001


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


<PAGE>   2


                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                    PAGE
                                                                                    ----
<S>                                                                                 <C>
ARTICLE I DEFINITIONS.................................................................2

         Section 1.1.      Definitions................................................2


ARTICLE II REPRESENTATIONS AND WARRANTIES.............................................6

         Section 2.1.      Representations and Warranties of the Company..............6
         Section 2.2.      Representations and Warranties of WELLC....................6
         Section 2.3.      Representations and Warranties of ERI......................7
         Section 2.4.      Representations and Warranties of the Belfer Group.........7
         Section 2.5.      Representations and Warranties of Westport.................8


ARTICLE III CORPORATE GOVERNANCE; CERTAIN CORPORATE ACTIONS...........................8

         Section 3.1.      Voting of Shares...........................................8
         Section 3.2.      Composition of the Board of Directors......................9
         Section 3.3.      Approval of Major Actions.................................10
         Section 3.4.      Amendments to Articles of Incorporation and Bylaws........11
         Section 3.5.      Self-Interested Transactions..............................11


ARTICLE IV STANDSTILL................................................................11

         Section 4.1.      Standstill................................................11


ARTICLE V REGISTRATION RIGHTS........................................................13

         Section 5.1.      Demand Registrations......................................13
         Section 5.2.      Piggyback Registrations...................................15
         Section 5.3.      Holdback Agreements.......................................16
         Section 5.4.      Registration Procedures...................................16
         Section 5.5.      Registration Expenses.....................................19
         Section 5.6.      Indemnification...........................................20
         Section 5.7.      Participation in Underwritten Registrations...............22
         Section 5.8.      Current Public Information................................22
         Section 5.9.      Cooperation...............................................22


ARTICLE VI GENERAL PROVISIONS........................................................23

         Section 6.1.      Notices...................................................23
         Section 6.2.      Assignment; Binding Effect; Benefit.......................24
</TABLE>


                                      -i-
<PAGE>   3


<TABLE>
<CAPTION>
                                                                                    PAGE
                                                                                    ----
<S>                                                                                 <C>
         Section 6.3.      Entire Agreement..........................................25
         Section 6.4.      Amendment.................................................25
         Section 6.5.      Governing Law.............................................25
         Section 6.6.      Counterparts..............................................25
         Section 6.7.      Headings..................................................25
         Section 6.8.      Interpretation............................................25
         Section 6.9.      Incorporation of Exhibits and Schedules...................25
         Section 6.10.     Severability..............................................25
         Section 6.11.     Enforcement of Agreement..................................26
         Section 6.12.     Confidentiality...........................................26
         Section 6.13.     Termination...............................................26
         Section 6.14.     Effective Time............................................27
         Section 6.15.     Belfer Group Representative...............................27
         Section 6.16.     Belfer Rights Holders.....................................27
</TABLE>


                                      -ii-
<PAGE>   4


                              AMENDED AND RESTATED
                             SHAREHOLDERS AGREEMENT

         This AMENDED AND RESTATED SHAREHOLDERS AGREEMENT, dated as of June 8,
2001 (this "Agreement"), is entered into by and among Belco Oil & Gas Corp., a
Nevada corporation (the "Company"), Westport Resources Corporation, a Delaware
corporation ("Westport"), Westport Energy LLC, a Delaware limited liability
company ("WELLC"), ERI Investments, Inc., a Delaware corporation ("ERI") and the
persons and entities named on Exhibit A (each such person or entity, a Belfer
Person, and collectively, the "Belfer Group").

         WHEREAS, Westport Oil and Gas Company, Inc. ("WOGC"), Equitable
Production Company ("EPC"), Equitable Production (Gulf) Company ("EPGC"),
Westport Energy Corporation ("WEC") and EPGC Merger Sub Corporation ("Merger
Sub") entered into a Merger Agreement, dated as of March 9, 2000 (the "EPGC
Merger Agreement") providing for the merger of Merger Sub with and into WOGC and
for the conversion of the WOGC capital stock held by WEC into shares of EPGC
capital stock, such that immediately after the merger, EPC owned approximately
49% of the capital stock of EPGC and WEC owned approximately 51% of the capital
stock of EPGC (the "EPGC Merger"); and

         WHEREAS, as a condition to the consummation of the transactions
contemplated by the EPGC Merger Agreement, WEC, EPC and EPGC entered into that
certain Shareholders Agreement dated as of March 9, 2000 (the "Original
Shareholders Agreement"); and

         WHEREAS, subsequent to the EPGC Merger, EPC assigned its interest in
EPGC to ERI, WEC became WELLC by statutory conversion, and EPGC changed its name
to Westport Resources Corporation; and

         WHEREAS, concurrently with the execution and delivery of this
Agreement, Westport and Belco entered into an Agreement and Plan of Merger dated
as of the date hereof (the "Merger Agreement") providing for, among other
things, the merger (the "Merger") of Westport with and into Belco, with Belco as
the surviving corporation, and for the conversion of 100% of the issued and
outstanding shares of Westport Common Stock, par value $.01 per share ("Old
Westport Common Stock") into Common Stock (as hereinafter defined) and the
automatic cancellation and retirement of the Old Westport Common Stock; and

         WHEREAS, it is a condition to the consummation of the transactions
contemplated by the Merger Agreement that the Original Shareholders Agreement be
amended and restated as provided for herein; and

         WHEREAS, the purpose of this amendment and restatement of the Original
Shareholders Agreement is to reflect the effects of the Merger by, among other
things, (i) having it apply to the shares of Common Stock issued to WELLC and
ERI in connection with the Merger in exchange for their Old Westport Common
Stock and (ii) adding the Company and the Belfer Group as parties;


<PAGE>   5


         NOW, THEREFORE, in consideration of the foregoing, and of the
representations, warranties, covenants and agreements contained herein, and for
other good and valuable consideration, the receipt and sufficiency of which is
hereby acknowledged, the parties hereto, intending to be legally bound, hereby
agree as follows:

                                    ARTICLE I
                                   DEFINITIONS

         Section 1.1. Definitions.

         "Affiliate" shall have the meaning set forth in Rule 12b-2 of the
regulations promulgated under the Exchange Act.

         "Agreement" shall have the meaning set forth in the preamble to this
Agreement.

         "Belfer Group" shall have the meaning set forth in the preamble to this
Agreement.

         "Belfer Parties" shall mean the Belfer Group and their Permitted
Transferees.

         "Belfer Person" shall mean any Person included in the Belfer Group.

         "Board of Directors" shall mean the board of directors of the Company.

         "Commission" shall mean the Securities and Exchange Commission or any
other Federal agency at the time administering the Securities Act.

         "Common Stock" shall mean the common stock of the Company, par value
$.01 per share, now or hereafter authorized to be issued.

         "Company" shall have the meaning set forth in the preamble to this
Agreement.

         "Consolidated Net Worth" shall mean, at any particular time, all
amounts which, in conformity with GAAP, would be included as common
stockholders' equity on a consolidated balance sheet of the Company and its
Subsidiaries.

         "Debt" shall mean (a) Funded Debt, plus (b) at any particular time, all
amounts which, in conformity with GAAP, would be included as preferred
stockholders' equity on a consolidated balance sheet of the Company and its
Subsidiaries less (c) cash of the Company and its Subsidiaries.

         "Demand Registrations" shall have the meaning set forth in Section
5.l(a).

         "Director" shall mean a member of the Board of Directors.

         "Disinterested Director" shall have the meaning set forth in Section
3.5.

         "Effective Time" shall have the meaning set forth in the Merger
Agreement.


                                      -2-
<PAGE>   6


         "EPC" shall have the meaning set forth in the preamble to this
Agreement.

         "EPGC" shall have the meaning set forth in the preamble to this
Agreement.

         "EPGC Merger Agreement" shall have the meaning set forth in the
preamble to this Agreement.

         "ERI" shall have the meaning set forth in the preamble to this
Agreement.

         "ERI Parties" shall mean ERI and its Permitted Transferees.

         "Exchange Act" shall mean the Securities Exchange Act of 1934, as
amended, and the rules and regulations of the Commission thereunder, all as the
same shall be in effect at the time.

         "Funded Debt" shall mean at any time (without duplication): (a) all
obligations of the Company and its Subsidiaries, or any of them, for borrowed
money and all obligations of the Company and its Subsidiaries, or any of them,
evidenced by bonds, notes, debentures, or other similar instruments, (b) all
capital lease obligations of the Company and its Subsidiaries, or any of them,
(c) all debt or other obligations of others guaranteed by the Company and its
Subsidiaries, or any of them to the extent of such guarantee, (d) all
reimbursement obligations of the Company and its Subsidiaries, or any of them
(whether contingent or otherwise) in respect of letters of credit, bankers'
acceptances, surety or other bonds and similar instruments, (e) all obligations
of the Company and its Subsidiaries, or any of them, to pay the deferred
purchase price of property or services, except trade accounts payable of the
Company and its Subsidiaries, or any of them, arising in the ordinary course of
business that are not past due by more than ninety (90) days, (f) all
obligations secured by a lien existing on property owned by the Company and its
Subsidiaries, or any of them, whether or not the obligations secured thereby
have been assumed by the Company and its Subsidiaries, or any of them, or are
non-recourse to the credit of the Company and its Subsidiaries, or any of them,
and (g) all other debt of the Company and its Subsidiaries, or any of them.

         "GAAP" shall mean generally accepted accounting principles in the
United States.

         "HSR Act" shall mean the Hart-Scott-Rodino Antitrust Improvements Act
of 1976, as amended.

         "Independent Director" shall mean an individual (i) who is not a
director, officer, employee or Affiliate of the Company, WELLC, the Belfer Group
or ERI, or any of their respective Affiliates, (ii) who is not a former
director, officer or employee of the Company, Westport, WELLC, the Belfer Group
or ERI, or any of their respective Affiliates, (iii) who has not had and who is
not a director, officer, 10% or more equity owner or Affiliate of any Person
that has had a direct or indirect interest in any transaction in the preceding
24 months with the Company, Westport, WELLC, the Belfer Group or ERI, or any of
their respective Affiliates, and (iv) who does not represent Westport, WELLC,
the Belfer Group or ERI, or any of their respective Affiliates, and any
Independent Director appointed shall be required to certify in writing to this
effect upon request.


                                      -3-
<PAGE>   7


         "Major Actions" shall mean those actions described in Sections 3.3.

         "Merger Agreement" shall have the meaning set forth in the preamble to
this Agreement.

         "Old Westport Common Stock" shall have the meaning set forth in the
preamble to this Agreement.

         "Original Shareholders Agreement" shall have the meaning set forth in
the preamble to this Agreement.

         "Party" or "Parties" shall mean ERI, WELLC and/or the Belfer Group.

         "Permitted Transferees" shall mean in the case of the WELLC Parties:
(A) WELLC, any spouse, issue, parent or relatives of the WELLC Parties, or (i)
trusts for the benefit of any of such Persons, (ii) entities controlling or
controlled by any of such Persons and (iii) in the event of the death of any
such individual person, heirs or testamentary legatees of such person, in each
case to whom a WELLC Party has transferred its Shares and who has agreed in
writing to be bound by the terms of this Agreement, and (B) any Subsidiary or
Affiliate of WELLC to which a WELLC Party has transferred its Shares and which
has agreed in writing to be bound by the terms of this Agreement; in the case of
the ERI Parties: (A) ERI, any spouse, issue, parent or relatives of the ERI
Parties, or (i) trusts for the benefit of any of such Persons, (ii) entities
controlling or controlled by any of such Persons and (iii) in the event of the
death of any such individual person, heirs or testamentary legatees of such
person, in each case to whom an ERI Party has transferred its Shares and who has
agreed in writing to be bound by the terms of this Agreement, and (B) any
Subsidiary or Affiliate of ERI to which an ERI Party has transferred its Shares
and which has agreed in writing to be bound by the terms of this Agreement; and
in the case of the Belfer Parties: a Belfer Person, any spouse, issue, parent or
relatives of the Belfer Parties, or (i) trusts for the benefit of any of such
Persons, (ii) entities controlling or controlled by any of such Persons and
(iii) in the event of the death of any such individual person, heirs or
testamentary legatees of such person, in each case to whom a Belfer Party has
transferred its Shares and who has agreed in writing to be bound by the terms of
this Agreement;

         "Person" shall mean any natural person, corporation, partnership,
limited liability company, firm, association, trust, government, governmental
agency or other entity, whether acting in an individual, fiduciary or other
capacity.

         "Piggyback Registration" shall have the meaning set forth in Section
5.2(a).

         "Registrable Securities" shall mean (i) any shares of Common Stock
owned by, or otherwise hereafter acquired by, the WELLC Parties, the ERI Parties
or the Belfer Parties, and (ii) any securities issued as a dividend on or other
distribution with respect to or in exchange, replacement or in subdivision of,
any such Common Stock. As to any particular Registrable Securities, such
securities shall cease to be Registrable Securities when (A) a registration
statement (other than the Form S-4 pursuant to which the issuance of Common
Stock in connection with the Merger is registered under the Securities Act) with
respect to the sale of such securities shall have been declared effective under
the Securities Act and such securities shall


                                      -4-
<PAGE>   8


have been disposed of in accordance with such registration statement, or (B)
such securities shall have been sold (other than in a privately negotiated sale)
pursuant to Rule 144 (or any successor provision) under the Securities Act.

         "Registration Expenses" shall have the meaning set forth in Section
5.5(a).

         "Securities Act" shall mean the Securities Act of 1933, as amended, and
the rules and regulations of the Commission thereunder, as the same shall be in
effect at the time.

         "Self-Interested Transaction" shall have the meaning set forth in
Section 3.5.

         "Shares" shall mean shares of Common Stock.

         "Short-Form Registrations" shall have the meaning set forth in Section
5.l(a).

         "Subsidiary" of any Person shall mean any corporation or other legal
entity of which such Person (either alone or through or together with any other
Subsidiary) owns, directly or indirectly, 50% or more of the stock or other
equity interests, the holders of which are generally entitled to vote for the
election of the board of directors or other governing body of such corporation
or other legal entity.

         "Supermajority Approval" shall mean approval by action of at least a
majority of all of the members of the Board of Directors which shall include not
less than one less than all of the Directors whom the Parties then have the
right to nominate pursuant to Section 3.2.; provided, however, with respect to
the approval of the issuance of Common Stock by the Company in a primary
underwritten offering by the Company of Common Stock within four months after
the Effective Time resulting in gross proceeds of not less than $90 million,
Supermajority Approval shall mean approval by action of at least a majority of
all of the members of the Board of Directors which shall include not less than
all of the Directors whom the ERI Parties and the WELLC Parties then have the
right to nominate pursuant to Section 3.2

         "Total Capitalization" shall mean the sum of (i) Consolidated Net Worth
and (ii) Debt.

         "Transfer" shall mean to sell, transfer, assign, pledge or otherwise
dispose.

         "Underwriter" shall mean nationally recognized investment banking firm
with experience serving as lead managing underwriter for public offerings of the
stock of companies engaged in the exploration, development and production of oil
and natural gas.

         "WELLC" shall have the meaning set forth in the preamble to this
Agreement.

         "WELLC Parties" shall mean WELLC and their Permitted Transferees.


                                      -5-
<PAGE>   9

                                   ARTICLE II
                         REPRESENTATIONS AND WARRANTIES

         Section 2.1. Representations and Warranties of the Company. The Company
hereby represents and warrants to the other parties hereto as follows: The
Company has all requisite corporate power and authority to enter into this
Agreement and to consummate the transactions contemplated hereby. The execution
and delivery by the Company of this Agreement, and the consummation by the
Company of the transactions contemplated hereby, have been duly authorized by
all necessary corporate action on the part of the Company. This Agreement has
been duly executed and delivered by the Company and constitutes a valid and
binding obligation of the Company enforceable against the Company in accordance
with its terms. No consent, approval, order or authorization of, or
registration, declaration or filing with, any court, administrative agency or
commission or other governmental authority or instrumentality, domestic or
foreign, is required by, or with respect to, the Company in connection with the
execution and delivery of this Agreement by the Company or the consummation by
the Company of the transactions contemplated hereby. The execution and delivery
of this Agreement by the Company and the consummation of the transactions
contemplated hereby by the Company does not conflict with, or result in a breach
of, any law or regulation of any governmental authority applicable to the
Company or any material agreement to which the Company is a party.

         Section 2.2. Representations and Warranties of WELLC. WELLC hereby
represents and warrants to the other parties hereto as follows:

                  (a) Authority. Each of the WELLC Parties has all requisite
corporate or other power and authority to enter into this Agreement and to
consummate the transactions contemplated hereby. The execution and delivery by
the WELLC Parties of this Agreement and the consummation by the WELLC Parties of
the transactions contemplated hereby have been duly authorized by all necessary
corporate or other action on the part of each of the WELLC Parties. This
Agreement has been duly executed and delivered by each of the WELLC Parties and
constitutes a valid and binding obligation of each of the WELLC Parties
enforceable against each of the WELLC Parties in accordance with its terms. No
consent, approval, order or authorization of, or registration, declaration or
filing with, any court, administrative agency or commission or other
governmental authority or instrumentality, domestic or foreign, is required by,
or with respect to, any of the WELLC Parties in connection with the execution
and delivery by the WELLC Parties of this Agreement or the consummation by the
WELLC Parties of the transactions contemplated hereby. The execution and
delivery by the WELLC Parties of this Agreement and the consummation by the
WELLC Parties of the transactions contemplated hereby do not conflict with, or
result in a breach of, any law or regulation of any governmental authority
applicable to any of the WELLC Parties or any material agreement to which any of
the WELLC Parties is a party.

                  (b) Shares. Schedule 2.2 sets forth the ownership of the
shares of Old Westport Common Stock held by the WELLC Parties as of the date
hereof and the pro forma ownership of Common Stock immediately subsequent to the
Merger.


                                      -6-
<PAGE>   10


         Section 2.3. Representations and Warranties of ERI. ERI hereby
represents and warrants to the other Parties hereto as follows:

                  (a) Authority. Each of the ERI Parties has all requisite
corporate or other power and authority to enter into this Agreement and to
consummate the transactions contemplated hereby. The execution and delivery by
the ERI Parties of this Agreement and the consummation by the ERI Parties of the
transactions contemplated hereby have been duly authorized by all necessary
corporate or other action on the part of each of the ERI Parties. This Agreement
has been duly executed and delivered by each of the ERI Parties and constitutes
a valid and binding obligation of each of the ERI Parties enforceable against
each of ERI Parties in accordance with its terms. No consent, approval, order or
authorization of, or registration, declaration or filing with, any court,
administrative agency or commission or other governmental authority or
instrumentality, domestic or foreign, is required by, or with respect to, any of
the ERI Parties in connection with the execution and delivery of this Agreement
by the ERI Parties or the consummation by each of the ERI Parties of the
transactions contemplated hereby. The execution and delivery by the ERI Parties
of this Agreement and the consummation by the ERI Parties of the transactions
contemplated hereby do not conflict with, or result in a breach of, any law or
regulation of any governmental authority applicable to any of the ERI Parties or
any material agreement to which any of the ERI Parties is a party.

                  (b) Shares. Schedule 2.3 sets forth the ownership of the
shares of Old Westport Common Stock held by the ERI Parties as of the date
hereof and the pro forma ownership of Common Stock immediately subsequent to the
Merger.

         Section 2.4. Representations and Warranties of the Belfer Group. Each
Belfer Person hereby severally and not jointly represents and warrants to the
other Parties hereto as follows:

                  (a) Authority. Such Belfer Person has all requisite corporate
or other power and authority to enter into this Agreement and to consummate the
transactions contemplated hereby. The execution and delivery by such Belfer
Person of this Agreement, and the consummation by such Belfer Person of the
transactions contemplated hereby, have been duly authorized by all necessary
corporate or other action on the part of such Belfer Person. This Agreement has
been duly executed and delivered by such Belfer Person and constitutes a valid
and binding obligation of such Belfer Person enforceable against such Belfer
Person in accordance with its terms. No consent, approval, order or
authorization of, or registration, declaration or filing with, any court,
administrative agency or commission or other governmental authority or
instrumentality, domestic or foreign, is required by, or with respect to, such
Belfer Person in connection with the execution and delivery of this Agreement by
such Belfer Person or the consummation by such Belfer Person of the transactions
contemplated hereby. The execution and delivery of this Agreement by such Belfer
Person and the consummation by such Belfer Person of the transactions
contemplated hereby by it do not conflict with, or result in a breach of, any
law or regulation of any governmental authority applicable to such Belfer Person
or any material agreement to which such Belfer Person is a party.


                                      -7-
<PAGE>   11


                  (b) Shares. Schedule 2.4 sets forth the ownership of the
Shares held by each Belfer Person as of the date hereof and the pro forma
ownership of Common Stock immediately subsequent to the Merger.

         Section 2.5. Representations and Warranties of Westport. Westport
hereby represents and warrants to the other Parties hereto as follows: Westport
has all requisite corporate power and authority to enter into this Agreement and
to consummate the transactions contemplated hereby. The execution and delivery
by Westport of this Agreement, and the consummation by Westport of the
transactions contemplated hereby, have been duly authorized by all necessary
corporate action on the part of Westport. This Agreement has been duly executed
and delivered by Westport and constitutes a valid and binding obligation of
Westport enforceable against Westport in accordance with its terms. No consent,
approval, order or authorization of, or registration, declaration or filing
with, any court, administrative agency or commission or other governmental
authority or instrumentality, domestic or foreign, is required by, or with
respect to, Westport in connection with the execution and delivery of this
Agreement by Westport or the consummation by Westport of the transactions
contemplated hereby. The execution and delivery of this Agreement by Westport
and the consummation of the transactions contemplated hereby by Westport does
not conflict with, or result in a breach of, any law or regulation of any
governmental authority applicable to Westport or any material agreement to which
Westport is a party.

                                  ARTICLE III
                 CORPORATE GOVERNANCE; CERTAIN CORPORATE ACTIONS

         Section 3.1. Voting of Shares.

                  (a) The WELLC Parties shall vote all shares of Common Stock
owned or controlled by them, and shall take all other necessary or desirable
actions within their control (including, without limitation, attendance at
meetings in person or by proxy for purposes of obtaining a quorum and execution
of written consents in lieu of meetings), to effectuate the provisions of this
Agreement.

                  (b) The ERI Parties shall vote all shares of Common Stock
owned or controlled by them, and shall take all other necessary or desirable
action within their control (including, without limitation, attendance at
meetings in person or by proxy for purposes of obtaining a quorum and execution
of written consents in lieu of meetings), to effectuate the provisions of this
Agreement.

                  (c) The Belfer Parties shall vote all shares of Common Stock
owned or controlled by them, and shall take all other necessary or desirable
action within their control (including, without limitation, attendance at
meetings in person or by proxy for purposes of obtaining a quorum and execution
of written consents in lieu of meetings), to effectuate the provisions of this
Agreement.


                                      -8-
<PAGE>   12


                  (d) The Company shall take all necessary or desirable actions
within its control (including, without limitation, calling special board and
stockholder meetings) to effectuate the provisions of this Agreement.

         Section 3.2. Composition of the Board of Directors. (i) WELLC shall, on
behalf of the WELLC Parties, vote all shares of Common Stock owned or controlled
by them, and shall take all necessary action within its control, (ii) ERI shall,
on behalf of the ERI Parties, vote all shares of Common Stock owned or
controlled by them, and shall take all necessary actions within its control and
(iii) the Belfer Group shall, on behalf of the Belfer Parties, vote all shares
of Common Stock owned or controlled by them, and shall take all necessary action
within its control, in each case, so that the composition of the Board of
Directors and the manner of selecting members thereof shall be as follows:

                  (a) The Board of Directors shall be comprised of eleven (11)
Directors (two of whom shall be Independent Directors) divided into three
classes, with Directors in each class having a three-year term following a
transition period in which the initial Class 1 Directors serve a one-year term,
the initial Class 2 Directors serve a two-year term and the initial Class 3
Directors serve a three-year term. WELLC and ERI shall each have the right to
designate one (1) Director to Class 3, one (1) Director to Class 2 and one (1)
Director to Class 1 and the Belfer Group shall have the right to designate one
(1) Director to Class 3 and one (1) Director to Class 1; provided, that the
initial membership of the Board of Directors at the Effective Time and the class
to which each director nominee shall belong shall be as set forth in Exhibit 2.3
of the Merger Agreement. Each of WELLC, ERI and the Belfer Group, respectively,
shall have the right (i) subject to applicable law, to remove, with or without
cause, any Director nominated in accordance with this Section 3.2 by WELLC, ERI
or the Belfer Group, respectively, and (ii) to designate any replacement for a
Director nominated in accordance with this Section 3.2 by WELLC, ERI or the
Belfer Group, respectively, upon the death, resignation, retirement,
disqualification or removal from office of such Director. The Board of Directors
shall duly appoint as a Director each person so designated to fill a vacancy on
the Board of Directors. Notwithstanding the foregoing:

                           (i) if either the WELLC Parties or the ERI Parties
own less than 18% of the Company's then outstanding Common Stock, then WELLC or
ERI, as the case may be, shall have the right to designate only: (x) one (1)
Director to the class of Directors having the then longest remaining term; and
(y) one (1) Director to the class of Directors having the next longest remaining
term; provided that in either case, if necessary to put one or more of a Party's
Director designees into such classes, the Company and the other Parties shall
cooperate as necessary to effect such designation; provided, further, that the
right to change such classes may only be exercised in connection with the
reduction in the number of the Party's Director designees;

                           (ii) if either the WELLC Parties, the ERI Parties or
the Belfer Parties own less than 8% of the Company's then outstanding Common
Stock, then WELLC, ERI or the Belfer Group, as the case may be, shall have the
right to designate only one (1) Director to the class of Directors having the
then longest remaining term; provided that if necessary to put a


                                      -9-
<PAGE>   13


Party's Director designee into such class, the Company and the other Parties
shall cooperate as necessary to effect such designation; provided, further, that
the right to change such classes may only be exercised in connection with the
reduction in the number of the Party's Director designees; and

                           (iii) if either the WELLC Parties, the ERI Parties or
the Belfer Parties own less than 5% of the Company's then outstanding Common
Stock, then WELLC, ERI or the Belfer Group, as the case may be, shall not have
the right to designate any Directors.

                  (b) For so long as any Party has the right to designate a
Director under this Agreement, the Company will give such Party written notice
of each regularly scheduled meeting of its Board of Directors as far in advance
as such notice is required to be delivered to the Directors (and at least three
business days prior to the date of each special meeting of the Board of
Directors), and the Board of Directors will permit up to two (2) representatives
of each such Party to attend as observers of all meetings of the Board of
Directors (including any meetings of committees thereof); provided that in the
case of telephonic meetings conducted in accordance with the Company's bylaws
and applicable law, each such Party's representatives will be given the
opportunity to listen to such telephonic meetings. Each representative will be
entitled to receive all written materials and other information (including,
without limitation, copies of meeting minutes and press releases) given to
Directors in connection with such meetings at the same time such materials and
information are given to the Directors. If the Board of Directors proposes to
take any action by written consent in lieu of a meeting of the Board of
Directors or of any committee thereof, the Company will give written notice
thereof to each such Party who has the right to designate a director under this
Agreement prior to the effective date of such consent describing in reasonable
detail the nature and substance of such action. The Company will reimburse each
Party that has observer rights under this Section 3.2(b) for all reasonable
expenses incurred by such Party's representatives in connection with attending
meetings of the Board of Directors and committees thereof.

         Section 3.3. Approval of Major Actions. The Company may take and may
permit its Subsidiaries to take and engage in the following Major Actions only
upon receiving Supermajority Approval:

                  (a) Issuance of Capital Stock. Any issuance, sale, grant or
award or entering into any agreement to issue, sell, grant or award any capital
stock of the Company other than (i) pursuant to agreements or obligations in
existence as of the Effective Time, (ii) the issuance of capital stock of the
Company pursuant to any rights or agreements including without limitation any
security convertible or exchangeable into or exercisable for, with or without
consideration, capital stock of the Company so long as such rights or agreements
received Supermajority Approval and (iii) the grant of options and the issuance
of restricted stock under Company stock incentive plans for the benefit of the
Company's employees and directors and the issuance of Common Stock upon the
exercise of such options.


                                      -10-
<PAGE>   14


                  (b) Debt to Total Capitalization. Incur Funded Debt of the
         Company and its Subsidiaries so that the ratio of Debt of the Company
         and its Subsidiaries to Total Capitalization is greater than 0.4 to
         1.0.

                  (c) Sale Transactions. Any merger or consolidation of the
         Company, the sale of all or substantially all of the assets of the
         Company or the sale of assets or transfer to a third party by sale of
         assets, merger or otherwise by the Company or any of its Subsidiaries
         (in one transaction or a series of related transactions) of any
         Subsidiary of the Company or the assets or business of the Company or a
         Subsidiary thereof which involves more than $150 million (or such other
         amount, established by resolution of the Board of Directors (approved
         by Supermajority Approval) from time to time), of the total assets of
         the Company and its Subsidiaries taken as a whole, including a sale of
         the Company effected by means of a sale of Common Stock, but excluding,
         however, dispositions of assets in the ordinary course of business
         (including, but not limited to, oil and gas production).

         Section 3.4. Amendments to Articles of Incorporation and Bylaws. The
Company, the WELLC Parties, the ERI Parties and the Belfer Parties shall take or
cause to be taken all lawful action necessary to ensure at all times that the
Company's Articles of Incorporation and Bylaws are at all times consistent with
the provisions of this Agreement.

         Section 3.5. Self-Interested Transactions. The consummation, amendment,
restatement, substitution or modification of any contract, agreement,
transaction or other arrangement between the Company or any Subsidiary of the
Company and any of WELLC, ERI, any Belfer Person or any Affiliate of WELLC, ERI
or any Belfer Person (a "Self-Interested Transaction") shall require, except
when the economic effect to the Company of any such action (or set of related
actions) is $50,000 or less, the affirmative vote of a majority of the
Disinterested Directors present at a duly called and noticed meeting at which a
quorum is present. "Disinterested Directors" shall include all Directors not
designated by the WELLC Parties, the ERI Parties or the Belfer Parties which is
or whose Affiliate is a party to the Self-Interested Transaction (other than any
Independent Directors).

                                   ARTICLE IV
                                   STANDSTILL

         Section 4.1. Standstill.

                  (a) WELLC agrees that from and after the Effective Time it
         will not, and will not act in concert with any Person so as to form a
         group (as such term is defined in Regulation 13D promulgated under the
         Exchange Act) to, in any manner, acquire, agree to acquire or make any
         proposal to acquire, directly or indirectly, beneficial ownership (as
         such term is defined in Regulation 13D promulgated under the Exchange
         Act) of any additional securities or debt instruments of the Company or
         any Subsidiary of the Company without the consent of ERI, so long as
         the ERI Parties hold at least 5% of the then outstanding Common Stock,
         and the Belfer Group, so long as the Belfer Parties hold at least 5% of
         the then outstanding Common Stock. The restrictions set forth in this
         Section 4.1(a) shall not apply (i) so long as (A) WELLC does not
         beneficially own more than 30% of the then outstanding Common Stock or
         (B) WELLC, makes


                                      -11-
<PAGE>   15


an offer in writing to the Company's Board of Directors to acquire for cash all
of the outstanding Common Stock not then held by it and the Board of Directors
(including a majority of the Disinterested Directors) approves the offer after
receipt of a written fairness opinion from a nationally recognized investment
banking firm to the effect that the consideration to be paid in the transaction
is fair from a financial point of view to all shareholders of the Company (other
than the offering shareholder) or (ii) if each of the ERI Parties and the Belfer
Parties hold less than 5% of the then outstanding Common Stock.

                  (b) ERI agrees that from and after the Effective Time it will
not, and that it will cause its Subsidiaries not to, and will not act in concert
with any Person so as to form a group (as such term is defined in Regulation 13D
promulgated under the Exchange Act) to, in any manner, acquire, agree to acquire
or make any proposal to acquire, directly or indirectly, beneficial ownership
(as such term is defined in Regulation 13D promulgated under the Exchange Act)
of any additional securities or debt instruments of the Company or any
Subsidiary of the Company without the consent of WELLC, so long as the WELLC
Parties hold at least 5% of the then outstanding Common Stock, and the Belfer
Group, so long as the Belfer Parties hold at least 5% of the then outstanding
Common Stock. The restrictions set forth in this Section 4.1(b) shall not apply
(i) so long as (A) ERI does not beneficially own more than 30% of the then
outstanding Common Stock or (B) ERI, makes an offer in writing to the Company's
Board of Directors to acquire for cash all of the outstanding Common Stock not
then held by it and the Board of Directors (including a majority of the
Disinterested Directors) approves the offer after receipt of a written fairness
opinion from a nationally recognized investment banking firm to the effect that
the consideration to be paid in the transaction is fair from a financial point
of view to all shareholders of the Company (other than the offering shareholder)
or (ii) if each of the WELLC Parties and the Belfer Parties hold less than 5% of
the then outstanding Common Stock.

                  (c) The Belfer Group agrees that from and after the Effective
Time they will not, and will not act in concert with any Person so as to form a
group (as such term is defined in Regulation 13D promulgated under the Exchange
Act) to, in any manner, acquire, agree to acquire or make any proposal to
acquire, directly or indirectly, beneficial ownership (as such term is defined
in Regulation 13D promulgated under the Exchange Act) of any additional
securities or debt instruments of the Company or any Subsidiary of the Company
without the consent of WELLC, so long as the WELLC Parties hold at least 5% of
the then outstanding Common Stock, and ERI, so long as the ERI Parties hold at
least 5% of the then outstanding Common Stock. The restrictions set forth in
this Section 4.1(c) shall not apply (i) so long as (A) the Belfer Parties do not
beneficially own more than 20% of the then outstanding Common Stock or (B) the
Belfer Parties make an offer in writing to the Company's Board of Directors to
acquire for cash all of the outstanding Common Stock not then held by it and the
Board of Directors (including a majority of the Disinterested Directors)
approves the offer after receipt of a written fairness opinion from a nationally
recognized investment banking firm to the effect that the consideration to be
paid in the transaction is fair from a financial point of view to all
shareholders of the Company (other than the offering shareholder) or (ii) if
each of the WELLC Parties and the ERI Parties hold less than 5% of the then
outstanding Common Stock.


                                      -12-
<PAGE>   16


                                   ARTICLE V
                               REGISTRATION RIGHTS

         Section 5.1. Demand Registrations.

                  (a) Requests for Registration. Each of WELLC, on behalf of the
WELLC Parties, ERI, on behalf of the ERI Parties, and the Belfer Group, on
behalf of the Belfer Parties, shall have the right to request registration under
the Securities Act of all or part of their Registrable Securities on Form S-1 or
any similar long-form registration or, if available, on Form S-2 or S-3 or any
similar short-form registration ("Short-Form Registrations") in accordance with
this Article V. All registrations requested pursuant to this Section 5.l(a) are
referred to herein as "Demand Registrations."

                  (b) Short-Form Registrations. Demand Registrations will be
Short-Form Registrations whenever the Company is permitted to use any applicable
short form. The Company will use its best efforts to make Short-Form
Registrations available for the sale of Registrable Securities. Demand
Registration requests may be for shelf registrations if the Company is then
eligible to effect shelf registrations.

                  (c) Restrictions on Demand Registrations. The registration
rights granted under this Section 5.1 are expressly subject to the following
terms and conditions:

                           1. The Company will not be obligated to effect any
Demand Registration within six (6) months after the effective date of a previous
Demand Registration.

                           2. The Company may postpone for up to ninety (90)
days the filing or the effectiveness of a registration statement for a Demand
Registration if the Company notifies the Party initiating the Demand
Registration within fifteen (15) days after receipt of request for such
registration (i) that the Company is at such time conducting or about to conduct
an underwritten public offering of its securities for its own account and the
Board of Directors has determined in its good faith judgment that such offering
would be materially adversely effected by such registration requested by such
Party or (ii) that the Board of Directors has determined, in its good faith
judgment, that such Demand Registration would reasonably be expected to have an
adverse effect on any proposal or plan by the Company or any of its Subsidiaries
to engage in any acquisition of assets (other than in the ordinary course of
business) or any merger, consolidation, tender offer or similar transaction;
provided, that, in such event, the holders of Registrable Securities initially
requesting such Demand Registration will be entitled to withdraw such request
and, if such request is withdrawn, such Demand Registration will not count as a
Demand Registration hereunder and the Company will pay all Registration Expenses
in connection with such request.

                           3. Any request for a Demand Registration shall not be
otherwise deemed to be effective unless such request includes the lesser of (i)
at least ten percent (10%) of the Company's outstanding Common Stock or (ii) all
of the Common Stock owned by the Parties making the request. Each request for a
Demand Registration shall specify the approximate


                                      -13-
<PAGE>   17


number of Registrable Securities requested to be registered and the anticipated
per share price range for such offering.

                           4. The WELLC Parties and the ERI Parties shall each
be entitled to initiate only three (3) Demand Registrations and the Belfer
Parties shall be entitled to initiate only two (2) Demand Registrations to
register Registrable Securities under the terms of this Section 5.1; provided,
if one of such Parties joins in the Demand Registration initiated by the other
in accordance with Section 5.1(c)(5), the initiating Party shall not be deemed
to have initiated the Demand Registration for purposes (and solely for the
purposes) of the limitation contained in this sentence.

                           5. If at any time or from time to time any of the
Parties shall request registration of any Registrable Securities in accordance
with this Section 5.1, the Company shall give the other Parties prompt written
notice of the proposed registration. The other Parties shall have the right to
join in such registration by giving notice to the Company within five (5)
business days after such Party receives notice of the proposed registration from
the Company and the Company shall include in such registration the number of
Registrable Securities requested by such other Parties on the same terms and
conditions as the Registrable Securities of the Party initiating the request. If
the managing underwriter or underwriters of a proposed offering for which
securities of more than one of the Parties are included pursuant to this Section
5.1(c)(5) advise the Company in writing that in its or their good faith judgment
the total amount of securities to be included in such offering exceeds the
number which can be sold in such offering within a price range reasonably
acceptable to the Parties, then in such event the securities to be included in
such offering shall be allocated pro rata among each such Parties and their
Permitted Transferees participating in the offering based upon the number of
Shares owned by each such Party and its Permitted Transferees.

                           6. Any registration statement filed on Form S-3
pursuant to Rule 415 of the Securities Act covering Registrable Securities shall
be restricted for use pursuant to a firmly underwritten offering of Common
Stock; provided, however, that a shelf registration statement filed under Rule
415 will not require a firm commitment underwritten offering for (i) sales of
Common Stock constituting block sales of less than five percent (5%) of the
Common Stock outstanding to institutional investors in solicited transactions,
or (ii) sales into the market in unsolicited brokers transactions if the total
amount of shares registered for sale in this manner involves less than ten
percent (10%) of the shares of Common Stock then outstanding. Each offering of
Registrable Securities under this Section 5.1 pursuant to a shelf registration
statement under Rule 415, other than offers and sales of Common Stock pursuant
to subsections (i) and (ii) of the preceding sentence, shall be treated as a
Demand Registration (other than for purposes of Section 5.1(c)(1)) and must
satisfy all requirements for a Demand Registration.

                  (d) Other Registration Rights. The Company will not grant to
any Person the right to request the Company to register any equity securities of
the Company with terms more favorable to such Person than those granted in this
Agreement without the prior written consent of WELLC, ERI and the Belfer Group.


                                      -14-
<PAGE>   18


         Section 5.2. Piggyback Registrations.

                  (a) Right to Piggyback. Whenever the Company proposes to
register any of its equity securities under the Securities Act (other than a
registration on Form S-4 or Form S-8 or any successor or similar forms and other
than a Demand Registration pursuant to Section 5.1) and the registration form to
be used may be used for the registration of Registrable Securities (a "Piggyback
Registration"), whether or not for sale for its own account, the Company will
give prompt written notice to WELLC, on behalf of the WELLC Parties, ERI, on
behalf of the ERI Parties, and the Belfer Group, on behalf of the Belfer
Parties, of its intention to effect such a registration and will include in such
registration all Registrable Securities with respect to which the Company has
received written requests for inclusion therein within twenty (20) days after
the receipt of the Company's notice. The Company will use its reasonable best
efforts to include, and to cause the managing underwriters, if applicable, to
include in the proposed offering such Registrable Securities on the same terms
and conditions as the securities of the Company included in such registration.

                  (b) Priority on Primary Registrations. If a Piggyback
Registration is an underwritten primary registration on behalf of the Company,
and the managing underwriters advise the Company in writing that in their
opinion the number of securities requested to be included in such registration
exceeds the number which can be sold in such offering within a price range
reasonably acceptable to the Company, the Company will include in such
registration (i) first, the securities the Company proposes to sell, to the
extent of availability and, (ii) second, all other securities (including the
Registrable Securities) requested to be included in such registration, pro rata
among the respective holders thereof on the basis of the number of securities
owned by each such holder.

                  (c) Priority on Secondary Registrations. If a Piggyback
Registration is an underwritten secondary registration on behalf of holders of
the Company's securities, and the managing underwriters advise the Company in
writing that in their opinion the number of securities requested to be included
in such registration exceeds the number which can be sold in such offering
within a price range reasonably acceptable to such holders, the securities which
can be included in such registration shall be allocated as follows: (i) first,
the securities (including the Registrable Securities) requested to be included
in such registration by the Persons exercising the Demand Registration, (ii)
then, to the extent of availability, securities to be registered for the account
of the Company and (iii) thereafter, to the extent of availability, to other
security holders exercising piggyback registration rights, pro rata based upon
the number of Shares owned by each such holder.

                  (d) Limited Purpose Shelf Registration Statement. In order to
facilitate the exercise by WELLC, ERI and the Belfer Group of their Piggyback
Registration rights, upon request of either WELLC, ERI or the Belfer Group (any
such request shall not constitute a Demand Registration for purposes of Section
5.1), the Company shall prepare and file with the Commission one or more
registration statements on Form S-3 under Rule 415 of the Securities Act
providing for the resale of Registrable Securities in an amount of shares to be
mutually agreed by Company and WELLC, ERI and the Belfer Group from time to
time, provided, that


                                      -15-
<PAGE>   19


such registration statement on Form S-3 shall be restricted for use by the
holders of the securities subject to such registration statement only for
participation pursuant to Section 5.2 in a firmly underwritten public offering
of Common Stock proposed by the Company for the account of the Company or the
account of any other security holder.

         Section 5.3. Holdback Agreements.

                  (a) If requested in writing by the Company or the managing
underwriters, if any, of any registration effected pursuant to Sections 5.1 or
5.2, WELLC agrees not to and will cause the other WELLC Parties not to, ERI
agrees not to and will cause the other ERI Parties not to, and the Belfer Group
agrees not to and will cause the other Belfer Parties not to effect any public
sale or distribution (including sales pursuant to Rule 144) of equity securities
of the Company, or any securities convertible into or exchangeable or
exercisable for such securities, during the time period reasonably requested by
the managing underwriters, not to exceed seven (7) days prior to and the 180-day
period beginning on the effective date of any underwritten Demand Registration,
any underwritten Piggyback Registration or other underwritten registration by
the Company of its securities (except as part of such underwritten
registration).

                  (b) If requested in writing by the managing underwriters of
any registration effected pursuant to Section 5.1 or 5.2, the Company agrees (i)
not to effect any public sale or distribution of its equity securities, or any
securities convertible into or exchangeable or exercisable for such securities,
during the time period reasonably requested by the managing underwriters, not to
exceed seven days prior to and during the 180-day period beginning on the
effective date of any underwritten Demand Registration or any underwritten
Piggyback Registration (except as part of such underwritten registration or
pursuant to registrations on Form S-4 or Form S-8 or any successor forms), and
(ii) to cause each holder of its Common Stock, or any securities convertible
into or exchangeable or exercisable for Common Stock, purchased from the Company
at any time after the date of this Agreement (other than in a registered public
offering), to so agree.

                  (c) If the Company has previously filed a registration
statement with respect to Registrable Securities pursuant to Sections 5.1 or
5.2, and if such previous registration has not been withdrawn or abandoned, the
Company will not file or cause to be effected any other registration of any of
its equity securities or securities convertible or exchangeable into or
exercisable for its equity securities under the Securities Act (except on Form
S-4 or Form S-8 or any successor forms), whether on its own behalf or at the
request of any holder or holders of such securities, until a period of at least
ninety (90) days has elapsed from the effective date of such previous
registration.

                  (d) Notwithstanding any provision herein to the contrary,
until four months after the Effective Time, none of the Belfer Parties shall be
permitted to sell, convey or otherwise transfer any capital stock of the Company
other than transfers to the Company.

         Section 5.4. Registration Procedures. Whenever WELLC, on behalf of the
WELLC Parties, ERI, on behalf of the ERI Parties, or the Belfer Group on behalf
of the Belfer Parties has requested that any Registrable Securities be
registered pursuant to this Agreement, the Company


                                      -16-
<PAGE>   20

will use its best efforts to effect the registration and the sale of such
Registrable Securities in accordance with the intended method of disposition
thereof, and pursuant thereto the Company will as expeditiously as possible:

                  (a) prepare and file with the Commission a registration
statement with respect to such Registrable Securities and thereafter use its
reasonable best efforts to cause such registration statement to become effective
(provided that, before filing a registration statement or prospectus or any
amendments or supplements thereto, the Company will furnish to the counsel
selected by the holders of the Registrable Securities covered by such
registration statement copies of all such documents proposed to be filed, which
documents will be subject to reasonable review of such counsel);

                  (b) prepare and file with the Commission such amendments and
supplements to such registration statement and the prospectus used in connection
therewith as may be necessary to keep such registration statement effective for
a period of either (i) not less than six months (subject to extension pursuant
to Section 5.7(b)) or, if such registration statement relates to an underwritten
offering, such longer period as in the opinion of counsel for the underwriters a
prospectus is required by law to be delivered in connection with sales of
Registrable Securities by an underwriter or dealer or (ii) such shorter period
as will terminate when all of the securities covered by such registration
statement have been disposed of in accordance with the intended methods of
disposition by the seller or sellers thereof set forth in such registration
statement (but in any event not before the expiration of any longer period
required under the Securities Act), and to comply with the provisions of the
Securities Act with respect to the disposition of all securities covered by such
registration statement until such time as all of such securities have been
disposed of in accordance with the intended methods of disposition by the seller
or sellers thereof set forth in such registration statement;

                  (c) furnish to each seller of Registrable Securities such
number of copies of such registration statement, each amendment and supplement
thereto, the prospectus included in such registration statement (including each
preliminary prospectus) and such other documents as such seller may reasonably
request in order to facilitate the disposition of the Registrable Securities
owned by such seller;

                  (d) use its best efforts to register or qualify such
Registrable Securities under such other securities or blue sky laws of such
jurisdictions as any seller reasonably requests and do any and all other acts
and things which may be reasonably necessary or advisable to enable such seller
to consummate the disposition in such jurisdictions of the Registrable
Securities owned by such seller (provided that the Company will not be required
to (i) qualify generally to do business in any jurisdiction where it would not
otherwise be required to qualify but for this subparagraph, (ii) subject itself
to taxation in any such jurisdiction or (iii) consent to general service of
process in any such jurisdiction);

                  (e) notify each seller of such Registrable Securities, at any
time when a prospectus relating thereto is required to be delivered under the
Securities Act, upon discovery that, or upon the discovery of the happening of
any event as a result of which, the prospectus


                                      -17-
<PAGE>   21


included in such registration statement contains an untrue statement of a
material fact or omits any fact necessary to make the statements therein not
misleading in the light of the circumstances under which they were made, and, at
the request of any such seller, the Company will prepare and furnish to such
seller a reasonable number of copies of a supplement or amendment to such
prospectus so that, as thereafter delivered to the purchasers of such
Registrable Securities, such prospectus will not contain an untrue statement of
a material fact or omit to state any fact necessary to make the statements
therein not misleading in the light of the circumstances under which they were
made;

                  (f) cause all such Registrable Securities to be listed on each
securities exchange on which similar securities issued by the Company are then
listed and, if not so listed, to be listed on the Nasdaq National Market or the
New York Stock Exchange;

                  (g) provide a transfer agent and registrar for all such
Registrable Securities not later than the effective date of such registration
statement;

                  (h) enter into such customary agreements (including
underwriting agreements in customary form for similar offerings) and take all
such other actions as the holders of a majority of the Registrable Securities
being sold or the underwriters, if any, reasonably request in order to expedite
or facilitate the disposition of such Registrable Securities (including, without
limitation, effecting a stock split or a combination of shares);

                  (i) make available for inspection by any seller of Registrable
Securities, any underwriter participating in any disposition pursuant to such
registration statement, and any attorney, accountant or other agent retained by
any such seller or underwriter, all financial and other records, pertinent
corporate documents and properties of the Company, and cause the Company's
officers, Directors, employees and independent accountants to supply all
information reasonably requested by any such seller, underwriter, attorney,
accountant or agent in connection with such registration statement;

                  (j) otherwise use its reasonable best efforts to comply with
all applicable rules and regulations of the Commission, and make available to
its security holders, as soon as reasonably practicable, an earnings statement
covering the period of at least twelve months beginning with the first day of
the Company's first full calendar quarter after the effective date of the
registration statement, which earnings statement shall satisfy the provisions of
Section 11(a) of the Securities Act and Rule 158 thereunder;

                  (k) in the event of the issuance of any stop order, injunction
or other order or requirement suspending the effectiveness of a registration
statement, or of any order suspending or preventing the use of any related
prospectus or suspending the qualification of any securities included in such
registration statement for sale in any jurisdiction, the Company will use its
reasonable best efforts promptly to obtain the withdrawal of such order and to
notify the holders of all of the Registrable Securities covered by the
registration statement of such order;

                  (l) obtain a cold comfort letter, dated the effective date of
such registration statement (and, if such registration includes an underwritten
public offering, dated the date of the


                                      -18-
<PAGE>   22


closing under the underwriting agreement), signed by the Company's independent
public accountants in customary form and covering such matters of the type
customarily covered by cold comfort letters as the holders of a majority of the
Registrable Securities being sold reasonably request (provided that such
Registrable Securities constitute at least 10% of the securities covered by such
registration statement);

                  (m) provide a legal opinion of the Company's outside counsel,
dated the effective date of such registration statement (and, if such
registration includes an underwritten public offering, dated the date of the
closing under the underwriting agreement), with respect to the registration
statement, each amendment and supplement thereto, the prospectus included herein
(including the preliminary prospectus) and such other documents relating thereto
in customary form and covering such matters of the type customarily covered by
legal opinions of such nature;

                  (n) promptly furnish to the managing underwriter, if any, and
each seller of Registrable Securities copies of any written request by the
Commission or any state securities authority for amendments or supplements to a
registration statement or prospectus or for additional information; and

                  (o) make reasonably available its employees and personnel and
otherwise provide reasonable assistance to any underwriters in the marketing of
Registrable Securities in any underwritten offering.

         The Company may require each seller of Registrable Securities as to
which any registration is being effected to furnish the Company such information
regarding such seller and the distribution of such securities as the Company may
from time to time reasonably request in writing.

         Section 5.5. Registration Expenses.

                  (a) The Company shall pay all Registration Expenses relating
to any registration of Registrable Securities hereunder. "Registration Expenses"
shall mean any and all fees and expenses incident to the Company's performance
of or compliance with this Article V, including, without limitation: (i)
Commission, stock exchange or National Association of Securities Dealers, Inc.
registration and filing fees and all listing fees and fees with respect to the
inclusion of securities on the Nasdaq National Market, (ii) fees and expenses of
compliance with state securities or "blue sky" laws and in connection with the
preparation of a "blue sky" survey, including, without limitation, reasonable
fees and expenses of blue sky counsel, (iii) printing expenses, (iv) messenger
and delivery expenses, (v) fees and disbursements of counsel for the Company,
(vi) with respect to each registration, reasonable fees and disbursements of one
counsel for the selling holders of Shares (selected by the holders making the
Demand Registration request, in the case of a registration pursuant to Section
5.1, and selected by the holders of a majority of the Registrable Securities
included in such registration, in the case of a registration pursuant to Section
5.2) as well as of one local counsel, (vii) fees and disbursements of all
independent public accountants (including the expenses of any audit and/or "cold
comfort" letter) and fees and expenses of other persons, including special
experts, retained by the


                                      -19-
<PAGE>   23


Company, and (viii) any other fees and disbursements of underwriters, if any,
customarily paid by issuers or sellers of securities.

                  (b) Notwithstanding the foregoing, (i) the provisions of this
Section 5.5 shall be deemed amended to the extent necessary to cause these
expense provisions to comply with "blue sky" laws of each state in which the
offering is made and (ii) in connection with any registration hereunder, each
holder of Registrable Securities being registered shall pay all underwriting
discounts and commissions and transfer taxes, if any, attributable to the
Registrable Securities included in the offering by such holder.

         Section 5.6. Indemnification.

                  (a) The Company agrees to indemnify and hold harmless, to the
extent permitted by law, each holder of Registrable Securities, its officers and
Directors and each Person who controls such holder (within the meaning of the
Securities Act) against any losses, claims, damages, liabilities, joint or
several, to which such holder or any such Director or officer or controlling
person may become subject under the Securities Act or otherwise, insofar as such
losses, claims, damages or liabilities (or actions or proceedings, whether
commenced or threatened, in respect thereof) arise out of or are based upon (i)
any untrue or alleged untrue statement of a material fact contained (A) in any
registration statement, prospectus or preliminary prospectus or any amendment
thereof or supplement thereto or (B) in any application or other document or
communication (in this Section 5.6 collectively called an "application")
executed by or on behalf of the Company or based upon written information
furnished by or on behalf of the Company filed in any jurisdiction in order to
qualify any securities covered by such registration statement under the "blue
sky" or securities laws thereof, or (ii) any omission or alleged omission of a
material fact required to be stated therein or necessary to make the statements
therein not misleading, and the Company will reimburse such holder and each such
Director, officer and controlling person for any legal or any other expenses
incurred by them in connection with investigating or defending any such loss,
claim, liability, action or proceeding; provided that the Company shall not be
liable in any such case to the extent that any such loss. claim, damage,
liability (or action or proceeding in respect thereof) or expense arises out of
or is based upon an untrue statement or alleged untrue statement, or omission or
alleged omission, made in such registration statement, any such prospectus or
preliminary prospectus or any amendment or supplement thereto, or in any
application, in reliance upon and in conformity with written information
prepared and furnished to the Company by such holder expressly for use therein
or by such holder's failure to deliver a copy of the registration statement or
prospectus or any amendments or supplements thereto after the Company has
furnished such holder with a sufficient number of copies of the same. In
connection with an underwritten offering, the Company will indemnify such
underwriters, their officers and Directors and each Person who controls such
underwriters (within the meaning of the Securities Act) to the same extent as
provided above with respect to the indemnification of the holders of Registrable
Securities.

                  (b) In connection with any registration statement in which a
holder of Registrable Securities is participating, each such holder will furnish
to the Company in writing such information and documents as the Company
reasonably requests for use in connection with


                                      -20-

<PAGE>   24


any such registration statement or prospectus and, to the extent permitted by
law, will indemnify and hold harmless the Company, its Directors and officers
and each other Person who controls the Company (within the meaning of the
Securities Act) against any losses, claims, damages, liabilities, joint or
several, to which the Company or any such Director or officer or controlling
person may become subject under the Securities Act or otherwise, insofar as such
losses, claims, damages or liabilities (or actions or proceedings, whether
commenced or threatened, in respect thereof) arise out of or are based upon (i)
any untrue or alleged untrue statement of a material fact contained in the
registration statement, prospectus or preliminary prospectus or any amendment
thereof or supplement thereto or in any application or (ii) any omission or
alleged omission of a material fact required to be stated therein or necessary
to make the statements therein not misleading, but only to the extent that such
untrue statement or omission is made in such registration statement, any such
prospectus or preliminary prospectus or any amendment or supplement thereto, or
in any application, in reliance upon and in conformity with written information
prepared and furnished to the Company by such holder expressly for use therein,
and such holder will reimburse the Company and each such Director, officer and
controlling person for any legal or any other expenses incurred by them in
connection with investigating or defending any such loss, claim, liability,
action or proceeding; provided that the obligation to indemnify will be
individual to each holder and will be limited to the net amount of proceeds
received by such holder from the sale of Registrable Securities pursuant to such
registration statement.

                  (c) Any Person entitled to indemnification hereunder will (i)
give prompt written notice to the indemnifying party of any claim with respect
to which it seeks indemnification and (ii) unless in such indemnified party's
reasonable judgment a conflict of interest between such indemnified and
indemnifying parties may exist with respect to such claim, permit such
indemnifying party to assume the defense of such claim with counsel reasonably
satisfactory to the indemnified party. If such defense is assumed, the
indemnifying party will not be subject to any liability for any settlement made
by the indemnified party without its consent (but such consent will not be
unreasonably withheld). An indemnifying party who is not entitled to, or elects
not to, assume the defense of a claim will not be obligated to pay the fees and
expenses of more than one counsel for all parties indemnified by such
indemnifying party with respect to such claim, unless in the reasonable judgment
of any indemnified party a conflict of interest may exist between such
indemnified party and any other of such indemnified parties with respect to such
claim.

                  (d) The indemnification provided for under this Agreement will
remain in full force and effect regardless of any investigation made by or on
behalf of the indemnified party or any officer, Director or controlling Person
of such indemnified party and will survive the transfer of securities by any
holder thereof. The Company also agrees to make such provisions, as are
reasonably requested by any indemnified party, for contribution to such party in
the event the Company's indemnification is unavailable for any reason.


                                      -21-
<PAGE>   25


         Section 5.7. Participation in Underwritten Registrations.

                  (a) If requested by the underwriters for any underwritten
offering pursuant to a Demand Registration requested under Section 5.1, the
Company shall enter into a customary underwriting agreement with the
underwriters. Such underwriting agreement shall be satisfactory in form and
substance to the Person who requested such registration and shall contain such
representations and warranties by, and such other agreements on the part of, the
Company and such other terms as are generally prevailing in agreements of that
type, including, without limitation, indemnities and contribution agreements.
Such underwriting agreement shall also contain such representations, warranties,
indemnities and contributions by the participating holders as are customary in
agreements of that type. In the case of a registration pursuant to Section 5.2
hereof, if the Company shall have determined to enter into any underwriting
agreements in connection therewith, all of the holders' Registrable Securities
to be included in such registration shall be subject to such underwriting
agreement. Such underwriting agreement shall also contain such representations,
warranties, indemnities and contributions by the participating holders as are
customary in agreements of that type.

                  (b) Each Person that is participating in any registration
hereunder agrees that, upon receipt of any notice from the Company of the
happening of any event of the kind described in Section 5.4(e) above, such
Person will forthwith discontinue the disposition of its Registrable Securities
pursuant to the registration statement until such Person's receipt of the copies
of a supplemented or amended prospectus as contemplated by such Section 5.4(e).
In the event the Company shall give any such notice, the applicable time period
mentioned in Section 5.4(b) during which a registration statement is to remain
effective shall be extended by the number of days during the period from and
including the date of the giving of such notice pursuant to this paragraph to
and including the date when each seller of a Registrable Security covered by
such registration statement shall have received the copies of the supplemented
or amended prospectus contemplated by Section 5.4(e).

         Section 5.8. Current Public Information. At all times after the Company
has filed a registration statement with the Commission pursuant to the
requirements of either the Securities Act or the Exchange Act, the Company will
file all reports required to be filed by it under the Act and the Exchange Act
and the rules and regulations adopted by the Commission thereunder, and will
take such further action as any holder or holders of Registrable Securities may
reasonably request, all to the extent required to enable such holders to sell
Registrable Securities pursuant to Rule 144.

         Section 5.9. Cooperation. If the Company determines to authorize and/or
issue any capital stock or other debt or equity securities in a public offering,
each of the Parties and their Permitted Transferees agrees to cooperate with the
Company and to take all action necessary to assist the Company in consummating
such transaction.


                                      -22-
<PAGE>   26

                                   ARTICLE VI
                               GENERAL PROVISIONS

         Section 6.1. Notices. Any notice required to be given hereunder shall
be sufficient if in writing, and sent by facsimile transmission and by courier
service (with proof of service), hand delivery or certified or registered mail
(return receipt requested and first-class postage prepaid), addressed as
follows:

                  If to the Belfer Group:

                           Robert A. Belfer
                           767 Fifth Avenue, 46th Floor
                           New York, New York 10153
                           Fax Number: (212) 644-2300
                           Phone Number: (212) 644-2200

                  With a copy to:

                           Vinson & Elkins L.L.P.
                           666 Fifth Avenue, 26th Floor
                           New York, New York 10103-0400
                           Attention: Alan P. Baden
                           Fax Number: (917) 206-8100
                           Phone Number: (917) 206-8001

                  If to Westport or the Company:

                           Donald D. Wolf,
                           Chairman and Chief Executive Officer
                           410 17th Street, Suite 2300
                           Denver, CO 80202
                           Fax Number: (303) 573-5609
                           Phone Number: (303) 573-5404

                  If to Westport Energy LLC:

                           Westport Energy LLC
                           21 Glen Oaks Ave.
                           Summit, NJ 07901
                           Attention: Erich Gerstberger
                           Fax Number: (908) 273-4437
                           Phone Number: (908) 273-4516


                                      -23-
<PAGE>   27


                  With a copy to:

                           Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                           1700 Pacific Avenue, Suite 4100
                           Dallas, Texas 75201-4675
                           Attention: Michael E. Dillard, P.C.
                           Fax Number: (214) 969-4343
                           Phone Number: (214) 969-2800

                  And to:

                           Michael Russell
                           Dr. Richard J. Haas Partners
                           Dukes Court
                           32 Duke Street, St. James's
                           London, SW1Y 6DF
                           Fax Number: 020.7.321.5242
                           Phone Number: 020.7.321.5200

                  If to ERI Investments, Inc.:

                           Johanna G. O'Loughlin
                           Vice President, General Counsel and Secretary
                           ERI Investments, Inc.
                           One Oxford Centre, Suite 3300
                           Pittsburgh, PA 15219
                           Telephone: (412) 553-7760
                           Telecopy: (412) 553-5970

                  With a copy to:

                           Stephen W. Johnson, Esquire
                           Buchanan Ingersoll Professional Corporation
                           One Oxford Centre, 20th Floor
                           Pittsburgh, PA 15219
                           Telephone: (412) 562-1859
                           Telecopy: (412) 562-1041

or to such other address as any party shall specify by written notice so given,
and such notice shall be deemed to have been delivered as of the date so
telecommunicated, personally delivered or mailed.

         Section 6.2. Assignment; Binding Effect; Benefit. Other than Transfers
to Permitted Transferees, neither this Agreement nor any of the rights,
interests or obligations hereunder shall be assigned by any of the Parties or
their Permitted Transferees without the prior written consent of the other
Parties; provided, that the WELLC Parties, the ERI Parties and the Belfer
Parties


                                      -24-
<PAGE>   28


may assign their rights under Article V in connection with any Transfer of
Registrable Securities made in accordance with this Agreement if immediately
after the Transfer, the transferee beneficially owns at least ten percent (10%)
of the Common Stock of the Company then outstanding, in which event each
transferee will have rights and obligations under Article V as if it was a party
to this Agreement. Subject to the preceding sentence, this Agreement shall be
binding upon and shall inure to the benefit of the parties hereto and their
respective successors and assigns. Notwithstanding anything contained in this
Agreement to the contrary, nothing in this Agreement, express or implied, is
intended to confer on any person other than the parties hereto or their
respective heirs, successors, executors, administrators and assigns any rights,
remedies, obligations or liabilities under or by reason of this Agreement.

         Section 6.3. Entire Agreement. The Merger Agreement, this Agreement,
the exhibits and schedules hereto and any certificate delivered by the parties
in connection herewith constitute the entire agreement among the parties with
respect to the subject matter hereof and supersede all prior agreements and
understandings (oral and written) among the parties with respect thereto.

         Section 6.4. Amendment. No amendment, modification or waiver of this
Agreement shall be effective against any Party unless it shall be in writing and
signed by such Party.

         Section 6.5. Governing Law. This Agreement shall be governed by and
construed in accordance with the laws of the State of Nevada without regard to
its rules of conflict of laws.

         Section 6.6. Counterparts. This Agreement may be executed by the
parties hereto in separate counterparts, each of which when so executed and
delivered shall be an original, but all such counterparts shall together
constitute one and the same instrument. Each counterpart may consist of a number
of copies of this Agreement, each of which may be signed by less than all of the
parties hereto, but together all such copies are signed by all of the parties
hereto.

         Section 6.7. Headings. Headings of the Articles and Sections of this
Agreement are for the convenience of the parties only and shall be given no
substantive or interpretive effect whatsoever.

         Section 6.8. Interpretation. In this Agreement, unless the context
otherwise requires: (i) words describing the singular number shall include the
plural and vice versa; (ii) "including" shall mean including, without
limitation; (iii) words denoting any gender shall include all genders; and (iv)
words denoting natural persons shall include corporations and partnerships and
vice versa.

         Section 6.9. Incorporation of Exhibits and Schedules. All exhibits and
schedules hereto are hereby incorporated herein and made a part hereof for all
purposes as if fully set forth herein.

         Section 6.10. Severability. Any term or provision of this Agreement
which is invalid or unenforceable in any jurisdiction shall, as to that
jurisdiction, be ineffective to the extent of such invalidity or
unenforceability without rendering invalid or unenforceable the remaining terms


                                      -25-
<PAGE>   29


and provisions of this Agreement or otherwise affecting the validity or
enforceability of any of the terms or provisions of this Agreement in any other
jurisdiction. If any provision of this Agreement is so broad as to be
unenforceable, the provision shall be interpreted to be only so broad as is
enforceable.

         Section 6.11. Enforcement of Agreement. The Parties hereto agree that
irreparable damage would occur in the event that any of the provisions of this
Agreement were not performed in accordance with its specific terms or was
otherwise breached. It is accordingly agreed that the Parties and their
Permitted Transferees shall be entitled to an injunction or injunctions to
prevent breaches of this Agreement and to enforce specifically the terms and
provisions hereof in any court, this being in addition to any other remedy to
which they may be entitled at law or in equity.

         Section 6.12. Confidentiality. None of WELLC, its Affiliates,
employees, agents or representatives, ERI, its Affiliates, employees, agents or
representatives nor the Belfer Group, their Affiliates, agents or
representatives shall disclose to any third party any information obtained about
the Company or its operations or business which it may have acquired pursuant to
this Agreement or the Original Shareholders Agreement without the prior written
consent of the Company; provided, that any information that is otherwise
publicly available, without breach of this provision, or has been obtained from
a third party without a breach of such third party's duties, shall not be deemed
confidential information.

         Section 6.13. Termination. This Agreement shall terminate and shall
cease to be binding on the Parties upon the earliest to occur of:

                  (a) prior to the consummation of the transactions contemplated
by the Merger Agreement, upon the termination of the Merger Agreement pursuant
to its terms, in which event this Agreement will be of no force or effect and
the terms of the Original Shareholders Agreement shall remain in full force and
effect as though the amendment and restatement contemplated hereby had not taken
place;

                  (b) subsequent to the consummation of the transactions
contemplated by the Merger Agreement, with respect to any Party and its
Permitted Transferees, the date on which such Party and its Permitted
Transferees cease to own at least 5.0% of the outstanding Common Stock; and

                  (c) subsequent to the consummation of the transactions
contemplated by the Merger Agreement, with respect to any Party and its
Permitted Transferees, the date on which such Party and its Permitted
Transferees cease to own at least 25% of the Common Stock owned by them or for
which they have the right to receive as a result of the Merger immediately
subsequent to the consummation of the transactions contemplated by the Merger
Agreement; and

                  (d) the date on which all of the Parties who are then bound
hereby mutually consent to terminate this Agreement in writing;


                                      -26-
<PAGE>   30


provided, however, notwithstanding the provisions of Section 6.13 (b), (c) and
(d) above, the provisions of Article V shall continue in effect with respect to
a Party and its Permitted Transferees as long as it holds Registrable Securities
and the provisions of Section 6.12 shall not terminate.

         Section 6.14. Effective Time. Except as set forth in the last sentence
of Section 6.16, notwithstanding anything herein to the contrary, this Agreement
shall become effective at the Effective Time, and the representations and
warranties contained herein shall be deemed made as of the Effective Time. If
the Merger Agreement is terminated for any reason prior to the consummation of
the Merger contemplated therein, this Agreement shall also terminate.

         Section 6.15. Belfer Group Representative. Robert A. Belfer shall be
the initial Belfer Group representative (the "Belfer Group Representative"). The
Belfer Group Representative may be changed by delivery of a written notification
delivered to the parties hereto and executed by all of the members of the Belfer
Group. Each member of the Belfer Group hereby appoints the person or entity who
is, from time to time, duly appointed under this Section 6.15 as the Belfer
Group Representative to give any consent or approval, exercise any right, take
any action contemplated under this Agreement on behalf of the Belfer Group. The
members of the Belfer Group shall be so bound by the Belfer Group Representative
and the parties to this Agreement shall be entitled to rely on the actions taken
by the Belfer Group Representative contemplated by this Agreement.

         Section 6.16. Belfer Rights Holders. Certain members of the Belfer
Group (the "Belfer Rights Holders") are party to that certain Registration
Rights Agreement, dated as of March 29, 1996 ("Registration Agreement"), among
Belco and certain stockholders of Belco. The Belfer Rights Holders represent to
Westport that they hold not less than 66-2/3% of the outstanding shares of the
Restricted Stock, as such term is defined in the Registration Agreement. In
accordance with Section 9 of the Registration Agreement, the Belfer Rights
Holders and Belco hereby terminate the Registration Agreement, including,
without limitation, any demand registration rights and piggyback registration
rights associated therewith, effective as of the Effective Time. The Belfer
Rights Holders hereby agree not to exercise any of their rights under the
Registration Agreement prior to the earlier to occur (i) the Effective Time or
(ii) the termination of the Merger Agreement. If a transfer of any of the Belfer
Rights Holders' Restricted Stock occurs prior to the Effective Time, the terms
of this Section 6.16 shall be binding on any such transferee. Notwithstanding
anything to the contrary in this Agreement, the terms of the preceding two
sentences shall be effective on the date of the execution of this Agreement by
the parties hereto.


                                      -27-
<PAGE>   31


         IN WITNESS WHEREOF, the parties have executed this Amended and Restated
Shareholders Agreement and caused the same to be duly delivered on their behalf
as of the day and year first written above, to be effective as of the Effective
Date.

                                           BELCO OIL & GAS CORP.:


                                           By: /s/ Robert A. Belfer
                                               ---------------------------------
                                           Name:   Robert A. Belfer
                                                   -----------------------------
                                           Title:  Chairman and CEO
                                                   -----------------------------


                                           WESTPORT RESOURCES CORPORATION:


                                           By: /s/ Donald D. Wolf
                                               ---------------------------------
                                           Name:   Donald D. Wolf
                                                   -----------------------------
                                           Title:  Chief Executive Officer
                                                   -----------------------------

                                           WESTPORT ENERGY LLC:

                                           By: WESTPORT INVESTMENTS LIMITED, its
                                           Managing Member

                                              By: /s/ Robert A. Haas
                                                  ------------------------------
                                              Name:   Robert A. Haas
                                                      --------------------------
                                              Title:
                                                      --------------------------


                                           ERI INVESTMENTS, INC.:


                                           By: /s/ Phillip P. Conti
                                               ---------------------------------
                                           Name:   Phillip P. Conti
                                                   -----------------------------
                                           Title:  President
                                                   -----------------------------

<PAGE>   32


                                           /s/ Robert A. Belfer
                                           -------------------------------------
                                           ROBERT A. BELFER



                                           /s/ Renee E. Belfer
                                           -------------------------------------
                                           RENEE E. BELFER



                                           /s/ Laurence D. Belfer
                                           -------------------------------------
                                           LAURENCE D. BELFER



                                           /s/ Jack Saltz
                                           -------------------------------------
                                           JACK SALTZ



                                           SALTZ INVESTMENT GROUP, LLC:



                                           By: /s/ Jack Saltz
                                               ---------------------------------
                                           Name:    Jack Saltz
                                           Title:   Manager and Member


                                           JACK & ANITA SALTZ FOUNDATION:


                                           By: /s/ Jack Saltz
                                               ---------------------------------
                                           Name:   Jack Saltz
                                           Title:  President


<PAGE>   33


                                           THE ROBERT A. AND RENEE E. BELFER
                                           FAMILY FOUNDATION:


                                           By: /s/ Robert A. Belfer
                                               ---------------------------------
                                           Name:   Robert A. Belfer
                                           Title:  Trustee and Donor


                                           BELFER CORP.:


                                           By: /s/ Robert A. Belfer
                                               ---------------------------------
                                           Name:   Robert A. Belfer
                                           Title:  President


                                           BELWEST PETROLEUM, INC.:


                                           By: /s/ Robert A. Belfer
                                               ---------------------------------
                                           Name:   Robert A. Belfer
                                           Title:  President


                                           A&B INVESTORS, INC.:


                                           By: /s/ Robert A. Belfer
                                               ---------------------------------
                                           Name:   Robert A. Belfer
                                           Title:


<PAGE>   34

                                           RENEE HOLDINGS PARTNERSHIP, L.P.:


                                           By: /s/ Robert A. Belfer
                                               ---------------------------------
                                           Name:   Robert A. Belfer
                                           Title:  General Partner


                                           TRUST FOR THE BENEFIT OF ELIZABETH
                                           KONES BELFER (T-6):


                                           By: /s/ Robert A. Belfer
                                               ---------------------------------
                                           Name:   Robert A. Belfer
                                           Title:  Trustee

                                           By: /s/ Renee E. Belfer
                                               ---------------------------------
                                           Name:   Renee E. Belfer
                                           Title:  Trustee


                                           TRUST FOR THE BENEFIT OF ELIZABETH
                                           KONES BELFER (T-7):


                                           By: /s/ Renee E. Belfer
                                               ---------------------------------
                                           Name:   Renee E. Belfer
                                           Title:  Trustee


                                           THE LAURENCE D. BELFER FAMILY
                                           FOUNDATION:


                                           By: /s/ Laurence D. Belfer
                                               ---------------------------------
                                           Name:   Laurence D. Belfer
                                           Title:  Trustee and Donor


<PAGE>   35


                                           LDB CORP.:


                                           By: /s/ Laurence D. Belfer
                                               ---------------------------------
                                           Name:   Laurence D. Belfer
                                           Title:  President


                                           ROBERT A. BELFER 1990 FAMILY TRUST:


                                           By: /s/ Laurence D. Belfer
                                               ---------------------------------
                                           Name:   Laurence D. Belfer
                                           Title:  Trustee


                                           VANTZ LIMITED PARTNERSHIP:


                                           By:  VANTZ LLC
                                                Its General Partner

                                                By:   /s/ Laurence D. Belfer
                                                    ----------------------------
                                                Name: Laurence D. Belfer
                                                Title:


<PAGE>   36


                                    EXHIBIT A

                              CERTAIN STOCKHOLDERS


Robert A. Belfer
Renee E. Belfer
Laurence D. Belfer
Jack Saltz
Saltz Investment Group, LLC
Jack & Anita Saltz Foundation
The Robert A. and Renee E. Belfer Family Foundation,
Belfer Corp.
Belwest Petroleum, Inc.
A&B Investors, Inc.
Renee Holdings Partnership, L.P.
Trust for the benefit of Elizabeth Kones Belfer (T-6)
Trust for the benefit of Elizabeth Kones Belfer (T-7)
The Laurence D. Belfer Family Foundation
LDB Corp.
Robert A. Belfer 1990 Family Trust
Vantz Limited Partnership



<PAGE>   37


                                  SCHEDULE 2.2

                           OWNERSHIP -- WELLC PARTIES

<TABLE>
<CAPTION>
                        Ownership of Old Westport      Pro forma ownership of
                             Common Stock as          Common Stock immediately
   Stockholder              of the date hereof        subsequent to the Merger
   -----------          -------------------------     -------------------------
<S>                     <C>                           <C>
Westport Energy LLC            14,238,001                      14,238,001
</TABLE>


<PAGE>   38


                                  SCHEDULE 2.3

                            OWNERSHIP -- ERI PARTIES


<TABLE>
<CAPTION>
                        Ownership of Old Westport      Pro forma ownership of
                             Common Stock as          Common Stock immediately
   Stockholder              of the date hereof        subsequent to the Merger
   -----------          -------------------------     -------------------------
<S>                     <C>                           <C>
ERI Investments, Inc.           13,911,152                    13,911,152
</TABLE>


<PAGE>   39


                                  SCHEDULE 2.4

                         OWNERSHIP -- EACH BELFER PERSON



<TABLE>
<CAPTION>
                                                                                   Pro forma ownership of
                                                            Shares held as        Common Stock immediately
   Stockholder                                             of the date hereof     subsequent to the Merger
   -----------                                             ------------------     ------------------------
<S>                                                        <C>                    <C>
Robert A. Belfer(1)                                             5,835,379                 2,407,093
Renee E. Belfer(1)                                              2,805,601                 1,157,310
Laurence D. Belfer(1)                                           2,104,449                   868,085
Jack Saltz(1)                                                      15,000                     6,187
Saltz Investment Group, LLC(2)                                  1,883,223                   776,829
Jack & Anita Saltz Foundation(2)                                  150,400                    62,040
The Robert A. and Renee E. Belfer Family Foundation(3)            713,500                   294,318
Belfer Corp.(3)                                                   845,271                   348,674
Belwest Petroleum, Inc.(3)                                            330                       136
A&B Investors, Inc.(3)                                                 --                        --
Renee Holdings Partnership, L.P.(3)                             1,193,415                   492,283
Trust for the benefit of Elizabeth Kones Belfer (T-6)(3)          503,446                   207,671
Trust for the benefit of Elizabeth Kones Belfer (T-7)(4)          503,446                   207,671
The Laurence D. Belfer Family Foundation(5)                        12,310                     5,077
LDB Corp.(5)                                                      272,855                   112,552
Robert A. Belfer 1990 Family Trust(5)                             557,674                   230,040
Vantz Limited Partnership(5)                                      634,210                   261,611
</TABLE>

-----------

(1)      767 Fifth Avenue, 46th Floor, New York, New York  10153

(2)      c/o Jack Saltz, 767 Fifth Floor Avenue, 46th Floor, New York,
         New York 10153

(3)      c/o Robert A. Belfer, 767 Fifth Avenue, 46th Floor, New York,
         New York 10153

(4)      c/o Rene E. Belfer, 767 Fifth Avenue, 46th Floor, New York,
         New York 10153

(5)      c/o Laurence D. Belfer, 767 Fifth Avenue, 46th Floor, New York,
         New York 10153