<PAGE>   1
                                                                     Exhibit 2.2

                                 TOM BROWN, INC.
                           (hereinafter, "Parent Co.")



                                       and



                            TOM BROWN RESOURCES LTD.
                             (hereinafter, "A Co.")



                                       and



                          STELLARTON ENERGY CORPORATION
                           (hereinafter, "Stellarton")





--------------------------------------------------------------------------------

                            PRE-ACQUISITION AGREEMENT

                                December 13, 2000

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<PAGE>   2




                                TABLE OF CONTENTS
<TABLE>
<CAPTION>
                                                                                          Page
                                                                                          ----

                                    ARTICLE I
                                 INTERPRETATION
<S>     <C>                                                                                <C>
        1.1    Definitions..................................................................1
        1.2    Singular, Plural, etc........................................................4
        1.3    Deemed Currency..............................................................5
        1.4    Headings, etc................................................................5
        1.5    Date for any Action..........................................................5
        1.6    Governing Law................................................................5
        1.7    Attornment...................................................................5
        1.8    Incorporation of Schedules...................................................5

                                   ARTICLE II
                                    THE OFFER

        2.1    The Offer....................................................................6
        2.2    Stellarton Directors' Circular...............................................8
        2.3    Offer Documents..............................................................9
        2.4    Outstanding Stock Options...................................................10

                                   ARTICLE III
                           PUBLICITY AND SOLICITATION

        3.1    Publicity...................................................................11
        3.2    Solicitation................................................................12

                                   ARTICLE IV
                 TRANSACTIONS FOLLOWING COMPLETION OF THE OFFER

        4.1    Second Stage Transaction....................................................12
        4.2    Information Circular, Etc...................................................12

                                    ARTICLE V
                    REPRESENTATIONS AND WARRANTIES OF PARENT CO. AND A CO.

        5.1    Organization and Qualification..............................................13
        5.2    Authority Relative to this Agreement........................................13
        5.3    No Violations...............................................................13
        5.4    Availability of Funds.......................................................14
        5.5    Knowledge...................................................................15

                                   ARTICLE VI
                  REPRESENTATIONS AND WARRANTIES OF STELLARTON

        6.1    Organization and Qualification..............................................15
        6.2    Authority Relative to this Agreement........................................15
        6.3    No Violations...............................................................15
        6.4    Capitalization..............................................................16
        6.5    No Material Adverse Change..................................................17
        6.6    No Undisclosed Material Liabilities.........................................17
        6.7    Impairment..................................................................17
</TABLE>


<PAGE>   3



<TABLE>
<S>     <C>                                                                                <C>
        6.8    Officer Obligations.........................................................17
        6.9    Brokerage and Other Fees....................................................17
        6.10   Conduct of Business.........................................................18
        6.11   Reports.....................................................................18
        6.12   Subsidiaries................................................................19
        6.13   Compliance with Law.........................................................19
        6.14   Material Agreements.........................................................19
        6.15   Interim Financial Statements................................................20
        6.16   Employment Agreements.......................................................20
        6.17   Employee Benefit Plans......................................................20
        6.18   United States Relationships and Operations..................................20
        6.19   Data and Information........................................................21
        6.20   Engineering Report..........................................................21
        6.21   Books and Records...........................................................21
        6.22   Litigation, etc.............................................................21
        6.23   Environmental...............................................................21
        6.24   Tax Matters.................................................................22
        6.25   Reporting Issuer Status.....................................................24
        6.26   Debt and Working Capital....................................................24
        6.27   Confidentiality Agreements..................................................24
        6.28   Insurance...................................................................24
        6.29   Secure Oil Tools Ltd........................................................24

                                   ARTICLE VII
                               CONDUCT OF BUSINESS

        7.1    Conduct of Business by Stellarton...........................................24
        7.2    Conduct of Business by Parent Co. and A Co..................................27
        7.3    Integration of Operations...................................................27
        7.4    Market Purchases............................................................27

                                  ARTICLE VIII
                             COVENANTS OF STELLARTON

        8.1    Notice of Material Change...................................................28
        8.2    Non-Completion Fee..........................................................28
        8.3    No Solicitation.............................................................29
        8.4    Stellarton Board of Directors...............................................30
        8.5    Representations and Warranties..............................................30
        8.6    Structure of Transaction....................................................31

                                   ARTICLE IX
                        COVENANTS OF PARENT CO. AND A CO.

        9.1    Representations and Warranties..............................................31
        9.2    Employment Agreements.......................................................31
        9.3    Indemnities.................................................................31
        9.4    Other Covenants.............................................................31

                                    ARTICLE X
                                MUTUAL COVENANTS

        10.1   Other Filings...............................................................32
        10.2   Additional Agreements.......................................................32
</TABLE>

                                       ii

<PAGE>   4



<TABLE>

                                   ARTICLE XI
                        TERMINATION, AMENDMENT AND WAIVER
<S>     <C>                                                                                <C>
        11.1   Termination.................................................................33
        11.2   Effect of Termination.......................................................34
        11.3   Amendment...................................................................34
        11.4   Waiver......................................................................34

                                   ARTICLE XII
                               GENERAL PROVISIONS

        12.1   Notices.....................................................................34
        12.2   Miscellaneous...............................................................36
        12.3   Directors' and Officers Insurance...........................................36
        12.4   Assignment..................................................................37
        12.5   Expenses....................................................................37
        12.6   Severability................................................................37
        12.7   Parent Co. Guarantee........................................................37
        12.8   Counterpart Execution.......................................................37

        SCHEDULE A      -   CONDITIONS TO THE OFFER
        SCHEDULE B      -   FORM OF PRE-TENDER AGREEMENT
</TABLE>

                                      iii

<PAGE>   5


                            PRE-ACQUISITION AGREEMENT


        THIS PRE-ACQUISITION AGREEMENT (the "Agreement") is made and entered
into as of this 13th day of December, 2000, by and between Tom Brown, Inc., a
corporation formed under the laws of the State of Delaware with its head and
principal office in the City of Denver, in the State of Colorado ("Parent Co."),
Tom Brown Resources Ltd., a corporation formed under the laws of the Province of
Alberta with an office in the City of Calgary, in the Province of Alberta ("A
Co.") and Stellarton Energy Corporation, a corporation duly amalgamated under
and governed by the laws of the Province of Alberta with its head and principal
office in the City of Calgary, in the Province of Alberta ("Stellarton"). Except
as otherwise set forth in this Agreement, capitalized terms shall have the
meanings set forth in Article 1.

RECITALS:

1.      The board of directors of Stellarton wishes to encourage Parent Co. to
        make a take-over bid to the securityholders of Stellarton by offering to
        purchase all of the issued and outstanding common shares of Stellarton.

2.      Parent Co., through its wholly-owned subsidiary A Co., is willing to
        make an offer subject to the terms and conditions of this Agreement.

3.      Parent Co. has agreed to guarantee the obligations of A Co. as
        contemplated herein.

4.      The board of directors of Stellarton has unanimously determined to
        recommend acceptance of the A Co. offer to the securityholders of
        Stellarton, to cooperate with A Co. and to take all reasonable action to
        support the A Co. offer.

5.      The board of directors of Stellarton has determined that it would be in
        the best interests of Stellarton to enter into this Agreement.

        NOW THEREFORE, in consideration of the mutual covenants hereinafter
contained and other good and valuable consideration (the receipt and adequacy
whereof is hereby acknowledged), the parties hereto agree as follows:


                                    ARTICLE I
                                 INTERPRETATION

1.1     DEFINITIONS

        In this Agreement, unless there is something in the subject matter or
context inconsistent therewith:

"A Co." means Tom Brown Resources Ltd., a wholly-owned subsidiary of Parent Co.;


                                       1
<PAGE>   6

"Act" means the Business Corporations Act (Alberta) as the same has been and may
hereafter from time to time be amended;

"affiliate" has the meaning set forth in the Act;

"Agreement", "this Agreement", "herein", "hereto", and "hereof" and similar
expressions refer to this Agreement, as the same may be amended or supplemented
from time to time and, where applicable, to the appropriate Schedules hereto;

"Business Day" means any day excepting a Saturday, Sunday or statutory holiday
in Calgary, Alberta;

"Corporate Laws" means all applicable corporate laws, including the Act;

"Data Room" means the data room maintained by Stellarton in connection with its
efforts to solicit proposals for the acquisition of Stellarton;

"diluted basis" means, with respect to the number of outstanding Stellarton
Shares at any time, such number of outstanding Stellarton Shares calculated
assuming that all outstanding options to purchase Stellarton Shares are
exercised;

"Disclosed Information" means the information disclosed to Parent Co. or A Co.
pursuant to or contemplated by the Parent Co. Confidentiality Agreement or made
available to Parent Co. or A Co. (or their respective representatives) in the
Data Room;

"Effective Time" means the time that A Co. shall have acquired ownership of and
paid for at least the Minimum Required Shares pursuant to the terms of the
Offer;

"Expiry Time" means the Initial Expiry Time unless the Offer has been extended,
in which case it means the expiry time of the Offer as extended from time to
time;

"in writing" means written information including documents, files, records,
books and other materials made available, delivered or produced to Parent Co. or
A Co. by or on behalf of Stellarton in the course of conducting its due
diligence review in respect of Stellarton between October 5, 2000, being the
date of the Parent Co. Confidentiality Agreement, and the date of this
Agreement;

"Initial Expiry Time" means 5:00 p.m. (Calgary time) on the first Business Day
which falls after the 21st day following the day of the mailing of the Offer
Documents to the shareholders of Stellarton (where the first day of this period
is the day immediately following the day of mailing);

"Material Adverse Change" means any change (or any condition, event or
development involving a prospective change) in the business, operations, results
of operations, petroleum and natural gas reserves, assets, capitalization,
financial condition, licenses, permits, leases, concessions, rights,
liabilities, prospects or privileges, whether contractual or otherwise, of
Stellarton and its subsidiaries which is materially adverse to the business of
Stellarton and its subsidiaries, considered as a whole, other than a change (i)
which arises out of hedging activities


                                       2
<PAGE>   7

undertaken by Stellarton prior to the date hereof, consistent with past
practice, (ii) which arises out of a matter that has been publicly disclosed or
otherwise disclosed in writing to A Co. prior to the date of this Agreement,
(iii) resulting from conditions affecting the oil and gas industry as a whole;
(iv) resulting from general economic, financial, currency exchange, securities
or commodity market conditions in Canada or elsewhere; or (v) resulting from the
drilling, completion or testing of any wells establishing that any such well or
prospect is not commercially viable or is less successful than anticipated by
Stellarton;

"Material Adverse Effect" means any event, change or effect that is or would
reasonably be expected to be materially adverse to the financial condition,
operations, assets, liabilities, or business of Stellarton and its subsidiaries,
considered as a whole; provided that a Material Adverse Effect shall not include
an adverse effect resulting from a change (i) which arises out of hedging
activities undertaken by Stellarton prior to the date hereof, consistent with
past practice, (ii) which arises out of a matter that has been publicly
disclosed or otherwise disclosed in writing to Parent Co. or A Co. prior to the
date of this Agreement, (iii) resulting from conditions affecting the oil and
gas industry as a whole; (iv) resulting from general economic, financial,
currency exchange, securities or commodity market conditions in Canada or
elsewhere; or (v) resulting from the drilling, completion or testing of any
wells establishing that any such well or prospect is not commercially viable or
is less successful than anticipated by Stellarton;

"Minimum Condition" means the condition set forth in paragraph (a) of Schedule
A;

"Minimum Required Shares" means at least that number of the outstanding
Stellarton Shares required pursuant to the Minimum Condition unless A Co. shall
have waived the Minimum Condition in which case "Minimum Required Shares" means
that number of the outstanding Stellarton Shares which A Co. takes up on the
Take-up Date, provided that such number of Stellarton Shares shall not be less
than 50% of the issued and outstanding Stellarton Shares on a diluted basis;

"Offer" has the meaning set forth in Section 2.1(a);

"Offer Documents" has the meaning set forth in Section 2.3(a);

"Officer Obligations" means any obligations or liabilities of Stellarton or any
of its subsidiaries to pay any amount to its or their officers, directors, or
employees, other than for salary, bonuses under its or their existing bonus
arrangements and directors' fees in the ordinary course in each case in amounts
consistent with historic practices and obligations or liabilities in respect of
insurance or indemnification contemplated by this Agreement or arising in the
ordinary and usual course of business and subject to Corporate Laws and, without
limiting the generality of the foregoing, Officer Obligations shall include the
obligations of Stellarton or any of its subsidiaries to officers or employees
(i) for severance or termination payments on or in connection with the change of
control of Stellarton pursuant to any executive involuntary severance and
termination agreements in the case of officers and pursuant to Stellarton's
severance policy in the case of employees; or (ii) retention bonus payments
pursuant to any retention bonus program, all as previously disclosed in the
Disclosed Information to A Co.;


                                       3
<PAGE>   8

"Parent Co. Confidentiality Agreement" means the confidentiality agreement dated
October 5, 2000 between Parent Co. and Stellarton;

"Second Stage Transaction" has the meaning set forth in Section 4.1;

"Securities Authorities" means the appropriate securities commissions or similar
regulatory authorities in Canada and each of the provinces and territories
thereof and in the United States and each of the states thereof;

"Securities Laws" has the meaning set forth in Section 2.3(a);

"Stellarton" means Stellarton Energy Corporation;

"Stellarton Governing Documents" means the Certificate and Articles of
Amalgamation and By-laws of Stellarton;

"Stellarton Options" means the outstanding options to acquire Stellarton Shares
under the Stock Option Plan;

"Stellarton Shares" means the Class A Voting Common Shares in the share capital
of Stellarton;

"Stock Option Plan" means the amended and restated stock option plan of
Stellarton dated May 25, 2000;

"subsidiary" has the meaning set forth in the Act;

"Superior Proposal" has the meaning ascribed to such terms in Section 8.3;

"Take-over Proposal" means a proposal or offer by a third party (other than by A
Co.), whether or not subject to a due diligence condition and whether or not in
writing, to acquire in any manner, directly or indirectly, beneficial ownership
of all or a material portion of the assets of Stellarton or to acquire in any
manner, directly or indirectly, beneficial ownership or control or direction
over more than 20% of the outstanding voting shares of Stellarton whether by an
arrangement, amalgamation, a merger, consolidation or other business
combination, by means of a sale of shares of capital stock, sale of assets,
tender offer or exchange offer or similar transaction involving Stellarton
including without limitation any single or multi-step transaction or series of
related transactions which is structured to permit such third party to acquire
beneficial ownership of all or a material portion of the assets of Stellarton or
to acquire in any manner, directly or indirectly, more than 20% of the
outstanding voting shares of Stellarton (other than the transactions
contemplated by this Agreement); and

"Take-up Date" means the date that A Co. first takes up and acquires Stellarton
Shares pursuant to the Offer.

1.2 SINGULAR, PLURAL, ETC.

        Words importing the singular number include the plural and vice versa
and words importing gender include the masculine, feminine and neuter genders.


                                       4
<PAGE>   9

1.3     DEEMED CURRENCY

        In the absence of a specific designation of any currency any undescribed
dollar amount herein shall be deemed to refer to Canadian dollars.

1.4     HEADINGS, ETC.

        The division of this Agreement into Articles and Sections, the provision
of a table of contents hereto and the insertion of the recitals and headings are
for convenience of reference only and shall not affect the construction or
interpretation of this Agreement and, unless otherwise stated, all references in
this Agreement or in the Schedules to Articles, Sections and Schedules refer to
Articles, Sections and Schedules of and to this Agreement or of the Schedules in
which such reference is made.

1.5     DATE FOR ANY ACTION

        In the event that any date on which any action is required to be taken
hereunder by any of the parties hereunder is not a Business Day, such action
shall be required to be taken on the next succeeding day which is a Business
Day.

1.6     GOVERNING LAW

        This Agreement shall be governed by and interpreted in accordance with
the laws of the Province of Alberta and the laws of Canada applicable therein.

1.7     ATTORNMENT

        The parties hereby irrevocably and unconditionally consent to and submit
to the courts of the Province of Alberta for any actions, suits or proceedings
arising out of or relating to this Agreement or the matters contemplated hereby
(and agree not to commence any action, suit or proceeding relating thereto
except in such courts) and further agree that service of any process, summons,
notice or document by single registered mail to the addresses of the parties set
forth in this Agreement shall be effective service of process for any action,
suit or proceeding brought against either party in such court. The parties
hereby irrevocably and unconditionally waive any objection to the laying of
venue of any action, suit or proceeding arising out of this Agreement or the
matters contemplated hereby in the courts of the Province of Alberta and hereby
further irrevocably and unconditionally waive and agree not to plead or claim in
any such court that any such action, suit or proceeding so brought has been
brought in an inconvenient forum.

1.8     INCORPORATION OF SCHEDULES

        Schedules A and B attached hereto and described below shall, for all
purposes hereof, form an integral part of this Agreement.

               Schedule A           Conditions to the Offer
               Schedule B           Form of Pre-tender Agreement


                                       5
<PAGE>   10

                                   ARTICLE II
                                    THE OFFER

2.1     THE OFFER

        (a)    Subject to the terms and conditions of this Agreement, A Co.
               shall use commercially reasonable efforts to mail before 11:59
               p.m. (Calgary time) on December 20, 2000 and in any event not
               later than 11:59 p.m. (Calgary time) on December 22, 2000, an
               offer to purchase all of the outstanding Stellarton Shares, which
               includes all Stellarton Shares which may become outstanding after
               the date of the Offer on the exercise of Stellarton Options for a
               cash consideration of $5.00 for each Stellarton Share which offer
               shall be made in accordance with Securities Laws and Corporate
               Laws and be subject only to the conditions set forth in Schedule
               A hereto (the "Offer", which term shall include any amendments
               to, or extensions of, such Offer, including, without limitation,
               increasing the consideration, removing or waiving any condition,
               as permitted, or extending the date by which Stellarton Shares
               may be tendered). The documentation relating to the Offer (the
               "Offer Documents") shall be prepared in both the English and
               French languages and in accordance with Securities Laws and
               Corporate Laws. A Co. shall, on a confidential basis, provide
               Stellarton with a draft of the Offer Documents prior to mailing
               for its review and comment, with the intent that Stellarton will
               have a reasonable opportunity to review and provide comments in
               respect of the Offer Documents. It is understood that the content
               of the Offer Documents will be determined by A Co., provided that
               such Offer Documents will not contain any information or
               statements that are inconsistent with matters that are
               specifically addressed or provided for in this Agreement or as
               otherwise contemplated hereby.

        (b)    Parent Co. may make the Offer itself, or through one or more
               direct or indirect wholly-owned subsidiaries, or any combination
               thereof (which, for the purposes hereof, may include a trust or
               partnership, all of the beneficiaries or partners of which are
               direct or indirect subsidiaries of Parent Co.). In the event that
               any such entities makes the Offer, the term "A Co." as used
               herein shall include all of such entities, but Parent Co. shall
               continue to be liable to Stellarton, as principal obligor, for A
               Co.'s obligations hereunder and for any default in performance by
               any such party.

        (c)    The Offer shall expire at the Initial Expiry Time, except that
               the Offer may be extended, subject to 2.1(d), at the sole
               discretion of A Co., if the conditions thereto set forth in
               Schedule A are not satisfied on the date and time at which the
               Offer expires or if A Co. shall have taken up the Minimum
               Required Shares under the Offer. If A Co. acquires the Minimum
               Required Shares pursuant to the Offer but the number of
               Stellarton Shares acquired at such time is less than the Minimum
               Condition, it will publicly announce such fact and extend the
               Offer for at least 10 days.


                                       6
<PAGE>   11

               Upon the satisfaction or waiver of the conditions set forth in
               Schedule A hereto, A Co. shall within one (1) Business Day,
               accept for payment and pay for all Stellarton Shares validly
               tendered (and not properly withdrawn) pursuant to the Offer. Each
               of A Co. and Stellarton shall use all commercially reasonable
               efforts to consummate the Offer, subject to the terms and
               conditions thereof.

               Notwithstanding the foregoing, if the conditions set out in
               paragraphs (b) or (c) of Schedule A have not been satisfied or
               waived on the Initial Expiry Time, A Co. agrees to extend the
               Offer for such period of time, not to exceed 60 days following
               the Initial Expiry Time, as is necessary to satisfy or fulfill
               such conditions, but only if A Co. has made a bona fide
               determination, acting reasonably, that there is a reasonable
               prospect that such conditions may be satisfied within such 60 day
               period.

        (d)    It is agreed that A Co. may, in its sole discretion:

               (i)    waive in whole or in part, any term or condition of the
                      Offer at any time and from time to time, provided that if
                      A Co. takes up and pays for any Stellarton Shares it shall
                      acquire not less than the Minimum Required Shares; and

               (ii)   amend any term or condition of the Offer, provided that A
                      Co. shall not:

                      (A)    change the number of Stellarton Shares for which
                             the Offer is made;

                      (B)    decrease the value or change the form of the
                             consideration to be paid for each Stellarton Share
                             provided that A Co. shall be permitted to increase
                             the consideration to be paid for each Stellarton
                             Share; or

                      (C)    modify or impose additional conditions to the Offer
                             in a manner that is, in the opinion of Stellarton,
                             acting reasonably, materially adverse to the
                             holders of Stellarton Shares (it being understood
                             that an extension of the Offer or a permitted
                             waiver of any condition thereto will not be
                             considered to be adverse to the holders of
                             Stellarton Shares).

        (e)    A Co. will instruct the depositary under the Offer to advise
               Stellarton from time to time, not less frequently than daily
               commencing five Business Days prior to the Initial Expiry Time
               until the day immediately prior to the Expiry Time and thereafter
               on an hourly basis, if requested by Stellarton and in such manner
               as Stellarton may reasonably request, as to the number of
               Stellarton Shares that have been tendered (and not withdrawn)
               under the Offer; provided that, subject to its public disclosure
               obligations under Corporate Laws, Securities Laws or stock
               exchange rules, Stellarton shall keep such information
               confidential. Stellarton agrees that A Co. may, if it so decides,
               retain Stellarton's transfer agent as the depositary and as
               information agent under the Offer.


                                       7
<PAGE>   12

        (f)    The obligation of A Co. to make the Offer as set forth in Section
               2.1(a) shall be conditional upon the following:

               (i)    no Material Adverse Change shall have occurred in respect
                      of Stellarton, no person shall have brought or threatened
                      to bring a bona fide action for injunctive relief against
                      the performance of this Agreement or the completion of the
                      Offer or for material damages against A Co. in connection
                      with this Agreement or the completion of the Offer and no
                      other event shall have occurred or circumstance shall
                      exist which would make it impracticable in the opinion of
                      A Co, acting reasonably, to satisfy one or more of the
                      conditions of the Offer described in Schedule A;

               (ii)   as at the date that the Offer is to be made, no
                      representation or warranty by Stellarton contained in this
                      Agreement shall have been determined by A Co., acting
                      reasonably, to be inaccurate in any material respect (or
                      in the case of representations and warranties that are
                      themselves qualified by a materiality limitation,
                      determined to be inaccurate) and no breach by Stellarton
                      of, or non-compliance by Stellarton with, any covenant or
                      obligation contained in this Agreement shall in a material
                      respect have occurred;

               (iii)  the board of directors of Stellarton shall have provided
                      and not have withdrawn, modified or changed any of its
                      recommendations, approvals, resolutions, or determinations
                      referred to in Section 2.2(a); and

               (iv)   A Co.'s receipt, concurrent with the execution of this
                      Agreement, of duly executed pre-tender agreements dated
                      the date hereof substantially in the form attached hereto
                      as Schedule B from each of the directors and senior
                      officers of Stellarton and certain other shareholders of
                      Stellarton in respect of Stellarton Shares which, in
                      aggregate, represent not less than 42% of the Stellarton
                      Shares on a diluted basis.

               The foregoing conditions are for the exclusive benefit of A Co.
               and may be waived by A Co., in whole or in part at any time and
               from time to time.

        (g)    Stellarton agrees to provide A Co. a certificate of the President
               or other officer of Stellarton acceptable to A Co., in such
               officer's capacity as an officer of Stellarton and not in such
               officer's personal capacity, dated the date of the Offer and on
               the Take-up Date under the Offer to the effect that Stellarton
               has complied with its covenants and obligations under the
               Agreement and that the representations and warranties of
               Stellarton contained in the Agreement are true and correct as of
               such date with the same force and effect as if given on and as of
               the date of such certificate.

2.2     STELLARTON DIRECTORS' CIRCULAR

        (a)    Stellarton hereby consents to the Offer as set forth in Section
               2.1 and confirms that its board of directors has (i) unanimously
               approved the Offer and this


                                       8
<PAGE>   13

               Agreement, (ii) after receiving the advice of its financial
               advisor, has determined that the consideration to be offered to
               Stellarton's shareholders pursuant to the Offer is fair, from a
               financial point of view, to the holders of Stellarton Shares and
               is in the best interests of Stellarton, and (iii) has unanimously
               resolved to recommend acceptance of the Offer by the holders of
               Stellarton Shares.

        (b)    Stellarton shall prepare and make available for mailing, in both
               the English and French languages, sufficient copies of a
               directors' circular prepared in accordance with Securities Laws
               and Corporate Laws. The directors' circular will set forth (among
               other things) the recommendation of the board of directors of
               Stellarton as described in Section 2.2(a). Stellarton shall
               provide A Co. with a draft copy of the directors' circular prior
               to its finalization and in reasonably sufficient time for A Co.'s
               review and comment, and the parties shall use all commercially
               reasonable efforts to cause the directors' circular to be mailed
               together with the Offer Documents without any delay in the time
               the Offer Documents would otherwise be mailed.

        (c)    After reasonable inquiry, Stellarton has been advised that each
               of the directors and senior officers of Stellarton intend to
               tender their Stellarton Shares under the Offer and to exercise
               their "in the money" options to acquire Stellarton Shares or to
               receive payment therefore as contemplated by Section 2.4.
               Stellarton hereby delivers concurrently with the execution of
               this Agreement, pre-tender agreements (in the form or
               substantially in the form of the agreement attached hereto as
               Schedule B) duly executed by such directors and senior officers
               in respect of 6,132,565 Stellarton Shares and Stellarton Options.
               The directors' circular shall reflect the execution and delivery
               of such pre-tender agreements and the agreement of the directors
               and senior officers to tender their Stellarton Shares pursuant to
               the Offer.

        (d)    Stellarton represents that it has obtained oral advice from
               Waterous Securities Inc. that the consideration to be offered to
               Stellarton's shareholders pursuant to the Offer is fair, from a
               financial point of view, to holders of Stellarton Shares and that
               such financial advisor will provide a written fairness opinion to
               such effect on or before the date of the directors circular. The
               fairness opinion will be attached to or referred to in the
               directors' circular referred to in Section 2.2(b).

2.3     OFFER DOCUMENTS

        (a)    A Co. shall file or cause to be filed with the appropriate
               Securities Authorities an Offer to Purchase and Take-over Bid
               Circular and the related Letter of Transmittal and Notice of
               Guaranteed Delivery pursuant to which the Offer will be made
               (collectively, the "Offer Documents"). The Offer Documents, when
               filed with Securities Authorities and when mailed to holders of
               Stellarton Shares, shall contain (or shall be amended in a timely
               manner to contain) all information which is required to be
               included therein in accordance with the Act and any applicable
               Canadian provincial securities laws, United States securities
               laws, the "blue sky"


                                       9
<PAGE>   14

               or securities laws of the states of the United States and any
               other applicable law (collectively, the "Securities Laws") and
               all Corporate Laws.

        (b)    Stellarton agrees to provide such assistance as A Co. or its
               agents may reasonably request in connection with communicating
               the Offer and any amendments and supplements thereto to the
               holders of the Stellarton Shares and to such other persons as are
               entitled to receive the Offer under Securities Laws, including
               providing lists and updated or supplemental lists of the
               shareholders of Stellarton and of the holders of Stellarton
               Options and other securities convertible into or exchangeable for
               Stellarton Shares and mailing labels with respect to all such
               holders of securities as soon as possible after the date of this
               Agreement but in any event no later than the close of business in
               Calgary on December 15, 2000 and updates or supplements thereto
               from time to time as may be requested by A Co.

2.4     OUTSTANDING STOCK OPTIONS

        (a)    Subject to the receipt of any necessary regulatory approvals,
               persons holding options pursuant to the Stock Option Plan who may
               do so under Securities Laws and in accordance with the Stock
               Option Plan (or pursuant to this section 2.4) shall be entitled
               to exercise all of their options and tender all Stellarton Shares
               issued in connection therewith under the Offer. The Stellarton
               board of directors shall not, prior to completion of the Offer,
               grant additional options pursuant to the Stock Option Plan. It is
               agreed by A Co. that all Stellarton Options which have been
               tendered to Stellarton for exercise, conditional on A Co. taking
               up Stellarton Shares under the Offer ("Conditional Option
               Exercise"), shall be deemed to have been exercised concurrently
               with the take-up of Stellarton Shares by A Co. Furthermore, A Co.
               shall accept as validly tendered under the Offer as of the
               Take-up Date all Stellarton Shares which are to be issued
               pursuant to the Conditional Option Exercise, provided that the
               holders of such options indicate that such shares are tendered
               pursuant to the Offer and provided that such holder agrees to
               surrender their remaining unexercised options to Stellarton for
               cancellation for no consideration effective immediately after the
               Take-up Date.

        (b)    Stellarton and A Co. agree that to the extent holders of
               Stellarton Options do not exercise their Stellarton Options and
               tender the Stellarton Shares they receive upon such exercise,
               Stellarton may agree with all remaining holders of Stellarton
               Options that, in lieu of such persons exercising their Stellarton
               Options, Stellarton will pay to such persons the difference
               between the exercise price of their Stellarton Options and the
               purchase price for the Stellarton Shares under the Offer
               immediately after the Expiry Time of the Offer in exchange for
               the termination of their Stellarton Options and provided that
               such holder agrees to surrender their remaining unexercised
               options to Stellarton for cancellation for no consideration
               effective immediately after the Take-up Date.

        (c)    Stellarton and A Co. agree that with respect to holders of
               Stellarton Options with exercise prices equal to or greater than
               $5.00 per Stellarton Share (other than any



                                       10
<PAGE>   15

               holder who is a director or officer of Stellarton), Stellarton
               may, on behalf of A Co., pay such person $0.05 for each
               Stellarton Option to purchase one (1) Stellarton Share in
               exchange for the cancellation of such Stellarton Option
               immediately after the Expiry Time of the Offer, provided that a
               holder of Stellarton Options receiving payment under this
               paragraph (c) shall not also be entitled to payment for the same
               Stellarton Options under paragraph (b) above.

        (d)    Stellarton agrees to use its reasonable commercial efforts and
               represents that its directors have:

               (i)    determined to use their respective reasonable commercial
                      efforts to encourage and facilitate all persons holding
                      options to acquire Stellarton shares to either:

                      (A)    exercise those options and tender all Stellarton
                             Shares issued in connection therewith to the Offer;
                             or

                      (B)    agree with Stellarton to the payment described in
                             Sections 2.4(b) and (c); or

                      (C)    terminate their rights to exercise any of those
                             Stellarton Options;

                      prior to the Expiry Time of the Offer;

               (ii)   authorized and directed Stellarton to cause the vesting of
                      option entitlements under the Stock Option Plan to
                      accelerate prior to or concurrently with the completion of
                      the Offer, such that all outstanding Stellarton Options
                      shall be exercisable and fully vested prior to the Expiry
                      Time of the Offer; and

               (iii)  determined to use reasonable commercial efforts to amend
                      the Stock Option Plan or applicable option agreements so
                      as to allow for the payment described in Section 2.4(b).


                                   ARTICLE III
                           PUBLICITY AND SOLICITATION

3.1     PUBLICITY

        (a)    So long as this Agreement is in effect, each of Parent Co., A Co.
               and Stellarton shall advise, consult and cooperate with the other
               party prior to issuing, or permitting any of its directors,
               officers, employees or agents to issue, any press release or
               other written public or private statement to the press with
               respect to this Agreement, the transactions contemplated hereby
               or any other matters from the date hereof until the Expiry Time.
               Parent Co., A Co. and Stellarton shall not issue any such press
               release or make any such written public or private statement
               prior to such consultation, except as may be required by
               applicable law or by


                                       11
<PAGE>   16

               obligations pursuant to any listing agreement with a stock
               exchange and only after using its reasonable efforts to consult
               the other party taking into account the time constraints to which
               it is subject as a result of such law or obligation.

        (b)    Stellarton and A Co. agree that a joint press release shall be
               issued immediately following the execution of this Agreement.

3.2     SOLICITATION

        Lehman Brothers Canada Inc. has been selected by A Co. to act as dealer
manager (the "Dealer Manager") in connection with the Offer and solicit
acceptances of the Offer. The Dealer Manager will form a soliciting dealer group
comprised of members of the Investment Dealers Association of Canada and of the
stock exchanges in Canada and their United States broker dealer affiliates to
solicit acceptances of the Offer.


                                   ARTICLE IV
                 TRANSACTIONS FOLLOWING COMPLETION OF THE OFFER

4.1     SECOND STAGE TRANSACTION

        If A Co. takes up and pays for Stellarton Shares pursuant to the terms
of the Offer, and thereby acquires at least the Minimum Required Shares, A Co.
agrees to use all commercially reasonable efforts to acquire, and Stellarton
agrees to use all commercially reasonable efforts to assist A Co. in acquiring,
the balance of the Stellarton Shares by way of a statutory arrangement,
amalgamation, merger, reorganization, consolidation, recapitalization or other
type of acquisition transaction or transactions ("Second Stage Transaction")
carried out for consideration per Stellarton Share which (i) consists of the
same kind or kinds of consideration paid pursuant to the Offer, and (ii) in
respect of each such kind of consideration, is not less than the consideration
paid pursuant to the Offer. Nothing herein shall be construed to prevent A Co.
from acquiring, directly or indirectly, additional Stellarton Shares in the open
market or in privately negotiated transactions, in another take-over bid, tender
or exchange offer, or otherwise in accordance with Securities Laws (including by
way of compulsory acquisition) following completion of the Offer.

4.2     INFORMATION CIRCULAR, ETC.

        Without limiting Section 4.1, Stellarton agrees that if A Co. is
required to effect a Second Stage Transaction which requires approval of
Stellarton's shareholders in a meeting of Stellarton's shareholders, Stellarton
shall take all action necessary in accordance with Securities Laws, other
applicable Canadian laws, the Stellarton Governing Documents and the
requirements of The Toronto Stock Exchange or any other regulatory authority
having jurisdiction to duly call, give notice of, convene and hold a meeting of
its shareholders as promptly as practicable to consider and vote upon the action
proposed by A Co. In the event of such a meeting or meetings, Stellarton shall
use all commercially reasonable efforts to mail to its shareholders an
Information Circular with respect to the meeting of Stellarton's shareholders.
The term "Information Circular" shall mean such proxy or other required
informational statement or circular, as the case may be, and all related
materials at the time required to be mailed to


                                       12
<PAGE>   17

Stellarton's shareholders and all amendments or supplements thereto, if any. A
Co. and Stellarton each shall use all commercially reasonable efforts to obtain
and furnish the information required to be included in any Information Circular.
The information provided and to be provided by A Co. and Stellarton for use in
the Information Circular, on both the date the Information Circular is first
mailed to Stellarton's shareholders and on the date any such meeting is held,
shall not contain any untrue statement of a material fact or omit to state a
material fact required to be stated therein or necessary to make the statements
therein, in light of the circumstances under which they are made, not misleading
and will comply in all material respects with all applicable requirements of
law. A Co. and Stellarton each agree to correct promptly any such information
provided by it for use in any Information Circular which shall have become false
or misleading.


                                    ARTICLE V
             REPRESENTATIONS AND WARRANTIES OF PARENT CO. AND A CO.

        Parent Co. and A Co. jointly and severally hereby represent and warrant
to Stellarton as follows and acknowledge that Stellarton is relying upon these
representations and warranties in connection with the entering into of this
Agreement:

5.1     ORGANIZATION AND QUALIFICATION

        Each of Parent Co. and A Co. is a corporation duly incorporated and
organized and validly existing under the laws of its respective jurisdiction of
incorporation and has the requisite corporate power and authority to carry on
its respective business as it is now being conducted.

5.2     AUTHORITY RELATIVE TO THIS AGREEMENT

        Each of Parent Co. and A Co. have the requisite corporate authority to
enter into this Agreement and to carry out its respective obligations hereunder.
The execution and delivery of this Agreement and the consummation by each of
Parent Co. and A Co. of the transactions contemplated hereby have been duly
authorized by each of the Parent Co. and A Co. boards of directors and no other
corporate proceedings on their part are or will be necessary to authorize this
Agreement and the transactions contemplated hereby. This Agreement has been duly
executed and delivered by each of Parent Co. and A Co. and constitutes legal,
valid and binding obligations of each of Parent Co. and A Co. enforceable
against them in accordance with its terms, subject to bankruptcy, insolvency,
fraudulent transfer, reorganization, moratorium and other laws relating to or
affecting creditors' rights generally and to general principles of equity.

5.3     NO VIOLATIONS

        (a)    Neither the execution and delivery of this Agreement by Parent
               Co. and A Co., the consummation by them of the transactions
               contemplated hereby nor compliance by them with any of the
               provisions hereof will: (i) violate, conflict with, or result in
               breach of any provision of, require any consent, approval or
               notice under, or constitute a default (or an event which, with
               notice or lapse of time or both, would constitute a default) or
               result in a right of termination or acceleration under, or result
               in a creation of any lien, security interest, charge or


                                       13
<PAGE>   18

               encumbrance upon any of the properties or assets of Parent Co. or
               A Co. or any of their subsidiaries under any of the terms,
               conditions or provisions of (x) the charter or bylaws of Parent
               Co. or A Co. or (y) any material note, bond, mortgage, indenture,
               loan agreement, deed of trust, agreement, lien, contract or other
               instrument or obligation to which Parent Co. or A Co. or any of
               their subsidiaries is a party or to which any of them, or any of
               their respective properties or assets, may be subject or by which
               Parent Co. or A Co. or any of their subsidiaries is bound; or
               (ii) subject to compliance with the statutes and regulations
               referred to in Section 5.3(b), violate any judgment, ruling,
               order, writ, injunction, determination, award, decree, statute,
               ordinance, rule or regulation applicable to Parent Co. or A Co.
               or any of their subsidiaries (except, in the case of each of
               clauses (i) and (ii) above, for such violations, conflicts,
               breaches, defaults, terminations, accelerations or creations of
               liens, security interests, charges or encumbrances which, or any
               consents, approvals or notices which if not given or received,
               would not have any Material Adverse Effect on the business,
               operations or financial condition of Parent Co. or A Co. and
               their respective subsidiaries taken as a whole or on the ability
               of Parent Co. or A Co. to consummate the transactions
               contemplated hereby); or (iii) cause the suspension or revocation
               of any authorization, consent, approval or license currently in
               effect which would have a Material Adverse Effect on the
               business, operations and financial condition of Parent Co. or A
               Co. and their subsidiaries taken as a whole.


        (b)    Other than in connection with or in compliance with the
               provisions of Corporate Laws, Securities Laws the United States
               Securities Exchange Act of 1934, as amended, state securities or
               "blue-sky" laws of the states of the United States, as amended
               and any pre-merger notification statutes, (i) there is no legal
               impediment to Parent Co.'s or A Co.'s consummation of the
               transactions contemplated by this Agreement and (ii) no filing or
               registration with, or authorization, consent or approval of, any
               domestic or foreign public body or authority is necessary by
               Parent Co. or A Co. in connection with the making or the
               consummation of the Offer, except for such filings or
               registrations which, if not made, or for such authorizations,
               consents or approvals, which, if not received, would not have a
               material adverse effect on the ability of Parent Co. or A Co. to
               consummate the transactions contemplated hereby.

5.4     AVAILABILITY OF FUNDS

        The aggregate cash consideration payable pursuant to the Offer is
available to A Co. so that A Co. is in a position to pay for all Stellarton
Shares tendered pursuant to the Offer in accordance with the terms of the Offer
and to pay all related fees and expenses; and A Co. will provide written
confirmation of its lenders, in a form satisfactory to Stellarton, acting
reasonably, dated the date hereof, to such effect.


                                       14
<PAGE>   19

5.5     KNOWLEDGE

        As of the date hereof, neither Parent Co. nor A Co. has any actual
knowledge of any misrepresentation, breach or non-performance by Stellarton of
any representation, warranty or covenant contained in this Agreement which would
have or would be reasonably likely to have a Material Adverse Effect on
Stellarton should the Offer be completed.


                                   ARTICLE VI
                  REPRESENTATIONS AND WARRANTIES OF STELLARTON

        Stellarton hereby represents and warrants (and, as applicable,
covenants) to Parent Co. and A Co. as follows and acknowledges that Parent Co.
and A Co. are relying upon these representations and warranties in connection
with the entering into of this Agreement:

6.1     ORGANIZATION AND QUALIFICATION

        Stellarton is a corporation duly amalgamated and organized and validly
existing under the laws of Alberta and has the requisite corporate power and
authority to own its properties and carry on its business as now owned and being
conducted. Stellarton is duly registered to do business and is in good standing
in each jurisdiction in which the character of its properties, owned or leased,
or the nature of its activities make such registration necessary, except where
the failure to be so registered or in good standing would not have a Material
Adverse Effect on Stellarton.

6.2     AUTHORITY RELATIVE TO THIS AGREEMENT

        Stellarton has the requisite corporate authority to enter into this
Agreement and to carry out its obligations hereunder. The execution and delivery
of this Agreement and the consummation of the transactions contemplated hereby
have been duly authorized by Stellarton's board of directors, and no other
corporate proceedings on the part of Stellarton are necessary to authorize this
Agreement (except for obtaining shareholder approval in respect of any Second
Stage Transaction) and the transactions contemplated hereby. This Agreement has
been duly executed and delivered by Stellarton and constitutes a legal, valid
and binding obligation of Stellarton enforceable against Stellarton in
accordance with its terms, subject to bankruptcy, insolvency, fraudulent
transfer, reorganization, moratorium and other laws relating to or affecting
creditors' rights generally and to general principles of equity.

6.3     NO VIOLATIONS

        (a)    Except as previously disclosed in the Disclosed Information to
               either Parent Co. or A Co., neither the execution and delivery of
               this Agreement by Stellarton, the consummation by it of the
               transactions contemplated hereby nor compliance by Stellarton
               with any of the provisions hereof will: (i) violate, conflict
               with, or result in a breach of any provision of, require any
               consent, approval or notice under, or constitute a default (or an
               event which, with notice or lapse of time or both, would
               constitute a default) or result in a right of termination or
               acceleration under, or result in a creation of any lien, security
               interest, charge or encumbrance


                                       15
<PAGE>   20

               upon any of the properties or assets of Stellarton or any of its
               subsidiaries under, any of the terms, conditions or provisions of
               (x) the Stellarton Governing Documents or (y) any material note,
               bond, mortgage, indenture, loan agreement, deed of trust,
               agreement, lien, contract or other instrument or obligation to
               which Stellarton or any of its subsidiaries is a party or to
               which Stellarton or any of its subsidiaries or any of their
               respective properties or assets, may be subject or by which
               Stellarton or any of its subsidiaries is bound, other than a
               potential breach of the Credit Facility with the National Bank of
               Canada dated April 12, 1998, as amended by letter agreements
               dated July 15, 2000, August 4, 2000 and November 6, 2000, and the
               Fixed and Floating Charge Demand Debenture and Negative Pledge
               issued by Stellarton to the National Bank of Canada dated October
               17, 1996, arising from a change of control and as a result of the
               necessity for lender consent; (ii) subject to compliance with the
               statutes and regulations referred to in Section 6.3(b), violate
               any judgment, ruling, order, writ, injunction, determination,
               award, decree, statute, ordinance, rule or regulation applicable
               to Stellarton or any of its subsidiaries (except, in the case of
               each of clauses (i) and (ii) above, for such violations,
               conflicts, breaches, defaults, terminations which, or any
               consents, approvals or notices which if not given or received,
               would not have any Material Adverse Effect on the business,
               operations or financial condition of Stellarton and its
               subsidiaries or on the ability of Stellarton to consummate the
               transactions contemplated hereby); or (iii) cause the suspension
               or revocation of any authorization, consent, approval or license
               currently in effect which would have a Material Adverse Effect on
               the business, operations and financial condition of Stellarton
               and its subsidiaries take as a whole.

        (b)    Other than in connection with or in compliance with the
               provisions of Corporate Laws, Securities Laws and the rules of
               The Toronto Stock Exchange, (i) there is no legal impediment to
               Stellarton's consummation of the transactions contemplated by
               this Agreement and (ii) no filing or registration with, or
               authorization, consent or approval of, any domestic or foreign
               public body or authority is necessary by Stellarton in connection
               with the making or the consummation of the Offer, except for such
               filings or registrations which, if not made, or for such
               authorizations, consents or approvals, which, if not received,
               would not have a Material Adverse Effect on the ability of
               Stellarton to consummate the transactions contemplated hereby.

6.4     CAPITALIZATION

        As of the date hereof, the authorized share capital of Stellarton
consists of an unlimited number of Class A Voting Common Shares, an unlimited
number of Class B Non-Voting Common Shares, and an unlimited number of Class 1
Preferred Shares. As of the date hereof, 22,403,046 Stellarton Shares are issued
and outstanding, and no Class B Non-Voting Common Shares or Class 1 Preferred
Shares are issued and outstanding. As of the date hereof, options to acquire an
aggregate of 2,010,333 Stellarton Shares have been granted under the Stock
Option Plan, details of which, including the number of such options at each
exercise price, are as set forth in the Disclosed Information. Except as set
forth above there are no options, warrants or other rights, agreements or
commitments of any character whatsoever (contingent or otherwise)


                                       16
<PAGE>   21

requiring the issuance, sale or transfer by Stellarton of any shares of
Stellarton (including the Stellarton Shares) or any securities convertible into,
or exchangeable or exercisable for, or otherwise evidencing a right to acquire,
any shares of Stellarton (including the Stellarton Shares), nor are there any
outstanding stock appreciation rights, phantom equity or similar rights,
agreements, arrangements or commitments based upon the book value, income or
other attribute of Stellarton. All outstanding Stellarton Shares have been duly
authorized and validly issued, are fully paid and non-assessable and are not
subject to, nor were they issued in violation of, any preemptive rights, and all
Stellarton Shares issuable upon exercise of outstanding stock options in
accordance with their respective terms will be duly authorized and validly
issued, fully paid and non-assessable and will not be subject to any preemptive
rights.

6.5     NO MATERIAL ADVERSE CHANGE

        Except as publicly disclosed, since December 31, 1999, there has not
been any Material Adverse Change in respect of Stellarton and its subsidiaries
taken as a whole.

6.6     NO UNDISCLOSED MATERIAL LIABILITIES

        Except (a) as disclosed or reflected in the consolidated audited
financial statements of Stellarton as at December 31, 1999 and the unaudited
interim financial statements of Stellarton as at September 30, 2000, previously
delivered to Parent Co. or A Co. as part of the Disclosed Information, and (b)
for liabilities and obligations (i) incurred in the ordinary course of business
and consistent with past practice or (ii) pursuant to the terms of this
Agreement, Stellarton and its subsidiaries, taken as a whole, has not incurred
any liabilities of any nature, whether accrued, contingent or otherwise (or
which would be required by generally accepted accounting principles to be
reflected on a consolidated balance sheet of Stellarton) that have constituted
or would be reasonably likely to constitute a Material Adverse Change.

6.7     IMPAIRMENT

        Neither the making of the Offer nor the successful completion of the
Offer will result in a Material Adverse Change pursuant to or as a result of the
provisions of any agreement or arrangement to which Stellarton is a party.

6.8     OFFICER OBLIGATIONS

        The Officer Obligations do not exceed an aggregate of $1,260,000 for
severance payable to officers and senior management, an aggregate of $850,000
payable to employees for retention bonuses and $950,000 for pro rata performance
bonuses payable to officers and employees.

6.9     BROKERAGE AND OTHER FEES

        Stellarton has not retained nor will it retain any financial advisor,
broker, agent or finder or paid or agreed to pay any financial advisor, broker,
agent or finder on account of this Agreement, any transaction contemplated
hereby or any transaction presently ongoing or contemplated, except that
Waterous Securities Inc. has been retained as Stellarton's financial advisor in
connection with certain matters including the transactions contemplated hereby.
Stellarton has delivered or will deliver concurrently with the execution hereof
to Parent Co. a


                                       17
<PAGE>   22

true and complete copy of its agreement with Waterous Securities Inc. Based upon
the terms of the Offer as contemplated as of the date hereof, the aggregate
payment payable by Stellarton pursuant to (i) the agreement with Waterous
Securities Inc. and (ii) expenses of independent engineers, legal counsel and
other third party service providers shall not exceed $2,000,000 plus applicable
Goods and Services Taxes.

6.10    CONDUCT OF BUSINESS

        Since September 30, 2000, Stellarton has not taken any action that would
be in violation of Section 7.1 if such provision had been in effect since such
date, other than violations which would not have any Material Adverse Effect or
would materially affect Stellarton's ability to consummate the transactions
contemplated hereby.

6.11    REPORTS

        (a)    Stellarton has heretofore made available to Parent Co. or A Co.
               true and complete copies of (i) Stellarton's 2000 Annual
               Information Form, Stellarton's Information Circular relating to
               its 2000 annual and special meeting of shareholders, Stellarton's
               1999 Annual Report to shareholders and unaudited interim
               financial statements for the periods ended March 31, 2000, June
               30, 2000 and September 30, 2000; and (ii) all prospectuses or
               other offering documents used by Stellarton in the offering of
               its securities and filed with Securities Authorities since
               September 16, 1996; and (iii) the audited financial statements of
               Stellarton dated December 31, 1999. As of their respective dates,
               such forms, statements, prospectuses and other offering documents
               (including all exhibits and schedules thereto and documents
               incorporated by reference therein) did not contain any untrue
               statement of a material fact or omit to state a material fact
               required to be stated therein or necessary to make the statements
               therein, in light of the circumstances under which they were
               made, not misleading and complied in all material respects with
               all applicable requirements of law. The audited financial
               statements and unaudited interim financial statements of
               Stellarton publicly issued by Stellarton, previously delivered to
               Parent Co. or A Co., or included or incorporated by reference in
               such form, statements, prospectuses and other offering documents
               were prepared in accordance with generally accepted accounting
               principles in Canada (except (i) as otherwise indicated in such
               financial statements and the notes thereto or, in the case of
               audited statements, in the related report of Stellarton's
               independent accountants or (ii) in the case of unaudited interim
               financial statements, to the extent they may not include
               footnotes or may be condensed or summary statements), and fairly
               present the financial position, results of operations and changes
               in financial position of Stellarton as of the dates thereof and
               for the periods indicated therein (subject, in the case of any
               unaudited interim financial statements, to normal year-end audit
               adjustments).

        (b)    Stellarton will deliver to Parent Co. as soon as they become
               available true and complete copies of any report or statement
               filed by it with Securities Authorities subsequent to the date
               hereof. As of their respective dates, such reports and


                                       18
<PAGE>   23

               statements (excluding any information therein provided by Parent
               Co. or A Co., as to which Stellarton makes no representation)
               will not contain any untrue statement of a material fact or omit
               to state a material fact required to be stated therein or
               necessary to make the statements therein, in light of the
               circumstances under which they are made, not misleading and will
               comply in all material respects with all applicable requirements
               of law. The financial statements of Stellarton issued by
               Stellarton or to be included in such reports and statements
               (excluding any information therein provided by Parent Co. or A
               Co., as to which Stellarton makes no representation) will be
               prepared in accordance with generally accepted accounting
               principles in Canada (except (i) as otherwise indicated in such
               financial statements and the notes thereto or, in the case of
               audited statements, in the related report of Stellarton's
               independent accountants or (ii) in the case of unaudited interim
               financial statements, to the extent they may not include
               footnotes or may be condensed or summary statements) and will
               present fairly the financial position, results of operations and
               changes in financial position of Stellarton as of the dates
               thereof and for the periods indicated therein (subject, in the
               case of any unaudited interim financial statements, to normal
               year-end audit adjustments).

6.12    SUBSIDIARIES

        Stellarton has no direct or indirect wholly-owned or partially owned
subsidiaries except for the following:

        (a)    Stellarton Energy International Corp.;

        (b)    Stellarton de Venezuela C.A.; and

        (c)    Secure Power Systems Ltd.

6.13    COMPLIANCE WITH LAW

        Stellarton and each of its subsidiaries has complied with and is in
compliance with all laws and regulations applicable to the operation of its
business, except where such non-compliance would not, considered individually or
in the aggregate, have a Material Adverse Effect or would materially affect the
ability of Stellarton to consummate the transactions contemplated hereby.

6.14    MATERIAL AGREEMENTS

        There are no agreements, permits, licenses, approvals, certificates and
other rights and authorizations material to the conduct of Stellarton's and its
subsidiaries' business except as contained in the Data Room at the time of the
attendance thereat by Parent Co.'s or A Co.'s representatives, and all such
agreements, permits, licences, approvals, certificates and other rights and
authorizations are valid and subsisting and neither Stellarton nor its
subsidiaries is in material default under any such agreements, permits,
licences, approvals, certificates and other rights and authorizations.

                                       19
<PAGE>   24


6.15    INTERIM FINANCIAL STATEMENTS

        The interim unaudited financial statements as at and for the nine months
ended September 30, 2000, a copy of which was provided to Parent Co. or A Co. by
Stellarton as part of Parent Co.'s or A Co.'s data review process, were prepared
in accordance with generally accepted accounting principles in Canada and
present fairly in all material respects, the financial position of Stellarton,
the results of its operations and the changes in its financial position for the
applicable period; provided however that such statements are condensed and do
not include notes. Except as disclosed in this Agreement or in such financial
statements, Stellarton and its subsidiaries had no material liabilities (whether
actual, accrued or contingent, and whether direct or indirect) at September 30,
2000.

6.16    EMPLOYMENT AGREEMENTS

        Except as disclosed in the Disclosed Information, Stellarton and its
subsidiaries are not party to any written employment or consulting agreement or
any verbal employment or consulting agreement with a term of more than thirty
(30) days or any written agreement which provides for a payment by Stellarton or
its subsidiaries on a change of control of Stellarton or severance of employment
and Stellarton and its subsidiaries agree not to amend the terms and conditions
of any of the foregoing which were disclosed in the Disclosed Information.

6.17    EMPLOYEE BENEFIT PLANS

        Stellarton does not have any employee benefit plans and has made no
promises with respect to increased benefits under such plans, other than: (i)
the Stock Option Plan; and (ii) existing health, dental, vision and short and
long term disability plan of general application, together with the employee
savings and stock purchase plan as disclosed in the Disclosed Information. All
contributions (including premiums) required by law or contract to and including
September 30, 2000 to have been paid or accrued, under or with respect to such
plans, have been paid or accrued as at that date, as the case may be.

6.18    UNITED STATES RELATIONSHIPS AND OPERATIONS

        (a)    Stellarton does not have actual knowledge that the level of
               ownership by U.S. holders of Stellarton Shares equals or exceeds
               10% of the total of such outstanding class of securities. The
               term "U.S. holder" means any person whose address appears on the
               records of Stellarton, any voting or other trustee, any
               depository, any share transfer agent or any person acting in a
               similar capacity on behalf of Stellarton, as being located in the
               United States. None of the securities of Stellarton are
               registered under the Securities Exchange Act of 1934 of the
               United States.

        (b)    Direct sales by Stellarton, if any, into the United States in
               calendar year 1999 and to date in calendar year 2000 are less
               than $25 million (U.S.) in the aggregate per period and the
               assets of Stellarton located in the United States, if any, have
               an aggregate value less than $10 million (U.S.).


                                       20
<PAGE>   25

6.19    DATA AND INFORMATION

        To the knowledge of Stellarton, the data and information in respect of
Stellarton and its subsidiaries and their respective assets, liabilities,
business, operations and capital provided by Stellarton to Parent Co. or A Co.
was and is accurate and correct in all material respects, taken as a whole, as
at the respective dates thereof and, taken as a whole, did not and does not now
omit any data or information necessary to make any data or information provided
not misleading in any material respects as at the respective dates thereof.
Stellarton agrees to preserve information contained in the Data Room (without
any amendment or changes to such information), with such information to be
maintained by Stellarton, and reasonable access shall be provided to Parent Co.
or A Co. upon reasonable request for purposes of identifying the information
relating to the index of information and to facilitate efforts under Section
7.3.

6.20    ENGINEERING REPORT

        Stellarton has provided to Gilbert Lausten Jung Associates Ltd. ("GLJ"),
independent geological and petroleum engineering consultants, all material
information concerning land descriptions and well data respecting the principal
oil and gas assets of Stellarton at September 1, 2000 in respect of the
evaluation report dated September 1, 2000 and, in particular, all material
information respecting Stellarton's interests in its principal oil and gas
assets and the royalty burdens and net profits interest burdens thereon and
Stellarton is not aware of any information not provided to GLJ that would have a
material adverse impact on the evaluation report, taken as a whole.

6.21    BOOKS AND RECORDS

        The corporate records and minute books of Stellarton have been
maintained in accordance with all applicable statutory requirements and are
complete and accurate in all material respects.

6.22    LITIGATION, ETC.

        Except as disclosed in writing to Parent Co. or A Co. or made available
in the Data Room prior to the date hereof, there are no actions, suits or
proceedings pending, or to the knowledge of Stellarton threatened, affecting
Stellarton or any of its subsidiaries before or by any federal, provincial,
state, local, foreign, municipal or other governmental department, commission,
board, bureau, agency, court or instrumentality, which action, suit or
proceeding involves a possibility of any judgment against or liability of
Stellarton or any of its subsidiaries or other person which, if successful,
would have a Material Adverse Effect, or materially adversely affect the ability
of Stellarton to consummate the transactions contemplated hereby.

6.23    ENVIRONMENTAL

        Except as disclosed in the information contained in the Data Room;

        (a)    Stellarton is not aware of, and has not received:

                                       21
<PAGE>   26

               (i)    any order or directive which relates to environmental
                      matters and which requires any material work, repairs,
                      construction, or capital expenditures; or

               (ii)   any demand or notice with respect to the material breach
                      of any environmental, health or safety law applicable to
                      Stellarton and its subsidiaries or any of their respective
                      business undertakings, including, without limitation, any
                      regulations respecting the use, storage, treatment,
                      transportation, or disposition of environmental
                      contaminants.

        (b)    Stellarton has not received notice of and is not aware of any
               material environmental liabilities related to its assets, other
               than obligations in the ordinary course of business to abandon
               wells when they have ceased to be productive, remove production
               equipment when they are no longer being used and restore and
               reclaim the surface sites thereof;

        (c)    all material environmental and health and safety permits,
               licenses, approvals, consents, certificates and other
               authorizations of any kind or nature ("Environmental Permits")
               necessary for the ownership, operation, development, maintenance,
               or use of any of the assets have been obtained and maintained in
               effect;

        (d)    Stellarton, its assets and the ownership, operation, development,
               maintenance and use thereof are in material compliance with all
               environmental laws and with all terms and conditions of all
               Environmental Permits; and

        (e)    all known spills or similar incidents pertaining to or affecting
               the business or the assets of Stellarton have been reported to
               the appropriate governmental entity to the extent required by
               environmental laws.

        For purposes of this section 6.23, Stellarton provides each of the
representations and warranties to its knowledge, without inquiry, with respect
to those operations and assets which it does not operate.

6.24    TAX MATTERS

        (a)    For purposes of this Agreement, the following definitions shall
               apply:

               (i)    The term "Taxes" shall mean all taxes, however
                      denominated, including any interest, penalties or other
                      additions that may become payable in respect thereof,
                      imposed by any federal, provincial, state, local or
                      foreign government or any agency or political subdivision
                      of any such government, which taxes shall include, without
                      limiting the generality of the foregoing, all income or
                      profits taxes (including, but not limited to, federal
                      income taxes and provincial income taxes), capital,
                      payroll and employee withholding taxes, labour taxes,
                      unemployment insurance, social insurance taxes, sales and
                      use taxes, ad valorem taxes, value added taxes, excise
                      taxes, franchise taxes, gross receipts taxes, business
                      license

                                       22
<PAGE>   27


                      taxes, occupation taxes, real and personal property taxes,
                      stamp taxes, environmental taxes, transfer taxes, workers'
                      compensation and other governmental charges, and other
                      obligations of the same or of a similar nature to any of
                      the foregoing, which Stellarton or any of its subsidiaries
                      is required to pay, withhold or collect.

               (ii)   The term "Returns" shall mean all reports, estimates,
                      declarations of estimated tax, information statements and
                      returns relating to, or required to be filed in connection
                      with, any Taxes.

        (b)    All Returns required to be filed by or on behalf of Stellarton or
               any or its subsidiaries have been duly filed on a timely basis
               (excepting thereout a Return for the year ended 1999 for the
               Sultanate of Oman, which Return will reflect Taxes payable of no
               more than $50,000) and such Returns are true, complete and
               correct in all material respects. All Taxes shown to be payable
               on the Returns or on subsequent assessments with respect thereto
               have been paid in full on a timely basis, and no other Taxes are
               payable by Stellarton or any subsidiaries with respect to items
               or periods covered by such Returns.

        (c)    Stellarton and each of its subsidiaries has paid or provided
               adequate accruals in its financial statements for the year ended
               dated December 31, 1999 for Taxes, including income taxes, labour
               taxes and related future taxes, in conformity with generally
               accepted accounting principles applicable in Canada.

        (d)    For all periods covered by the filed tax returns disclosed in the
               Disclosed Information, Parent Co. or A Co. has been furnished by
               Stellarton true and complete copies of (i) relevant portions of
               income tax audit reports, statements of deficiencies, closing or
               other agreements received by Stellarton or on behalf of
               Stellarton or any of its subsidiaries relating to Taxes, and (ii)
               all federal, provincial, state, local or foreign income or
               franchise tax returns for Stellarton or any of its subsidiaries.

        (e)    No material deficiencies exist or have been asserted with respect
               to Taxes of Stellarton or any of its subsidiaries. Neither
               Stellarton nor any of its subsidiaries is a party to any action
               or proceeding for assessment or collection of Taxes, nor has such
               event been asserted or threatened against Stellarton or any of
               its subsidiaries or any of their respective assets. No waiver or
               extension of any statute of limitations is in effect with respect
               to Taxes or Returns of Stellarton or any of its subsidiaries.
               Except as disclosed in the Disclosed Information, the Returns of
               Stellarton or any of its subsidiaries have not been audited by a
               government or taxing authority within the last three (3) years,
               nor is any such audit in process, pending or threatened.

        (f)    Stellarton has provided adequate accruals in its financial
               statements for the year ended December 31, 1999 (or, in either
               case, such amounts are fully funded) for all employee benefit
               obligations of Stellarton arising under or relating to each of
               the pension or retirement income plans or other employee benefit
               plans or


                                       23
<PAGE>   28

               agreements or policies maintained by or binding on Stellarton or
               any of its subsidiaries.

6.25    REPORTING ISSUER STATUS

        Stellarton is a "reporting issuer" in material compliance with all
applicable securities laws of British Columbia, Alberta, Manitoba, Ontario and
Quebec.

6.26    DEBT AND WORKING CAPITAL

        As at November 30, 2000, Stellarton's consolidated debt (other than
trade debt) does not exceed $17,000,000 and, as at September 30, 2000, its
working capital deficiency is not greater than $3,400,000.

6.27    CONFIDENTIALITY AGREEMENTS

        All agreements entered into by Stellarton with persons other than Parent
Co. or A Co. regarding the confidentiality of information provided to such
persons or reviewed by such persons in the Data Room are in substantially the
form of the Parent Co. Confidentiality Agreement. Stellarton has not negotiated
any Take-over Proposal with any person who has not entered into such a
confidentiality agreement or provided access to the Data Room to any person who
has not entered into such a confidentiality agreement. Stellarton agrees to
fully enforce all such confidentiality agreements and Stellarton, subject to
this Agreement, will not amend, modify or provide any consents under such
confidentiality agreements or provide any release from, or relaxation of, the
obligations under such confidentiality agreements to any of the parties thereto.

6.28    INSURANCE

        Policies of insurance in force as of the date hereof naming Stellarton
as an insured adequately cover all risks reasonably and prudently foreseeable in
the operation and conduct of the business of Stellarton and its subsidiaries.
All such policies of insurance shall remain in force and effect and shall not be
canceled or otherwise terminated as a result of the transactions contemplated
hereby or by the Offer.

6.29    SECURE OIL TOOLS LTD.

        All holdback amounts due and receivable pursuant to the sale of Secure
Oil Tools Ltd. have been received.


                                   ARTICLE VII
                               CONDUCT OF BUSINESS

7.1     CONDUCT OF BUSINESS BY STELLARTON

        Stellarton covenants and agrees that, during the period from the date of
this Agreement until the earlier of either: (i) the Effective Time; or (ii) this
Agreement is terminated by its terms,


                                       24
<PAGE>   29

unless A Co. shall otherwise agree in writing, except as required by law or as
otherwise expressly permitted or specifically contemplated by this Agreement:

        (a)    the business of Stellarton and its subsidiaries shall be
               conducted only in, and Stellarton shall not take and Stellarton
               shall cause its subsidiaries not to take any action except in the
               usual and ordinary course of business and consistent with past
               practice, and Stellarton shall use and shall cause its
               subsidiaries to use all commercially reasonable efforts to
               maintain and preserve its applicable business organization,
               assets, employees and advantageous business relationships;

        (b)    Stellarton shall not directly or indirectly do or permit to occur
               any of the following: (i) amend the Stellarton Governing
               Documents; (ii) declare, set aside or pay any dividend or other
               distribution or payment (whether in cash, shares or property) in
               respect of its shares owned by any person; (iii) issue, grant,
               sell or pledge or agree to issue, grant, sell or pledge any
               shares of Stellarton or any of its subsidiaries, or securities
               convertible into or exchangeable or exercisable for, or otherwise
               evidencing a right to acquire, shares of Stellarton or any of its
               subsidiaries, other than Stellarton Shares issuable pursuant to
               the terms of the Stellarton Options; (iv) redeem, purchase or
               otherwise acquire any of its outstanding shares or other
               securities including, without limitation, under a normal course
               issuer bid; (v) split, combine or reclassify any of its shares;
               (vi) adopt a plan of liquidation or resolutions providing for the
               liquidation, dissolution, merger, consolidation or reorganization
               of Stellarton or any of its subsidiaries; (vii) reduce the stated
               capital of Stellarton or any of its subsidiaries, or (viii) enter
               into or modify any contract, agreement, commitment or arrangement
               with respect to any of the foregoing, except as permitted above;

        (c)    Since September 30, 2000, neither Stellarton nor any of its
               subsidiaries has, other than as disclosed, and shall not, without
               prior consultation with and the consent of A Co., such consent
               not to be unreasonably withheld, directly or indirectly do any of
               the following: (i) sell, pledge, dispose of or encumber any
               assets having an individual value in excess of $250,000
               (excepting thereout Stellarton's interest in Secure Power Systems
               Ltd., it being acknowledged that Stellarton shall consult with A
               Co. with respect to the treatment of such interest, but A Co.'s
               consent to the treatment is not required); (ii) acquire (by
               merger, amalgamation, consolidation or acquisition of shares or
               assets) any corporation, partnership or other business
               organization or division thereof, or make any investment either
               by purchase of shares or securities, contributions of capital or
               property transfer; (iii) acquire any assets with an acquisition
               cost which would exceed (A) $250,000 individually or (B) $750,000
               in the aggregate, with the exception of purchases at crown lease
               sales and freehold lease acquisitions where A Co. has been
               consulted with prior to such acquisition; (iv) incur any
               indebtedness for borrowed money in excess of existing facilities,
               or any other material liability or obligation or issue any debt
               securities or assume, guarantee, endorse or otherwise as an
               accommodation become responsible for, the obligations of any
               other individual or entity, or make any loans or advances, other
               than the Officer Obligations and fees payable to legal advisors
               in the ordinary course and fees payable to legal and



                                       25
<PAGE>   30

               financial advisors in respect of the Offer; (v) authorize,
               recommend or propose any release or relinquishment of any
               material contract right; (vi) waive, release, grant or transfer
               any material rights of value or modify or change in any material
               respect any existing material license, lease, contract,
               production sharing agreement, government land concession or other
               material document; (vii) enter into or terminate any hedges,
               swaps or other financial instruments or like transactions; (viii)
               enter into any agreements with directors or officers of
               Stellarton or their respective affiliates; (x) enter into
               commitments of a capital expenditure nature or incur any
               contingent liability other than in accordance with ordinary
               course expenditures, including AFE's approved prior to the date
               hereof and the drilling of individual wells with a cost of up to
               $500,000 each, having an aggregate cost of up to $10,000,000
               except: (A) as may be necessary for the maintenance of existing
               facilities, machinery and equipment in good operating condition
               and repair in the ordinary course of business; or (B) as may be
               required by law; or (x) authorize or propose any of the
               foregoing, or enter into or modify any contract, agreement,
               commitment or arrangement to do any of the foregoing;

        (d)    Stellarton shall not create any new Officer Obligations and,
               except for payment of the existing Officer Obligations (from
               which Stellarton shall make appropriate withholdings as required
               by applicable tax laws), Stellarton shall not grant to any
               officer or director an increase in compensation in any form,
               grant any general salary increase other than in accordance with
               the requirements of any existing collective bargaining or union
               contracts, grant to any other employee any increase in
               compensation in any form other than routine increases in the
               ordinary course of business consistent with past practices, make
               any loan to any officer or director, or take any action with
               respect to the grant of any severance or termination pay arising
               from the Offer or a change of control of Stellarton or the
               entering into of any employment agreement with, any senior
               officer or director, or with respect to any increase of benefits
               payable under its current severance or termination pay policies;

        (e)    Stellarton shall use its reasonable commercial efforts to cause
               the current insurance (or re-insurance) policies of Stellarton,
               taken as a whole, not to be cancelled or terminated or any of the
               coverage thereunder to lapse, unless simultaneously with such
               termination, cancellation or lapse, replacement policies
               underwritten by insurance and re-insurance companies of
               nationally recognized standing providing coverage equal to or
               greater than the coverage under the cancelled, terminated or
               lapsed policies for substantially similar premiums are in full
               force and effect;

        (f)    Stellarton shall and shall cause each of its subsidiaries to not
               take any action that would render, or that reasonably may be
               expected to render, any representation or warranty made by it in
               this Agreement untrue in any material respect;

        (g)    neither Stellarton nor any of its subsidiaries shall adopt or
               amend or make any contribution to any bonus, profit sharing,
               option, deferred compensation, insurance, incentive compensation,
               other compensation or other similar plan,


                                       26
<PAGE>   31

               agreement, trust, fund or arrangements for the benefit of
               employees, except as is necessary to comply with the law or with
               respect to existing provisions of any such plans, programs,
               arrangements or agreements; and

        (h)    Stellarton shall and shall cause each of its subsidiaries to
               comply in all material respects with all applicable laws and
               material contracts.

        Notwithstanding the foregoing, Stellarton may, prior to the Expiry Time,
enter into a transaction contemplating the sale, transfer or other treatment of
Stellarton's interest in Secure Power Systems Ltd., provided that any proceeds
from such sale will be retained by Stellarton.

7.2     CONDUCT OF BUSINESS BY PARENT CO. AND A CO.

        Parent Co. and A Co. each covenant and agree that, during the period
from the date of this Agreement until this Agreement is terminated in accordance
with its terms, unless Stellarton shall otherwise agree in writing, except as
required by law or as otherwise expressly permitted or specifically contemplated
by this Agreement:

        (a)    each of Parent Co. and A Co. and their respective subsidiaries
               will not take any actions which would or might be reasonably
               expected to materially impede or otherwise frustrate the
               completion of the Offer; and

        (b)    each of Parent Co. and A Co. shall and shall cause each of its
               respective subsidiaries to not take any action that would render,
               or that reasonably may be expected to render, any representation
               or warranty made by it in this Agreement untrue in any material
               respect.

7.3     INTEGRATION OF OPERATIONS

        From and after the mailing of the Offer, A Co. and its representatives
will be permitted reasonable access to Stellarton's premises, field operations,
records, computer systems, properties, books, contracts, records management
personnel and employees to permit A Co. to be in a position to expeditiously and
efficiently integrate the business and operations of Stellarton with that of A
Co. immediately upon but not prior to, the Effective Time without causing any
unreasonable disruptions to Stellarton's business or operations prior to the
Effective Time.

7.4     MARKET PURCHASES

        Stellarton agrees that A Co., notwithstanding anything to the contrary
contained in the Parent Co. Confidentiality Agreement, after the date hereof may
purchase Stellarton Shares in the market or otherwise, provided that such
purchases are made in compliance with the provisions of Securities Laws and
provided that any Stellarton Shares so acquired shall be included in determining
whether the Minimum Condition has been satisfied.


                                       27
<PAGE>   32



                                  ARTICLE VIII
                             COVENANTS OF STELLARTON

8.1     NOTICE OF MATERIAL CHANGE

        From the date hereof until the termination of this Agreement, Stellarton
shall promptly notify Parent Co. in writing of:

        (a)    any material change (actual, anticipated, contemplated or, to the
               knowledge of Stellarton, threatened, financial or otherwise) in
               the business, affairs, operations, assets, liabilities
               (contingent or otherwise) or capital of Stellarton or any of its
               subsidiaries;

        (b)    any change in the facts relating to any representation or
               warranty set forth in Article 6 which change is or may be of such
               a nature as to render any such representation or warranty
               misleading or untrue in a material respect; or

        (c)    any material fact which arises and which would have been required
               to be stated herein had the fact arisen on or prior to the date
               of this Agreement.

        Stellarton shall in good faith discuss with A Co. any change in
circumstances (actual, anticipated, contemplated or, to the knowledge of
Stellarton, threatened, financial or otherwise) which is of such a nature that
there may be a reasonable question as to whether notice need to be given to A
Co. pursuant to this section.

8.2     NON-COMPLETION FEE

        If at any time after the execution of this Agreement:

        (a)    the board of directors of Stellarton has withdrawn or, in any
               manner adverse to A Co., redefined, modified or changed any of
               its recommendations or determinations referred to in Section
               2.2(a) prior to the Expiry Time of the Offer, or shall have
               resolved to do so;

        (b)    any bona fide Take-over Proposal for the Stellarton Shares is
               publicly announced or commenced, and the board of directors of
               Stellarton shall have failed to publicly reaffirm and maintain
               its recommendation of the Offer to Stellarton's shareholders
               within 5 days after the commencement of any such Take-over
               Proposal;

        (c)    the board of directors of Stellarton shall have recommended that
               Stellarton's shareholders deposit their Stellarton Shares under,
               vote in favour of, or otherwise accept, a Take-over Proposal;

        (d)    Stellarton shall have entered into any contractual agreement with
               any person with respect to a Take-over Proposal prior to the
               Expiry Time of the Offer, excluding a confidentiality agreement
               entered into in compliance with Section 8.3; or


                                       28
<PAGE>   33


        (e)    another Take-over Proposal is publicly announced, proposed,
               offered or made to all or substantially all holders of Stellarton
               Shares or to Stellarton prior to the Expiry Time, the Offer has
               expired and has not been consummated by reason of the Minimum
               Condition not having been satisfied, and before or within six
               months of the Expiry Time of the Offer, the Take-over Proposal
               (as originally proposed or as amended) or any other Take-over
               Proposal is completed.

Stellarton shall forthwith upon the occurrence of any such event and in any
event within two Business Days pay to A Co. the amount of $4,500,000.

        Any payment pursuant to Section 8.2 shall be without prejudice to the
rights or remedies available to A Co. upon the breach of any provision of this
Agreement.

8.3     NO SOLICITATION

        Stellarton shall immediately cease and cause to be terminated any
existing solicitation, initiation, encouragement, activity, discussion,
negotiation or other procedures with any parties conducted heretofore by
Stellarton, or its officers, directors, employees, financial advisors, legal
counsel, representatives and agents ("Representatives") with respect to a
Take-over Proposal (as defined herein) whether or not initiated by Stellarton
and in connection therewith, Stellarton shall not release any third party from
any confidentiality or standstill agreement to which Stellarton and such third
party is a party or amend any of the foregoing and shall exercise all rights to
require the return of information regarding Stellarton previously provided to
such parties and shall exercise all rights to require the destruction of all
materials including or incorporating any information regarding Stellarton. From
and after the date hereof, Stellarton will not, and will not authorize or permit
any of their Representatives to, directly or indirectly, solicit, initiate or
encourage (including by way of furnishing information) or participate in or take
any other action to facilitate any inquiries or the making of any proposal which
constitutes or may reasonably be expected to lead to a Take-over Proposal from
any person, or engage in any discussion, negotiations or inquiries relating
thereto or accept any Take-over Proposal; provided, however, that Stellarton
may: (i) engage in discussions or negotiations with a third party who (without
any solicitation, initiation or encouragement, directly or indirectly, by
Stellarton, or the Representatives after the date hereof) seeks to initiate such
discussions or negotiations and may furnish such third party information
concerning Stellarton and its business, properties and assets which has
previously been provided to Parent Co. or A Co. if, and only to the extent that:
(A) the third party has first made a bona fide written Take-over Proposal that
is financially superior to the Offer and has demonstrated that such proposal
constitutes a commercially feasible transaction which could be carried out
within a time frame that is reasonable in the circumstances and that the funds
or other consideration necessary for the Take-over Proposal are available (as
determined in good faith in each case by Stellarton's board of directors after
receiving the advice of its financial advisors) (a "Superior Proposal") and
Stellarton's board of directors has concluded in good faith, after considering
applicable law and receiving the advice of legal counsel that such action is
required by the Stellarton board of directors to comply with fiduciary duties
under applicable law; (B) prior to furnishing such information to or entering
into discussions or negotiations with such person or entity, Stellarton provides
immediate notice orally and in writing to A Co. specifying that it is furnishing
information to or entering into discussions or negotiations with such person or
entity in respect to a Superior Proposal, receives


                                       29
<PAGE>   34


from such person or entity an executed confidentiality agreement having
confidentiality and standstill terms substantially similar to those contained in
the Parent Co. Confidentiality Agreement, and provides A Co. with a copy of such
Superior Proposal and any amendments thereto excepting thereout the name of the
party making the Superior Proposal and confirming in writing the determination
of Stellarton's board that the Take-over Proposal if completed would constitute
a Superior Proposal; (C) Stellarton provides immediate notice to A Co. at such
time as it or such person or entity terminates any such discussions or
negotiations; and (D) Stellarton immediately provides to A Co. any information
provided to any such person or entity whether or not previously made available
to A Co.; (ii) comply with Rules 14d-9 and 14e-2 promulgated under the Exchange
Act with regard to a tender or exchange offer, if applicable, and similar rules
under applicable Canadian securities laws relating to the provision of
directors' circulars, and make appropriate disclosure with respect thereto to
Stellarton's shareholders; and (iii) accept, recommend, approve or implement a
Superior Proposal from a third party, but only (in the case of this clause
(iii)) if prior to such acceptance, recommendation, approval or implementation,
Stellarton's board of directors shall have concluded in good faith, after
considering provisions of applicable law and after giving effect to all
proposals to adjust the terms and conditions of this Agreement and the Offer
which may be offered by A Co. during the three Business Days notice period set
forth below and after receiving the advice of legal counsel, and Stellarton
terminates this Agreement in accordance with Sections 8.2 and 11.1(g).
Stellarton shall give A Co. orally and in writing at least three Business Days
advance notice of any decision by the Board of Stellarton to accept, recommend,
approve or implement a Superior Proposal which notice shall identify the party
making the Superior Proposal and shall provide a true and complete copy thereof
and any amendments thereto. In addition Stellarton shall, and shall cause its
respective financial and legal advisors to, negotiate in good faith with A Co.
to make such adjustments in the terms and conditions of this Agreement and the
Offer as would enable Stellarton to proceed with the Offer as amended rather
than the Superior Proposal. In the event A Co. proposes to amend this Agreement
and the Offer to provide substantially equivalent or superior value to that
provided under the Superior Proposal within the three Business Days time period
specified above, then Stellarton shall not enter into any agreement regarding
the Superior Proposal.

8.4     STELLARTON BOARD OF DIRECTORS

        As soon as reasonably practicable following the acquisition by A Co. of
more than 50% of the outstanding Stellarton Shares pursuant to the Offer, the
board of directors of Stellarton shall be immediately reconstituted through
resignations of all existing Stellarton directors and the appointment of A Co.
nominees in their stead. Stellarton shall, in accordance with the foregoing and
subject to the provisions of the Act, assist A Co. to secure the resignations of
all Stellarton directors to be effective at such time as may be required by A
Co. and to use its best efforts to cause the election or appointment of the A
Co. nominees to fill the vacancies so created in order to effect the foregoing
without the necessity of a shareholder meeting.

8.5     REPRESENTATIONS AND WARRANTIES

        Stellarton covenants and agrees that at all times when the Offer is
outstanding, Stellarton shall not take any action, or fail to take any action,
which would or could result in the representations and warranties set out in
Article VI being untrue in any material respect, and


                                       30
<PAGE>   35

Stellarton will provide a certificate of an officer as to the status of the
representations and warranties set out in Article VI on the Take-up Date.

8.6     STRUCTURE OF TRANSACTION

        Stellarton shall use reasonable commercial efforts in cooperating with A
Co. in structuring the acquisition by A Co. of Stellarton in a tax efficient
manner, provided that no such cooperation shall be required where such
structuring shall have a material adverse effect on the business, operations or
financial condition of Stellarton or cause any breach of or default under this
Agreement by Stellarton.


                                   ARTICLE IX
                        COVENANTS OF PARENT CO. AND A CO.

9.1     REPRESENTATIONS AND WARRANTIES

        Parent Co. and A Co. covenant and agree that at all times when the Offer
is outstanding, neither Parent Co. nor A Co. shall take any action, or fail to
take any action, which would or could result in the representations and
warranties set out in Article V being untrue in any material respect.

9.2     EMPLOYMENT AGREEMENTS

        Parent Co. and A Co. covenant and agree, and after the Effective Time
will cause Stellarton and any successor to Stellarton to agree, to honour and
comply with the terms of those existing executive employment agreements,
termination, severance and retention agreements, plans or policies of Stellarton
which Stellarton has disclosed to Parent Co. or A Co. in writing prior to the
date hereof.

9.3     INDEMNITIES

        Parent Co. and A Co. agree that if A Co. acquires the Stellarton Shares
under the Offer they shall cause Stellarton to fulfill its obligations pursuant
to indemnities provided or available to past and present officers and directors
of Stellarton pursuant to the provisions of the articles, by-laws or similar
constating documents of Stellarton, applicable corporate legislation and any
written indemnity agreements between any of Stellarton and its past and current
officers and directors.

9.4     OTHER COVENANTS

        Parent Co. and A Co. covenant and agree that, from and including the
date hereof until the termination of this Agreement, unless Stellarton agrees
otherwise in writing:

        (a)    each of Parent Co. and A Co. shall use its best efforts to
               consummate the Offer, subject only to the terms and conditions
               hereof and thereof; and


                                       31
<PAGE>   36


        (b)    each of Parent Co. and A Co. shall use its best efforts to obtain
               all of the regulatory approvals, waivers and consents set out in
               paragraphs (b) and (c) of Schedule A.


                                    ARTICLE X
                                MUTUAL COVENANTS

10.1    OTHER FILINGS

        A Co. and Stellarton shall, as promptly as practicable hereafter,
prepare and file any filings required under any Securities Law, the rules of The
Toronto Stock Exchange, the United States Securities Exchange Act of 1934, as
amended, state securities or "blue-sky" laws of the states of the United States,
as amended, or any other applicable law relating to the transactions
contemplated herein.

10.2    ADDITIONAL AGREEMENTS

        Subject to the terms and conditions herein provided and to fiduciary
obligations under applicable law as advised by counsel, each of the parties
hereto agrees to use all commercially reasonable efforts to take, or cause to be
taken, all action and to do, or cause to be done, all things necessary, proper
or advisable to consummate and make effective as promptly as practicable the
transactions contemplated by this Agreement and to cooperate with each other in
connection with the foregoing, including using commercially reasonable efforts
(i) to obtain all necessary waivers, consents and approvals from other parties
to material agreements, leases and other contracts or agreements (including,
without limitation, the agreement of any persons as may be required pursuant to
any agreement, arrangement or understanding relating to Stellarton's
operations), (ii) to obtain all necessary consents, approvals and authorizations
as are required to be obtained under any federal, provincial or foreign law or
regulations, (iii) to defend all lawsuits or other legal proceedings challenging
this Agreement or the consummation of the transactions contemplated hereby, (iv)
to cause to be lifted or rescinded any injunction or restraining order or other
order adversely affecting the ability of the parties to consummate the
transactions contemplated hereby, (v) to effect all necessary registrations and
other filings and submissions of information requested by governmental
authorities, and (vi) to fulfill all conditions and satisfy all provisions of
this Agreement and the Offer. For purposes of the foregoing, the obligation to
use "commercially reasonable efforts" to obtain waivers, consents and approvals
to loan agreements, leases and other contracts shall not include any obligation
to agree to a materially adverse modification of the terms of such documents or
to prepay or incur additional material obligations to such other parties.


                                       32
<PAGE>   37


                                   ARTICLE XI
                        TERMINATION, AMENDMENT AND WAIVER

11.1    TERMINATION

        This Agreement, other than any obligations heretofore accrued, may be
terminated by written notice promptly given to the other party hereto, at any
time prior to the time A Co. first takes up and pays for Stellarton Shares:

        (a)    by mutual agreement by A Co. and Stellarton; or

        (b)    by either A Co. or Stellarton if a court of competent
               jurisdiction or a governmental, regulatory or administrative
               agency or commission shall have issued an order, decree or ruling
               or taken any other action permanently restraining, enjoining or
               otherwise prohibiting any of the transactions contemplated by
               this Agreement and such order, decree, ruling or other action
               shall have become final; or

        (c)    by Stellarton, if A Co. has not mailed the Offer Documents to
               Stellarton's Shareholders on or before 11:59 p.m. (Calgary time)
               on December 22, 2000; or

        (d)    by A Co., if the conditions to the Offer set forth in Schedule
               "A" have not been satisfied or waived by A Co. on or before the
               Expiry Time; or

        (e)    by either A Co. or Stellarton, if A Co. has not taken up and paid
               for the Stellarton Shares deposited under the Offer on or before
               the date which is 60 days following the day of mailing of the
               Offer Documents; or

        (f)    by A Co. or Stellarton, if the Offer terminates or expires at the
               Expiry Time without A Co. taking up and paying for any of the
               Stellarton Shares as a result of the failure of any condition to
               the Offer to be satisfied or waived, unless the absence of such
               occurrence shall be due to the failure of the party seeking to
               terminate this Agreement to perform the obligations under this
               Agreement required to be performed by it; or

        (g)    by A Co. or Stellarton, if the fee referred to in Section 8.2
               becomes payable and payment is made to A Co.; or

        (h)    by either A Co. or Stellarton, if there has been a breach or
               non-performance by the other party of any representation,
               warranty or covenant contained in this Agreement which would have
               or would be reasonably likely to have a material adverse effect
               on the party seeking to terminate, provided the breaching party
               has been given notice of and three days to cure any such
               misrepresentation, breach or non-performance, other than in
               respect of Section 8.2 and Section 8.3.


                                       33
<PAGE>   38

11.2    EFFECT OF TERMINATION

        In the event of the termination of this Agreement as provided in Section
11.1, this Agreement shall forthwith have no further force or effect and there
shall be no obligation on the part of A Co. or Stellarton hereunder except as
set forth in Section 8.2 and Section 12.5 and this Section 11.2, which
provisions shall survive the termination of this Agreement. Nothing herein shall
relieve any party from liability for any breach of this Agreement.

11.3    AMENDMENT

        This Agreement may be amended by mutual agreement between the parties
hereto. This Agreement may not be amended except by an instrument in writing
signed by the appropriate officers on behalf of each of the parties hereto.

11.4    WAIVER

        A Co., on the one hand, and Stellarton, on the other hand, may (i)
extend the time for the performance of any of the obligations or other acts of
the other, (ii) waive compliance with any of the other's agreements or the
fulfillment of any conditions to its own obligations contained herein or (iii)
waive inaccuracies in any of the other's representations or warranties contained
herein or in any document delivered by the other party hereto; provided,
however, that any such extension or waiver shall be valid only if set forth in
an instrument in writing signed on behalf of such party.


                                   ARTICLE XII
                               GENERAL PROVISIONS

12.1    NOTICES

        All notices and other communications given or made pursuant hereto shall
be in writing and shall be deemed to have been duly given or made as of the date
delivered or sent if delivered personally or sent by cable, telegram, telecopier
or telex or sent by prepaid overnight courier to the parties at the following
addresses (or at such other addresses as shall be specified by the parties by
like notice):

        (a)    if to A Co.:

               Tom Brown Resources Ltd.
               Suite 1410, 311 -- 6th Avenue S.W.
               Calgary, Alberta  T2P 3H2

               Attention:    Amar Pandila
                             Vice President and General Manager

               Telecopy No.: (403) 264-5586

        and to Parent Co.:


                                       34
<PAGE>   39


               Tom Brown, Inc.
               555 Seventeenth Street
               Suite 1850
               Denver, Co  80202-3918

               Attention:    James D. Lightner
                             President

               Telecopy No.: (303) 260-5095

        with a copy to:

               Macleod Dixon LLP
               3700, 400 -- 3rd Avenue S.W.
               Calgary, Alberta
               T2P 4H2

               Attention:    Kent D. Kufeldt

               Telecopy No.: (403) 264-5973

        (b)    if to Stellarton:

               Stellarton Energy Corporation
               700, 736 -- 8th Avenue S.W.
               Calgary, Alberta
               T2P 1H4

               Attention:    Robert D. Steele
                             President

               Telecopy No.: (403) 250-2586

        with a copy to:

               Bennett Jones LLP
               4500 Bankers Hall East
               855 - 2nd Street S.W.
               Calgary, Alberta
               T2P 4K7

               Attention:    R. Vance Milligan

               Telecopy No.: (403) 265-7219


                                       35
<PAGE>   40

12.2    MISCELLANEOUS

        (a)    This Agreement (i) except for the Parent Co. Confidentiality
               Agreement between the parties hereto, constitutes the entire
               agreement and supersedes all other prior agreements and
               understandings, both written and oral, between the parties, with
               respect to the subject matter hereof and (ii) shall be binding
               upon and enure to the benefit of the parties hereto and their
               respective successors and assigns. The parties hereto shall be
               entitled to rely upon delivery of an executed facsimile copy of
               the Agreement, and such facsimile copy shall be legally effective
               to create a valid and binding agreement among the parties hereto.
               Stellarton agrees in favour of Parent Co. and A Co. that the
               standstill provisions of the Parent Co. Confidentiality Agreement
               are waived and terminated to the extent necessary to permit A Co.
               to purchase Stellarton's Shares in accordance with Securities
               Laws and for so long as the Offer remains outstanding. 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 their specific terms or were
               otherwise breached. It is accordingly agreed that the parties
               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 of the Province of Alberta
               having jurisdiction, this being in addition to any other remedy
               to which they are entitled at law or in equity.

        (b)    Subject to the prior consent of A Co., acting reasonably, as to
               the form and substance thereof, Stellarton agrees coincidentally
               with the mailing of the Offer Documents to deliver a letter to
               all parties to, and recipients under, the confidentiality
               agreements who received evaluation material requesting the return
               or destruction of such evaluation material in accordance with
               terms of the applicable confidentiality agreement and advising
               such parties and recipients as to their obligations under the
               confidentiality agreements in the context of this Agreement and
               the Offer.

12.3    DIRECTORS' AND OFFICERS INSURANCE

        If prior to the Effective Date, Stellarton secures directors' and
officers' liability insurance for Stellarton's current and former directors and
officers, covering claims made prior to or within six years after the date that
A Co. first takes up and pays for any Stellarton Shares pursuant to the Offer
which has a scope and coverage substantially equivalent in scope and coverage to
that provided by Stellarton's current directors' and officers' insurance policy,
A Co. agrees to cause Stellarton to maintain such insurance in place (or, if
such insurance is unavailable during such six year period, use reasonable
commercial efforts to obtain equivalent insurance) and agrees not to take any
action, or to cause Stellarton to take any action, to terminate such directors'
and officers' liability insurance or any indemnity agreements (whether pursuant
to Stellarton's articles, by-laws or similar constating documents of Stellarton
or any written indemnity agreements but subject to Corporate Laws) in favour of
current and former directors and officers of Stellarton, provided in all events
that the total premium therefor does not exceed $20,000.


                                       36
<PAGE>   41

12.4    ASSIGNMENT

        Except as expressly permitted by the terms hereof, neither this
Agreement nor any of the rights, interests or obligations hereunder shall be
assigned by any of the parties hereto without the prior written consent of the
other parties. A Co. may assign all or any part of its rights or obligations
under this Agreement to a direct or indirect wholly-owned subsidiary of A Co.,
provided that if such assignment takes place, A Co. shall continue to be liable
to Stellarton, as principal obligor, for any default in performance by the
assignee.

12.5    EXPENSES

        Except as provided in Section 8.2, all fees, costs and expenses incurred
in connection with this Agreement and the transactions contemplated hereby shall
be paid by the party incurring such cost or expense, whether or not the Offer is
consummated.

12.6    SEVERABILITY

        Whenever possible, each provision of this Agreement shall be interpreted
in such manner as to be effective and valid under applicable law. Any provision
of this Agreement that is invalid or unenforceable in any jurisdiction shall be
ineffective to the extent of such invalidity or unenforceability without
invalidating or rendering unenforceable the remaining provisions hereof, and any
such invalidity or unenforceability in any jurisdiction shall not invalidate or
render unenforceable such provision in any other jurisdiction.

12.7    PARENT CO. GUARANTEE

        Parent Co. hereby unconditionally and irrevocably guarantees the
performance of all covenants and obligations of A Co. in this Agreement. Parent
Co. waives, diligence, presentment, demand of payment, any right to require
proceeding first against A Co., protest notice and all demands whatsoever.
Parent Co. agrees that this guarantee will not be discharged except by complete
performance of the covenants and obligations of A Co. under this Agreement.

12.8    COUNTERPART EXECUTION

        This Agreement may be executed in any number of counterparts and each
such counterpart shall be deemed to be an original instrument but all such
counterparts together shall constitute one agreement.


                                       37
<PAGE>   42

        IN WITNESS WHEREOF, Parent Co., A Co. and Stellarton have caused this
Agreement to be executed as of the date first written above by their respective
officers thereunto duly authorized.



STELLARTON ENERGY CORPORATION                TOM BROWN, INC.


Per:   "R.D. Steele"                         Per:  "James D. Lightner"
       Name: R.D. Steele                           Name: James D. Lightner
       Title: President                            Title: President

Per:   "Dell Chapman"
       Name: Dell Chapman
       Title: Chief Financial Officer


                                             TOM BROWN RESOURCES LTD.


                                             Per:  "James D. Lightner"
                                                   -----------------------------
                                                   Name: James D. Lightner
                                                   Title: President



                                       38
<PAGE>   43


                                   SCHEDULE A

                             CONDITIONS TO THE OFFER

        The capitalized terms used in this Schedule A have the meanings set
forth in the attached Pre-Acquisition Agreement dated December 13, 2000 (the
"Agreement") between Parent Co., A Co. and Stellarton, except that the term
"Offeror" shall be deemed to refer to A Co.

        Notwithstanding any other provision of the Offer, but subject to the
provisions of the Agreement, the Offeror reserves the right to withdraw or
terminate the Offer and not take up and pay for, or to extend the period of time
during which the Offer is open and postpone taking up and paying for, any
Stellarton Shares deposited under the Offer unless all of the following
conditions are satisfied or waived by the Offeror:

        (a)    prior to the Expiry Time, and at the time the Offeror first takes
               up and pays for Stellarton Shares under the Offer, there shall
               have been validly deposited under the Offer and not withdrawn at
               least 66 2/3% of the outstanding Stellarton Shares (calculated on
               a diluted basis) (the "Minimum Condition");

        (b)    all necessary approvals under the Investment Canada Act in
               connection with the Offer and the acquisition of the Stellarton
               Shares pursuant to the Offer shall have been obtained or deemed
               to be obtained;

        (c)    all requisite regulatory approvals and regulatory consents
               (including, without limitation, those of any stock exchanges or
               other securities or regulatory authorities) which are considered
               by A Co., acting reasonably, as being necessary to complete the
               Offer shall have been obtained on terms and conditions
               satisfactory to the Offeror, acting reasonably, and all
               applicable statutory or regulatory waiting periods shall have
               expired or been terminated and no unresolved objection or
               opposition shall have been filed, initiated or made during any
               applicable statutory or regulatory period;

        (d)    (i) no act, action, suit, proceeding, objection or opposition
               shall have been threatened or taken before or by any domestic or
               foreign court or tribunal or governmental agency or other
               regulatory authority or administrative agency or commission by
               any elected or appointed public official or by any private person
               in Canada or elsewhere, whether or not having the force of law,
               and (ii) no law, regulation or policy (including applicable tax
               laws and regulations in those jurisdictions in which Stellarton
               or any of its subsidiaries carries on business) shall have been
               proposed, enacted, promulgated, amended or applied, which in
               either case, in the sole judgment of the Offeror, acting
               reasonably:

               (A)    has the effect or may have the effect to cease trade,
                      enjoin, prohibit or impose material limitations, damages
                      or conditions on the purchase by, or the sale to, the
                      Offeror of the Stellarton Shares or the right of the
                      Offeror to own or exercise full rights of ownership of the
                      Stellarton Shares;

               (B)    has had, or if the Offer was consummated would result in,
                      a material adverse change or, in the case of (ii) above,
                      would have a material adverse affect on the Offeror's
                      ability to complete the Offer as determined by the
                      Offeror, acting reasonably;


                                      A-1
<PAGE>   44


               (C)    has a material adverse effect on the ability to complete
                      any compulsory acquisition or any amalgamation, statutory
                      arrangement or other transaction involving the Offeror
                      and/or an affiliate of the Offeror and Stellarton and/or
                      the holders of Stellarton Shares for the purposes of
                      Stellarton becoming, directly or indirectly, a
                      wholly-owned subsidiary of the Offeror or affecting an
                      amalgamation or merger of Stellarton's business and assets
                      with or into the Offeror and/or an affiliate of the
                      Offeror (a "Subsequent Acquisition Transaction");

        (e)    the Offeror shall have determined, in its sole judgment, acting
               reasonably, that there shall not exist any prohibition at law
               against the Offeror making the Offer or taking up and paying for
               all of the Stellarton Shares under the Offer or completing any
               compulsory acquisition or Subsequent Acquisition Transaction in
               respect of any Stellarton Shares not acquired under the Offer;

        (f)    the Offeror shall have determined, in its sole judgment, acting
               reasonably, that there shall not have occurred, developed or come
               into effect or existence any event, action, state, condition or
               major financial occurrence of national or international
               consequence or any law, regulation, action, government
               regulation, enquiry or other occurrence of any nature whatsoever
               which, in the sole judgment of the Offeror, acting reasonably,
               have a materially adverse effect on the business or operations of
               Stellarton;

        (g)    there shall not have occurred any actual or threatened change
               (including any proposal by the Minister of Finance (Canada) to
               amend the Income Tax Act (Canada) or any announcement,
               governmental or regulatory initiative, condition, event or
               development involving a change or a prospective change) that, in
               the sole judgment of the Offeror, acting reasonably, directly or
               indirectly, has or may have material adverse significance with
               respect to the business or operations of any of the Offeror and
               Stellarton and their respective subsidiaries or entities, in each
               case taken as a whole, in which either of them has a material
               interest or with respect to the regulatory regime applicable to
               their respective businesses and operations or with respect to
               completing any compulsory acquisition or Subsequent Acquisition
               Transaction;

        (h)    the Offeror shall have determined in its sole judgment, acting
               reasonably, that (i) Stellarton shall not have breached, or
               failed to comply with, in any material respect, any of its
               covenants or other obligations under the Agreement, and (ii) all
               representations and warranties of Stellarton contained in the
               Agreement shall have been true and correct in all material
               respects as of the date of the Agreement, shall continue to be
               true and correct as though made on each successive date
               thereafter and shall not have ceased to be true and correct in
               any material respect thereafter;

        (i)    the Agreement shall not have been terminated pursuant to its
               terms; and

        (j)    the Offeror shall, in its sole judgment, acting reasonably, be
               satisfied that all outstanding stock options, warrants and all
               other rights to acquire any Stellarton Shares shall have either
               been exercised or terminated or may be terminated or otherwise
               dealt with on a basis acceptable to the Offeror in its sole
               judgment, acting reasonably, prior to the Offeror taking-up any
               Stellarton Shares pursuant to the Offer.


                                      A-2
<PAGE>   45


                                   SCHEDULE B

                          FORM OF PRE-TENDER AGREEMENT





                                                   December 13, 2000



Dear Sir:

        RE:    OFFER BY A CO. TO PURCHASE ALL OF THE STELLARTON SHARES

        Reference is made to the Pre-Acquisition Agreement dated December 13,
2000 (the "Pre-Acquisition Agreement") between Tom Brown Resources Ltd. (herein
called "A Co."), Tom Brown, Inc., as guarantor of the obligations of A Co. and
Stellarton Energy Corporation (herein called "Stellarton") pursuant to which A
Co. has agreed, on certain terms and conditions, to make an offer to purchase
all of the issued and outstanding Stellarton Shares. All capitalized terms
referred to herein shall have the meanings attributed thereto in the
Pre-Acquisition Agreement.

        We understand that you (the "Selling Shareholder") beneficially own,
directly or indirectly, or exercise control or direction over, the number of
Stellarton Shares and options to acquire further Stellarton Shares set forth in
your acceptance at the end of this Agreement.

1.      Covenants of Selling Shareholder

        By the acceptance of this letter agreement, the Selling Shareholder
hereby agrees, subject to the terms of paragraph 3 of this letter agreement,
from the date hereof until the completion of the Offer:

        (a)    not to sell, assign, convey or otherwise dispose of any of the
               Stellarton Shares owned, controlled or directed by such Selling
               Shareholder except pursuant to the Offer;

        (b)    unconditionally to accept the Offer made by A Co. by tendering or
               causing to be tendered the Stellarton Shares presently owned,
               controlled or directed or hereafter acquired, controlled or
               directed (including any Stellarton Shares hereafter acquired
               pursuant to the exercise of any options to purchase Stellarton
               Shares) by such Selling Shareholder prior to the expiry of the
               Offer and in accordance with the terms and conditions of the
               Offer free and clear of any and all liens, encumbrances, charges
               and rights and interests of third parties whatsoever;

        (c)    to sell or surrender to Stellarton or exercise all options held
               by the Selling Shareholder to acquire Stellarton Shares (the
               "Options") that have an exercise price less than the
               consideration offered pursuant to the Offer, and to forthwith


                                      B-1
<PAGE>   46


               surrender all remaining Options to Stellarton immediately
               following the Effective Time;

        (d)    not to exercise any statutory or other rights of withdrawal with
               respect to any Stellarton Shares owned by such Selling
               Shareholder once deposited pursuant to the Offer unless this
               letter agreement is terminated prior to A Co. taking up the
               Stellarton Shares under the Offer; and

        (e)    not to exercise any shareholder rights or remedies available at
               common law or pursuant to the Business Corporations Act (Alberta)
               or applicable securities legislation to delay, hinder, upset or
               challenge the Offer.

2.  Expenses

        A Co. and the Selling Shareholder agree to pay their own respective
expenses incurred in connection with this letter agreement.

3.      Termination

        It is understood and agreed that the respective rights and obligations
hereunder of A Co. and the Selling Shareholder shall cease and this letter
agreement shall terminate:

        (a)    if, prior to the expiry of the Offer, another bona fide Take-over
               Proposal is announced, proposed, offered or made to the holders
               of Stellarton Shares or Stellarton which, in the opinion of
               Stellarton's board of directors after consultation with its
               financial advisors, would constitute a Superior Proposal and
               which permits the board of directors of Stellarton to withdraw,
               modify or change any recommendation regarding the Offer in
               accordance with Section 2.2(a) of the Pre-Acquisition Agreement
               and to terminate the Pre-Acquisition Agreement as a consequence
               thereof; or

        (b)    in the event that the Pre-Acquisition Agreement is terminated
               pursuant to Section 11.1 thereof.

        In the event of termination of this letter agreement, the Selling
Shareholder may withdraw all of the Stellarton Shares deposited in accordance
with the terms and conditions of the Offer, this letter agreement shall
forthwith be of no further force and effect and there shall be no liability on
the part of either the Selling Shareholder or A Co., except to the extent that
either such party is in default of its obligations herein contained.

4.      Amendment

        Except as expressly set forth herein, this letter agreement constitutes
the whole of the agreement between the parties and may not be modified, amended,
altered or supplemented except upon the execution and delivery of a written
agreement executed by the parties hereto.

5.  Assignment

        Except as expressly set forth herein, no party to this letter agreement
may assign any of its rights or obligations under this letter agreement without
the prior written consent of the other party.



                                      B-2
<PAGE>   47

6.      Disclosure

        Prior to first public disclosure of the existence and terms and
conditions of this letter, none of the parties hereto shall disclose the
existence of this letter agreement, or any details hereof, to any person other
than Stellarton, its directors and officers, without the prior written consent
of the other parties hereto, except to the extent required by law. The existence
and terms and conditions of this letter agreement may be disclosed by A Co. and
Stellarton in the press release issued in connection with the execution of the
Pre-Acquisition Agreement and the Offer Documents and the Directors Circular
prepared by Stellarton.

7.      Enurement

        This letter agreement will be binding upon and enure to the benefit of A
Co., the Selling Shareholder and their respective executors, administrators,
successors and permitted assigns.

8.      Applicable Law

        This letter agreement shall be governed and construed in accordance with
the laws of the Province of Alberta and the federal laws of Canada applicable
therein and each of the parties hereto irrevocably attorns to the jurisdiction
of the courts of the Province of Alberta.

9.      Counterparts

        This letter agreement may be signed in counterparts which together shall
be deemed to constitute one valid and binding agreement and delivery of such
counterparts may be effected by means of telecopier.


                                              Yours truly,

                                              TOM BROWN RESOURCES LTD.



                                              Per:   _________________________



                                      B-3
<PAGE>   48

                                   ACCEPTANCE

        The foregoing is hereby accepted as of and with effect from the ___ day
of December, 2000 and the undersigned hereby confirms that the undersigned
beneficially owns ___________ Stellarton Shares and options to acquire a further
__________ Stellarton Shares.




--------------------------------            ------------------------------------
Witness                                     Name:
                                            Title: