<PAGE>
                                                                    EXHIBIT 4.12


                                CREDIT AGREEMENT


                           Dated as of March 18, 1997


                                     Among


                           UMC RESOURCES CANADA LTD.,
                                as the Company,


                      THE CHASE MANHATTAN BANK OF CANADA,
                                   as Agent,


                                      and


                          THE LENDERS SIGNATORY HERETO
<PAGE>
 
                               TABLE OF CONTENTS
                               -----------------
                                                                           Page
                                                                           ----

                 Article I: Definitions and Accounting Matters

     Section 1.01  Terms Defined Above...................................   -1-
     Section 1.02  Certain Defined Terms.................................   -1-
     Section 1.03  Other Defined Terms...................................   -5-
     Section 1.04  Accounting Terms and Determinations...................   -5-

                           Article II:  Commitments

     Section 2.01  Loans and Bankers' Acceptances........................   -6-
     Section 2.02  Borrowings, Renewals, Conversions, and Issuances......   -7-
     Section 2.03  Changes of Commitments................................   -8-
     Section 2.04  Commitment Fee and Other Fees.........................   -9-
     Section 2.05  Lending Offices.......................................   -9-
     Section 2.06  Several Obligations...................................  -10-
     Section 2.07  Notes.................................................  -10-
     Section 2.08  Prepayments...........................................  -10-
     Section 2.09  Available Canadian Commitment.........................  -11-
     Section 2.10  Acceptance Date Procedure.............................  -11-
     Section 2.11  Purchase of Bankers' Acceptances......................  -12-
     Section 2.12  Payment of Bankers' Acceptances.......................  -12-

               Article III:  Payments of Principal and Interest

     Section 3.01  Repayment of Loans....................................  -12-
     Section 3.02  Interest..............................................  -13-

         Article IV:  Payments; Pro Rata Treatment; Computations; Etc.

     Section 4.01  Payments..............................................  -13-
     Section 4.02  Pro Rata Treatment....................................  -13-
     Section 4.03  Computations..........................................  -14-
     Section 4.04  Non-receipt of Funds by the Administrative Agent......  -14-
     Section 4.05  Sharing of Payments, Etc..............................  -14-

                  Article V:  Yield Protection and Illegality

     Section 5.01  Additional Costs......................................  -15-
     Section 5.02  Illegality............................................  -16-
     Section 5.03  Additional Cost in Respect of Tax.....................  -17-
     Section 5.04  Base Rate Loans pursuant to Sections 5.01 and 5.02....  -18-
     Section 5.05  Compensation..........................................  -18-
     Section 5.06  Avoidance of Taxes and Additional Costs...............  -18-
<PAGE>
 
     Section 5.07  Limitation on Right to Compensation...................  -19-

                       Article VI:  Conditions Precedent

     Section 6.01  Initial Loan or Bankers' Acceptance...................  -19-
     Section 6.02  Subsequent Borrowings.................................  -20-

                  Article VII:  Representations and Warranties

     Section 7.01  Incorporation By Reference............................  -20-

                     Article VIII:  Affirmative Covenants

     Section 8.01  Incorporation By Reference............................  -21-

                        Article IX:  Negative Covenants

     Section 9.01  Affirmation of Certain Covenants in Article IX
                    of the U. S. Credit Agreement........................  -21-

                         Article X:  Events of Default

     Section 10.01  Events of Default....................................  -22-

                     Article XI:  The Administrative Agent

     Section 11.01  Incorporation by Reference...........................  -22-

                          Article XII:  Miscellaneous

     Section 12.01  Incorporation by Reference...........................  -23-
     Section 12.02  Amendments, Etc......................................  -23-
     Section 12.03  Assignments and Participations.......................  -23-
     Section 12.04  Survival.............................................  -24-
     Section 12.05  GOVERNING LAW........................................  -24-
     Section 12.06  Effectiveness........................................  -25-
     Section 12.07  Interpretation of Security Instruments...............  -25-
     Section 12.08  Debt Characterization for Indenture Purposes.........  -25-

Exhibit A - Form of Note
Exhibit B - Form of Bankers' Acceptances
Exhibit C - Form of Assignment and Acceptance
Exhibit D - Form of Borrowing Request
<PAGE>
 
          This CREDIT AGREEMENT dated as of March 18, 1997 is among:  UMC
RESOURCES CANADA LTD., a company continued under the laws of the Province of
British Columbia and formerly known as Norwich Resources Canada Ltd. (the
"Company"); each of the lenders that is a signatory hereto (individually, a
"Lender" and, collectively, the "Lenders"); and THE CHASE MANHATTAN BANK OF
CANADA, as administrative agent for the Lenders (in such capacity, together with
its successors in such capacity, the "Administrative Agent").

                                    Recitals

     A.   The Company, the Administrative Agent and the Lenders entered into
that certain Amended and Restated Credit Agreement dated July 18, 1994, as
amended by that certain First Joint Amendment to Amended and Restated Credit
Agreement and Amended and Restated Credit Agreement (Canada) dated September 2,
1994, as further amended by that certain Second Joint Amendment to Amended and
Restated Credit Agreement and Amended and Restated Credit Agreement (Canada)
dated as of November 15, 1994, as further amended by that certain Third Joint
Amendment to Amended and Restated Credit Agreement and Amended and Restated
Credit Agreement (Canada) dated as of December 31, 1994, as further amended by
that certain Fourth Joint Amendment to Amended and Restated Credit Agreement and
Amended and Restated Credit Agreement (Canada) dated as of October 30, 1995, and
as further amended by that certain Fifth Joint Amendment to Amended and Restated
Credit Agreement and Amended and Restated Credit Agreement (Canada) dated as of
November 1, 1996 (such credit agreement, as amended, the "Prior Credit
Agreement").

     B.   The Company has requested that the Administrative Agent and the
Lenders amend and restate the Prior Credit Agreement and make credit available
to and on behalf of the Company on the terms and conditions stated herein.

     C.   The Administrative Agent and the Lenders, subject to the terms and
conditions stated herein, are willing to amend and restate the Prior Credit
Agreement and to make such credit facilities available.

     D.   Subject to the terms and conditions set forth herein, the
Administrative Agent and the Lenders have agreed to make certain credit
available to the Company; and accordingly, the parties hereto agree as follows:

                 ARTICLE I: DEFINITIONS AND ACCOUNTING MATTERS

      SECTION 1.01  TERMS DEFINED ABOVE.  As used in this Agreement, the terms
"Administrative Agent", "Company", "Lender", "Lenders" and "Prior Credit
Agreement" shall have the meanings indicated above.

     SECTION 1.02  CERTAIN DEFINED TERMS.  As used herein, the following terms
shall have the following meanings (all terms defined in this Article I or in
other provisions of this Agreement in the singular to have the same meanings
when used in the plural and vice versa):

                                      -1-
<PAGE>
 
     "Acceptance Date" shall mean any Business Day on which a Bankers'
Acceptance is issued and accepted by the Accepting Lender.

     "Acceptance Exposure" means, at any time, the aggregate face amount of all
Bankers' Acceptances outstanding at such time for which the Company has not yet
reimbursed the Accepting Lenders.

     "Accepting Lender" shall mean, as to any Bankers' Acceptance, the
Administrative Agent or any other Lender which has accepted such Bankers'
Acceptance pursuant to the terms of this Agreement.

     "Additional Costs" shall have the meaning assigned to that term in Section
5.01.

     "Aggregate Commitments" at any time shall equal the sum of the Commitments
of all of the Lenders.

     "Affected Loans" shall have the meaning assigned to that term in Section
5.04.

     "Agreement" shall mean this Credit Agreement, as amended, supplemented or
modified from time to time.

     "Allocated Canadian Borrowing Base" shall mean the amount designated as
such by Petroleum under Section 2.09 of the U. S. Credit Agreement.

     "Applicable Lending Office" shall mean, for each Lender, the lending office
of such Lender (or an Affiliate of such Lender) located in Canada designated on
the signature pages hereof or such other offices of such Lender (or of an
Affiliate of such Lender) located in Canada as such Lender may from time to time
specify to the Administrative Agent and the Company as the office at which its
Loans are to be made and maintained and Bankers' Acceptances are to be accepted.

     "Applicable Margin" shall mean:

     (a) with respect to Base Rate Loans:  the Applicable Margin for Base Rate
Loans that are Conventional Loans under the U. S. Credit Agreement plus the then
applicable Facility Fee Rate; provided, that if at any time, the Applicable
Margin for Base Rate Loans plus the Base Rate is less than the Applicable Margin
for Bankers' Acceptances plus the Discount Rate for Bankers' Acceptances having
an Interest Period of 30 days, the Applicable Margin for Base Rate Loans shall
be increased so that the Applicable Margin for Base Rate Loans plus the Base
Rate will be not less than the Applicable Margin for Bankers' Acceptances plus
the Discount Rate for Bankers' Acceptances having an Interest Period of 30 days;
and

     (b) with respect to Bankers' Acceptances:  the Applicable Margin for
Eurodollar Loans that are Conventional Loans under the U. S. Credit Agreement
plus the then applicable Facility Fee Rate.

     "Assignment and Acceptance" shall have the meaning assigned such term in
Section 12.03(b).

                                      -2-
<PAGE>
 
     "Available Proceeds" shall mean the face amount of the Bankers' Acceptance
less the applicable Discount Amount and the Stamping Fee.

     "Bankers' Acceptance" shall mean a bill of exchange drawn by the Company,
duly completed and accepted by a Lender, in a form customarily used by the
Administrative Agent in creating bankers' acceptances and which otherwise meets
any requirements of the Administrative Agent.

     "Base Rate" shall mean, with respect to any Base Rate Loan, for any day,
the rate equal to the Prime Rate for such day.  Each change in any interest rate
provided for herein based upon the Base Rate resulting from a change in the Base
Rate shall take effect at the time of such change in the Base Rate.

     "Base Rate Loans" shall mean loans which bear interest at the Base Rate.

     "Borrowing" shall mean a utilization of the Commitments by way of Loans or
by the issuance, acceptance and purchase of Bankers' Acceptances.

     "Business Day" shall mean any day on which commercial banks are not
authorized or required to close in Toronto, Canada.

     "Chase" shall mean The Chase Manhattan Bank of Canada.

     "Commitment" shall mean, as to each Lender, the obligation of such Lender
to make Loans to the Company or accept Bankers' Acceptances from the Company in
an aggregate amount at any one time outstanding equal to the amount set forth
opposite such Lender's name on Annex I to the U. S. Credit Agreement under the
caption " Canadian Commitment" (as the same may be reduced from time to time
pursuant to Section 2.03 or modified pursuant to Assignment and Acceptances
pursuant to Section 12.03(b)).

     "Commitment Percentage" shall mean, as to any Lender, the percentage of the
Commitments to be provided by such Lender under this Agreement as indicated on
Annex I to the U. S. Credit Agreement as the Canadian Commitment Percentage, as
modified from time to time to reflect any assignments permitted by Section
12.03(b), such percentage being the quotient of such Lender's Commitment divided
by the aggregate Commitments for all Lenders.

     "Discount Amount" shall mean, with respect to any Bankers' Acceptance, an
amount equal to the face amount thereof multiplied by the Discount Rate.

     "Discount Rate" shall mean at any time, with respect to any Bankers'
Acceptance, the then current bid rate in effect quoted by the Administrative
Agent on such day, which shall be a Business Day, for purchase by the
Administrative Agent of bankers' acceptances of the same face amount and having
maturities on the same date as the maturity date of such Bankers' Acceptance.

     "Dollars" and "$" shall mean Canadian Dollars.

     "Effective Date" shall have the meaning assigned such term in Section
12.16.

                                      -3-
<PAGE>
 
     "Guarantors" shall mean United Meridian and Petroleum.

     "Guaranty Agreements" shall mean an agreement executed by each of the
Guarantors in form and substance satisfactory to the Administrative Agent
guarantying payment of the Indebtedness.

     "Indebtedness" shall mean any and all amounts owing or to be owing by the
Company or the Guarantors to the Administrative Agent, and/or the Lenders in
connection with the Notes, any Bankers' Acceptance or any Security Instrument,
including this Agreement and all renewals, extensions and/or rearrangements
thereof.

     "Insolvency Event" shall mean any of the Events of Default described in
Section 10.01(f), (g) or (h) of the U. S. Credit Agreement.

     "Initial Funding" shall mean the funding of the initial Borrowing pursuant
to Section 6.01.

     "Interest Period" shall mean, with respect to any Bankers' Acceptances, the
period (which shall be 30 days, 60 days, 90 days, and subject to availability,
180 days, or such other period longer than 90 days requested by the Company and
agreed to by all the Lenders) commencing on the date such Bankers' Acceptance is
issued, accepted and purchased.

Notwithstanding the foregoing (unless otherwise agreed to by the Company and all
of the Lenders):  (i) no Interest Period may commence before and end after any
Commitment Reduction Date unless, after giving effect thereto, the aggregate
principal amount of the Loans and Bankers' Acceptances having Interest Periods
which end after such Commitment Reduction Date shall be equal to or less than
the amount to which the Aggregate Commitments are to be automatically reduced on
such Commitment Reduction Date pursuant to Section 2.03(a); and (ii) each
Interest Period which would otherwise end on a day which is not a Business Day
shall end on the next succeeding Business Day.

     "Loans" shall have the meaning assigned to that term in Section 2.01.

     "Note" shall mean a promissory note issued by the Company described in
Section 2.07(a) payable to the order of any Lender and being substantially in
the form of Exhibit A evidencing the aggregate Loans to the Company by such
Lender.

     "Petroleum" shall mean UMC Petroleum Corporation, a Delaware corporation.

     "Prime Rate" shall mean the rate of interest from time to time announced by
the Administrative Agent at the Principal Office as its prime commercial lending
rate.  Such rate is set by the Administrative Agent as a general reference rate
of interest, taking into account such factors as the Administrative Agent may
deem appropriate, it being understood that many of the Administrative Agent's
commercial or other loans are priced in relation to such rate, that it is not
necessarily the lowest or best rate actually charged to any customer and that
the Administrative Agent may make various commercial or other loans at rates of
interest having no relationship to such rate.

                                      -4-
<PAGE>
 
     "Principal Office" shall mean the principal office of the Administrative
Agent and Chase in Canada, presently located in Toronto, Ontario, Canada.

     "Regulatory Change" shall mean, with respect to any Lender, any change
after the date of this Agreement in United States Federal, Canadian, state,
provincial, or foreign law or regulations or the adoption or making after such
date of any interpretations, directives or requests applying to a class of
lenders or insurance companies (including such Lender or its Applicable Lending
Office) of or under any United States Federal, Canadian, state, provincial or
foreign law or regulations (whether or not having the force of law) by any court
or governmental or monetary authority charged with the interpretation or
administration thereof.

     "Required Payment" shall have the meaning assigned to that term in Section
4.04.

     "Security Instruments" shall mean this Agreement, the Notes, the Bankers'
Acceptances, the Guaranty Agreements, and all instruments, documents and
agreements which are "Security Instruments" under the U. S. Credit Agreement,
and any and all other agreements or instruments now or hereafter executed and
delivered by United Meridian or any of its Subsidiaries, including the Company,
or any other Person (other than participation or similar agreements between any
Lender and any other lender or creditor with respect to any Indebtedness
pursuant to this Agreement) in connection with, or as security for the payment
or performance of, the Notes or this Agreement, as such agreements may be
amended or supplemented from time to time.

     "Stamping Fee" shall mean, with respect to any Bankers' Acceptance, an
amount equal to the face amount thereof multiplied by the Applicable Margin for
Bankers' Acceptances.

     "U.S. Administrative Agent" shall mean The Chase Manhattan Bank as
Administrative Agent for the U.S. Lenders, together with its successors in such
capacity.

     "U.S. Commitments" shall mean the "Commitments" as defined in the U. S.
Credit Agreement.

     "U.S. Indebtedness" shall mean the sum of all Loans and the LC Exposure
under the U. S. Credit Agreement, as such terms are defined therein.

     "U.S. Lenders shall mean the "Lenders" as defined in the U. S. Credit
Agreement.

     "U.S. Credit Agreement" shall mean that certain Global Credit Agreement of
even date herewith among Petroleum, United Meridian, as a guarantor, The Chase
Manhattan Bank, as Administrative Agent, Morgan Guaranty Trust Company of New
York, as Syndication Agent, NationsBank of Texas, N.A. and Societe Generale as
Documentation Agents, Banque Paribas, Colorado National Bank and Wells Fargo
Bank, N.A., as Co-Agents, and the lenders parties thereto, as amended, restated,
supplemented or modified from time to time.

     SECTION 1.03  OTHER DEFINED TERMS.  All other capitalized terms not defined
herein shall have the meanings assigned such terms in the U. S. Credit
Agreement.

                                      -5-
<PAGE>
 
     SECTION 1.04  ACCOUNTING TERMS AND DETERMINATIONS.  Unless otherwise
specified herein, all accounting terms used herein shall be interpreted, all
determinations with respect to accounting matters hereunder shall be made, and
all financial statements and certificates and reports as to financial matters
required to be furnished to the Administrative Agent or the Lenders hereunder
shall be prepared, in accordance with Canadian generally accepted accounting
principles as in effect, applied on a basis consistent with the audited
consolidated financial statements of the Company and the consolidated
Subsidiaries referred to in Section 7.02 (except for changes concurred with by
the Company's independent public accountants).

                            ARTICLE II:  COMMITMENTS

     SECTION 2.01  LOANS AND BANKERS' ACCEPTANCES.

     (a) LOANS - Each Lender severally agrees, on the terms and conditions of
this Agreement, to make to the Company during the period from and including the
Effective Date to and including the Termination Date, revolving credit loans
(the "Loans") in an aggregate principal amount at any one time outstanding up
to, but not exceeding, the amount of such Lender's Commitment as then in effect;
provided, that the aggregate principal amount of (i) all Loans made by each
Lender shall not exceed (1) such Lender's Commitment Percentage of the Available
Canadian Commitment minus (2) such Lender's Acceptance Exposure and (ii) all
Loans made by all Lenders hereunder at any one time outstanding shall not exceed
the Available Canadian Commitment, as then in effect, minus the aggregate amount
of Acceptance Exposure for all Lenders.  Subject to the terms of this Agreement,
during the period from the Effective Date to and including the Termination Date,
the Company may borrow, repay and reborrow the amount of the Commitments, as
then in effect.

     (b) BANKERS' ACCEPTANCES - Each Lender severally agrees, on the terms and
conditions of this Agreement, to accept and, immediately thereafter, purchase
Bankers' Acceptances from the Company from and after the Effective Date with a
maturity or Interest Period not beyond the Termination Date in an aggregate
amount at any one time outstanding up to, but not exceeding, the amount of such
Lenders' Commitment as then in effect; provided, that the Acceptance Exposure at
any one time (i) for each Lender shall not exceed (1) such Lender's Commitment
Percentage of the Available Canadian Commitment minus (2) such Lender's
outstanding Loans and (ii) for all Lenders shall not exceed the Available
Canadian Commitment, as then in effect, minus the aggregate amount of all
outstanding Loans.

     (c) DELIVERY OF BANKERS' ACCEPTANCES - Upon execution of this Agreement,
the Company shall deliver to each Lender bills of exchange, in the form for
Bankers' Acceptances of such Lender, executed in blank in sufficient quantity
and thereafter shall, from time to time upon request of the Administrative
Agent, deliver to the Lenders further quantities of such bills of exchange (on
the Administrative Agent's forms) so executed, and the Lenders shall hold such
bills of exchange in safekeeping.  The present form of Bankers' Acceptances of
each Lender is set out in Exhibit B.

     (d) SAFEKEEPING OF BANKERS' ACCEPTANCES - The bills of exchange so executed
in blank and delivered to each Lender shall be held in safekeeping in the vault
of one of each such Lender's branches.  The standard of care that each Lender
shall maintain in its safekeeping of such bills of exchange shall

                                      -6-
<PAGE>
 
be at least as high as that maintained by such Lender in the safekeeping of its
own securities.  Each Lender shall indemnify and hold and save harmless the
Company from loss or damage resulting from the failure of such Lender to
maintain such standard of care.

     (e) LOANS UNDER PRIOR CREDIT AGREEMENT.  On the Effective Date:

     (i) the Company shall pay all accrued and unpaid commitment fees
outstanding under the Prior Credit Agreement for the account of each "Lender"
under the Prior Credit Agreement;

     (ii) each "Bankers' Acceptance" outstanding under the Prior Credit
Agreement shall be deemed a Bankers' Acceptance hereunder in the amount, with
the same Discount Amount, Stamping Fee and Interest Period as such "Bankers'
Acceptance" under the Prior Credit Agreement, and the obligations of the Company
with respect to such "Bankers' Acceptance" shall be deemed carried forward
hereunder (and, as such, such Bankers' Acceptances may not be allocated in
accordance with the percentages set forth on Annex I to the U. S. Credit
Agreement), and the execution and delivery of this Agreement and the
continuation of such Bankers' Acceptances hereunder shall not entitle any
"Lender" under the Prior Credit Agreement to seek compensation pursuant to
Section 5.05 hereof or thereof;

     (iii)  each "Base Rate Loan" under the Prior Credit Agreement shall be
deemed to be repaid with the proceeds of a new Base Rate Loan under this
Agreement; and

     (iv) the Prior Credit Agreement and the commitments thereunder shall be
superseded by this Agreement and such commitments shall terminate.

     SECTION 2.02  BORROWINGS, RENEWALS, CONVERSIONS, AND ISSUANCES.

     (a) BORROWINGS.  The Company shall give the Administrative Agent (which
shall promptly notify the Lenders) advance notice as hereinafter provided of
each borrowing, renewal, and conversion, which shall specify the aggregate
amount of such Borrowing, and the date (which shall be a Business Day) of the
Borrowing to be borrowed, renewed or converted, all of which must be reasonably
acceptable to the Administrative Agent, and in the case of Bankers' Acceptances,
all details of the proposed issue, specifying the aggregate amount of Bankers'
Acceptances to be accepted and purchased by the Lenders and the duration of the
Interest Period therefor.  Promptly following such notice the Administrative
Agent will notify the Company and the Lenders of the Discount Rate for the
specified Acceptance Date.

     (b) MINIMUM AMOUNTS.  All Base Rate Loans (as part of the same borrowing)
shall be in aggregate amounts among all Lenders of at least $1,000,000 (or whole
multiples thereof) or the remaining unused portion of the Commitments.  All
Bankers' Acceptances (as part of the same borrowing) shall be in aggregate
amounts among all Lenders of not less than $1,000,000 and in whole multiples of
$100,000.

     (c) NOTICES, ETC. FOR LOANS.  All borrowings, renewals and conversions
shall require advance written notice from the Company to the Administrative
Agent, in the form of Exhibit D, or such

                                      -7-
<PAGE>
 
other form as may be accepted by the Administrative Agent from time to time,
which in each case shall be irrevocable and effective only upon receipt by the
Administrative Agent and shall be received by the Administrative Agent not later
than (i) in the case of a Base Rate Loan, 11:00 a.m. Toronto time on the date of
such borrowing, renewal or conversion; and (ii) in the case of Bankers'
Acceptances, 12:00 noon Toronto time on a day that is not less than one (1)
Business Day prior to the date of such borrowing, renewal or conversion.  Not
later than 12:00 noon Toronto time on the date specified for each borrowing
hereunder or each request for the acceptance and purchase of a Bankers'
Acceptance, each Lender shall make available the amount of the Loan or the
Available Proceeds of the Bankers' Acceptance to be made by such Lender on such
date to the Administrative Agent, at account number 219274 maintained by the
Administrative Agent at The Royal Bank of Canada, Correspondent Banking
Division, Toronto, Canada, in immediately available funds for the account of the
Company.  The amounts so received by the Administrative Agent shall, subject to
the terms and conditions of this Agreement, be made available to the Company by
depositing the same, in immediately available funds, in an account of the
Company designated by the Company.

     (d) REPLACEMENT/RENEWAL ACCEPTANCES.  Subject to the terms of this
Agreement, the Company may elect to cause a new replacement Bankers' Acceptance
to be issued, accepted and purchased to replace all or any part of any Bankers'
Acceptance at the maturity thereof by giving one (1) Business Day's advance
notice to the Administrative Agent of such election, specifying the amount of
such new Bankers' Acceptance and the Interest Period therefor.  In the absence
of such a timely and proper election, the Company shall be deemed to have
elected to convert such Bankers' Acceptance to a Base Rate Loan as provided in
Section 2.12(b).  All or any part of any Bankers' Acceptance may be renewed as
provided herein, provided that (i) any renewal Bankers' Acceptance shall meet
all requirements for Bankers' Acceptances hereunder, (ii) no Default shall have
occurred and be continuing and (iii) the Company shall have paid to the
Administrative Agent for the account of Lenders an amount equal to the
difference between the amount due on the maturing Bankers' Acceptance and the
Available Proceeds of the new Bankers' Acceptance.  If a Default shall have
occurred and be continuing, each Bankers' Acceptance shall be converted to a
Base Rate Loan on the last day of the Interest Period applicable thereto unless
the Termination Date has occurred in which event all sums due thereon shall be
immediately due and payable.

     (e) CONVERSION OPTIONS.  The Company may elect to convert any Bankers'
Acceptance on the last day of the then current Interest Period relating thereto
to a Base Rate Loan by giving advance notice to the Administrative Agent of such
election.  If no Default shall have occurred and be continuing, subject to the
terms of this Agreement, the Company may elect to convert all or any part of a
Base Rate Loan at any time and from time to time to a Bankers' Acceptance by
giving one (1) Business Day's advance notice to the Administrative Agent of such
election; provided that any conversion of any Base Rate Loan into a Bankers'
Acceptance shall be in the amount not less than $1,000,000 in the aggregate for
all Lenders and in whole multiples of $100,000.

     (f) PRO RATA TREATMENT.  Unless otherwise agreed among the Lenders, all
Loans shall be made by all Lenders pro rata relative to their respective
Commitment Percentage and the aggregate amount of all Bankers' Acceptances
issued hereunder shall be issued pro rata by all Lenders relative to their
respective Commitment Percentage, rounded, upwards or downwards, as the case may
be, to the nearest $100,000.

                                      -8-
<PAGE>
 
     SECTION 2.03  CHANGES OF COMMITMENTS.

     (a) SCHEDULED REDUCTIONS.  Unless the Commitments of the Lenders have
already been reduced pursuant to Section 2.03 (c),  the Aggregate Commitments
shall automatically reduce as follows:

(i)   on the initial Commitment Reduction Date, the Aggregate Commitments shall
      reduce to 91.6667% of the Aggregate Commitments in effect on the Effective
      Date (or such other amount as may be specified in an amendment to this
      Agreement, the "Initial Aggregate Commitments");

(ii)  on the second Commitment Reduction Date, the Aggregate Commitments shall
      reduce to 83.3333% of the Initial Aggregate Commitments;

(iii) on the third Commitment Reduction Date, the Aggregate Commitments
      shall reduce to 75% of the Initial Aggregate Commitments;

(iv)  on the fourth Commitment Reduction Date, the Aggregate Commitments shall
      reduce to 66.6667% of the Initial Aggregate Commitments;

(v)   on the fifth Commitment Reduction Date, the Aggregate Commitments shall
      reduce to 58.3333% of the Initial Aggregate Commitments; and

(vi)  on the Termination Date, the Aggregate Commitments shall be reduced to
      zero.

     (b) WAIVER AND EXTENSION OF CREDIT REDUCTION DATES.  All of the Lenders and
the U.S. Lenders may waive any reduction scheduled to occur on a Commitment
Reduction Date as set forth in Section 2.03(b) of the U.S. Credit Agreement,
which section is hereby incorporated by reference into this Agreement and made a
part of this Agreement to the same extent as if set forth in full herein, except
that for purposes hereof, references therein to "Lenders" and "Canadian Lenders"
shall be deemed to be references to "U.S. Lenders" and "Lenders," respectively,
and, as appropriate in the context, other corresponding changes shall be made,
mutatis mutandis.

     (c) OPTIONAL REDUCTION.  The Company shall have the right to terminate or
to reduce the amount of the Commitments at any time or from time to time upon
not less than one (1) Business Day's prior notice to the Administrative Agent
(which shall promptly notify the Lenders) of each such termination or reduction,
which notice shall specify the effective date thereof and the amount of any such
reduction (which shall not be less than $5,000,000, or any whole multiple of
$1,000,000 in excess thereof), and shall be irrevocable and effective only upon
receipt by the Administrative Agent.

     (d) REINSTATEMENT.  Other than increases pursuant to Section 2.09, the
Commitments once terminated or reduced may not be reinstated.  The amount of the
Available Canadian Commitment may increase or decrease from time to time in
accordance with the terms of this Agreement, including but not limited to,
Section 2.09.

                                      -9-
<PAGE>
 
     SECTION 2.04  COMMITMENT FEE AND OTHER FEES.  The Company shall pay to the
Administrative Agent for the account of the Lenders an aggregate commitment fee
on the daily average unused amount of such Lender's Available Canadian
Commitment for the period from and including the Effective Date of this
Agreement to and including the Termination Date, at a rate per annum equal to
the Facility Fee Rate.  The commitment fee shall be payable in arrears on each
Quarterly Date and on the Termination Date.

     SECTION 2.05  LENDING OFFICES.  The Loans made and Bankers' Acceptances
accepted and purchased by each Lender shall be made and maintained at such
Lender's Applicable Lending Office, which shall be located in Canada.

     SECTION 2.06  SEVERAL OBLIGATIONS.  The failure of any Lender to make any
funds available in connection with any Borrowing to be funded by such Lender on
the date specified therefor shall not relieve any other Lender of its obligation
to provide such funds on such date, but neither the Administrative Agent nor any
Lender shall be responsible for the failure of any other Lender to provide funds
to be provided by such other Lender.

     SECTION 2.07  NOTES.

     (a) SINGLE PROMISSORY NOTE.  The Loans made by each Lender shall be
evidenced by a single promissory note of the Company in substantially the form
of Exhibit A hereto, dated as of the Effective Date or such later date upon a
permitted assignment of all or any portion of such Note, payable to the order of
such Lender in a principal amount equal to the maximum amount of its Commitment
as originally in effect and otherwise duly completed.  The date, amount,
interest rate and maturity date of each Loan made by each Lender, and all
payments made on account of the principal thereof, shall be recorded by such
Lender on its books and, prior to any transfer of the Note held by it, endorsed
by such Lender on the schedule attached to such Note or any continuation
thereof.

     (b) NO RIGHT TO SUBDIVIDE.  No Lender shall be entitled to have its Note
subdivided, by exchange for promissory notes of lesser denominations or
otherwise, except in connection with a permitted assignment of all or any
portion of such Lender's Commitment, Loans and Note pursuant to Section
12.03(b).

     SECTION 2.08  PREPAYMENTS.

     (a) OPTIONAL PREPAYMENTS.  The Company may prepay any Loans or Bankers'
Acceptances on any Business Day upon notice to the Administrative Agent (which
shall promptly notify the Lenders), which notice shall be given by the Company
not later than 12:00 noon Toronto time on such Business Day, shall specify the
amount of the prepayment (which shall be not less than $1,000,000 or the remain
ing balance of Base Rate Loans outstanding, if less) and shall be irrevocable
and effective only upon receipt by the Administrative Agent, provided that
interest on the principal prepaid on any Loan, accrued to the prepayment date,
shall be paid on the prepayment date.  Any prepayment of any Bankers'
Acceptances shall be subject to the provisions of Sections 2.08(d) and 5.05.

                                      -10-
<PAGE>
 
     (b) MANDATORY PREPAYMENT UPON REDUCTION OF COMMITMENT.  If, after giving
effect to any termination or reduction of the Commitments pursuant to Section
2.03, the sum of the outstanding aggregate principal amount of the Loans and the
Acceptance Exposure exceeds the aggregate amount of the Commitments, then the
Company shall on the date of such termination or reduction pay or prepay the
amount of such excess amount for application first, towards reduction of the
outstanding principal balance of the Notes and then, if necessary, by prepaying
Bankers' Acceptances, if any, then outstanding subject to the provisions of
Section 2.08(d).  The Company shall on the date of such termination or reduction
also pay any amounts payable pursuant to Section 5.05 in connection therewith.

     (c) NO PENALTY OR PREMIUMS.  Subject to compensation requirements of
Section 5.05 hereof, all prepayments shall be without premium or penalty.

     (d) PRO RATA TREATMENT.  Without duplication of Section 5.05, any
prepayment of Bankers' Acceptances shall be in an amount equal to the full face
amount of any Bankers' Acceptance so prepaid (less any unearned Discount Amount
and Stamping Fee), and be pro rata among all Lenders relative to their
respective Commitments.

     SECTION 2.09  AVAILABLE CANADIAN COMMITMENT.

     (a) ALLOCATED CANADIAN BORROWING BASE.  The Allocated Canadian Borrowing
Base in effect from time to time shall represent the maximum amount of Loans and
Bankers' Acceptances that the Lenders will loan or accept to or for the Company
at any one time prior to the Termination Date.  On the Effective Date, the
Allocated Canadian Borrowing Base shall be U.S. $17,582,418.00.

     (b) REALLOCATION.  The Company, the Administrative Agent and the Lenders
agree that Petroleum shall have the right to request that the Allocated Canadian
Borrowing Base be increased or decreased, and the Allocated U.S. Borrowing Base
be decreased or increased, respectively, in a corresponding amount, all as more
particularly set forth in Sections 2.09(a)(iv) and 2.09(a)(v) of the U.S. Credit
Agreement, which provisions are hereby incorporated by reference into this
Agreement and made a part of this Agreement to the same extent as if set forth
in full herein, except that for purposes hereof, references therein to "Lenders"
and "Canadian Lenders" shall be deemed to be references to "U.S. Lenders" and
"Lenders," respectively, and, as appropriate in the context, other corresponding
changes shall be made, mutatis mutandis.

     (c) NO CHANGE TO GLOBAL COMMITMENT.  The Company, the Administrative Agent
and the Lenders agree that reallocations of the Allocated U. S. Borrowing Base
and Allocated Canadian Borrowing Base shall not, without the prior agreement of
all the U.S. Lenders, the Lenders and Petroleum, affect the Global Commitment
Percentage.

     SECTION 2.10  ACCEPTANCE DATE PROCEDURE.  On the Acceptance Date, the
following provisions shall apply:

     (a) On or before 10:30 a.m. Toronto time on the Acceptance Date, the
Administrative Agent shall promptly determine the Discount Rate and notify each
Lender as to:

                                      -11-
<PAGE>
 
(i)   the Discount Rate;

(ii)  the face amount of the Bankers' Acceptances to be purchased by such Lender
      on such Acceptance Date;

(iii) the amount of the Stamping Fee applicable to those Bankers' Acceptances to
      be accepted and purchased by such Lender on such Acceptance Date, such
      Lender being authorized by the Company to collect the Discount Amount and
      the Stamping Fee out of the proceeds of the Bankers' Acceptances upon the
      Lender's acceptance and purchase thereof;

(iv)  the Available Proceeds by subtracting the Discount Amount and the Stamping
      Fee mentioned in subsection (iii) from the face amount mentioned in
      subsection (ii).

     (b) As provided in Section 2.02(c), not later than 12:00 noon Toronto time
that same day, each Lender shall make available to the Administrative Agent its
Available Proceeds and the Administrative Agent shall make the Available
Proceeds available to the Company.

     SECTION 2.11  PURCHASE OF BANKERS' ACCEPTANCES.  The Lenders shall, on the
Acceptance Date, accept the Bankers' Acceptances, by inserting the appropriate
face amount, Acceptance Date and maturity date thereof in accordance with the
Company's notice relating thereto and affixing their acceptance stamps thereto,
and shall purchase same as provided in Section 2.10.

     SECTION 2.12  PAYMENT OF BANKERS' ACCEPTANCES. The Bankers' Acceptances
shall be payable in accordance with the following provisions:

     (a)   If such Bankers' Acceptances are held by or presented to the
Accepting Lender or the Administrative Agent, the Company shall pay to the
Administrative Agent for the account of each Lender an amount equal to the face
amount of the Bankers' Acceptances of such Lender on their respective maturity
dates.  In the event that any Bankers' Acceptance is presented to the Company,
rather than the Accepting Lender thereof, for payment on its respective maturity
date and the Company shall have made payments to the holders thereof, then the
Company shall give notice to the Administrative Agent to such effect together
with the original cancelled Bankers' Acceptance and the Administrative Agent
shall promptly notify the Lenders.

     (b) In the event the Company fails to notify the Administrative Agent in
writing, not later than 12:00 Noon, one (1) Business Day prior to any maturity
date of a Bankers' Acceptance, that the Company intends to pay with its own
funds the amount of the Bankers' Acceptances due on such maturity date, the
Company shall be deemed, for all purposes, to have given the Administrative
Agent notice to convert the amount of such Bankers' Acceptances into a Base Rate
Loan and the provisions of Section 2.02(f) shall apply, except save that:

(i)such maturity date shall be considered to be the borrowing date of such Base
Rate Loan;

                                      -12-
<PAGE>
 
(ii)  the proceeds of such Base Rate Loan shall be used to pay the amount of the
      Bankers' Acceptance due on such maturity date; and

(iii) on such maturity date, each Lender, instead of making its funds available
      to the Administrative Agent to fund such Base Rate Loan, shall first
      directly apply its pro rata share of such Loan in payment of its pro rata
      share in the amount of its Bankers' Acceptances due on such date.

                ARTICLE III:  PAYMENTS OF PRINCIPAL AND INTEREST

     SECTION 3.01  REPAYMENT OF LOANS.  The Company will pay on the Termination
Date to the Administrative Agent for the account of each Lender the then-
outstanding principal amount of each Loan made by such Lender and the amount of
the Acceptance Exposure.

     SECTION 3.02  INTEREST.

     (a) The Company will pay to the Administrative Agent for the account of
each Lender interest on the unpaid principal amount of each Loan made by such
Lender for the period commencing on the date of such Loan to but excluding the
date such Loan shall be paid in full, at the Base Rate (as in effect from time
to time) plus the Applicable Margin for such Loan, but in no event to exceed the
Highest Lawful Rate.

     (b) Accrued interest on each Loan shall be payable quarterly on each
Quarterly Date, except that interest payable after maturity shall be payable
from time to time on demand.

     (c) Promptly after the determination of any interest rate provided for
herein or any change therein, the Administrative Agent shall notify the Lenders
to which such interest is payable and the Company.

         ARTICLE IV:  PAYMENTS; PRO RATA TREATMENT; COMPUTATIONS; ETC.

     SECTION 4.01  PAYMENTS.  Except to the extent otherwise provided herein,
all payments of principal, interest and other amounts to be made by the Company
under this Agreement, the Notes and the Bankers' Acceptances shall be made in
Dollars, in immediately available funds, to the Administrative Agent at transit
#09591, account number 219-2474-4 maintained by the Administrative Agent at
Royal Bank of Canada, Correspondent Banking Division, Toronto Canada, not later
than 12:00 noon Toronto Time on the date on which such payments shall become due
(each such payment made after such time on such due date to be deemed to have
been made on the next succeeding Business Day).  The Company shall, subject to
Section 4.02, at the time of making each payment under this Agreement or any
Note or Bankers' Acceptance, specify to the Administrative Agent the Loans,
Bankers' Acceptances or other amounts payable by the Company hereunder to which
such payment is to be applied (and in the event that it fails to so specify, and
such day is not a Quarterly Date or other day on which a payment of either
interest or principal is due, then such payments shall be applied in the
following order:  first, to interest accrued on Loans, second, any excess to
reduce the aggregate principal amount then outstanding on the Loans and, third,
any excess to Bankers' Acceptances; provided, however, that if an Event of
Default has

                                      -13-
<PAGE>
 
occurred and is continuing, the Administrative Agent may distribute such payment
to the Lenders in such manner as it or the Required Lenders may determine to be
appropriate, subject to Section 4.02).  Each payment received by the
Administrative Agent under this Agreement or any Note or Bankers' Acceptance for
the account of a Lender shall be paid promptly to such Lender, in immediately
available funds, for account of such Lender's Applicable Lending Office for the
Loan or Bankers' Acceptances in respect of which such payment is made.  If the
due date of any payment under this Agreement or any Security Instrument would
otherwise fall on a day which is not a Business Day such date shall be extended
to the next succeeding Business Day and interest shall be payable for any amount
so extended for the period of such extension.

     SECTION 4.02  PRO RATA TREATMENT.  Except to the extent agreed among the
Lenders or otherwise provided herein:  (a) each borrowing from the Lenders under
Section 2.01 shall be made from the Lenders, each payment of commitment fee or
other fees under Section 2.04 shall be made for account of the Lenders, and each
termination or reduction of the amount of the Commitments under Section 2.03
shall be applied to the Commitments of the Lenders, pro rata according to their
respective Commitment Percentages, (b) each payment of Bankers' Acceptances or
principal of Loans by the Company shall be made for account of the Lenders pro
rata in accordance with the aggregate unpaid principal amount of Loans and face
amount of Bankers' Acceptances held or purchased by the Lenders, and (c) each
payment of interest on Loans by the Company shall be made for account of the
Lenders pro rata in accordance with the amounts of interest due and payable on
such Loans to the respective Lenders.

     SECTION 4.03  COMPUTATIONS.  Interest on Loans and fees shall be computed
on the basis of a year of 365 or 366 days, as the case may be, and actual days
elapsed (including the first day but excluding the last day) occurring in the
period for which payable.  The Applicable Margin for determining the Stamping
Fee for Bankers' Acceptances shall be computed on the basis of a year of 365
days.  Any rates of interest not expressed in this Credit Agreement on the basis
of a 365 day or 366 day year are the equivalent, expressed on a calendar year
basis, of the same rate of interest multiplied by a fraction, the numerator of
which is the actual number of days in the applicable calendar year and the
denominator of which is the number of days on which interest is expressed to be
based.

     SECTION 4.04  NON-RECEIPT OF FUNDS BY THE ADMINISTRATIVE AGENT.  Unless the
Administrative Agent shall have been notified by a Lender or the Company prior
to the date on which a payment is scheduled to be made to the Administrative
Agent of (in the case of a Lender) the proceeds of a Borrowing to be made by it
hereunder or (in the case of the Company) a payment to the Administrative Agent
for account of one or more of the Lenders hereunder (such payment being herein
called a "Required Payment"), which notice shall be effective upon receipt, that
it does not intend to make the Required Payment to the Administrative Agent, the
Administrative Agent may assume that the Required Payment has been made and may,
in reliance upon such assumption (but shall not be required to), make the amount
thereof available to the intended recipient(s) on such date and, if such Lender
or the Company (as the case may be) has not in fact made the Required Payment to
the Administrative Agent, the recipient(s) of such payment shall, on demand,
repay to the Administrative Agent the amount so made available together with
interest thereon in respect of each day during the period commencing on the date
such amount was so made available by the Administrative Agent until the date the
Administrative Agent recovers such amount at a rate per annum equal to the Base
Rate for such day, but in no event to exceed the Highest Lawful Rate.

                                      -14-
<PAGE>
 
     SECTION 4.05  SHARING OF PAYMENTS, ETC.

     (a) The Company agrees that, in addition to (and without limitation of) any
right of set-off, bankers' lien or counterclaim a Lender may otherwise have,
each Lender shall be entitled (after consultation with the Administrative
Agent), at its option, during the existence of an Event of Default, to offset
balances held by it for account of the Company at any of its offices, in Dollars
or in any other currency, against any principal of or interest on any of such
Lender's Loans or Bankers' Acceptances, or any other amount payable to such
Lender hereunder which is not paid when due (regardless of whether such balances
are then due to the Company), in which case such Lender shall promptly notify
the Company and the Administrative Agent thereof, provided that such Lender's
failure to give such notice shall not affect the validity thereof.

     (b) If any Lender shall obtain payment of any principal of or interest on
any Loan or reimbursement on any Bankers' Acceptance made available to the
Company under this Agreement through the exercise of any right of set-off,
banker's lien or counterclaim or similar right or otherwise, and, as a result of
such payment, such Lender shall have received a greater percentage of the
principal or interest or reimbursement obligation then due hereunder by the
Company to such Lender than the percentage received by any other Lenders, such
Lender shall promptly purchase from such other Lenders participations in (or, if
and to the extent specified by such Lender, direct interests in) the Loans or
Bankers' Acceptances made by such other Lenders (or in interest due thereon, as
the case may be), and make such other adjustments from time to time as shall be
equitable, to the end that all the Lenders shall share the benefit of such
excess payment (net of any expenses which may be incurred by such Lender in
obtaining or preserving such excess payment) pro rata in accordance with the
aggregate unpaid principal and interest on the Loans and reimbursement
obligations on the Bankers' Acceptances held or accepted by each of the Lenders.
To such end, all the Lenders shall make appropriate adjustments among themselves
(by the resale of participations sold or otherwise) if such payment is rescinded
or must otherwise be restored.  The Company agrees that any Lender so purchasing
a participation (or direct interest) in the Loans or Bankers' Acceptances made
by other Lenders (or in interest due thereon, as the case may be) may exercise
all rights of set-off, bankers' lien, counterclaim or similar rights with
respect to such participation as fully as if such Lender were a direct holder of
Loans or acceptor of Bankers' Acceptances, as the case may be, in the amount of
such participation.  Nothing contained herein shall require any Lender to
exercise any such right or shall affect the right of any Lender to exercise, and
retain the benefits of exercising, any such right with respect to any other
indebtedness or obligation of the Company.  If under any applicable bankruptcy,
insolvency or other similar law, any Lender receives a secured claim in lieu of
a set-off to which this Section 4.05 applies, such Lender shall, to the extent
practicable, exercise its rights in respect of such secured claim in a manner
consistent with the rights of the Lenders entitled under this Section 4.05 to
share the benefits of any recovery on such secured claim.

                                      -15-
<PAGE>
 
                  ARTICLE V:  YIELD PROTECTION AND ILLEGALITY

     SECTION 5.01  ADDITIONAL COSTS.

     (a) REGULATORY CHANGE.  The Company shall pay directly to each Lender from
time to time such amounts as such Lender may determine to be necessary to
compensate it for any increased costs incurred by the Lender which such Lender
determines are attributable to its making or maintaining any Loans or Bankers'
Acceptances or its obligation to make any Loans or Bankers' Acceptances
hereunder, or any reduction in any amount receivable by such Lender hereunder in
respect of any of such Loans or Bankers' Acceptances (such increases in costs
and reductions in amounts receivable being herein called "Additional Costs"),
resulting from any Regulatory Change which:  (i) changes the basis of taxation
of any amounts payable to such Lender under this Agreement in respect of any of
such Loans or Bankers' Acceptances (other than franchise taxes, taxes on capital
and/or gross receipts or taxes imposed on the overall net income of such Lender
or of its Applicable Lending Office for any of such Loans or Bankers'
Acceptances by the jurisdiction in which such Lender has its principal office or
such Applicable Lending Office ("Excluded Taxes")); or (ii) imposes or modifies
any reserve, special deposit, minimum capital, capital ratio or similar
requirements relating to any extensions of credit or other assets of, or any
deposits with or other liabilities of, such Lender, or any Commitment of such
Lender; or (iii) imposes any other condition affecting this Agreement or its
Loans or Bankers' Acceptances (or any of such extensions of credit or
liabilities) or Commitment. If any Lender requests compensation from the Company
under this Section 5.01, the Company may, by notice to such Lender (with a copy
to the Administrative Agent), suspend the obligation of such Lender to make
additional Loans or accept and purchase additional Bankers' Acceptances of the
type with respect to which such compensation is requested until the Regulatory
Change giving rise to such request ceases to be in effect (in which case the
provisions of Section 5.04 shall be applicable).

     (b) CAPITAL ADEQUACY.  Without limiting the effect of the foregoing
provisions of this Section 5.01 (but without duplication), the Company shall pay
directly to each Lender from time to time on request such amounts as such Lender
may determine to be necessary to compensate such Lender for any costs which it
determines are attributable to the maintenance by such Lender (or any Applicable
Lending Office), pursuant to any law or regulation or any interpretation,
directive or request (whether or not having the force of law) of any court or
governmental or monetary authority following any Regulatory Change, of capital
in respect of its Commitment, such compensation to include, without limitation,
an amount equal to any reduction of the rate of return on assets or equity of
such Lender (or any Applicable Lending Office) to a level below that which such
Lender (or any Applicable Lending Office) could have achieved but for such law,
regulation, interpretation, directive or request.

     (c) COMPENSATION PROCEDURE.  Each Lender will notify the Company of any
event occurring after the date of this Agreement which will entitle such Lender
to compensation pursuant to this Section 5.01 as promptly as practicable after
it obtains knowledge thereof and determines to request such compensation, and
will furnish the Company with a certificate setting forth the basis and amount
of each request by such Lender for compensation under this Section 5.01.
Determinations and allocations by any Lender for purposes of this Section 5.01
of the effect of any Regulatory Change pursuant to Section 5.01(a), or of the
effect of capital maintained pursuant to Section 5.01(b), on its costs or rate
of return of accepting and purchasing Bankers' Acceptances or maintaining Loans
or its obligation to make

                                      -16-
<PAGE>
 
Loans or accept and purchase Bankers' Acceptances, or on amounts receivable by
it in respect of Loans or Bankers' Acceptances, and of the additional amounts
required to compensate such Lender under this Section 5.01, shall be conclusive,
provided that such determinations and allocations are made on a reasonable
basis.

     SECTION 5.02  ILLEGALITY.  If the introduction of or any change in,
applicable law, regulation, treaty or official directive, or regulatory
requirement or in the interpretation or application thereof by any court or by
any governmental authority charged with the administration thereof, makes it
unlawful, or prohibited for any Lender (in its sole opinion) to accept,
purchase, trade or hold Bankers' Acceptances, such Lender may, by written notice
to the Administrative Agent, which notice shall be promptly communicated by the
Administrative Agent to the Company, terminate its obligations to accept,
purchase, trade or hold Bankers' Acceptances and the Company shall prepay such
Bankers' Acceptances then outstanding forthwith together with any payments
required under Section 5.05, or at the end of such period as such Lender in its
discretion agrees, (it being understood and agreed that the Lender shall use its
best efforts to permit such prepayment to occur on the maturity date of Bankers'
Acceptances, if this is legally permissible) together with all additional
amounts as may be applicable to the date of payment and may reborrow, subject to
the terms hereof, any amount which has been prepaid pursuant to this Section
5.02, by way of one of the remaining legal basis of Borrowings available under
this Agreement.

     SECTION 5.03  ADDITIONAL COST IN RESPECT OF TAX.

     (a) PAYMENTS FREE AND CLEAR.  Each payment to be made by the Company
hereunder or in connection herewith to any Lender or any other Person shall be
made free and clear of and without deduction for or on account of any Tax unless
the Company is required to make such payment subject to the deduction or
withholding of Tax, in which case (except for Excluded Taxes) the sum payable by
the Company in respect of which such deduction or withholding is required to be
made shall be increased to the extent necessary to ensure that, after the making
of such deduction or withholding, such other Person receives and retains (free
from any liability in respect of any such deduction or withholding) a net sum
equal to the sum which it would have received and so retained had not such
deduction or withholding been made or required to be made.

     (b) OBLIGATION TO INDEMNIFY.  If (i) any Lender or the Administrative
Agent, on behalf of such Lender or on its own behalf, is required by law to make
any payment on account of any Tax (except for Excluded Taxes) on or in relation
to any sum received or receivable hereunder by such Lender or the Administrative
Agent, or (ii) any liability in respect of any such payment is asserted,
imposed, levied or assessed against such Lender or the Administrative Agent (as
the case may be) against such payment or liability, the Company shall promptly
pay to the Administrative Agent or such Lender, as the case may be, any
additional amounts necessary to compensate the Administrative Agent or such
Lender for such payment together with any interest, penalties and expenses
payable or incurred in connection therewith.  If the Administrative Agent or a
Lender has paid over on account of Tax (other than Excluded Taxes) an amount
paid to the Administrative Agent or such Lender by the Company pursuant to the
foregoing indemnification and the amount so paid over is subsequently refunded
to the Administrative Agent or such Lender, in whole or in part, the
Administrative Agent or such Lender, as appropriate, shall promptly remit such
amount refunded to the Company.

                                      -17-
<PAGE>
 
     (c) COMPENSATION PROCEDURE.  A Lender intending to make a claim pursuant to
Section 5.03 shall deliver to the Administrative Agent, reasonably promptly
after becoming aware of the circumstances giving rise to the claim, a
certificate to that effect specifying the event by reason of which it is
entitled to make such claim and setting out in reasonable detail the basis and
computation of such claim.  The Administrative Agent shall promptly deliver to
the Company a copy of such certificate or its own certificate if it intends to
make such a claim.

     (d) NOTICE OF CHANGES; PROOF OF PAYMENT.  If at any time the Company is
required by law to make any deduction or withholding from any sum payable by it
hereunder or in connection herewith (or if thereafter there is any change in the
rates at which or the manner in which such deductions or withholdings are
calculated) the Company shall promptly notify the Administrative Agent thereof.
If the Company makes any payment hereunder or in connection herewith in respect
of which it is required by law to make any deduction or withholding it shall pay
the full amount to be deducted or withheld to the relevant taxation or other
authority within the time allowed for such payment under applicable law and
shall deliver to the Administrative Agent within thirty (30) days after it has
made such payment to the applicable authority (i) a receipt issued by such
authority or (ii) other evidence reasonably satisfactory to the Administrative
Agent evidencing the payment to such authority of all amounts so required to be
deducted or withheld from such payment.

     SECTION 5.04  BASE RATE LOANS PURSUANT TO SECTIONS 5.01 AND 5.02.  If the
obligation of any Lender to accept and purchase Bankers' Acceptances shall be
suspended pursuant to Section 5.01 or 5.02 ("Affected Loans"), all Affected
Loans which would otherwise be made available by such Lender shall be made
instead as Base Rate Loans (and, if an event referred to in Section 5.01(a) or
Section 5.02 has occurred and such Lender so requests by notice to the Company
with a copy to the Administrative Agent, all Affected Loans of such Lender then
outstanding shall be automatically converted into Base Rate Loans, subject to
Section 5.05, on the date specified by such Lender in such notice) and, to the
extent that Affected Loans are so made as (or converted into) Base Rate Loans,
all payments which would otherwise be applied to such Lender's Affected Loans
shall be applied instead to its Base Rate Loans.

     SECTION 5.05  COMPENSATION.  The Company shall pay to the Administrative
Agent for account of each Lender, upon the request of such Lender through the
Administrative Agent, such amount or amounts as shall be sufficient (in the
reasonable opinion of such Lender) to compensate it for any loss, cost or
expense which such Lender determines are attributable to:

     (a) any payment or conversion of a Bankers' Acceptance for any reason
(including, without limitation, the acceleration of the Loans pursuant to
Section 10.01) on a date other than the last day of the Interest Period for such
Bankers' Acceptance; or

     (b) any failure by the Company for any reason (including but not limited
to, the failure of any of the conditions precedent specified in Article VI to be
satisfied) to issue a Bankers' Acceptance to such Lender on the date for such
issuance specified in the relevant notice of borrowing given pursuant to Section
2.02.

                                      -18-
<PAGE>
 
     SECTION 5.06  AVOIDANCE OF TAXES AND ADDITIONAL COSTS.

     (a) CHANGE APPLICABLE FUNDING OFFICE.  If a Lender makes any claim under
Section 5.01 or Section 5.03 in respect of Additional Costs or Taxes, such
Lender shall be obligated to use reasonable efforts to designate a different
Applicable Lending Office for the Commitment or the Loans or the Bankers
Acceptances of such Lender affected by such event if such designation will avoid
the need for, or reduce the amount of, such compensation or the imposition of
any Taxes and will not, in the sole opinion of such Lender, be disadvantageous
to such Lender; provided that such Lender shall have no obligation to so
designate an Applicable Lending Office located outside of Canada.

     (b) REPLACEMENT.  If any Lender claims (i) payment of Additional Costs,
(ii) the inability to make or  maintain the Bankers Acceptances pursuant to
Section 5.01 or 5.02 (when such inability is not then being claimed by
substantially all of the Lenders) or (iii) payment of any Taxes pursuant to
Section 5.03, then the Company shall have the right, upon payment of such
requested Additional Costs or Taxes to (i) prepay the Loans made, or repurchase
the Bankers Acceptances discounted, by such Lender and terminate the Commitment
of such Lender on a non pro rata basis or (ii) subject to the approval of the
Administrative Agent (such approval not to be unreasonably withheld or delayed),
find one or more Persons willing to assume the Loans, Commitment and other
obligations of such Lender and replace such Lender pursuant to an Assignment and
Acceptance.  Any such assumption shall be effected pursuant to Section 12.03(b).
The Company shall not, however, be entitled to replace any Lender if an event
which with notice or lapse of time, or both, would constitute a Default or an
Event of Default exists at the time.

     SECTION 5.07  LIMITATION ON RIGHT TO COMPENSATION.  Any demand for
compensation pursuant to Article V (other than Section 5.03) must be made on or
before twelve (12) months after the Lender incurs the expense, cost or economic
loss referred to or such Lender shall be deemed to have waived the right to such
compensation.  Any demand for compensation pursuant to Section 5.03 must be made
on or before twenty-four (24) months after the Lender incurs the expense, cost
or economic loss referred to or such Lender shall be deemed to have waived the
right to such compensation.

                       ARTICLE VI:  CONDITIONS PRECEDENT

     SECTION 6.01  INITIAL LOAN OR BANKERS' ACCEPTANCE. The obligation of the
Lenders to make the initial Borrowing hereunder is subject to the receipt by the
Administrative Agent of the following documents and satisfaction of the other
conditions provided in this Section 6.01, each of which shall be satisfactory to
the Administrative Agent in form and substance:

     (a) A Certificate of the Secretary or Assistant Secretary of the Company
setting forth (i) that the resolutions of its board of directors attached to
such certificate are in full force and effect with respect to the authorization
of the execution, delivery and performance of the obligations contained in the
Notes, this Agreement and the other Security Instruments to which it is a party,
(ii) that the officers of the Company specified in such Secretary's Certificate
are authorized to sign this Agreement, the Notes, and the other Security
Instruments to which it is a party and who, until replaced by another officer or
officers duly authorized for that purpose, will act as the Company's respective
representative for the purposes of signing documents and giving notices and
other communications in connection with this

                                      -19-
<PAGE>
 
Agreement, the Security Instruments to which it is a party and the transactions
contemplated hereby and thereby, (iii) specimen signatures of the officers so
authorized, and (iv) that attached to such certificate are true and complete
copies of the articles and memorandum of the Company.  The Administrative Agent
and the Lenders may conclusively rely on such certificate until the
Administrative Agent receives notice in writing from the Company to the
contrary.

     (b) A certificate of the Secretary or Assistant Secretary of each Guarantor
setting forth (i) that the resolutions of its board of directors attached to
such certificate are in full force and effect with respect to the authorization
of the execution, delivery and performance of the obligations contained in the
Security Instruments to which it is a party, (ii) that the officers of such
Guarantor specified in such Secretary's Certificate are authorized to sign the
Security Instruments to which it is a party and who, until replaced by another
officer or officers duly authorized for that purpose, will act as its
representative(s) for the purposes of signing documents and giving notices and
other communications in connection with such Security Instruments and the
transactions contemplated thereby, (iii) specimen signatures of the officers so
authorized, and (iv) that attached to such certificate are true and complete
copies of the certificate of incorporation and the bylaws of such Guarantor.
The Administrative Agent and the Lenders may conclusively rely on such
certificate until the Administrative Agent receives notice in writing from such
Guarantor to the contrary.

     (c)  The following legal opinions:

     (i)  An opinion of Akin, Gump, Strauss, Hauer & Feld, L.L.P., counsel to 
the Company, addressing such matters as may be reasonably requested by the
Administrative Agent.

     (ii) An opinion of Bennett Jones Verchere, special Canadian counsel to the
Company, addressing such matters as may be reasonably requested by the
Administrative Agent.

    (iii) An opinion of Ladner Downs, special British Columbia counsel to the
Company, addressing such matters as may be reasonably requested by the
Administrative Agent.

     (d) The Notes and bills of exchange referred to in Section 2.01, duly
completed and executed.

     (e) The Guaranty Agreements, duly completed and executed.

     (f) All conditions precedent to the Initial Funding under the U. S. Credit
Agreement shall have been satisfied to the satisfaction of the Administrative
Agent.

     SECTION 6.02  SUBSEQUENT BORROWINGS.

     (a) The obligation of the Lenders to provide funds (other than with respect
to Base Rate Loans which are made pursuant to the terms hereof solely to replace
existing Bankers' Acceptances which have matured in the normal course on the
last day of an Interest Period therefor or pursuant to Section 5.02) to the
Company upon the occasion of each borrowing or to accept and purchase a Bankers'

                                      -20-
<PAGE>
 
Acceptance hereunder is subject to the further conditions precedent that, as of
the date of such Loans or acceptance and purchase and after giving effect
thereto:  (i) no Default or Event of Default shall have occurred and be
continuing; (ii) no event or circumstance having a Material Adverse Effect shall
have occurred since December 31, 1996, and (iii) the representations and
warranties made by the Company in Article VII and the Security Instruments shall
be true in all material respects on and as of the date of such Borrowing with
the same force and effect as if made on and as of such date and following such
new Borrowing, except as such representations and warranties are modified to
give effect to transactions expressly permitted hereby.

     (b) Each notice of borrowing, conversion or renewal (other than Base Rate
Loans which are made pursuant to the terms hereof solely to replace existing
Bankers' Acceptances which have matured in the normal course on the last day of
an Interest Period therefor or pursuant to Section 5.02) and election for
acceptance or renewal of a Bankers' Acceptance by the Company hereunder shall
constitute a certification by the Company to the effect set forth in the
preceding sentence (both as of the date of such notice and, unless the Company
otherwise notifies the Administrative Agent, immediately following such
Borrowing).

                  ARTICLE VII:  REPRESENTATIONS AND WARRANTIES

     SECTION 7.01  INCORPORATION BY REFERENCE.  Except as expressly stated in
this Agreement, each of the representations and warranties contained in Article
VII of the U. S. Credit Agreement (together with the relevant provisions of any
other Section or Sections to which they refer, including definitions) is hereby
incorporated by reference into this Agreement and made a part of this Agreement
to the same extent as if those terms were set forth in full herein, provided
that, as and when appropriate, in the context:  (a) any reference to "Company"
shall be deemed a reference to UMC Resources Canada Ltd.; (b) any reference to
the "Guarantors" shall be deemed a reference to United Meridian and Petroleum;
(c) any references to U.S. Governmental Requirements shall, when appropriate in
the context, be deemed to be references to corresponding Canadian Governmental
Requirements governing such subject matter, if such exist; and (d) any other use
of any capitalized term defined in both this Agreement and the U. S. Credit
Agreement shall be deemed to refer to such term as defined in this Agreement,
where appropriate in the context.  As so incorporated, the Company hereby makes
and affirms each such representation and warranty.  All amendments,
modifications, approvals, consents and waivers under the U. S. Credit Agreement
entered into by the parties to the U. S. Credit Agreement with respect to
Article VII thereof shall be binding upon the Administrative Agent, the Lenders
and the Company and shall constitute corresponding amendments, modifications,
approvals, consents and waivers hereto.

                      ARTICLE VIII:  AFFIRMATIVE COVENANTS

     The Company agrees that, so long as any of the Commitments are in effect
and until payment in full of all Loans and Bankers' Acceptances hereunder, all
interest thereon and all other amounts payable by the Company hereunder:

     SECTION 8.01  INCORPORATION BY REFERENCE.  The Company will not, and will
not permit any of its Subsidiaries to, enter into, make, take, cause or suffer
to exist any transaction, action, omission or condition, if such transaction,
action, omission or condition constitutes a breach of any covenant set forth

                                      -21-
<PAGE>
 
in Sections 8.01, 8.02, 8.03, 8.04, 8.08 and 8.09 of the U.S. Credit Agreement,
which Sections (together with the relevant provisions of any other Section or
Sections of the U.S. Credit Agreement to which they refer, including
definitions) are hereby incorporated by reference into this Agreement and made a
part of this Agreement to the same extent as if those provisions were set forth
in full herein, provided that, for purposes of this Section, all defined terms
used in such provisions shall have the meanings set forth in the U.S. Credit
Agreement.  As so incorporated, the Company hereby repeats and affirms each such
covenant and further covenants and agrees to strictly comply with each such
covenant.  All amendments, modifications, approvals, consents and waivers under
the U. S. Credit Agreement entered into by the parties to the U. S. Credit
Agreement with respect to Article VIII thereof shall be binding upon the
Administrative Agent, the Lenders and the Company and shall constitute
corresponding amendments, modifications, approvals, consents and waivers hereto.

                        ARTICLE IX:  NEGATIVE COVENANTS

     The Company agrees that, so long as any of the Commitments are in effect
and until payment in full of all Loans and Bankers' Acceptances hereunder, all
interest thereon and all other amounts payable by the Company hereunder:

     SECTION 9.01  AFFIRMATION OF CERTAIN COVENANTS IN ARTICLE IX OF THE U. S.
CREDIT AGREEMENT.  The Company will not, and will not permit any of its
Subsidiaries to, enter into, make, take, cause or suffer to exist any
transaction, action, omission or condition, if such transaction, action,
omission or condition constitutes a breach of any covenant set forth in Sections
9.01, 9.02, 9.03, 9.06, 9.07, 9.08, 9.09, 9.10, 9.11, 9.13, 9.14, 9.15, 9.16,
9.17, 9.18, 9.20, 9.21 and 9.22 of the U.S. Credit Agreement, which Sections
(together with the relevant provisions of any other Section or Sections of the
U.S. Credit Agreement to which they refer, including definitions) are hereby
incorporated by reference into this Agreement and made a part of this Agreement
to the same extent as if those provisions were set forth in full herein,
provided that, for purposes of this Section, all defined terms used in such
provisions shall have the meanings set forth in the U.S. Credit Agreement.  As
so incorporated, the Company hereby repeats and affirms each such covenant and
further covenants and agrees to strictly comply with each such covenant.  All
amendments, modifications, approvals, consents and waivers under the U. S.
Credit Agreement, entered into by the parties to the U. S. Credit Agreement with
respect to Article IX thereof, shall be binding upon the Administrative Agent,
the Lenders and the Company and shall constitute corresponding amendments,
modifications, approvals, consents and waivers hereto.

                         ARTICLE X:  EVENTS OF DEFAULT

     SECTION 10.01  EVENTS OF DEFAULT.  If one or more Events of Default shall
occur and be continuing, then (a) in the case of an Event of Default other than
an Insolvency Event with respect to the Company and either Guarantor, the
Administrative Agent may and, upon request of the Required Lenders, shall, by
notice to the Company, cancel the Commitments and/or declare the principal
amount then outstanding of and the accrued interest on the Loans and all other
amounts payable by the Company hereunder and under the Notes and the Bankers'
Acceptances to be forthwith due and payable, whereupon such amounts shall be
immediately due and payable without presentment, demand, protest, notice of
intent to accelerate, notice of acceleration or other formalities of any kind,
all of which are hereby expressly waived by the Company; and (b) in the case of
the occurrence of an Insolvency Event

                                      -22-
<PAGE>
 
with respect to the Company and either Guarantor, the Commitments shall be
automatically canceled and the principal amount of the Loans, together with
accrued interest, and all other amounts payable by the Company hereunder and
under the Notes and the Bankers' Acceptances shall become automatically
immediately due and payable without presentment, demand, protest, notice of
intent to accelerate, notice of acceleration or other formalities of any kind,
all of which are hereby expressly waived by the Company and, in either case, the
Administrative Agent and the Lenders may pursue all rights and remedies of the
Lenders and the Administrative Agent under the Security Instruments.

                     ARTICLE XI:  THE ADMINISTRATIVE AGENT

     SECTION 11.01  INCORPORATION BY REFERENCE.  Sections 11.01 through 11.08 of
the U.S. Credit Agreement (together with the relevant provisions of any other
Section or Sections of the U.S. Credit Agreement to which they refer, including
definitions) are hereby incorporated by reference into this Agreement and made a
part of this Agreement to the same extent as if those provisions were set forth
in full herein, provided that, for purposes of such incorporated Sections, as
appropriate in the context, (i) references therein to "Administrative Agent,"
"Agreement," "Company" and "Lenders" shall mean such terms as defined in this
Agreement; (ii) references therein to "Loans" shall mean "Loans" and "Bankers
Acceptances" as such terms are defined in this Agreement; (iii) references
therein to "Notes" shall mean "Notes" and "Bankers Acceptances" as such terms
are defined in this Agreement; and (iv) as appropriate in the context, other
corresponding changes shall be made, mutatis mutandis.

                          ARTICLE XII:  MISCELLANEOUS

     SECTION 12.01  INCORPORATION BY REFERENCE. Sections 12.01, 12.02, 12.03,
12.05, 12.07, 12.08, 12.09, 12.11, 12.12, 12.14, 12.15 and 12.18 of the U.S.
Credit Agreement (together with the relevant provisions of any other Section or
Sections of the U.S. Credit Agreement to which they refer, including
definitions) are hereby incorporated by reference into this Agreement and made a
part of this Agreement to the same extent as if those provisions were set forth
in full herein, provided that, for purposes of such incorporated Sections, as
appropriate in the context, (i) references therein to "Administrative Agent,"
"Agreement," "Company" and "Lenders" shall mean such terms as defined in this
Agreement; (ii) references therein to "Loans" shall mean "Loans" and "Bankers
Acceptances" as such terms are defined in this Agreement; (iii) references
therein to "Notes" shall mean "Notes" and "Bankers Acceptances" as such terms
are defined in this Agreement; and (iv) as appropriate in the context, other
corresponding changes shall be made, mutatis mutandis.

     SECTION 12.02  AMENDMENTS, ETC.  Subject to the terms of the Intercreditor
Agreement, any provision of this Agreement or any other Security Instruments may
be amended, modified or waived as provided in the U. S. Credit Agreement;
provided that no amendment, modification or waiver which extends the maturity of
the Loans or any Bankers' Acceptances, increases the Available Canadian
Commitment, or reduces the interest rate applicable to the Loans or the Stamping
Fee shall be effective without consent of all Lenders.

                                      -23-
<PAGE>
 
     SECTION 12.03  ASSIGNMENTS AND PARTICIPATIONS.

     (a) The Company may not assign its rights or obligations hereunder without
the prior consent of all of the Lenders and the Administrative Agent.

     (b) Each Lender may, upon the written consent of the Company which consent
shall not be unreasonably withheld or delayed, assign to one or more assignees
all or a portion of its rights and obligations under this Agreement pursuant to
an Assignment and Acceptance Agreement substantially in the form of Exhibit C
(an "Assignment and Acceptance") provided, however, that (i) any such assignment
shall be in the aggregate amount of at least $5,000,000 or such lesser amount to
which the Company has consented, (ii) the assignee shall pay to the
Administrative Agent a processing and recordation fee of $2,500; provided that
such fee shall not be payable in conjunction with any assignments occurring
within 30 days of the Effective Date, and (iii) the assignee is a resident of
Canada for purposes of the Income Tax Act (Canada).  Any such assignment will
become effective upon the issuance by the Administrative Agent of a letter of
acknowledgment reflecting such assignment and the resultant effects thereof on
the Commitments of the assignor and assignee, and the principal amount
outstanding of the Loans owed to the assignor and assignee, the Administrative
Agent hereby agreeing to effect such issuance no later than five (5) Business
Days after its receipt of an Assignment and Acceptance executed by all parties
thereto.  Promptly after receipt of an Assignment and Acceptance executed by all
parties thereto, the Administrative Agent shall send to the Company a copy of
such executed Assignment and Acceptance.  Upon receipt of such executed
Assignment and Acceptance, the Company, will, at its own expense, execute and
deliver new Notes to the assignor and/or assignee, as appropriate, in accordance
with their respective interests as they appear on the Administrative Agent's
letter of acknowledgment.  Upon the effectiveness of any assignment pursuant to
this Section, the assignee will become a "Lender," if not already a "Lender,"
for all purposes of this Agreement and the other Security Instruments.  The
assignor shall be relieved of its obligations hereunder to the extent of such
assignment (and if the assigning Lender no longer holds any rights or
obligations under this Agreement, such assigning Lender shall cease to be a
"Lender" hereunder except for the purposes of Section 12.04 hereof and the
Sections referred to therein).  The Administrative Agent will prepare on the
last Business Day of each month during which an assignment has become effective
pursuant to this Section a revised Annex I to the U. S. Credit Agreement giving
effect to all such assignments effected during such month, and will promptly
provide the same to the Company and each of the Lenders.

     (c) Each Lender may transfer, grant or assign participations in all or any
part of such Lender's interests hereunder pursuant to this subsection to any
Person, provided that: (i) such Lender shall remain a "Lender" for all purposes
of this Agreement and the transferee of such participation shall not constitute
a "Lender" hereunder; and (ii) no participant under any such participation shall
have rights to approve any amendment to or waiver of this Agreement, the Notes
or any Security Instrument except to the extent such amendment or waiver would
(x) extend the Termination Date, (y) reduce the interest rate (other than as a
result of waiving the applicability of any post-default increases in interest
rates) or fees applicable to any of the Commitments or Loans in which such
participant is participating, or postpone the payment of any thereof, or (z)
release all or substantially all of the collateral (except as expressly provided
in the Security Instruments) supporting any of the Commitments or Loans in which
such participant is participating.  In the case of any such participation, the
participant shall not have any rights under this Agreement or any of the
Security Instruments (the participant's rights against the granting Lender in
respect of such participation to be those set forth in the agreement with such
Lender

                                      -24-
<PAGE>
 
creating such participation), and all amounts payable by the Company hereunder
shall be determined as if such Lender had not sold such participation, provided
that if the participant is a resident of Canada for purposes of the Income Tax
Act (Canada) and has its principal office in Canada, such participant shall be
entitled to receive additional amounts under Article V on the same basis as if
it were a Lender.  In addition, each agreement creating any participation must
include agreements by the participant to be bound by the provisions of Section
12.14 of the U.S. Credit Agreement as incorporated herein and forbidding the
transfer, assignment or sub-participation of such participation.

     (d) The Lenders may furnish any information concerning the Company in the
possession of the Lenders from time to time to assignees and participants
(including prospective assignees and participants); provided that, such Persons
agree in writing to be bound by the provisions of Section 12.14 of the U.S.
Credit Agreement as incorporated herein by Section 12.01.

     SECTION 12.04  SURVIVAL.  The obligations of the Company, the Agent and the
Lenders under Sections 5.01, 5.03 and 5.05 hereof, and Sections 12.03 and 12.14
of the U.S. Credit Agreement as incorporated herein by Section 12.01 shall
survive the repayment of the Loans and the termination of the Commitments.

     SECTION 12.05  GOVERNING LAW; SUBMISSION TO JURISDICTION.
                    -------------  -------------------------- 

     (A) THIS AGREEMENT AND THE NOTES SHALL BE GOVERNED BY, AND CONSTRUED IN
ACCORDANCE WITH, THE LAWS OF THE PROVINCE OF ALBERTA, CANADA.

     (B) ANY LEGAL ACTION OR PROCEEDING WITH RESPECT TO THIS AGREEMENT, THE
NOTES, ANY BANKERS' ACCEPTANCE, OR THE OTHER SECURITY INSTRUMENTS MAY BE BROUGHT
IN THE COURTS OF TORONTO, ONTARIO, AND, BY EXECUTION AND DELIVERY OF THIS
AGREEMENT, THE COMPANY HEREBY ACCEPTS FOR ITSELF AND (TO THE EXTENT PERMITTED BY
LAW) IN RESPECT OF ITS PROPERTY, GENERALLY AND UNCONDITIONALLY, THE JURISDICTION
OF THE AFORESAID COURTS.  THE COMPANY HEREBY IRREVOCABLY WAIVES ANY OBJECTION,
INCLUDING, WITHOUT LIMITATION, ANY OBJECTION TO THE LAYING OF VENUE OR BASED ON
THE GROUNDS OF FORUM NON CONVENIENS, WHICH IT MAY NOW OR HEREAFTER HAVE TO THE
BRINGING OF ANY SUCH ACTION OR PROCEEDING IN SUCH RESPECTIVE JURISDICTIONS.
THIS SUBMISSION TO JURISDICTION IS NONEXCLUSIVE AND DOES NOT PRECLUDE THE
ADMINISTRATIVE AGENT OR ANY LENDER FROM OBTAINING JURISDICTION OVER THE COMPANY
IN ANY COURT OTHERWISE HAVING JURISDICTION.

     (c) Nothing herein shall affect the right of the Administrative Agent or
any Lender or any holder of a Note to serve process in any manner permitted by
law or to commence legal proceedings or otherwise proceed against the Company in
any other jurisdiction.

     (d) EACH OF THE PARTIES HERETO WAIVES, TO THE FULLEST EXTENT PERMITTED BY
APPLICABLE LAW, ANY RIGHT TO A TRIAL BY JURY IN ANY ACTION

                                      -25-
<PAGE>
 
OR PROCEEDING TO ENFORCE OR TO DEFEND ANY RIGHTS UNDER THIS AGREEMENT, THE NOTES
OR ANY OTHER SECURITY INSTRUMENT OR UNDER ANY AMENDMENT, INSTRUMENT, DOCUMENT OR
AGREEMENT DELIVERED OR WHICH MAY IN THE FUTURE BE DELIVERED IN CONNECTION
HEREWITH OR THEREWITH OR ARISING FROM ANY RELATIONSHIP EXISTING IN CONNECTION
WITH THIS AGREEMENT, THE NOTES OR ANY OTHER SECURITY INSTRUMENT AND AGREES THAT
ANY SUCH ACTION OR PROCEEDING SHALL BE TRIED BEFORE A COURT AND NOT BEFORE A
JURY.

     SECTION 12.06  EFFECTIVENESS.  This Agreement shall not be effective until
the date (the "Effective Date") that it is delivered to the Lenders in Toronto,
Ontario, Canada, accepted by the Lenders in such place, and executed by the
Lenders in such place.

     SECTION 12.07  INTERPRETATION OF SECURITY INSTRUMENTS.  If in the event of
any conflict between the terms of Articles VII, VIII, IX and X of this Agreement
and the representations, warranties, covenants or events of default contained in
any of the Security Instruments (other than the U. S. Credit Agreement), the
terms of Articles VII, VIII, IX and X of this Agreement, as appropriate, shall
govern.

     SECTION 12.08  DEBT CHARACTERIZATION FOR INDENTURE PURPOSES.  If so
designated by United Meridian or UMC Canada in its internal records (which
designation may be made in its sole and absolute discretion), any Debt incurred
hereunder and under the U.S. Credit Agreement and all guarantees thereof shall
constitute "Indebtedness" other than "Permitted Indebtedness" (as such terms are
defined in the Indenture) for purposes of the Indenture.

                                      -26-
<PAGE>
 
          The parties hereto have caused this Agreement to be duly executed as
of the day and year first above written.

                                      COMPANY:
                                  
                                      UMC RESOURCES CANADA LTD.
                                  
                                  
                                      By:
                                         -------------------------------
                                         Kevin McMillan
                                         Vice President and Treasurer
                                  
                                      10th Floor, First Canadian Centre
                                      Suite 1000
                                      350-7th Avenue S.W.
                                      Calgary, Alberta  T2P 3N9
                                      Telecopier No:  (403) 298-8984
                                      Telephone No.   (403) 264-3333
                                      
                                      with a copy to:
                                      
                                      1201 Louisiana, Suite 1400
                                      Houston, Texas 77002
                                      
                                      Telecopier No.: (713) 653-5024
                                      Telephone No.:  (713) 654-9110
                                      Attention:  Kevin McMillan

                                      -27-
<PAGE>
 
                                      THE CHASE MANHATTAN BANK OF CANADA


                                      By:
                                         -------------------------------
                                         Christine Chen
                                         Vice President

                                      Lending Office for Base Rate Loans:
                                      
                                      The Chase Manhattan Bank of Canada
                                      1 First Canadian Place
                                      100 King Street West
                                      Suite 6900, P.O. Box 106
                                      Toronto, Ontario M5X 1A4
                                      
                                      Address for Notices:
                                      
                                      The Chase Manhattan Bank of Canada
                                      1 First Canadian Place
                                      100 King Street West
                                      Suite 6900, P.O. Box 106
                                      Toronto, Ontario M5X 1A4
                                      Attn:  Richard Jerome
                                      
                                      with a copy to:
                                      
                                      Chase Manhattan Southwest
                                      1100 Milam, Suite 2345
                                      Houston, Texas  77002
                                      Telecopier No.:  (713) 751-9122
                                      Telephone No.:  (713) 751-5661
                                      Attention:  Peter Licalzi

                                      -28-
<PAGE>
 
                                      SOCIETE GENERALE (CANADA)


                                      By:
                                         -------------------------------
                                         George Benay
                                         Vice President

                                      Lending Office for Base Rate Loans:
                              
                                      Societe Generale (Canada)
                                      100 Yonge Street, Scotia Plaza
                                      Suite 1002
                                      Toronto, Ontario, M5C2W1 Canada
                                      Attn: Bert Coish
                              
                                      Address for Notices:
                              
                                      Societe Generale (Canada)
                                      100 Yonge Street, Scotia Plaza
                                      Suite 1002
                                      Toronto, Ontario, M5C2W1 Canada
                                      Attn:  Bert Coish
                              
                                      with a copy to:
                              
                                      Societe Generale
                                      1111 Bagby, Suite 2020
                                      Houston, Texas  77002
                                      Telecopier No.:  (713) 650-0824
                                      Telephone No.:  (713) 759-6318
                                      Attention:  Richard Erbert
                                                  Vice President

                                      -29-
<PAGE>
 
                                      THE CHASE MANHATTAN BANK OF CANADA, 
                                       as Administrative Agent


                                      By:
                                         -------------------------------
                                         Christine Chen
                                         Vice President

                                      Address for Notices to Chase
                                      Administrative Agent:
                            
                                      The Chase Manhattan Bank of Canada
                                      1 First Canadian Place
                                      100 King Street West
                                      Suite 6900, P.O. Box 106
                                      Toronto, Ontario M5X 1A4
                                      Attn:  Richard Jerome
                            
                                      Telecopier No.: (416) 216-4161
                                      Telephone No.:  (416) 216-4145

                                      -30-
<PAGE>
 
                                   EXHIBIT A

                                  FORM OF NOTE
                                  ------------


$________________                                       ______________, 199__


     FOR VALUE RECEIVED, UMC RESOURCES CANADA, LTD., a company continued under
the laws of the Province of British Columbia (the "Company"), hereby promises to
pay to the order of ___________________ (the "Lender"), for the account of its
Applicable Lending Office as provided for by the Credit Agreement (as
hereinafter defined), at the Principal Office of The Chase Manhattan Bank of
Canada, as Administrative Agent, the principal sum of _____________________
____________________ ($__________) (or such lesser amount as shall equal the
aggregate unpaid principal amount of the Loans made by the Lender to the Company
under the Credit Agreement) in lawful money of Canada and in immediately
available funds, on the dates and in the principal amounts provided in the
Credit Agreement, and to pay interest on the unpaid principal amount of each
such Loan, at such Principal Office, in like money and funds, for the period
commencing on the date of such Loan until such Loan shall be paid in full, at
the rates per annum and on the dates provided in the Credit Agreement.

     The date, amount, interest rate and maturity of each Loan made by the
Lender to the Company, and each payment made on account of the principal
thereof, shall be recorded by the Lender on its books and, prior to any transfer
of this Note, endorsed by the Lender on the schedules attached hereto or any
continuation thereof.

     This Note is a Note referred to in that certain Credit Agreement dated as
of March 18, 1997 between the Company, each of the lenders that is a signatory
thereto and The Chase Manhattan Bank of Canada, as the administrative agent (as
such may be amended from time to time, the "Credit Agreement"), and evidences
the Loans made by the Lender thereunder.  Capitalized terms used in this Note
have the respective meanings assigned to them in the Credit Agreement.

          This Note is issued pursuant to the Credit Agreement and is entitled
to the benefits provided for in the Credit Agreement and the Security
Instruments.  The Credit Agreement provides for the acceleration of the maturity
of this Note upon the occurrence of certain events and for prepayments of Loans
upon the terms and conditions specified therein and other pertinent terms.

                                      A-1
<PAGE>
 
          THIS NOTE SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE
LAWS OF THE PROVINCE OF ALBERTA, CANADA.


                                        UMC RESOURCES CANADA LTD.



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

                                      A-2
<PAGE>
 
                                   SCHEDULE
                                      OF
                  LOAN AND PAYMENTS OF PRINCIPAL AND INTEREST
                  -------------------------------------------

<TABLE>
<CAPTION>
 
                    Amount of                Unpaid    
                    Principal   Amount of   Principal  
        Amount of    Paid or    Interest     Balance    Notation
Date      Loan       Prepaid      Paid       of Loan    Made by
------  ---------   ---------   ---------   ---------   --------
<S>     <C>         <C>         <C>         <C>         <C>
                                                       
------  ---------  ----------  ----------  ----------  ---------
------  ---------  ----------  ----------  ----------  ---------
------  ---------  ----------  ----------  ----------  ---------
------  ---------  ----------  ----------  ----------  ---------
------  ---------  ----------  ----------  ----------  ---------
------  ---------  ----------  ----------  ----------  ---------
------  ---------  ----------  ----------  ----------  ---------
------  ---------  ----------  ----------  ----------  ---------
------  ---------  ----------  ----------  ----------  ---------
------  ---------  ----------  ----------  ----------  ---------
------  ---------  ----------  ----------  ----------  ---------
------  ---------  ----------  ----------  ----------  ---------
------  ---------  ----------  ----------  ----------  ---------
------  ---------  ----------  ----------  ----------  ---------
------  ---------  ----------  ----------  ----------  ---------
------  ---------  ----------  ----------  ----------  ---------
------  ---------  ----------  ----------  ----------  ---------
------  ---------  ----------  ----------  ----------  ---------
------  ---------  ----------  ----------  ----------  ---------
------  ---------  ----------  ----------  ----------  ---------
------  ---------  ----------  ----------  ----------  ---------
------  ---------  ----------  ----------  ----------  ---------
------  ---------  ----------  ----------  ----------  ---------
------  ---------  ----------  ----------  ----------  ---------
------  ---------  ----------  ----------  ----------  ---------
 
</TABLE>

                                      A-3
<PAGE>
 
                                   EXHIBIT B

                          FORM OF BANKER'S ACCEPTANCE
                          ---------------------------

                                      B-1
<PAGE>
 
                                   EXHIBIT C

                                   [FORM OF]

                           ASSIGNMENT AND ACCEPTANCE
                           -------------------------

                         Dated: _______________, 199__

          Reference is made to that certain Credit Agreement dated as of March
18, 1997 among UMC Resources Canada, Ltd., a company continued under the laws of
the Province of British Columbia (the "Company"), The Chase Manhattan Bank of
Canada, as Administrative Agent, and the lenders parties thereto (such Credit
Agreement together with all amendments and supplements thereto being the "Credit
Agreement").  Capitalized terms used herein and not otherwise defined shall have
the meanings assigned to such terms in the Credit Agreement.  This Assignment
and Acceptance, between the Assignor (as defined and set forth on Schedule I
hereto and made a part hereof) and the Assignee (as defined and set forth on
Schedule I hereto and made a part hereof) is dated as of the Effective Date (as
set forth on Schedule I hereto and made a part hereof).

          1.        The Assignor hereby irrevocably sells and assigns to the
Assignee without recourse to the Assignor, and the Assignee hereby irrevocably
purchases and assumes from the Assignor without recourse to the Assignor, as of
the Effective Date, an undivided interest (the "Assigned Interest") in and to
all the Assignor's rights and obligations under the Credit Agreement respecting
those, and only those, Commitments, Loans and Bankers' Acceptances contained in
the Credit Agreement as are set forth on Schedule I, in a principal amount as
set forth on Schedule I.

          2.        The Assignor (i) represents and warrants that it owns the
Assigned Interest free and clear from any lien or adverse claim; (ii) other than
the representation and warranty set forth in clause (i) above, makes no
representation or warranty and assumes no responsibility with respect to any
statements, warranties or representations made in or in connection with the
Credit Agreement or any other instrument, document or agreement delivered in
connection therewith, or the execution, legality, validity, enforceability,
genuineness, sufficiency or value of the Credit Agreement, or any other
instrument or document furnished pursuant thereto, other than that it is the
legal and beneficial owner of the interest being assigned by it hereunder and
that such interest is free and clear of any adverse claim; (iii) makes no
representation or warranty and assumes no responsibility with respect to the
financial condition of either United Meridian or the Company or the performance
or observance by United Meridian or any of its Subsidiaries, including the
Company, or of any of their respective obligations under the Credit Agreement,
or any other instrument or document furnished pursuant thereto; and (iv)
attaches the Notes held by it evidencing the Assigned Interest and requests that
the Company exchange such Notes for new Notes payable to the Assignor (if the
Assignor has retained any interest in the Assigned Interest) and new Notes
payable to the Assignee in the respective amounts which reflect the assignment
being made hereby (and after giving effect to any other assignments which have
become effective on the Effective Date).

          3.        The Assignee (i) represents and warrants that it is legally
authorized to enter into this Assignment and Acceptance; (ii) confirms that it
has received a copy of the Credit

                                      C-1
<PAGE>
 
Agreement, together with copies of the financial statements referred to in
Section 7.02, or if later, the most recent financial statements delivered
pursuant to Section 8.01 thereof, and such other documents and information as it
has deemed appropriate to make its own credit analysis; (iii) agrees that it
will, independently and without reliance upon either the Administrative Agent,
any other Lender or the Assignor and based on such documents and information as
it shall deem appropriate at the time, continue to make its own credit decisions
in taking or not taking action under the Credit Agreement; (iv) agrees that it
will be bound by the provisions of the Credit Agreement and will perform in
accordance with its terms all the obligations which by the terms of the Credit
Agreement are required to be performed by it and (v) represents and warrants
that it is a resident of Canada for purposes of the Income Tax Act (Canada) and
has its principal office in Canada.

          4.        Following the execution of this Assignment and Acceptance,
it will be delivered to the Company effective as of the Effective Date (which
Effective Date shall, unless otherwise agreed, be at least five (5) Business
Days after the execution of this Assignment and Acceptance).

          5.        Upon delivery to the Company, all payments under the Credit
Agreement in respect of the Assigned Interest (including without limitation, all
payments of principal, interest and fees with respect thereto) for the period up
to, but not including, the Effective Date, shall be made to the Assignor, and
for the period from and after the Effective Date shall be made to the Assignee.
Assignor and Assignee hereby agree that if Assignor receives any of the payments
referred to in the preceding sentence which should have been made to Assignee,
or if Assignee receives any of the payments referred to in the previous sentence
which should have been made to Assignor, such payments shall promptly be paid by
Assignor to Assignee, or by Assignee to Assignor, as the case may be, in full.

          6.        From and after the Effective Date, (i) the Assignee shall be
a party to the Credit Agreement and, to the extent provided in this Assignment
and Acceptance and Section 12.03 of the Credit Agreement, have the rights and
obligations thereunder, and (ii) the Assignor shall, to the extent provided in
this Assignment and Acceptance and Section 12.03 of the Credit Agreement,
relinquish its rights and be released from its obligations under the Credit
Agreement.

          7.        THIS ASSIGNMENT AND ACCEPTANCE SHALL BE GOVERNED BY, AND
CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE PROVINCE OF ALBERTA, CANADA.

                                      C-2
<PAGE>
 
          IN WITNESS WHEREOF, the parties hereto have caused this Assignment and
Acceptance to be executed by their respective duly authorized officers on
Schedule I hereto.


 
                               ------------------------------------------
                               as Assignor

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


 
                               ------------------------------------------
                               as Assignee

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

                                      C-3
<PAGE>
 
                               APPROVED:

                               UMC RESOURCES CANADA LTD.



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

                               Title:


                               THE CHASE MANHATTAN BANK OF CANADA, 
                                as Administrative Agent



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

                               Title:

                                      C-4
<PAGE>
 
                    SCHEDULE I TO ASSIGNMENT AND ACCEPTANCE


Assignor: __________________________________________________

          Total Commitment of Assignor Prior to Effective Date:  $_____________
          Total Commitment of Assignor After Effective Date:     $_____________ 
                                                                 

Assignee: __________________________________________________

          Total Commitment of Assignee Prior to Effective Date:  $_____________
          Total Commitment of Assignee After Effective Date:     $_____________ 
                

Effective Date of Assignment: ______________________________, 199__

Amount of Total Commitment Assigned: $______________________


          Principal Amount                      Percentage Assigned
       (or amount of Commitment)             (Shown as a percentage of
              Assigned                         aggregate Commitments)
       ------------------------              -------------------------

            $______________                          ________%


                               Assignee's

                               Address for Notice:
                               ______________________________
                               ______________________________
                               ______________________________
 

                               Lending Office:

                               ______________________________
                               ______________________________
                               ______________________________

                               Attn:_________________________

                               Telex No:_____________________

                               Telecopy No:__________________

                               Telephone No:_________________
 

                                      C-5
<PAGE>
 
                                   EXHIBIT D

                                   [FORM OF]

                   BORROWING, RENEWAL AND CONVERSION REQUEST


                          _____________________, 199__

          UMC Resources Canada Ltd., a company continued under the laws of the
Province of British Columbia  (the "Company"), pursuant to the Credit Agreement
dated as of March 18, 1997 among the Company, The Chase Manhattan Bank of
Canada, as Administrative Agent, and the lenders parties thereto (such Credit
Agreement together with all amendments and supplements thereto being the "Credit
Agreement"), hereby makes the requests indicated below (unless otherwise defined
herein, capitalized terms are defined in the Credit Agreement):


1.  Borrowings:

(a) Aggregate amount of new Borrowings to be $________________;

(b) Requested funding date is _________________, 199__;

(c) $_____________________ of such Borrowings are to be Bankers' Acceptances;

    $_____________________ of such Borrowings are to be Base Rate Loans; and

(d) Length of Interest Period for Bankers' Acceptances is:

    _________________________.


2.  Bankers' Acceptance Renewals for Bankers' Acceptances maturing on
    _________________:

(a) Aggregate amount to be renewed as Bankers' Acceptances is $_______________;

(b) Aggregate amount to be converted to Base Rate Loans is $_______________;

(c) Length of Interest Period for renewed (or reissued) Bankers' Acceptances is
    ________________________.

                                      D-1
<PAGE>
 
3. Conversion of Outstanding Base Rate Loans by issuance of Bankers'
   Acceptances:

   Convert $__________________ of the outstanding Base Rate Loans by issuance of
   Bankers' Acceptances on ____________________ with an Interest Period of
   ______________________.

          The undersigned certifies that he is the _____________________ of the
Company, and that as such he is authorized to execute this certificate on behalf
of the Company.  The undersigned further certifies, represents and warrants on
behalf of the Company that the Company is entitled to receive the requested
Borrowing, continuation or conversion under the terms and conditions of the
Credit Agreement.

                                          UMC RESOURCES CANADA LTD.


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

                                      D-2