<PAGE>   1
                                                                    EXHIBIT 10.3

                                                                  EXECUTION COPY



                           PARTIAL ASSIGNMENT OF NOTES

                  THIS PARTIAL ASSIGNMENT OF NOTES ("Agreement") dated as of
February 17, 2000, by and among Bank of Montreal, a Canadian bank (the "BMO"),
Societe Generale, Southwest Agency ("Soc-Gen"), Shell Capital Inc., a Delaware
corporation (the "Assignee") and Brigham Oil & Gas, L.P., a Delaware limited
partnership (the "Borrower").

                                    RECITALS

                  A. Pursuant to that certain Credit Agreement (the "Original
Credit Agreement") dated as of January 26, 1998 among the Borrower and BMO, as
amended by that certain First Amendment to Credit Agreement dated as of August
20, 1998 among the Borrower, BMO and Soc-Gen (the "First Amendment"), that
certain Second Amendment to Credit Agreement dated as of March 26, 1999 among
the Borrower, BMO and Soc-Gen (the "Second Amendment"), that certain Third
Amendment to Credit Agreement dated as of July 19, 1999 among the Borrower, BMO
and Soc-Gen (the "Third Amendment") and that certain Fourth Amendment to Credit
Agreement dated as of October 7, 1999 among the Borrower, BMO and Soc-Gen (the
"Fourth Amendment") (the Original Credit Agreement as amended by the First
Amendment, the Second Amendment, the Third Amendment and the Fourth Amendment
being hereafter called the "Prior Credit Agreement"), BMO and Soc-Gen provided
to the Borrower loans and extensions of credit, which loans and extensions of
credit are evidenced by those certain promissory notes from the Borrower in the
aggregate principal amount of $75,000,000 (the "Prior Notes").

                  B. BMO and Soc-Gen (collectively the "Assignors") propose to
sell, assign and transfer to the Assignee, and the Assignee proposes to purchase
and assume from the Assignors, a 53.333% interest in the Prior Notes (the
Assigned Interest, as hereinafter defined) upon the occurrence of certain
conditions provided herein, and BMO and Soc-Gen, as the case may be, propose to
sell, assign and transfer to the Assignee, and the Assignee proposes to purchase
and assume from BMO and/or Soc-Gen the Retained Interest, as hereinafter
defined, all on the terms and conditions of this Agreement.

                  C. Pursuant to that certain Amended and Restated Credit
Agreement (the "Current Credit Agreement") dated as of February 17, 2000 among
the Borrower, BMO, in its individual capacity, Soc-Gen and Assignee, and BMO, in
its capacity as Agent for Soc-Gen and Assignee (in such capacity, together with
its successors in such capacity, the "Agent") have agreed to provide senior
secured debt in the amount of up to $75,000,000 (the "Current Notes") consisting
of a rearrangement of the Prior Notes and advances to the Borrower for general
corporate purposes and the Borrower, BMO, Soc-Gen, Assignee and the Agent agree
to amend and restate in their entirety the Prior Credit Agreement by means of
the Current Credit Agreement, and the Prior Notes, by means of the Current
Notes.

                  D. In consideration of the foregoing and the mutual agreements
contained herein, and for other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties hereto agree as
follows:


<PAGE>   2


                                   ARTICLE 1

                                  Definitions.

         Section 1.01 Definitions. All capitalized terms used but not defined
herein have the respective meanings given to such terms in the Credit Agreement
if defined therein.

         Section 1.02 Other Definitions. As used herein, the following terms
have the following respective meanings:

                 "Assigned Interest" shall mean that portion of each of BMO's
         and Soc-Gen's rights and obligations (i) under the Prior Credit
         Agreement and the other Loan Documents in respect of the Maximum Credit
         Amount of each of BMO and Soc-Gen in the principal amount as set forth
         on Schedule A to this Agreement ("Schedule A"), and (ii) to make Loans
         under the Maximum Credit Amount and any right to receive payments for
         the Loans outstanding under the Maximum Credit Amount as set forth on
         Schedule A, plus the interest and fees which will accrue on the
         Assigned Interest from and after the Assignment Date.

                 "Assignee Subordinated Indebtedness" shall mean the principal
         balance due to Assignee (excluding any Debt of the Borrower under
         Hedging Agreements made with the Assignee or an Affiliate of Assignee
         as provided in the Current Credit Agreement) of all loans advanced to
         or issued for the account of Borrower pursuant to the terms and
         conditions of the Prior Credit Agreement and the Current Credit
         Agreement, not to exceed $75,000,000 and accrued but unpaid interest
         thereon, and of all fees, expenses, reimbursement obligations,
         liabilities, indemnities or other monetary obligations of Borrower
         whether any of the foregoing is (i) absolute or contingent, direct or
         indirect, joint, several or independent, (ii) now outstanding or owing
         or which may hereafter be existing or incurred, (iii) due or to become
         due, or (iv) held or to be held by Assignee, and all renewals,
         extensions, rearrangements, refundings and modifications thereof
         permitted by the terms hereof.

                 "Assignment Date" shall mean February 17, 2000.

                 "BMO/Soc-Gen Senior Indebtedness" shall mean the principal
         balance due (i) to Assignors of all loans advanced to or issued for the
         account of Borrower pursuant to the terms and conditions of the Prior
         Credit Agreement and the Current Credit Agreement, not to exceed
         $75,000,000 and accrued but unpaid interest thereon, and of all fees,
         expenses, reimbursement obligations, liabilities, indemnities or other
         monetary obligations of Borrower under the Credit Agreement, and (ii)
         of all swap settlement amounts or other amounts due and payable under
         any Hedging Agreement in existence as of the date hereof or hereafter
         arising between (i) Borrower and BMO and its successors or assigns (a
         "BMO Hedge Party") and Soc-Gen and its successors or assigns (a
         "Soc-Gen Hedge Party") entered into while such BMO Hedge Party or such
         Soc-Gen Hedge Party is a Lender; and (ii) Borrower and SCI and its
         successors or assigns (with


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<PAGE>   3


         Loans or Commitments of $20 million or more) or any Affiliate of SCI
         (SCI and any Affiliate of SCI a "SCI Hedge Party") entered into while
         such SCI Hedge Party or Fathom Energy Capital I, L.L.C, is a Lender,
         whether any of the foregoing is (w) absolute or contingent, direct or
         indirect, joint, several or independent, (x) now outstanding or owing
         or which may hereafter be existing or incurred, (y) due or to become
         due, or (z) held or to be held by the Assignors or any Assignor, and
         all renewals, extensions, rearrangements, refundings and modifications
         thereof permitted by the terms hereof. The parties intend that any
         Hedging Agreement entered into between the Borrower and a Lender or in
         the case of SCI, a SCI Hedge Party, while such Person was a party to
         the Credit Agreement shall continue to be secured even after the time
         such Person ceases to be a party to the Credit Agreement as a Lender
         and shall be "BMO/Soc-Gen Senior Indebtedness".

                 "Retained Interest" shall mean that portion of each of BMO and
         Soc-Gen's rights and obligations (i) under the Prior Credit Agreement,
         the Current Credit Agreement and the other Loan Documents in respect of
         the BMO/Soc-Gen Senior Indebtedness of each of BMO and Soc-Gen in the
         principal amount as set forth in Schedule B to this Agreement
         ("Schedule B") and (ii) to make Loans under the BMO/Soc-Gen Senior
         Indebtedness as set forth on Schedule B (the "Retained Loan
         Commitment"), plus the interest and fees which will accrue on the
         Retained Interest from and after the Assignment Date.

                                   ARTICLE 2

                              Sale and Assignment.

         Section 2.01 Sale and Assignment.

                 (a) On the terms and conditions set forth herein, effective on
         and as of the Assignment Date, the Assignors hereby sell, assign and
         transfer to the Assignee, and the Assignee hereby purchases and assumes
         from the Assignors, all of the right, title and interest of the
         Assignors in and to, and all of the obligations of the Assignors in
         respect of, the Assigned Interest. Such sale, assignment and transfer
         is without recourse and, except as expressly provided in this
         Agreement, without representation or warranty.

                 (b) At the election of each BMO/Soc-Gen Lender, Assignee shall
         be obligated to purchase the Retained Interest of such BMO/Soc-Gen
         Lender on March 31, 2002 provided that the amount of the Borrowing Base
         on such date determined in accordance with Section 2.08 of the Credit
         Agreement is greater than the aggregate outstanding principal amounts
         of the Loans, there are no Defaults or Events of Default under the
         Current Credit Agreement, and such BMO/Soc-Gen Lender requests in
         writing no later than March 15, 2002 that the Assignee purchase the
         Retained Interest of such BMO/Soc-Gen Lender. The sale, assignment and
         transfer of such Retained Interest to Assignee will be without recourse
         and without representation or warranty, except for representations


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<PAGE>   4


         substantially the same to those provided in this Agreement and shall be
         in form substantially similar to this Agreement.

         Section 2.02 Assumption of Obligations. The Assignee agrees with the
Assignors (for the express benefit of the Assignors and the Borrower) that the
Assignee will, from and after the Assignment Date, perform all of the
obligations of the Assignors accruing after the Assignment Date in respect of
the Assigned Interest. From and after the Assignment Date: (a) the Assignors
shall be released from the Assignors' obligations in respect of the Assigned
Interest, and (b) the Assignee shall, except as otherwise provided in this
Agreement, including, without limitation, Section 3.03 which, among the
Assignors, Assignee and the Borrower, governs the allocation of payments on the
Assigned Interest and Section 3.05 which, among the Assignors, Assignee and the
Borrower, governs future obligations to make loans under the Current Credit
Agreement, be entitled to all of the Assignors' rights, powers and privileges
under the Credit Agreement and the other Loan Documents in respect of the
Assigned Interest.

         Section 2.03 Purchase Price for Assigned Interest. As consideration for
the sale, assignment and transfer of the Assigned Interest contemplated by
Section 2.01(a) hereof, the Assignee shall, on the Assignment Date, assume
Assignors' obligations accruing after the Assignment Date in respect of the
Assigned Interest and pay to BMO an amount equal to $13,892,323.85 and to
Soc-Gen an amount equal to $7,107,676.15. Except as otherwise provided in this
Agreement, all payments hereunder shall be made in Dollars and in immediately
available funds, without setoff, deduction or counterclaim.

         Section 2.04 Purchase Price for Retained Interest. Upon satisfaction of
the conditions specified in Section 2.01(b) hereof, Assignee shall pay to each
BMO/Soc-Gen Lender who makes the election to assign its Retained Interest to
Assignee an amount equal to the then outstanding principal and interest of the
Retained Loan Commitment owed to such BMO/Soc-Gen Lender in consideration of the
sale, assignment and transfer of the Retained Interest as provided herein. Such
payment shall be made in Dollars and in immediately available funds, without
setoff, deduction or counterclaim and shall be made no later than March 31,
2002.

         Section 2.05 Delivery of Notes. Promptly following the receipt by the
Assignors of the consideration required to be paid under Section 2.03 or 2.04
hereof, the Assignors shall, in the manner contemplated by Section 12.06(d) of
the Current Credit Agreement, (i) deliver to the Agent (or its counsel) a Note
corresponding to the Assigned Interest or any applicable Retained Interest, as
the case may be, and (ii) notify the Agent to request that the Borrower execute
and deliver new Notes in accordance with the terms of the Current Credit
Agreement to the Assignors and the Assignee.

                                   ARTICLE 3

                                  Subordination

         Section 3.01 Agreement to Subordinate. The payment of any and all
Assignee Subordinated Indebtedness and the rights of Assignee with respect to
the Assignee Subordinated


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<PAGE>   5


Indebtedness are expressly subordinated to the BMO/Soc-Gen Senior Indebtedness
to the extent and in the manner set forth in Sections 3.02 through 3.05 hereof.

         Section 3.02 Certain Voting Rights.

                 (a) The Assignors and Assignee agree that, except as otherwise
         expressly provided herein or in the Current Credit Agreement, on any
         date prior to March 31, 2002 any act, event, document or condition
         requiring pursuant to the terms of the Current Credit Agreement the
         consent, agreement or waiver of, or approval, notice, selection,
         designation or appointment by, or request, direction or election of,
         the Lenders, shall require the unanimous agreement of the Majority
         Lenders;

                 (b) Notwithstanding the provisions of Section 2.08(a) of the
         Current Credit Agreement, the BMO/Soc-Gen Majority Lenders shall in
         their sole discretion determine the Target Asset Value as provided in
         Section 8.13 of the Current Credit Agreement and whether to waive any
         default arising from Borrower's non-compliance with Section 8.13 of the
         Current Credit Agreement;

                 (c) The SCI Majority Lenders, in their sole discretion, shall
         determine (i) the Risk Adjusted Proved Reserve Value, (ii) the PDP
         Reserve value for purposes of subparagraph (c) of the definition of
         Increase Event, (iii) whether to waive any default under Section
         9.22(e) of the Current Credit Agreement, and (iv) whether to convert
         the Assigned Interest into equity of Borrower pursuant to the Equity
         Conversion Agreement;

                 (d) At the request of the Agent, the Assignee agrees to execute
         any consents, agreements, waivers, approvals, requests, or other
         instruments or documents necessary or desirable to give effect to the
         agreements specified in Section 3.02(b); and

                 (e) At the request of the Assignee, each of the Assignors agree
         to execute any consents, agreements, waivers, approvals, requests, or
         other instruments or documents necessary or desirable to give effect to
         the agreements specified in Section 3.02(c).

         Section 3.03 Payments on Assigned Interest.

                 (a) The Assignors, the Assignee and Borrower (to the extent
         required) agree, that:

                     (i) the Assignee Subordinated Indebtedness is subordinate
                 in right of payment, to the extent and in the manner provided
                 in this Agreement, to the prior payment in full of all
                 principal of the BMO/Soc-Gen Senior Indebtedness (whether
                 outstanding on the date hereof or hereafter created, incurred,
                 assumed or guaranteed);


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<PAGE>   6


                     (ii) the Borrower may not, except as otherwise agreed to in
                 writing by Assignors and Assignee, make any payment (whether by
                 redemption, purchase, retirement, defeasance, set-off or
                 otherwise) upon or in respect of the Assignee Subordinated
                 Indebtedness, until all principal and other obligations with
                 respect to the BMO/Soc-Gen Senior Indebtedness has been paid in
                 full:

                     (iii) the Borrower may commence payments on, and
                 distributions in respect of, the Assignee Subordinated
                 Indebtedness upon payment in full of all BMO/Soc-Gen Senior
                 Indebtedness (whether outstanding on the date hereof or
                 hereafter created, incurred, assumed or guaranteed).

                     (iv) Notwithstanding the foregoing, and provided that no
                 Event of Default has occurred and is continuing, the Borrower
                 may pay to the SCI Lenders, and the SCI Lenders may receive and
                 retain, all amounts due and payable to the SCI Lenders for
                 accrued interest on the SCI Loans and other fees due to SCI in
                 accordance with Sections 3.02 and 4.02 of the Current Credit
                 Agreement and the SCI Fee Letter.

                     (v) Upon any payment or distribution of property or
                 securities to creditors of the Borrower in a liquidation or
                 dissolution of such person or its property, or in an assignment
                 for the benefit of creditors or any marshaling of its assets
                 and liabilities:

                         (A) each of the Assignors shall be entitled to receive
                     payment in full of all BMO/Soc-Gen Senior Indebtedness
                     before the Assignee shall be entitled to receive any
                     payment with respect to the Assignee Subordinated
                     Indebtedness; and

                         (B) until the BMO/Soc-Gen Senior Indebtedness is paid
                     in full, any payment or distribution to which the Assignee
                     would be entitled shall be made to each of the Assignors
                     for its benefit.

                         (C) under the circumstances described in this clause
                     (iv), the Borrower or any receiver, trustee in bankruptcy,
                     liquidating trustee, agent or other similar Person making
                     any payment or distribution of cash or other property or
                     securities is authorized or instructed to make any payment
                     or distribution to which the Assignee would otherwise be
                     entitled (other than securities that are subordinated at
                     least to the same extent as the Assignee Subordinated
                     Indebtedness) directly to each of the Assignors for its
                     benefit to the extent necessary to pay all BMO/Soc-Gen
                     Senior Indebtedness in full, after giving effect to any
                     concurrent payment, distribution or provision therefor to
                     or for the Assignors.


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<PAGE>   7


                 (b) The foregoing provisions of this Section 3.03 shall not
         impair or prohibit the rights of the Assignee to receive payments (i)
         through conversion of any of the Assignee Subordinated Indebtedness to
         equity as provided in the Equity Conversion Agreement or (ii) in the
         form of other equity securities or additional subordinated debt that is
         subordinated to the BMO/Soc-Gen Senior Indebtedness in accordance with
         the terms substantially similar to the terms of this Agreement.

         Section 3.04 Payments Received or Made in Violation of this Agreement.
In the event the Assignee shall receive any payment or distribution on account
of the Assignee Subordinated Indebtedness which it is not entitled to receive
under the provisions of Section 3.03, the Assignee will hold any amount so
received in trust for the Assignors and will forthwith turn over such payment to
the Assignors in the form received by it (together with any necessary
endorsement) to be applied to the BMO/Soc-Gen Senior Indebtedness.

         Section 3.05 Assignee Funding. Assignors, Assignee and Borrower agree
that, subsequent to the Assignment Date, (i) Assignors shall have no further
obligation to make Loans under the Current Credit Agreement; and (ii) Assignee
shall have the sole responsibility to meet any obligation that may arise under
the Credit Agreement to make Loans under the Credit Agreement, provided,
however, Assignee's obligations to make Loans under the Current Credit Agreement
shall not exceed its Commitment.

                                   ARTICLE 4

                              Conditions Precedent.

         Section 4.01 Conditions Precedent. The effectiveness of the sale,
assignment and transfer of the Assigned Interest contemplated hereby is subject
to the satisfaction of each of the following conditions precedent:

                 (a) the execution and delivery of this Agreement by the
         Assignors and the Assignee;

                 (b) the receipt by the Assignors of the payment required to be
         made by the Assignee under Section 2.03 hereof;

                 (c) the acknowledgment by the Agent and the Borrower
         contemplated by Section 2.05 hereof;

                 (d) the execution and delivery of the Notes contemplated by
         Section 2.06 hereof;

                 (e) the satisfaction of the conditions of the Initial Funding
         set forth in Section 6.01 of the Current Credit Agreement; and

                 (f) the execution and delivery of the Current Credit Agreement.


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<PAGE>   8


                                   ARTICLE 5

                         Representations and Warranties.

         Section 5.01 Representations and Warranties of the Assignors.

                 (a) Each of the Assignors represents and warrants for itself
         that:

                     (i) it has all requisite power and authority, and has taken
                 all action necessary to execute and deliver this Agreement and
                 to fulfill its obligations under, and consummate the
                 transactions contemplated by, this Agreement;

                     (ii) the execution, delivery and compliance with the terms
                 hereof by it and the delivery of all instruments required to be
                 delivered by it hereunder do not and will not violate any
                 Governmental Requirement applicable to it;

                     (iii) this Agreement has been duly executed and delivered
                 by it and constitutes the legal, valid and binding obligation
                 of such Assignor, enforceable against it in accordance with its
                 terms;

                     (iv) all approvals and authorizations of, all filings with
                 and all actions by any Governmental Authority necessary for the
                 validity or enforceability of its obligations under this
                 Agreement have been obtained;

                     (v) it has good title, to and is the sole legal and
                 beneficial owner of, the Assigned Interest, free and clear of
                 all Liens, claims, participations or other charges of any
                 nature whatsoever and has the right to transfer to the
                 Assignee, the rights being transferred; and

                     (vi) the amounts set forth on Schedule A and Schedule B by
                 each of the respective Assignors as its portion of the Assigned
                 Interest and Retained Interest is true and correct.

                 (b) Each of the Assignors does not (i) make any representation
         or warranty or assume any responsibility with respect to any
         statements, warranties or representations made (x) by the Borrower in
         or in connection with the Credit Agreement or (y) with respect to the
         execution, legality, validity, enforceability, genuineness, sufficiency
         or value of the Credit Agreement, any other Loan Document or any other
         instrument or document furnished pursuant hereto or thereto, or any
         collateral or the legality, validity, perfection or priority of any
         Lien granted or purported to be granted pursuant to any Security
         Instrument, or (ii) make any representation or warranty or assume any
         responsibility with respect to the financial condition of Borrower or
         any other obligor or the performance or observance by Borrower or any
         other obligor of any of their respective obligations under the Credit
         Agreement or any other Loan Document or any other instrument or
         document furnished pursuant hereto or thereto.


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<PAGE>   9


         Section 5.02 Representations and Warranties of the Assignee. The
Assignee represents and warrants to each of the Assignors as follows:

                 (a) it has all requisite power and authority, and has taken all
         action necessary to execute and deliver this Agreement and to fulfill
         its obligations under, and consummate the transactions contemplated by,
         this Agreement;

                 (b) the execution, delivery and compliance with the terms
         hereof by Assignee and the delivery of all instruments required to be
         delivered by it hereunder do not and will not violate any Governmental
         Requirement applicable to it;

                 (c) this Agreement has been duly executed and delivered by it
         and constitutes the legal, valid and binding obligation of the
         Assignee, enforceable against it in accordance with its terms;

                 (d) all approvals and authorizations of, all filings with and
         all actions by any Governmental Authority necessary for the validity or
         enforceability of its obligations under this Agreement have been
         obtained; and

                 (e) the Assignee has fully reviewed the terms of the Credit
         Agreement and the other Loan Documents and has independently and
         without reliance upon the Assignors, and based on such information as
         the Assignee has deemed appropriate, made its own credit analysis and
         decision to enter into this Agreement.

                                   ARTICLE 6

                                 Miscellaneous.

         Section 6.01 Notices. All notices and other communications provided for
herein (including, without limitation, any modifications of, or waivers,
requests or consents under, this Agreement) shall be given or made in writing
(including, without limitation, by telex or telecopy) to the intended recipient
at its "Address for Notices" specified below its name on the signature pages
hereof or, as to either party, at such other address as shall be designated by
such party in a notice to the other party.

         Section 6.02 Amendment, Modification or Waiver. No provision of this
Agreement may be amended, modified or waived except by an instrument in writing
signed by the Assignors and the Assignee, and consented to by the Agent.

         Section 6.03 Further Assurances. The Assignors and the Assignee hereby
agree to execute and deliver such other instruments, and take such other
actions, as either party may reasonably request to correct any errors or as
otherwise required to accomplish the transactions contemplated by this
Agreement.

         Section 6.04 Successors and Assigns. This Agreement shall be binding
upon and inure to the benefit of the parties hereto and their respective
successors and permitted


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<PAGE>   10


assigns. The representations and warranties made herein by the Assignee are also
made for the benefit of the Agent and the Borrower, and the Assignee agrees that
the Agent and the Borrower are entitled to rely upon such representations and
warranties.

         Section 6.05 Assignments. None of the parties hereto may assign any of
its rights or obligations hereunder except in accordance with the terms of the
Credit Agreement.

         Section 6.06 Captions. The captions and section headings appearing
herein are included solely for convenience of reference and are not intended to
affect the interpretation of any provision of this Agreement.

         Section 6.07 Counterparts. This Agreement may be executed in any number
of counterparts, each of which shall be identical and all of which, taken
together, shall constitute one and the same instrument, and each of the parties
hereto may execute this Agreement by signing any such counterpart.

         Section 6.08 Governing Law. This Agreement shall be governed by, and
construed in accordance with, the law of the State of Texas.

         Section 6.09 Expense. To the extent not paid by the Borrower pursuant
to the terms of the Credit Agreement, each party hereto shall bear its own
expenses in connection with the execution, delivery and performance of this
Agreement.

         Section 6.10 Waiver of Jury Trial. EACH OF THE PARTIES HERETO HEREBY
IRREVOCABLY WAIVES, TO THE FULLEST EXTENT PERMITTED BY LAW, ANY AND ALL RIGHT TO
TRIAL BY JURY IN ANY LEGAL PROCEEDING ARISING OUT OF OR RELATING TO THIS
AGREEMENT OR THE TRANSACTIONS CONTEMPLATED HEREBY.


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<PAGE>   11


                  IN WITNESS WHEREOF, the parties hereto have caused this
Assignment Agreement to be executed and delivered as of the date first above
written.

                                          ASSIGNORS

                                          BANK OF MONTREAL



                                          By:
                                             ----------------------------------
                                          Name:   Thomas E. McGraw
                                          Title:  Director

                                          Address for Notices:
                                          700 Louisiana Street, Suite 4400
                                          Houston, Texas 77002

                                          Telecopier No.:  (713) 223-0477
                                          Telephone No.:  (713) 223-4400

                                          Attention:  Thomas E. McGraw


                                          SOCIETE GENERALE, SOUTHWEST AGENCY



                                          By:
                                             ----------------------------------
                                          Name:   Mark A. Cox
                                          Title:  Director

                                          Address for Notices:
                                          1111 Bagby Street, Suite 2020
                                          Houston, Texas 77002

                                          Telecopier No: (713) 650-0824
                                          Telephone No:  (713) 759-6315



                                       S

<PAGE>   12



                                          ASSIGNEE

                                          SHELL CAPITAL INC.

                                          By:
                                             ----------------------------------
                                          Name:  Robert L. Roberts
                                          Title: Vice President


                                          Address for Notices:

                                          910 Louisiana Street, Suite 5000
                                          Houston, Texas 77002-4916

                                          Telecopier No.:  (713) 241-5222
                                          Telephone No.:  (713) 241-4130
                                          Attention:  Robert L. Roberts

                                          BORROWER:

                                          BRIGHAM OIL & GAS, L.P.

                                          By:  Brigham, Inc., General Partner



                                          By:
                                             ----------------------------------
                                          Name:    Curtis F. Harrell
                                          Title:   Chief Financial Officer


                                          BANK OF MONTREAL, as Agent



                                          By:
                                             ----------------------------------
                                          Name:    Thomas E. McGraw
                                          Title:   Director


                                       S

<PAGE>   13



                                   SCHEDULE A


<TABLE>
<CAPTION>
                                               Principal Amount    Loan Commitment
                                               ----------------    ---------------
<S>                                            <C>                 <C>
Bank of Montreal                               $  13,892,323.85    $ 26,461,554.62
Societe Generale, Southwest Agency             $   7,107,676.15    $ 13,538,445.38
</TABLE>


                                 SCH. A, PAGE 1

<PAGE>   14




                                   SCHEDULE B

<TABLE>
<CAPTION>
                                                                Retained Loan
                                           Principal Amount      Commitment
                                           ----------------    ---------------
<S>                                        <C>                 <C>
Bank of Montreal                           $  23,153,830.00    $ 23,153,830.00
Societe Generale, Southwest Agency         $  11,846,170.00    $ 11,846,170.00
</TABLE>




                                 SCH. B, PAGE 1