VINTAGE PETROLEUM INC
10-Q, 1998-11-13
CRUDE PETROLEUM & NATURAL GAS
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<PAGE>
 
                                 UNITED STATES
                      SECURITIES AND EXCHANGE COMMISSION
                            Washington, D.C.  20549
                                   FORM 10-Q

(Mark One)

[X]             QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d)
                    OF THE SECURITIES EXCHANGE ACT OF 1934
               For the quarterly period ended September 30, 1998

                                      OR


[ ]            TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d)
                    OF THE SECURITIES EXCHANGE ACT OF 1934
                     For the transition period from    to

Commission file number   1-10578
                       -----------

                            VINTAGE PETROLEUM, INC.
              (Exact name of registrant as specified in charter)

           Delaware                                     73-1182669
(State or other jurisdiction of                     (I.R.S. Employer
 incorporation or organization)                    Identification No.)


4200 One Williams Center  Tulsa, Oklahoma                  74172
(Address of principal executive offices)                 (Zip Code)

                                (918) 592-0101
             (Registrant's telephone number, including area code)
                                        
                                NOT APPLICABLE
   (Former name, former address and former fiscal year, if changed since last
                                    report)

Indicate by check mark whether the registrant (1) has filed all reports required
to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during
the preceding 12 months (or for such shorter period that the registrant was
required to file such reports), and (2) has been subject to such filing
requirements for the past 90 days.

Yes   X      No
    -----       -----        

Indicate the number of shares outstanding of each of the registrant's classes of
common stock, as of the latest practicable date.

           Class                            Outstanding at November 10, 1998
Common Stock, $.005 Par Value                           53,103,066

                                      -1-
<PAGE>
 
                                    PART I



                             FINANCIAL INFORMATION

                                      -2-
<PAGE>
 
                         ITEM 1.  FINANCIAL STATEMENTS

                   VINTAGE PETROLEUM, INC. AND SUBSIDIARIES

                          CONSOLIDATED BALANCE SHEETS
                         (IN THOUSANDS, EXCEPT SHARES
                            AND PER SHARE AMOUNTS)
                                  (UNAUDITED)


                                     ASSETS

<TABLE>
<CAPTION>
                                                              September 30,  December 31,
                                                                  1998           1997
                                                              -------------  ------------
                                                                              (Restated)
<S>                                                           <C>            <C>
CURRENT ASSETS:                                            
   Cash and cash equivalents                                     $    2,556    $    5,797
   Accounts receivable -                                                       
       Oil and gas sales                                             51,367        60,878
       Joint operations                                               5,686         6,358
   Deferred income taxes                                                  -         4,206
   Prepaids and other current assets                                 10,769        12,443
                                                                 ----------    ----------
          Total current assets                                       70,378        89,682
                                                                 ----------    ----------
                                                                               
PROPERTY, PLANT AND EQUIPMENT, at cost:                                        
   Oil and gas properties, successful efforts method              1,289,901     1,158,749
   Oil and gas gathering systems                                     14,464        12,943
   Other                                                             11,034         8,420
                                                                 ----------    ----------
                                                                  1,315,399     1,180,112
                                                                               
   Less accumulated depreciation, depletion and amortization        450,672       373,225
                                                                 ----------    ----------
                                                                    864,727       806,887
                                                                 ----------    ----------
OTHER ASSETS, net                                                    29,669        18,825
                                                                 ----------    ----------
   TOTAL ASSETS                                                  $  964,774    $  915,394
                                                                 ==========    ==========
</TABLE>



           See notes to unaudited consolidated financial statements.

                                      -3-
<PAGE>
 
                   VINTAGE PETROLEUM, INC. AND SUBSIDIARIES
                   
                     LIABILITIES AND STOCKHOLDERS' EQUITY
                     


<TABLE>
<CAPTION>
                                                              September 30,  December 31,
                                                                  1998           1997
                                                              -------------  ------------
                                                                              (Restated)
<S>                                                           <C>            <C>
CURRENT LIABILITIES:
   Revenue payable                                                 $ 18,228      $ 27,085
   Accounts payable - trade                                          18,916        21,088
   Other payables and accrued liabilities                            22,469        31,504
                                                                   --------      --------
                                                                   
       Total current liabilities                                     59,613        79,677
                                                                   --------      --------
                                                                   
LONG-TERM DEBT                                                      563,379       451,096
                                                                   --------      --------
                                                                   
DEFERRED INCOME TAXES                                                25,652        43,135
                                                                   --------      --------
                                                                   
OTHER LONG-TERM LIABILITIES                                           1,021         3,908
                                                                   --------      --------
                                                                   
STOCKHOLDERS' EQUITY per accompanying statement:                   
   Preferred stock, $.01 par, 5,000,000 shares authorized,         
       zero shares issued and outstanding                                 -             -
   Common stock, $.005 par, 80,000,000 shares                      
       authorized, 51,778,066 and 51,558,886 shares                
       issued and outstanding                                           259           258
   Capital in excess of par value                                   203,916       202,008
   Retained earnings                                                110,934       135,312
                                                                   --------      --------
                                                                   
                                                                    315,109       337,578
                                                                   --------      --------
                                                                   
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY                         $964,774      $915,394
                                                                   ========      ========
</TABLE>

           See notes to unaudited consolidated financial statements.

                                      -4-
<PAGE>
 
                   VINTAGE PETROLEUM, INC. AND SUBSIDIARIES
                   
                       CONSOLIDATED STATEMENTS OF INCOME
                   (IN THOUSANDS, EXCEPT PER SHARE AMOUNTS)
                                  (UNAUDITED)

<TABLE>
<CAPTION>
                                                   Three Months Ended       Nine Months Ended
                                                      September 30,           September 30,
                                                  ---------------------   --------------------
                                                    1998        1997        1998        1997
                                                  --------    ---------   ---------   --------
                                                             (Restated)              (Restated)
<S>                                               <C>         <C>         <C>         <C>
REVENUES:                                                                             
   Oil and gas sales                              $ 65,072    $ 88,901    $207,055    $258,264
   Oil and gas gathering                             1,476       4,300       6,811      13,514
   Gas marketing                                    12,593      10,803      39,664      31,641
   Other income                                        144         383         681          45
                                                  --------    --------    --------    --------
                                                    79,285     104,387     254,211     303,464
                                                  --------    --------    --------    --------
                                                                                      
COSTS AND EXPENSES:                                                                   
   Lease operating, including production taxes      29,487      30,457      91,693      83,847
   Exploration costs                                 6,569       2,408      18,939       8,321
   Oil and gas gathering                             1,334       3,590       5,851      11,354
   Gas marketing                                    12,061      10,168      37,701      29,999
   General and administrative                        7,825       6,548      23,922      19,737
   Depreciation, depletion and amortization         26,797      25,056      80,283      70,820
   Interest                                         11,525       9,503      30,795      27,455
                                                  --------    --------    --------    --------
                                                    95,598      87,730     289,184     251,533
                                                  --------    --------    --------    --------
       Income (loss) before income                                                    
          taxes and minority interest              (16,313)     16,657     (34,973)     51,931
                                                                                      
PROVISION (BENEFIT) FOR INCOME TAXES:                                                 
   Current                                            (125)      1,308        (586)      3,293
   Deferred                                         (6,263)      1,823     (13,372)      6,147
                                                                                      
MINORITY INTEREST IN                                                                  
   INCOME OF SUBSIDIARY                                  -           -           -        (203)
                                                  --------    --------    --------    --------
NET INCOME (LOSS)                                 $ (9,925)   $ 13,526    $(21,015)   $ 42,288
                                                  ========    ========    ========    ========
                                                                                      
EARNINGS (LOSS) PER SHARE:                                                            
   Basic                                          $  $(.19)   $    .26    $   (.41)       $.83
                                                  ========    ========    ========    ========
   Diluted                                        $  $(.19)   $    .26    $   (.41)       $.81
                                                  ========    ========    ========    ========
                                                                                      
Weighted average common shares outstanding:                                           
   Basic                                            51,733      51,549      51,664      51,049
                                                  ========    ========    ========    ========
   Diluted                                          51,733      53,180      51,664      52,403
                                                  ========    ========    ========    ========
</TABLE>

           See notes to unaudited consolidated financial statements.

                                      -5-
<PAGE>
 
                   VINTAGE PETROLEUM, INC. AND SUBSIDIARIES

           CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS' EQUITY

                 FOR THE NINE MONTHS ENDED SEPTEMBER 30, 1998
                   (IN THOUSANDS, EXCEPT PER SHARE AMOUNTS)
                                  (UNAUDITED)

<TABLE>
<CAPTION>
                                                                               
                                                                       Capital                 
                                                  Common Stock        In Excess                
                                               -----------------        of Par        Retained 
                                               Shares     Amount        Value         Earnings        Total
                                               ------     ------       --------       --------       --------
<S>                                            <C>        <C>         <C>             <C>            <C>     
Balance at December 31, 1997 (Restated)        51,559       $258       $202,008       $135,312       $337,578
                                                                                                     
   Net loss                                         -          -              -        (21,015)       (21,015)
   Exercise of stock options and                                                                     
     resulting tax effects                        219          1          1,908              -          1,909
   Cash dividends declared                                                                           
     ($.065 per share)                              -          -              -         (3,363)        (3,363)
                                               ------     ------       --------       --------       --------
                                                                                                     
Balance at September 30, 1998                  51,778       $259       $203,916       $110,934       $315,109
                                               ======     ======       ========       ========       ========
</TABLE>

           See notes to unaudited consolidated financial statements.

                                      -6-
<PAGE>
 
                    VINTAGE PETROLEUM, INC. AND SUBSIDIARIES

                     CONSOLIDATED STATEMENTS OF CASH FLOWS
                                 (IN THOUSANDS)
                                  (UNAUDITED)
<TABLE>
<CAPTION>
                                                                      Nine Months Ended  
                                                                        September 30,    
                                                                 --------------------------
                                                                    1998             1997
                                                                 ---------        ---------
                                                                                  (Restated)   
<S>                                                              <C>              <C>
CASH FLOWS FROM OPERATING ACTIVITIES:                                       
   Net income (loss)                                             $ (21,015)       $  42,288
   Adjustments to reconcile net income (loss) to                            
       cash provided by operating activities -                              
          Depreciation, depletion and amortization                  80,283           70,820
          Exploration costs                                         18,939            8,321
          Provision (benefit) for deferred income taxes            (13,372)           6,147
          Minority interest in income of subsidiary                      -              203
                                                                 ---------        ---------
                                                                    64,835          127,779
                                                                            
   Decrease in receivables                                          10,184           12,642
   Decrease in payables and accrued liabilities                    (13,971)          (2,294)   
   Other                                                            (4,062)            (500)   
                                                                 ---------        ---------
          Cash provided by operating activities                     56,986          137,627
                                                                 ---------        ---------
                                                                            
CASH FLOWS FROM INVESTING ACTIVITIES:                                       
   Additions to property, plant and equipment -                             
       Oil and gas properties                                     (152,532)        (202,124)   
       Other property and equipment                                 (4,408)          (1,886)   
   Purchase of subsidiary                                                -          (39,027)   
   Other                                                            (3,245)            (987)   
                                                                 ---------        ---------
          Cash used by investing activities                       (160,185)        (244,024)   
                                                                 ---------        ---------
                                                                            
CASH FLOWS FROM FINANCING ACTIVITIES:                                       
   Sale of common stock                                                879           47,910
   Sale of 8 5/8% Senior Subordinated Notes                              -           96,270
   Advances on revolving credit facility and other borrowings      123,651          174,858
   Payments on revolving credit facility and other borrowings      (16,515)        (202,914)   
   Dividends paid                                                   (4,392)          (2,266)   
   Other                                                            (3,665)          (1,110)   
                                                                 ---------        ---------
          Cash provided by financing activities                     99,958          112,748
                                                                 ---------        ---------
                                                                            
Net increase (decrease) in cash and cash equivalents                (3,241)           6,351
                                                                            
Cash and cash equivalents, beginning of period                       5,797            2,774
                                                                 ---------        ---------
                                                                            
Cash and cash equivalents, end of period                         $   2,556        $   9,125
                                                                 =========        =========
</TABLE>

           See notes to unaudited consolidated financial statements.

                                      -7-
<PAGE>
 
                    VINTAGE PETROLEUM, INC. AND SUBSIDIARIES

              NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS

                          SEPTEMBER 30, 1998 AND 1997

1.   GENERAL

     Effective January 1, 1998, the Company elected to change its accounting
     method for oil and gas properties from the full cost method to the
     successful efforts method. Management believes that the successful efforts
     method is preferable and that the accounting change more accurately
     presents the results of the Company's exploration and development
     activities, minimizes asset write-offs caused by temporary declines in oil
     and gas prices and reflects an impairment in the carrying value of the
     Company's oil and gas properties only when there has been a permanent
     decline in their fair value. As required by generally accepted accounting
     principles, all financial statements presented herein have been
     retroactively restated to give effect to this change in accounting method.

     The accompanying financial statements are unaudited. The consolidated
     financial statements include the accounts of the Company and its wholly-
     and majority-owned subsidiaries. Management believes that all material
     adjustments (consisting of only normal recurring adjustments) necessary for
     a fair presentation have been made. These financial statements and notes
     should be read in conjunction with the 1997 audited financial statements
     and related notes, as restated in the Company's Form 8-K dated August 18,
     1998.

     On September 12, 1997, the Company's Board of Directors approved a two-for-
     one stock split of its common stock effective October 7, 1997, to
     stockholders of record on September 26, 1997. All references to the number
     of shares and per share amounts in the financial statements and notes
     thereto have been restated to reflect the stock split.

                                      -8-
<PAGE>
 
2.   SIGNIFICANT ACCOUNTING POLICIES

     Change in Accounting Method

     As a result of the accounting change to the successful efforts method,
     prior year and interim financial statements have been restated. The effect
     of the restatements on the balance sheet as of September 30, 1997, is as
     follows:

                                              September 30, 1997
                                            ----------------------
                                             Reported    Restated
                                            ----------  ----------
                                                 (In thousands)
Assets:
 Current Assets                             $   79,214  $   79,214
 Property, Plant and Equipment, net            848,848     788,895
 Other Assets                                   20,265      20,265
                                            ----------  ----------
Total Assets                                $  948,327  $  888,374
                                            ==========  ==========
                                                          
Liabilities and Stockholders' Equity:                     
 Current Liabilities                        $   69,154  $   69,154
 Long-Term Debt                                447,868     447,868
 Deferred Income Taxes                          63,752      40,710
 Other Long-Term Liabilities                     2,531       2,531
 Minority Interest                               2,110       2,066
 Stockholders' Equity                          362,912     326,045
                                            ----------  ----------
Total Liabilities and Stockholders' Equity  $  948,327  $  888,374
                                            ==========  ==========


     The effect of the accounting change on the income statements is as follows:

                        Three Months Ended    Nine Months Ended
                        September 30,1997     September 30, 1997
                       --------------------  --------------------
                       Reported   Restated   Reported   Restated
                       ---------  ---------  ---------  ---------
                       (In thousands, except per share amounts)
                       
Revenues               $ 104,387  $ 104,387  $ 303,464  $ 303,464
Costs and Expenses        85,273     87,730    238,713    251,533
                       ---------  ---------  ---------  ---------
 Pretax Income            19,114     16,657     64,751     51,931
Income Taxes               3,880      3,131     14,092      9,440
Minority Interest              -          -       (203)      (203)
                       ---------  ---------  ---------  ---------
 Net Income            $  15,234  $  13,526  $  50,456  $  42,288
                       =========  =========  =========  =========
 
Earnings Per Share:
 Basic                  $    .30   $    .26   $    .99  $    .83
 Diluted                $    .29   $    .26   $    .96  $    .81

                                      -9-
<PAGE>
 
     Oil and Gas Properties

     Under the successful efforts method of accounting, the Company capitalizes
     all costs related to property acquisitions and successful exploratory
     wells, all development costs and the costs of support equipment and
     facilities. All costs related to unsuccessful exploratory wells are
     expensed when such wells are determined to be non-productive; other
     exploration costs, including geological and geophysical costs, are expensed
     as incurred. The Company recognizes gain or loss on the sale of properties
     on a field basis.

     Unproved leasehold costs are capitalized and are reviewed periodically for
     impairment. Costs related to impaired prospects are charged to expense.

     Costs of development dry holes and proved leaseholds are amortized on the
     unit-of-production method based on proved reserves on a field basis. The
     depreciation of capitalized drilling costs is based on the unit-of-
     production method using proved developed reserves on a field basis.
     Estimated abandonment costs, net of salvage value, are included in the
     depreciation and depletion calculation.

     The Company reviews its proved oil and gas properties for impairment on a
     field basis. For each field, an impairment provision is recorded whenever
     events or circumstances indicate that the carrying value of those
     properties may not be recoverable. The impairment provision is based on the
     excess of the carrying value over fair value. Fair value is defined as the
     present value of the estimated future net revenues from the production of
     oil and gas over the economic life of the reserves. No impairment provision
     was required during the nine month periods ended September 30, 1998 and
     1997.

     Prior to the adoption of Statement of Financial Accounting Standards No.
     121, Accounting for the Impairment of Long-Lived Assets, and for Long-Lived
     Assets to be Disposed of ("SFAS No. 121"), on January 1, 1996, the Company
     determined the impairment of oil and gas properties on a world-wide basis.
     The Company would record an impairment provision based on the excess of
     capitalized costs over the undiscounted net revenues from proved reserves
     using period-end prices. The impact of implementing SFAS No.121 was not
     significant.

     Statements of Cash Flows

     Cash payments for interest totaled $28,985,776 and $22,384,069 and cash
     payments for U.S. Federal and state income taxes were $1,473,252 and
     $3,385,382 during the nine months ended September 30, 1998 and 1997,
     respectively. During the nine months ended September 30, 1998 and 1997, the
     Company made cash payments of $1,256,041 and $5,204, respectively, for
     foreign income taxes.

                                      -10-
<PAGE>
 
     Income Taxes

     Deferred income taxes are provided on transactions which are recognized in
     different periods for financial and tax reporting purposes. Such temporary
     differences arise primarily from the deduction of certain oil and gas
     exploration and development costs which are capitalized for financial
     reporting purposes and differences in the methods of depreciation. The
     Company follows the provisions of Statement of Financial Accounting
     Standards No. 109 when calculating the deferred income tax provision for
     financial purposes.

     Earnings Per Share

     In February 1997, the Financial Accounting Standards Board issued Statement
     No. 128, Earnings Per Share ("SFAS No. 128"), establishing new standards
     for computing and presenting earnings per share. The provisions of SFAS No.
     128 are effective for earnings per share calculations for periods ending
     after December 15, 1997. The Company has adopted SFAS No. 128 effective
     December 31, 1997, and all earnings per share amounts disclosed herein have
     been calculated under the provisions of SFAS No. 128. The adoption of SFAS
     No. 128 did not have a material effect on previously reported earnings per
     share or on 1997 earnings per share. Basic earnings per common share were
     computed by dividing net income by the weighted average number of shares
     outstanding during the period. Diluted earnings per common share were
     computed assuming the exercise of all dilutive options, as determined by
     applying the treasury stock method. Because the Company reported a loss for
     the three months and nine months ended September 30, 1998, all options were
     considered to be anti-dilutive and therefore were not included in the
     calculation of diluted earnings per share for those periods.

     Comprehensive Income

     In June 1997, the Financial Accounting Standards Board issued Statement No.
     130, Reporting Comprehensive Income ("SFAS No. 130"), establishing
     standards for reporting and display of comprehensive income and its
     components in financial statements. SFAS No. 130 defines comprehensive
     income as the total of net income and all other non-owner changes in
     equity. The Company had no non-owner changes in equity other than net
     income and losses during the three month and nine month periods ended
     September 30, 1998 and 1997.

     Derivatives and Hedging Activities

     In June 1998, the Financial Accounting Standards Board issued Statement of
     Financial Accounting Standards No. 133, Accounting for Derivative
     Instruments and Hedging Activities ("SFAS No. 133"). SFAS No. 133
     establishes accounting and reporting standards requiring that every
     derivative instrument (including certain derivative instruments embedded in
     other contracts) be recorded in the balance sheet as either an asset or
     liability measured at its fair value. SFAS No. 133 requires that changes in
     the derivative's fair value be recognized currently in earnings unless
     specific hedge accounting criteria are met. Special accounting for
     qualifying hedges allows a derivative's gains and losses to offset related
     results on the hedged item in the income statement. Companies must formally
     document, designate, and assess the effectiveness of transactions that
     receive hedge accounting.

                                      -11-
<PAGE>
 
     SFAS No. 133 is effective for fiscal years beginning after June 15, 1999,
     however, companies may implement the statement as of the beginning of any
     fiscal quarter beginning June 16, 1998. SFAS No. 133 cannot be applied
     retroactively and must be applied to (a) derivative instruments and (b)
     certain derivative instruments embedded in hybrid contracts that were
     issued, acquired, or substantively modified after December 31, 1997 (and,
     at the company's election, before January 1, 1998).

     The Company has not yet quantified the impact of adopting SFAS No. 133 on
     its financial statements and has not determined the timing of or method of
     the adoption of SFAS No. 133. In September 1998, the Company entered into
     ten natural gas basis swaps for the calender year 1999 covering a total of
     82,000 MMBtu of gas per day. Natural gas basis swaps are used to hedge the
     basis differential between the derivative financial instrument index price
     and industry delivery point indexes. While the Company has not yet
     quantified the impact of SFAS No. 133 on these derivative instruments, it
     does not believe it would have a material adverse impact on the Company's
     financial condition or results of operations.
 
3.   LONG-TERM DEBT

     Long-term debt at September 30, 1998, and December 31, 1997, consisted of
     the following:

                                                   September 30,    December 31,
                                                       1998            1997
                                                   -------------    ------------
                                                          (In thousands)
 
     Revolving credit facility                     $     314,400    $    202,200
     Senior subordinated notes -                                     
       9% Notes due 2005, less unamortized   
                   discount                              149,704         149,674
       8 5/8% Notes due 2009, less unamortized                      
                   discount                               99,275          99,222
                                                   -------------    ------------
                                                   $     563,379    $    451,096
                                                   =============    ============


     Revolving Credit Facility

     The Company has available an unsecured revolving credit facility under an
     Amended and Restated Credit Agreement dated October 21, 1998 (the "Credit
     Agreement"), between the Company and certain banks. The Credit Agreement
     establishes a borrowing base (currently $550 million including the impact
     of the Western Acquisition and the Texaco Acquisition discussed in Note 4
     below) based on the banks' evaluation of the Company's oil and gas
     reserves.

     Outstanding advances under the Credit Agreement bear interest payable
     quarterly at a floating rate based on Bank of Montreal's alternate base
     rate (as defined) or, at the Company's option, at a fixed rate for up to
     six months based on the Eurodollar market rate ("LIBOR"). The Company's
     interest rate increments above the alternate base rate and LIBOR vary based
     on the level of outstanding senior debt to the borrowing base. In addition,
     the Company must pay a commitment fee ranging from 0.25 to 0.375 percent
     per annum on the unused portion of the banks' commitment.

                                      -12-
<PAGE>
 
     On a semiannual basis, the Company's borrowing base is redetermined by the
     banks based upon their review of the Company's oil and gas reserves. If the
     sum of outstanding senior debt exceeds the borrowing base, as redetermined,
     the Company must repay such excess. Any principal advances outstanding at
     September 11, 2001, will be payable in 8 equal consecutive quarterly
     installments commencing December 1, 2001, with final maturity at September
     11, 2003.

     The terms of the Credit Agreement impose certain restrictions on the
     Company regarding the pledging of assets and limitations on additional
     indebtedness. In addition, the Credit Agreement requires the maintenance of
     a minimum current ratio (as defined) and tangible net worth (as defined) of
     $250 million plus 75 percent of the net proceeds of any future equity
     offerings.

     SENIOR SUBORDINATED NOTES

     On December 20, 1995, the Company issued $150 million of its 9% Senior
     Subordinated Notes Due 2005 (the "9% Notes"). The 9% Notes are redeemable
     at the option of the Company, in whole or in part, at any time on or after
     December 15, 2000. The 9% Notes mature on December 15, 2005, with interest
     payable semiannually on June 15 and December 15 of each year.

     On February 5, 1997, the Company issued $100 million of its 8 5/8% Senior
     Subordinated Notes Due 2009 (the "8 5/8% Notes"). The 8 5/8% Notes are
     redeemable at the option of the Company, in whole or in part, at any time
     on or after February 1, 2002. The 8 5/8% Notes mature on February 1, 2009,
     with interest payable semiannually on February 1 and August 1 of each year.

     The 9% Notes and 8 5/8% Notes (collectively, the "Notes") are unsecured
     senior subordinated obligations of the Company, rank subordinate in right
     of payment to all senior indebtedness (as defined) and rank pari passu with
     each other. Upon a change in control (as defined) of the Company, holders
     of the Notes may require the Company to repurchase all or a portion of the
     Notes at a purchase price equal to 101 percent of the principal amount
     thereof, plus accrued and unpaid interest. The indentures for the Notes
     contain limitations on, among other things, additional indebtedness and
     liens, the payment of dividends and other distributions, certain
     investments and transfers or sales of assets.

4.   SUBSEQUENT EVENTS

     Subsequent to September 30, 1998, the Company announced that it had made
     three separate acquisitions of producing oil and gas properties. Two were
     in the form of asset acquisitions and the third was a stock acquisition.
     All three acquisitions will be accounted for using the purchase method.

     On October 29, 1998, producing oil and gas properties located in East Texas
     were purchased from Western Gas Resources, Inc. for $47.4 million in cash
     (the "Western Acquisition"). On November 10, 1998, producing oil and gas
     properties located in northern California were purchased from Texaco
     Exploration and Production, Inc. and an affiliate for $28.7 million in cash
     (the "Texaco Acquisition"). Funds for both acquisitions were provided
     through advances on the Company's revolving credit facility and both
     acquisitions included provisions for post-closing adjustments to the
     purchase prices.

     On November 4, 1998, the Company, through a wholly-owned subsidiary,
     purchased from Elf Aquitaine 100 percent of the outstanding shares of its
     French subsidiary, Elf Hydrocarbures Equateur, S.A. ("EHE"). EHE has
     producing oil and gas operations, along with substantial undeveloped
     acreage, in Ecuador. The acquisition price for EHE was $39.7 million,
     including working capital of $7.2 million, and was funded through a cash
     payment of $13.2 million provided through an advance on the Company's
     revolving credit facility and the issuance of 1,325,000 shares of common
     stock of the Company valued at a guaranteed amount of $20 per share, or
     $26.5 million. If the prevailing share price is not equal to at least $20
     per share after two years, then the Company will be required to deliver
     additional consideration under the price guarantee provisions of the
     agreement. Such additional consideration, if any, is payable, at the
     Company's option, in cash or additional shares of the Company's common
     stock. The legal transfer of the stock of EHE to the Company is subject to
     the prior approval by the Ecuadorian government.

                                      -13-
<PAGE>
 
                 ITEM 2.  MANAGEMENT'S DISCUSSION AND ANALYSIS
               OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS


CHANGE IN ACCOUNTING METHOD

     Effective January 1, 1998, the Company elected to convert from the full
cost method to the successful efforts method of accounting for its investments
in oil and gas properties. The Company believes that the successful efforts
method of accounting is preferable, as it more accurately presents the results
of the Company's exploration and development activities, minimizes asset write-
offs caused by temporary downward oil and gas price movements and reflects an
impairment in the carrying value of its oil and gas properties only when there
has been a permanent decline in their fair value. Accordingly, the December 31,
1997, consolidated balance sheet, the consolidated statements of income for the
three months and nine months ended September 30, 1997, and the consolidated
statement of cash flows for the nine months ended September 30, 1997, included
in this Form 10-Q have been restated to conform with successful efforts
accounting. (See the Company's Form 8-K dated August 18, 1998, for the restated
financial statements and notes thereto for the years ended December 31, 1997, 
1996 and 1995, and selected financial data for the three months ended 
March 31, 1998.) The effect, net of income taxes, was to reduce December
31, 1997, retained earnings by $46.0 million. For the statements of income for
the three months and nine months ended September 30, 1997, the effect of the
accounting change was to decrease net income by $1.7 million ($.03 per diluted
share) and $8.2 million ($.15 per diluted share), respectively.

 

                                      -14-
<PAGE>
 
RESULTS OF OPERATIONS

     The Company's results of operations have been significantly affected by its
success in acquiring oil and gas properties and its ability to maintain or
increase production through its exploitation and exploration activities.
Fluctuations in oil and gas prices have also significantly affected the
Company's results. The following table reflects the Company's oil and gas
production and its average oil and gas prices for the periods presented:

 
                           Three Months Ended      Nine Months Ended
                              September 30,           September 30,
                           ------------------      ------------------
                             1998       1997         1998       1997
                           -------    -------      -------    -------
Production:         
   Oil (MBbls) -    
       U.S. (1)...........   2,500      2,560        7,509      7,090
       Argentina..........   1,552      1,430        4,637      4,157
       Bolivia............      30         39           99         98
       Total..............   4,082      4,029       12,245     11,345
                                                              
   Gas (MMcf) -                                               
       U.S. (1)...........  10,386     10,020       31,530     26,202
       Bolivia............   1,372      1,711        4,036      4,554
       Total..............  11,758     11,731       35,566     30,756
                                                              
   Total MBOE (1).........   6,042      5,984       18,172     16,471
                                                              
Average prices:                                               
   Oil (per Bbl) -                                            
       U.S................ $ 11.08    $ 16.10      $ 11.64    $ 17.47
       Argentina..........   10.43      16.29        11.18      17.11
       Bolivia............   10.24      13.81        11.49      16.18
       Total..............   10.83      16.15        11.46      17.33
                                                              
   Gas (per Mcf) -                                            
       U.S................ $  1.91    $  2.21      $  2.01    $  2.16
       Bolivia............     .73       1.02          .81       1.12
       Total..............    1.77       2.03         1.87       2.01


- --------------------
(1)  First nine months of 1998 production was reduced by approximately 167 MBbls
     of oil and 877 MMcf of gas, or 313 MBOE, due to severe weather conditions
     in California and the Gulf of Mexico. Third quarter 1998 production was
     reduced by approximately 8 MBbls of oil and 391 MMcf of gas, or 73 MBOE,
     due to severe weather conditions in California and the Gulf of Mexico.

                                      -15-
<PAGE>
 
     Average U.S. oil prices received by the Company fluctuate generally with
changes in the West Texas Intermediate ("WTI") posted prices for oil.  The
Company's Argentina oil production is sold at WTI spot prices less a specified
differential.  The Company experienced a 34 percent decrease in its average oil
price in the first nine months of 1998 compared to the first nine months of
1997. During the first nine months of 1997, the impact of Argentina oil hedges
reduced the Company's overall average oil price 23 cents to $17.33 per Bbl and
its average Argentina oil price was reduced 64 cents to $17.11 per Bbl.  The
Company was not a party to any oil hedges in the first nine months of 1998. The
Company realized an average oil price for the first nine months of 1998 which
was approximately 92 percent of WTI posted prices compared to a realization of
93 percent (before the impact of oil hedges) of WTI posted prices for the year
earlier nine months.  However, due to an increase in the differential between
WTI posted prices and the NYMEX reference price ("NYMEX"), the Company's average
realized prices (before hedges) declined to 77 percent of NYMEX in the first
nine months of 1998 compared to 84 percent of NYMEX in the first nine months of
1997.

     Average U.S. gas prices received by the Company fluctuate generally with
changes in spot market prices, which may vary significantly by region.  The
Company's Bolivia average gas price is tied to a long-term contract under which
the base price is adjusted for changes in specified fuel oil indexes. During
1998, these fuel oil indexes have decreased in conjunction with the current low
oil price environment.  The Company's average gas price for the first nine
months of 1998 was seven percent lower than 1997's first nine months.

     The Company has previously engaged in oil and gas hedging activities and
intends to continue to consider various hedging arrangements to realize
commodity prices which it considers favorable. Currently, there are no oil or
gas hedges in place related to 1998 production.  In September 1998, the Company
entered into ten natural gas basis swaps for the calender year 1999 covering a
total of 82,000 MMBtu of gas per day. These natural gas basis swaps were used to
hedge the basis differential between the NYMEX reference price and industry
delivery point indexes under which the gas is sold.

     Relatively modest changes in either oil or gas prices significantly impact
the Company's results of operations and cash flow.  However, the impact of
changes in the market prices for oil and gas on the Company's average realized
prices may be reduced from time to time based on the level of the Company's
hedging activities.  Based on third quarter 1998 oil production, a change in the
average oil price realized by the Company of $1.00 per Bbl would result in a
change in net income and cash flow before income taxes on a quarterly basis of
approximately $2.5 million and $4.0 million, respectively. A 10 cent per Mcf
change in the average price realized by the Company for gas would result in a
change in net income and cash flow before income taxes on a quarterly basis of
approximately $0.7 million and $1.1 million, respectively, based on third
quarter 1998 gas production.

PERIOD TO PERIOD COMPARISON

THREE MONTHS ENDED SEPTEMBER 30, 1998, COMPARED TO THREE MONTHS ENDED SEPTEMBER
30, 1997

     The Company reported a net loss of $9.9 million for the quarter ended
September 30, 1998, compared to net income of $13.5 million for the same period
in 1997.  An increase in the Company's oil and gas production of one percent on
an equivalent barrel basis was more than offset by a 33 percent decrease in
average oil prices and a 13 percent decrease in average gas prices.

                                      -16-
<PAGE>
 
     Oil and gas sales decreased $23.8 million (27 percent), to $65.1 million
for the third quarter of 1998 from $88.9 for the third quarter of 1997. A 33
percent decrease in average oil prices, partially offset by a one percent
increase in oil production, accounted for a decrease of $20.8 million. A 13
percent decrease in average gas prices accounted for an additional decrease of
$3.0 million.

     Oil and gas gathering net margins decreased $0.6 million (80 percent), to
$0.1 million for the third quarter of 1998 from $0.7 million for the third
quarter of 1997, due primarily to the sale by the Company of its two largest
gathering systems in December 1997 and June 1998.

     Lease operating expenses, including production taxes, decreased $1.0
million (3 percent), to $29.5 million for the third quarter of 1998 from $30.5
million for the third quarter of 1997. The decrease in lease operating expenses
is due primarily to the Company's continued efforts to reduce operating costs.
Third quarter 1998 costs included estimated costs of $225,000 related to storm
damage repair and cleanup as a result of the severe weather in the Gulf of
Mexico. Lease operating expenses per equivalent barrel produced decreased to
$4.88 ($4.84 before the effects of the severe weather in the Gulf of Mexico) in
the third quarter of 1998 from $5.09 for the same period in 1997.

     Exploration costs increased $4.2 million (173 percent), to $6.6 million for
the third quarter of 1998 from $2.4 million for the third quarter of 1997.
During the third quarter of 1998, the Company's exploration costs included $2.8
million for the acquisition of 3-D seismic data primarily in the U.S. Gulf Coast
area and Bolivia, $2.2 million for unsuccessful exploratory drilling, $1.2
million for lease expirations and $0.4 million in other geological and
geophysical costs.  The Company's third quarter 1997 exploration costs consisted
primarily of $1.5 million in 3-D seismic acquisition costs in the U.S. and South
America and $0.9 million related to unsuccessful exploratory drilling.

     General and administrative expenses increased $1.3 million (20 percent), to
$7.8 million for the third quarter of 1998 from $6.5 million for the third
quarter of 1997.  General and administrative expenses increased primarily due to
the Company's increased emphasis on exploration activities, and additional costs
associated with international acquisition and business development activities.

     Depreciation, depletion and amortization increased $1.7 million (7
percent), to $26.8 million for the third quarter of 1998 from $25.1 million for
the third quarter of 1997. The Company's average DD&A rate per equivalent barrel
produced for the third quarter of 1998 was $4.23 compared to $4.07 in the year
earlier period.

     Interest expense increased $2.0 million (21 percent), to $11.5 million for
the third quarter of 1998 from $9.5 million for the third quarter of 1997, due
primarily to a 21 percent increase in the Company's total average outstanding
debt and costs of $0.5 million related to the restructuring of the Company's
unsecured revolving credit facility.  The increase in interest expense was
partially offset by a decrease in the Company's overall average interest rate
from 7.99% in the third quarter of 1997 to 7.74% in the third quarter of 1998.

                                      -17-
<PAGE>
 
NINE MONTHS ENDED SEPTEMBER 30, 1998, COMPARED TO NINE MONTHS ENDED SEPTEMBER
30, 1997

     The Company reported a net loss of $21.0 million for the nine months ended
September 30, 1998, compared to net income of $42.3 million for the same period
in 1997.  An increase in the Company's oil and gas production of 10 percent on
an equivalent barrel basis was more than offset by a 34 percent decrease in
average oil prices and a seven percent decrease in average gas prices.  The
production increases primarily relate to the acquisition of certain oil and gas
properties from Burlington Resources Inc. (the "Burlington Properties") in April
1997, the exploitation activities in Argentina and the exploration activities in
the Galveston Bay area in the Gulf of Mexico. The production increases were
reduced by the impact of the severe weather in California during the first
quarter of 1998 and the Gulf of Mexico in the third quarter of 1998.  The
resulting mudslides and flooding in California and the presence of various
hurricanes in the Gulf of Mexico forced the Company to temporarily shut-in some
of its oil and gas properties for portions of the first three quarters lowering
production for the first nine months of 1998 by approximately 167,000 barrels of
oil and 877,000 Mcf of gas.

     Oil and gas sales decreased $51.2 million (20 percent), to $207.1 million
for the first nine months of 1998 from $258.3 million for the first nine months
of 1997. A 34 percent decrease in average oil prices, partially offset by an
eight percent increase in oil production, accounted for a decrease of $56.2
million. A 16 percent increase in gas production, partially offset by a seven
percent decrease in average gas prices, reduced by $5.0 million the negative
impact of the decline in average oil prices.

     Oil and gas gathering net margins decreased $1.2 million (56 percent), to
$1.0 million for the first nine months of 1998 from $2.2 million for the first
nine months of 1997, due primarily to the sale by the Company of its two largest
gathering systems in December 1997 and June 1998.

     Lease operating expenses, including production taxes, increased $7.9
million (9 percent), to $91.7 million for the first nine months of 1998 from
$83.8 million for the first nine months of 1997. The increase in lease operating
expenses is in line with the 10 percent increase in production and is due
primarily to operating costs associated with the Burlington Properties and
estimated costs of $2.2 million for the first nine months of 1998 related to
storm damage repair and cleanup as a result of the severe weather in California
and the Gulf of Mexico. Lease operating expenses per equivalent barrel produced
decreased to $5.05 ($4.95 before the effects of the severe weather in California
and the Gulf of Mexico) in the first nine months of 1998 from $5.09 for the same
period in 1997.

     Exploration costs increased $10.6 million (128 percent), to $18.9 million
for the first nine months of 1998 from $8.3 million for the comparable period in
1997. During the first nine months of 1998, the Company's exploration costs
included $12.8 million for the acquisition of 3-D seismic data primarily in the
U.S. Gulf Coast area and Bolivia, $2.7 million for unsuccessful exploratory
drilling, $1.9 million for lease expirations and $1.5 million in other
geological and geophysical costs. The Company's first nine months 1997
exploration costs consisted primarily of $5.3 million in 3-D seismic acquisition
costs, $1.5 million related to the abandonment of a non-commercial discovery in
Ecuador, and $1.5 million in other unsuccessful exploratory drilling costs.

                                      -18-
<PAGE>
 
     General and administrative expenses increased $4.2 million (21 percent), to
$23.9 million for the first nine months of 1998 from $19.7 million for the first
nine months of 1997, due primarily to the addition of personnel as a result of
the acquisition of the Burlington Properties and the Company's increased
emphasis on exploration activities, and additional costs associated with
international acquisition and business development activities and unsuccessful
acquisition activities.

     Depreciation, depletion and amortization increased $9.5 million (13
percent), to $80.3 million for the first nine months of 1998 from $70.8 million
for the first nine months of 1997, due primarily to the 10 percent increase in
production on an equivalent barrel basis. The Company's average DD&A rate per
equivalent barrel produced for the first nine months of 1998 was $4.25 compared
to $4.18 for the year earlier period.

     Interest expense increased $3.3 million (12 percent), to $30.8 million for
the first nine months of 1998 from $27.5 million for the first nine months of
1997, due primarily to a 17 percent increase in the Company's total average
outstanding debt as a result of the acquisition of the Burlington Properties in
April 1997 and increased capital spending in the Company's exploitation and
exploration programs.  The increase in interest expense was partially offset by
a decrease in the Company's overall average interest rate from 8.04% in the
first nine months of 1997 to 7.80% in the first nine months of 1998.

CAPITAL EXPENDITURES

     During the first nine months of 1998, the Company's domestic oil and gas
capital expenditures totaled $94.1 million.  Exploratory activities accounted
for $50.1 million of the domestic capital expenditures with exploitation
activities contributing $44.0 million.  During the first nine months of 1998,
the Company's international oil and gas capital expenditures totaled $60.0
million, including $38.2 million in Argentina, primarily on exploitation
activities, and $16.9 million in Bolivia, primarily on exploration activities.

     Subsequent to September 30, 1998, the Company announced that it had made
three separate acquisitions of producing oil and gas properties.  Two were in
the form of asset acquisitions and the third was a stock acquisition.  All three
acquisitions will be accounted for using the purchase method.

     On October 29, 1998, producing oil and gas properties located in East Texas
were purchased from Western Gas Resources, Inc. for $47.4 million in cash (the
"Western Acquisition").  On November 10, 1998, producing oil and gas properties
located in northern California were purchased from Texaco Exploration and
Production, Inc. and an affiliate for $28.7 million in cash (the "Texaco
Acquisition"). Funds for both acquisitions were provided through advances on the
Company's revolving credit facility and both acquisitions included provisions
for post-closing adjustments to the purchase prices.

                                      -19-
<PAGE>
 
     On November 4, 1998, the Company, through a wholly-owned subsidiary,
purchased from Elf Aquitaine 100 percent of the outstanding shares of its French
subsidiary, Elf Hydrocarbures Equateur, S.A. ("EHE"). EHE has producing oil and
gas operations, along with substantial undeveloped acreage, in Ecuador. The
acquisition price for EHE was $39.7 million, including working capital of $7.2
million, and was funded through a cash payment of $13.2 million provided through
an advance on the Company's revolving credit facility and the issuance of
1,325,000 shares of common stock of the Company valued at a guaranteed amount of
$20 per share, or $26.5 million. If the prevailing share price is not equal to
at least $20 per share after two years, then the Company will be required to
deliver additional consideration under the price guarantee provisions of the
agreement. Such additional consideration, if any, is payable, at the Company's
option, in cash or additional shares of the Company's common stock. The legal
transfer of the stock of EHE to the Company is subject to the prior approval by
the Ecuadorian government.

     The Company is committed to perform 17,728 work units related to its
concession rights in the Naranjillos field in Santa Cruz Province, Bolivia
awarded in late 1997.  The work unit commitment is guaranteed by the Company
through an $88.6 million letter of credit; however, the Company anticipates that
it will fulfill this three-year work unit commitment through approximately $50
to $60 million of various seismic and drilling capital expenditures.  In
addition, the Company's commitment to perform 1,400 work units related to an
exploration program within the Chaco Block in Bolivia was fulfilled during 1998
through acquisitions of 3-D seismic and the drilling of two wells.  Under the
Company's exploration contract on Block 19 in Ecuador, the Company is required
to participate in the drilling of one additional well.  The Company expects to
drill the well during 1999 at a cost of approximately $4.0 million.

     The Company is also committed to spend approximately $11.0 million in the
Republic of Yemen over a two and one-half year period which began in July 1998.
The expenditures will include the acquisition and interpretation of 150
square kilometers of seismic and the drilling of three exploration wells.  At
the end of the first two and one-half years, the Company has the option to
extend the work program for a second two and one-half year period with similar
work and capital commitments required.

     Except for the commitments discussed above, the timing of most of the
Company's capital expenditures is discretionary with no material long-term
capital expenditure commitments. Consequently, the Company has a significant
degree of flexibility to adjust the level of such expenditures as circumstances
warrant. The Company uses internally generated cash flow to fund capital
expenditures other than significant acquisitions and anticipates that its cash
flow, net of debt service obligations, coupled with advances under its revolving
credit facility, will be sufficient to fund its planned $185 million of non-
acquisition capital expenditures during 1998. The Company's planned 1998 non-
acquisition capital expenditure budget is allocated approximately 60 percent to
exploitation activities, including development and infill drilling, and
approximately 40 percent to exploration activities. In addition, the Company
recently announced a preliminary capital budget for 1999 of $115 million,
exclusive of acquisitions. The Company does not have a specific acquisition
budget since the timing and size of acquisitions are difficult to forecast. The
Company is actively pursuing additional acquisitions of oil and gas properties.
In addition to internally generated cash flow and advances under its revolving
credit facility, the Company may seek additional sources of capital to fund any
future significant acquisitions (see "--Liquidity").

                                      -20-
<PAGE>
 
LIQUIDITY

     Internally generated cash flow and the borrowing capacity under its
revolving credit facility are the Company's major sources of liquidity. In
addition, the Company may use other sources of capital, including the issuance
of additional debt securities or equity securities, to fund any major
acquisitions it might secure in the future and to maintain its financial
flexibility.

     In the past, the Company has accessed the public markets to finance
significant acquisitions and provide liquidity for its future activities.  In
conjunction with the purchase of substantial oil and gas assets in 1990, 1992
and 1995, the Company completed three public equity offerings, as well as a
public debt offering in 1995, which provided the Company with aggregate net
proceeds of approximately $272 million.

     On February 5, 1997, the Company completed a public offering of 3,000,000
shares (after giving effect to the Company's two-for-one common stock split
effected on October 7, 1997) of common stock, all of which were sold by the
Company.  Net proceeds to the Company of approximately $47 million were used to
repay a portion of existing indebtedness under the revolving credit facility.
Concurrently with the common stock offering, the Company issued $100 million of
its 8 5/8% Senior Subordinated Notes Due 2009. Net proceeds to the Company of
approximately $96 million were used to repay a portion of existing indebtedness
under the revolving credit facility.

     The Company's unsecured revolving credit facility under the Amended and
Restated Credit Agreement dated October 21, 1998 (the "Credit Agreement"),
establishes a borrowing base (currently $550 million including the impact of the
Western Acquisition and the Texaco Acquisition) determined by the banks'
evaluation of the Company's oil and gas reserves.

     Outstanding advances under the Credit Agreement bear interest payable
quarterly at a floating rate based on Bank of Montreal's alternate base rate (as
defined) or, at the Company's option, at a fixed rate for up to six months based
on the Eurodollar market rate ("LIBOR").  The Company's interest rate increments
above the alternate base rate and LIBOR vary based on the level of outstanding
senior debt to the borrowing base.  As of November 4, 1998, the Company had
elected a fixed rate based on LIBOR for a substantial portion of its outstanding
advances, which resulted in an average interest rate of approximately 6.5
percent per annum.  In addition, the Company must pay a commitment fee ranging
from 0.25 to 0.375 percent per annum on the unused portion of the banks'
commitment.

                                      -21-
<PAGE>
 
     On a semiannual basis, the Company's borrowing base is redetermined by the
banks based upon their review of the Company's oil and gas reserves.  If the sum
of outstanding senior debt exceeds the borrowing base, as redetermined, the
Company must repay such excess.  Any principal advances outstanding under the
Credit Agreement at September 11, 2001, will be payable in 8 equal consecutive
quarterly installments commencing December 1, 2001, with final maturity at
September 11, 2003.

     At November 10, 1998, the unused portion of the Credit Agreement was
approximately $115 million based on the current borrowing base established in
October 1998. The unused portion of the Credit Agreement and the Company's
internally generated cash flow provide liquidity which may be used to finance
future capital expenditures, including acquisitions. As additional acquisitions
are made and properties are added to the borrowing base, the banks'
determination of the borrowing base and their commitments may be increased. The
impact of continued lower oil and gas prices on the banks' next borrowing base
determination is unknown at this time.

     The Company's internally generated cash flow, results of operations and 
financing for its operations are dependent on oil and gas prices. For the first 
nine months of 1998, approximately 67 percent of the Company's production was
oil. Realized oil prices for the period decreased by 34 percent as compared to
the same period in 1997. As a result, although total production on a BOE basis
increased by 10 percent, the Company's earnings and cash flows have been
materially reduced compared to 1997. The Company believes that its cash flows
and unused availability under the Credit Agreement are sufficient to fund its
planned capital expenditures for the foreseeable future. However, a continuation
of low oil prices may adversely affect the Company's cash flows, borrowing base
and other loan covenants to the extent that planned capital expenditures,
dividends, and other disbursements may be reduced.

INFLATION

     In recent years inflation has not had a significant impact on the Company's
operations or financial condition.

INCOME TAXES

     The Company incurred a current benefit for income taxes of approximately
$0.6 million for the first nine months of 1998 and a current provision of $3.3
million for the first nine months of 1997. The total provision for U.S. income
taxes is based on the Federal corporate statutory income tax rate plus an
estimated average rate for state income taxes. Earnings of the Company's foreign
subsidiary, Vintage Petroleum Boliviana, Ltd., are subject to Bolivia income
taxes. Earnings of the Company's foreign subsidiary, Vintage Oil Argentina,
Inc., are subject to Argentina income taxes.

     As of December 31, 1997, the Company had estimated net operating loss
carryforwards of $35.4 million for Argentina income tax reporting purposes which
can be used to offset future taxable income in Argentina.  The carryforward
amount includes certain Argentina net operating loss carryforwards which were
acquired in a purchase business combination and are recorded at cost, which is
less than the calculated value under the provisions of Statement of Financial
Accounting Standards No. 109, Accounting for Income Taxes.  These unrecorded net
operating loss carryforwards will reduce the Company's foreign income tax
provision for financial purposes in future years by approximately $4.5 million
when their benefit is realized.  No U.S. deferred tax liability will be
recognized related to the unremitted earnings of these foreign subsidiaries as
it is the Company's intention, generally, to reinvest such earnings permanently.

     The Company has a U.S. Federal alternative minimum tax ("AMT") credit
carryforward of approximately $2.9 million which does not expire and is
available to offset U.S. Federal regular income taxes in future years, but only
to the extent that U.S. Federal regular income taxes exceed the AMT in such
years.  The Company expects to incur a tax net operating loss ("NOL") for U.S.
purposes in 1998 and will be able to carry back the NOL two years and/or forward
20 years to receive a refund of prior income taxes paid or to offset future
income taxes to be paid.

                                      -22-
<PAGE>
 
FOREIGN OPERATIONS

     A significant portion of the Company's foreign operations are located in
Argentina.  The Company believes Argentina offers a relatively stable political
environment and does not anticipate any significant change in the near future.
The current democratic form of the government has been in place since 1983 and,
since 1989, has pursued a steady process of privatization, deregulation and
economic stabilization and reforms involving the reduction of inflation and
public spending.  Argentina's 12-month trailing inflation rate measured by the
Argentine Consumer Price Index declined from 200.7 percent as of June 1991 to a
negative 4.04 percent (-4.04%) as of September 1998.

     The Company believes that its Argentine operations present minimal currency
risk.  All of the Company's Argentine revenues are U.S. dollar based, while a
large portion of its costs are denominated in Argentine pesos.  The Argentina
Central Bank is obligated by law to sell dollars at a rate of one Argentine peso
to one U.S. dollar and has sought to prevent appreciation of the peso by buying
dollars at rates of not less than 0.998 peso to one U.S. dollar.  As a result,
the Company believes that should any devaluation of the Argentine peso occur its
revenues would be unaffected and its operating costs would not be significantly
increased.  At the present time, there are no foreign exchange controls
preventing or restricting the conversion of Argentine pesos into dollars.

     Since the mid-1980's, Bolivia has been undergoing major economic reform,
including the establishment of a free-market economy and the encouragement of
foreign private investment. Economic activities that had been reserved for
government corporations were opened to foreign and domestic private investments.
Barriers to international trade have been reduced and tariffs lowered. A new
investment law and revised codes for mining and the petroleum industry, intended
to attract foreign investment, have been introduced.

     On February 1, 1987, a new currency, the Boliviano ("Bs"), replaced the
peso at the rate of one million pesos to one Boliviano. The exchange rate is set
daily by the Government's exchange house, the Bolsin, which is under the
supervision of the Bolivian central bank. Foreign exchange transactions are not
subject to any controls. The US$:Bs exchange rate at September 30, 1998, was
US$1:Bs5.58. The Company believes that any currency risk associated with its
Bolivian operations would not have a material impact on the Company's financial
position or results of operations.

YEAR 2000

     The Year 2000 issue represents a potentially serious information systems
problem because many software applications and operational systems written in
the past may not properly recognize calendar dates beginning in the Year 2000.
This problem could force computers to either shut down or provide incorrect data
or information.  In consultation with its software and hardware providers, the
Company began the process of identifying the changes required to its major
financial/administrative systems and hardware in early 1997.  Software upgrades
designed to correct the Year 2000 issue for its U.S. financial systems were
implemented in mid-1998 and testing is scheduled for completion by year-end
1998.  A replacement financial system has been selected for the Company's
international locations and implementation has commenced in Bolivia with
conversion of other international locations scheduled prior to April 1, 1999.

                                      -23-
<PAGE>
 
     The Company is currently in the process of assessing the potential impact
that the Year 2000 issue will have on its field operating equipment and systems
and has not yet completed its evaluation of the impact that the Year 2000 issue
will have on such equipment and systems.  In addition, the Company is also
uncertain how it will be indirectly affected by the impact that the Year 2000
issue will have on the companies with which it conducts business.  The Company
does not believe that costs to address the Year 2000 issue will have a material
adverse impact on its business, financial condition or results of operation.

FORWARD-LOOKING STATEMENTS

     This Form 10-Q includes certain statements that may be deemed to be
"forward-looking statements" within the meaning of the Private Securities
Litigation Reform Act of 1995. All statements in this Form 10-Q, other than
statements of historical facts, that address activities, events or developments
that the Company expects, believes or anticipates will or may occur in the
future, including future capital expenditures (including the amount and nature
thereof), the drilling of wells, reserve estimates, future production of oil and
gas, future cash flows, future reserve activity and other such matters are
forward-looking statements. Although the Company believes the expectations
expressed in such forward-looking statements are based on reasonable assumptions
within the bounds of its knowledge of its business, such statements are not
guarantees of future performance and actual results or developments may differ
materially from those in the forward-looking statements.

     Factors that could cause actual results to differ materially from those in
forward-looking statements include: oil and gas prices; exploitation and
exploration successes; continued availability of capital and financing; general
economic, market or business conditions; acquisition opportunities (or lack
thereof); changes in laws or regulations; risk factors listed from time to time
in the Company's reports filed with the Securities and Exchange Commission; and
other factors.  The Company assumes no obligation to update publicly any
forward-looking statements, whether as a result of new information, future
events or otherwise.

                                      -24-
<PAGE>
 
                                    PART II



                               OTHER INFORMATION

                                      -25-
<PAGE>
 
Item 1.  Legal Proceedings

         For information regarding legal proceedings, see the Company's Form 10-
         K for the year ended December 31, 1997.

Item 2.  Changes in Securities and Use of Proceeds

         Not applicable.

Item 3.  Defaults Upon Senior Securities

         Not applicable.

Item 4.  Submission of Matters to a Vote of Security Holders

         Not applicable.

Item 5.  Other Information

         The Company recently announced that it had acquired producing oil and
         gas properties in three separate transactions involving both asset
         purchases and a stock purchase. (See Note 4 to the consolidated
         financial statements included herein.) The Company estimates that 35.9
         million barrels of oil equivalent ("BOE") were acquired in these three
         transactions for an aggregate cost attributable to oil and gas assets
         of $103.9 million, for an average cost of $2.90 per BOE.

Item 6.  Exhibits and Reports on Form 8-K

         a) Exhibits

                The following documents are included as exhibits to this Form 
                10-Q. Those exhibits below incorporated by reference herein are
                indicated as such by the information supplied in the
                parenthetical thereafter. If no parenthetical appears after an
                exhibit, such exhibit is filed herewith.

                10    Amended and Restated Credit Agreement dated as of October
                      21, 1998, among Vintage Petroleum, Inc., as the Borrower,
                      and Certain Commercial Lending Institutions, as the
                      Lenders, Bank of Montreal, acting through certain U.S.
                      branches or agencies, as administrative agent,
                      NationsBank, N.A., as syndication agent, and Societe
                      Generale, Southwest Agency, as documentation agent.

                27    Financial Data Schedule.

                                      -26-
<PAGE>
 
         b) Reports on Form 8-K
                Form 8-K was filed August 18, 1998, to report under Item 5 the
                restatement of the Company's financial statements and notes
                thereto, management's discussion and analysis of financial
                condition and results of operations, and summary financial and
                operating data for the years ended December 31, 1997, 1996 and
                1995, previously reported in the Company's 1997 annual report
                and selected financial information for the three months ended
                March 31, 1998, previously reported in the Company's March 31,
                1998, Form 10-Q as a result of the Company's election to change
                its accounting method for oil and gas properties from the full
                cost method to the successful efforts method effective January
                1, 1998.



********************************************************************************

                                      -27-
<PAGE>
 
                                  Signatures


Pursuant to the requirements of the Securities Exchange Act of 1934, the
registrant has duly caused this report to be signed on its behalf by the
undersigned thereunto duly authorized.



                                       VINTAGE PETROLEUM, INC.
                                       -----------------------
                                            (Registrant)
                                
                                
                                
DATE:   November 13, 1998              \s\ Michael F. Meimerstorf
       ------------------              -----------------------------------
                                       Michael F. Meimerstorf
                                       Vice President and Controller
                                       (Principal Accounting Officer)

                                      -28-
<PAGE>
 
                                 EXHIBIT INDEX



The following documents are included as exhibits to this Form 10-Q.  Those
exhibits below incorporated by reference herein are indicated as such by the
information supplied in the parenthetical thereafter.  If no parenthetical
appears after an exhibit, such exhibit is filed herewith.


Exhibit
Number                            Description
- -------      -------------------------------------------------------------------

10           Amended and Restated Credit Agreement dated as of October 21, 1998,
             among Vintage Petroleum, Inc., as the Borrower, and Certain
             Commercial Lending Institutions, as the Lenders, Bank of Montreal,
             acting through certain U.S. branches or agencies, as administrative
             agent, NationsBank, N.A., as syndication agent, and Societe
             Generale, Southwest Agency, as documentation agent.

27           Financial Data Schedule.

<PAGE>
 
                                                                      Exhibit 10

                     AMENDED AND RESTATED CREDIT AGREEMENT


                         dated as of October 21, 1998


                                     among

                           VINTAGE PETROLEUM, INC.,
                               as the Borrower,

                                      and

                   CERTAIN COMMERCIAL LENDING INSTITUTIONS,
                                as the Lenders,

                               BANK OF MONTREAL,
               acting through certain U.S. branches or agencies,
                           as administrative agent,

                              NATIONSBANK, N.A.,
                             as syndication agent,

                                      and

                      SOCIETE GENERALE, SOUTHWEST AGENCY,
                            as documentation agent.


                               BANK OF MONTREAL
                                  AS ARRANGER
<PAGE>
 
                               TABLE OF CONTENTS

                                                                           PAGE

I    DEFINITIONS AND ACCOUNTING TERMS                                         2
     1.1.      Defined Terms...............................................   2
     1.2.      Use of Defined Terms........................................  17
     1.3.      Cross-References............................................  17
     1.4.      Accounting and Financial                                   
               Determinations..............................................  17
                                                                          
II   COMMITMENTS, BORROWING PROCEDURES AND NOTES...........................  17
     2.1.      Commitments.................................................  17
     2.1.1.    Revolving Loan Commitment...................................  18
     2.1.2.    Term Loan Commitment........................................  18
     2.1.3.    Commitment to Issue Revolving Loan Letters of Credit........  18
     2.1.4.    Bolivian Letter of Credit...................................  18
     2.1.5.    Lenders Not Permitted or Required To Make Loans            
               or Issue or Participate in Revolving Letters of            
               Credit Under Certain Circumstances..........................  18
     2.1.6.    Procedures with respect to the Maximum Commitment          
               Amount......................................................  19
     2.2.      Termination and Reduction of Commitment Amounts.............  21
     2.2.1.    Optional....................................................  21
     2.2.2.    Mandatory as to Revolving Loans.............................  21
     2.2.3.    Mandatory as to Term Loans..................................  21
     2.2.4.    Mandatory as to Bolivian Letter of Credit...................  21
     2.3.      Borrowing Procedure.........................................  21
     2.4.      Continuation and Conversion Elections.......................  22
     2.5.      Funding.....................................................  22
     2.6.      Notes.......................................................  22
     2.7.      Determination of the Borrowing Base.........................  23
     2.7.1.    Annual Scheduled Determinations of the Borrowing Base.......  23
     2.7.2.    Semi-Annual Scheduled Determination of the Borrowing       
               Base........................................................  23
     2.7.3.    Discretionary Determination of the Borrowing Base...........  24
     2.7.4.    Reduction of the Borrowing Base Upon Sales of Oil and      
               Gas Properties..............................................  24
     2.8.      Letters of Credit...........................................  24
     2.8.1.    Issuance Requests...........................................  24
     2.8.2.    Issuances...................................................  24
     2.8.3.    Aggregate Amount Available Under Revolving Loan            
               Letters of Credit...........................................  24
     2.8.4.    Other Lenders' Participation................................  25
     2.8.5.    Disbursements...............................................  26
     2.8.6.    Reimbursement...............................................  26
     2.8.7.    Deemed Disbursements........................................  26
     2.8.8.    Nature of Reimbursement Obligations.........................  27
     2.8.9.    Increased Costs; Indemnity..................................  28
     2.8.10.   Letter of Credit Collateral Account.........................  28

                                       i
<PAGE>
 
                               TABLE OF CONTENTS
                                  (CONTINUED)
                                                                            PAGE

III  REPAYMENTS, PREPAYMENTS, INTEREST AND FEES                              29
     3.1.      Repayments and Prepayments..................................  29
     3.1.1.    Repayments..................................................  29
     3.1.2.    Mandatory Prepayments on Loans..............................  29
     3.1.3.    Repayment Upon Acceleration.................................  30
     3.1.4.    Voluntary Repayments........................................  30
     3.2.      Interest Provisions.........................................  30
     3.2.1.    Rates.......................................................  30
     3.2.2.    Post-Maturity Rates.........................................  31
     3.2.3.    Payment Dates...............................................  32
     3.3.      Fees........................................................  32
     3.3.1.    Commitment Fee..............................................  32
     3.3.2.    Agent's Fee.................................................  32
     3.3.3.    Letter of Credit Face Amount Fee............................  32

IV   CERTAIN LIBO RATE AND OTHER PROVISIONS................................  33
     4.1.      If LIBO Rate Lending Unlawful...............................  33
     4.2.      If  Deposits Unavailable....................................  33
     4.3.      Increased LIBO Rate Loan Costs, etc.........................  33
     4.4.      Funding Losses..............................................  33
     4.5.      Increased Capital Costs.....................................  34
     4.6.      Taxes.......................................................  34
     4.7.      Payments, Computations, etc.................................  35
     4.8.      Sharing of Payments.........................................  35
     4.9.      Setoff......................................................  36
     4.10.     Use of Proceeds.............................................  36

V    CONDITIONS TO BORROWING...............................................  36
     5.1.      Initial Borrowing...........................................  36
     5.1.1.    Resolutions, etc............................................  36
     5.1.2.    Delivery of Notes...........................................  36
     5.1.3.    [Reserved]..................................................  37
     5.1.4.    Compliance with Representations and Warranties..............  37
     5.1.5.    Opinions of Counsel.........................................  37
     5.1.6.    Closing Fees, Expenses, etc.................................  37
     5.1.7.    [Reserved]..................................................  37
     5.2.      Conditions Precedent to Revolving Loans.....................  37
     5.2.1.    Compliance with Warranties, No Default, etc.................  37
     5.2.2.    Borrowing Request...........................................  38
     5.2.3.    Satisfactory Legal Form.....................................  38
     5.3.      Conditions Precedent to the Making of the Term Loans........  38

                                       ii
<PAGE>
 
                               TABLE OF CONTENTS
                                  (CONTINUED)
                                                                            PAGE

VI   REPRESENTATIONS AND WARRANTIES........................................  38
     6.1.      Organization, etc...........................................  38
     6.2.      Due Authorization, Non-Contravention, etc...................  39
     6.3.      Government Approval, Regulation, etc........................  39
     6.4.      Validity, etc...............................................  39
     6.5.      Financial Information.......................................  39
     6.6.      No Material Adverse Change..................................  39
     6.7.      Litigation, Labor Controversies, etc........................  39
     6.8.      Subsidiaries................................................  40
     6.9.      Ownership of Properties.....................................  40
     6.10.     Taxes.......................................................  40
     6.11.     Pension and Welfare Plans...................................  40
     6.12.     Environmental Warranties....................................  40
     6.13.     Regulations  U and X........................................  41
     6.14.     Accuracy of Information.....................................  41
     6.15.     No Default..................................................  41
     6.16.     No Violation of Applicable Law..............................  42
     6.17.     Permits.....................................................  42
     6.18.     Year 2000 Matters...........................................  42

VII  COVENANTS.............................................................  43
     7.1.      Affirmative Covenants.......................................  43
     7.1.1.    Financial Information, Reports, Notices, etc................  43
     7.1.2.    Compliance with Laws, etc...................................  44
     7.1.3.    Maintenance of Properties...................................  44
     7.1.4.    Insurance...................................................  44
     7.1.5.    Books and Records...........................................  44
     7.1.6.    Environmental Covenant......................................  44
     7.1.7.    Employee Benefit Plans......................................  45
     7.1.8.    Designated Senior Indebtedness..............................  45
     7.2.      Negative Covenants..........................................  45
     7.2.1.    Business Activities.........................................  45
     7.2.2.    Indebtedness................................................  45
     7.2.3.    Liens.......................................................  46
     7.2.4.    Financial Condition.........................................  47
     7.2.5.    Take or Pay Contracts.......................................  47
     7.2.6.    Consolidation, Merger, etc..................................  47
     7.2.7.    Asset Dispositions, etc.....................................  47
     7.2.8.    Guaranties, Loans or Advances...............................  48
     7.2.9.    Other Agreements............................................  48
     7.2.10.   Transactions with Affiliates................................  48

                                      iii
<PAGE>
 
                               TABLE OF CONTENTS
                                  (CONTINUED)
                                                                            PAGE

     7.2.11.   Negative Pledges, Restrictive Agreements, etc...............  48
     7.2.12.   Investment in Subsidiaries..................................  49
     7.2.13.   Acquisition of Capital Stock................................  49

VIII EVENTS OF DEFAULT.....................................................  49
     8.1.      Listing of Events of Default................................  49
     8.1.1.    Non-Payment of Obligations..................................  50
     8.1.2.    Breach of Warranty..........................................  50
     8.1.3.    Non-Performance of Certain Covenants and Obligations........  50
     8.1.4.    Non-Performance of Other Covenants and Obligations..........  50
     8.1.5.    Default on Other Indebtedness...............................  50
     8.1.6.    Other Material Obligations..................................  50
     8.1.7.    Judgments...................................................  50
     8.1.8.    Pension Plans...............................................  51
     8.1.9.    Bankruptcy, Insolvency, etc.................................  51
     8.1.10.   Change of Control...........................................  51
     8.2.      Action if Bankruptcy........................................  51
     8.3.      Action if Other Event of Default............................  51


IX   THE AGENT.............................................................  52
     9.1.      Actions.....................................................  52
     9.2.      Funding Reliance, etc.......................................  52
     9.3.      Exculpation.................................................  53
     9.4.      Successor...................................................  53
     9.5.      Loans by Bank of Montreal...................................  53
     9.6.      Credit Decisions............................................  53
     9.7.      Copies, etc.................................................  54
     9.8.      Syndication Agent, Documentation Agent......................  54

                                       iv
<PAGE>
 
                               TABLE OF CONTENTS
                                  (CONTINUED)
                                                                            PAGE

X    MISCELLANEOUS PROVISIONS..............................................  54
     10.1.     Waivers, Amendments, etc....................................  54
     10.2.     Notices.....................................................  55
     10.3.     Payment of Costs and Expenses...............................  55
     10.4.     Indemnification.............................................  55
     10.5.     Survival....................................................  56
     10.6.     Severability................................................  56
     10.7.     Headings....................................................  56
     10.8.     Execution in Counterparts, Effectiveness, etc...............  56
     10.9.     Governing Law; Entire Agreement.............................  56
     10.10.    Successors and Assigns......................................  57
     10.11.    Sale and Transfer of Loans and Notes; Participations in
               Loans and Notes.............................................  57

     10.11.1.  Assignments.................................................  57
     10.11.2.  Participations..............................................  58
     10.11.3.  Pledges to Federal Reserve Banks............................  58
     10.12.    Other Transactions..........................................  59
     10.13.    Sale and Purchase of Loans..................................  59
     10.14.    Forum Selection and Consent to Jurisdiction.................  59
     10.15.    Waiver of Jury Trial........................................  60

                                       v
<PAGE>
 
SCHEDULE A   -    Bolivian Letter of Credit*
SCHEDULE I   -    Disclosure Schedule*
 
EXHIBIT A    -    Form of Note
EXHIBIT B    -    Form of Borrowing Request
EXHIBIT C    -    Form of Continuation/Conversion Notice
EXHIBIT D    -    Form of Lender Assignment Agreement
EXHIBIT E-1  -    Form of Opinion of Counsel to the Borrower*
EXHIBIT E-2  -    Form of Opinion of Counsel to the Borrower*
EXHIBIT F    -    Commitments*
EXHIBIT G    -    Form of Issuance Request
EXHIBIT H    -    Exxon Properties*
EXHIBIT I    -    Form of Notice of Commitment Increase
 
- --------------------
* Omitted. The Registrant agrees to furnish supplementally a copy of any such
  omitted schedules or exhibits to the Securities and Exchange Commission upon
  its request.

                                       vi
<PAGE>
 
          THIS AMENDED AND RESTATED CREDIT AGREEMENT, dated as of October 21,
1998, among VINTAGE PETROLEUM, INC., a Delaware corporation (the "Borrower"),
the various financial institutions as are or may become parties hereto
(collectively, the "Lenders"), NATIONSBANK,  N.A., as syndication agent, SOCIETE
GENERALE, SOUTHWEST AGENCY, as documentation agent, and BANK OF MONTREAL, acting
through certain of its U.S. branches or agencies ("Bank of Montreal"), as
administrative agent (the "Agent") for the Lenders.

                             W I T N E S S E T H:

          WHEREAS, the Borrower is engaged directly and through its various
Subsidiaries in the businesses of exploration for and production of oil and gas,
oil and gas gathering and marketing, and related activities; and

          WHEREAS, the Borrower, various financial institutions (the "Original
Lenders") and Bank of Montreal in its capacity as Agent, heretofore entered into
a Credit Agreement dated as of September 11, 1998 (such agreement, the "Original
Credit Agreement") pursuant to which the lenders party to the Original Credit
Agreement agreed to make loans (therein referred to as the "Original Loans") to,
and issue letters of credit for, the Borrower; and

          WHEREAS, the Borrower would like to obtain Commitments from the
Lenders pursuant to which Revolving Loans and Term Loans, in a maximum aggregate
principal amount at any one time outstanding not to exceed the amounts
hereinafter provided, will be made to the Borrower from time to time prior to
the applicable Commitment Termination Dates for such Commitments; and

          WHEREAS, the Lenders are willing, on the terms and subject to the
conditions hereinafter set forth (including Article V), to extend such
Commitments and make such Loans to, and issue Letters of Credit for, the
Borrower; and

          WHEREAS, the proceeds of such Loans and the Revolving Loan Letters of
Credit will be used (a) for acquisitions of oil and gas properties, gathering
systems and related assets; and (b) for general corporate purposes and working
capital purposes of the Borrower and its Subsidiaries and the Bolivian Letter of
Credit will be used to comply with certain Bolivian requirements; and

          WHEREAS, certain financial institutions not previously a party to the
Original Credit Agreement intend to become a party to the credit facilities
extended to the Borrower as more fully described in the next succeeding
paragraph; and

          WHEREAS, the Borrower has requested that the Lenders, and the Lenders
have agreed to, restructure, rearrange, renew, extend and refinance all
indebtedness evidenced by and outstanding under the Original Credit Agreement as
of the Effective Date (the "Prior Indebtedness") into obligations and
commitments hereunder; and

                                       1
<PAGE>
 
          WHEREAS, as part of the restructuring and rearranging of the Prior
Indebtedness, the Lenders shall modify their respective commitments under the
Original Credit Agreement such that on the Effective Date each Lender shall be
obligated hereunder, subject to the terms hereof, to the Commitment stated on
Exhibit F for such Lender; and

          WHEREAS, any loans outstanding under the Original Credit Agreement on
the Effective Date shall be deemed continued as Loans under this Agreement, any
loans outstanding under the Original Credit Agreement, on the Effective Date,
bearing interest at a LIBO Rate (as defined therein) shall be deemed continued
as Loans under this Agreement at such LIBO Rate and for the Interest Period with
respect thereto under the Original Credit Agreement and any letters of credit
outstanding under the Original Credit Agreement on the Effective Date shall be
deemed continued as Revolving Loan Letters of Credit and the Bolivian Letter of
Credit, as the case may be, under this Agreement; and

          WHEREAS, the Borrower, the Lenders, and the Agent intend to amend and
restate the Original Credit Agreement in its entirety as hereinafter set forth;
and

          WHEREAS, the parties hereto intend that on the Effective Date hereof
pursuant to Article V, (1) the Commitments, outstanding Notes, and Loans under
the Original Credit Agreement shall become Commitments, Notes, and Loans,
respectively, hereunder, (2) interest accrued on the Loans and Commitment fees
accrued under the Original Credit Agreement through the Effective Date hereof
shall be deemed due and payable hereunder and (3) the Lenders hereunder shall be
deemed to have purchased participations in the outstanding Letters of Credit,
pro rata according to their respective Percentages.

          NOW, THEREFORE, in consideration of the premises and mutual covenants
herein contained the parties hereto hereby agree as follows:


                                  ARTICLE  I

                       DEFINITIONS AND ACCOUNTING TERMS


     SECTION 1.1    Defined Terms.  The following terms (whether or not
underscored) when used in this Agreement, including its preamble and recitals,
shall, except where the context otherwise requires, have the following meanings
(such meanings to be equally applicable to the singular and plural forms
thereof):

     "Acquisition" means any transaction, or any series of related transactions,
consummated after the date of this Agreement, by which the Borrower or any of
the Subsidiaries (i) acquires any going business or all or substantially all of
the assets of any firm, corporation or division thereof, whether through
purchase of assets or otherwise or (ii) directly or indirectly acquires (in one
transaction or as the most recent transaction in a series of transactions) at
least a controlling interest of the ownership of a Person.

                                       2
<PAGE>
 
     "Affiliate" of any Person means any other Person which, directly or
indirectly, controls, is controlled by or is under common control with such
Person (excluding any trustee under, or any committee with responsibility for
administering, any Plan).  A Person shall be deemed to be "controlled by" any
other Person if such other Person possesses, directly or indirectly, power (a)
to vote 10% or more of the securities (on a fully diluted basis) having ordinary
voting power for the election of directors or managing general partners; or (b)
to direct or cause the direction of the management and policies of such Person
whether by contract or otherwise.

     "Agent" is defined in the preamble and includes each other Person as shall
have subsequently been appointed as the successor Agent pursuant to Section 9.4.

     "Agreement" means, on any date, this Amended and Restated Credit Agreement
as originally in effect on the Effective Date and as thereafter from time to
time amended, supplemented, amended and restated, or otherwise modified and in
effect on such date.

     "Alternate Base Rate" means, on any date and with respect to all Base Rate
Loans, a fluctuating rate of interest per annum equal to the higher of (a) the
rate of interest most recently announced by Bank of Montreal at its Domestic
Office as its base rate for Dollar loans made in the United States; and (b) the
Federal Funds Rate most recently determined by the Agent plus  1/2%.  The
Alternate Base Rate is not necessarily intended to be the lowest rate of
interest determined by Bank of Montreal in connection with extensions of credit.
Changes in the rate of interest on that portion of any Loans maintained as Base
Rate Loans will take effect simultaneously with each change in the Alternate
Base Rate.  The Agent will give notice promptly to the Borrower and the Lenders
of changes in the Alternate Base Rate.

     "Applicable Lenders" means Lenders (including the Agent) with an aggregate
Percentage of at least 100% for increases in the Borrowing Base and 75% for all
other Borrowing Base determinations.

     "Assignee Lender" is defined in Section 10.11.1.

     "Authorized Officer" means, relative to the Borrower, those of its officers
whose signatures and incumbency shall have been certified to the Agent and the
Lenders pursuant to Section 5.1.1.

     "Bank of Montreal" is defined in the preamble.

     "Base Rate Applicable Margin" means (a) on any date for which it is
determined and on which the outstanding principal balance of Senior Debt,
including any Term Loans, shall be less than or equal to the Borrowing Base then
in effect, zero percent (0%); and (b) on any date on which the outstanding
principal balance of Senior Debt, including all Loans, exceeds the Borrowing
Base then in effect, one-quarter of one percent (.250%).

     "Base Rate Loan" means a Loan bearing interest at a fluctuating rate
determined by reference to the Alternate Base Rate.

                                       3
<PAGE>
 
     "Bolivian Letter of Credit" means Bank of Montreal's letter of credit
number SLCDC3896/912399 dated December 8, 1997, a copy of which is attached as
Schedule A hereto.

     "Bolivian Letter of Credit Outstandings" means, at any time, an amount
equal to the face amount at such time of the Bolivian Letter of Credit then
outstanding and undrawn (as such face amount shall be adjusted from time to
time, as a result of drawings, or otherwise) plus (b) the then aggregate amount
of all unpaid and outstanding Reimbursement Obligations relating to the Bolivian
Letter of Credit.

     "Borrower" is defined in the preamble.

     "Borrowing" means (i) the Loans of the same type and, in the case of LIBO
Rate Loans, having the same Interest Period made by all Lenders on the same
Business Day and pursuant to the same Borrowing Request in accordance with
Section 2.1 and (ii) Letters of Credit issued pursuant to Section 2.1.3 or
Section 2.1.4.

     "Borrowing Base" is defined in Section 2.7.1.

     "Borrowing Request" means a loan request and certificate duly executed by
an Authorized Officer of the Borrower, substantially in the form of Exhibit B
hereto.

     "Business Day" means (a) any day which is neither a Saturday or Sunday nor
a legal holiday on which banks are authorized or required to be closed in
Chicago, Illinois; and (b) relative to the making, continuing, prepaying or
repaying of any LIBO Rate Loans, any day described in clause (a) which is also a
day on which dealings in Dollars are carried on in the London interbank market.

     "Cadipsa" means Cadipsa S.A., a Republic of Argentina corporation.

     "Capital Stock" in any Person means, for purposes of the definitions of
"Voting Stock" and "Change of Control," any and all shares, interests,
participations or other equivalents in the equity interest (however designated)
in such Person and any rights (other than debt securities convertible into an
equity interest), warrants or options to subscribe for or to acquire an equity
interest in such Person; provided that Capital Stock of such Person shall not
include any equity security of such Person that by its terms (or by the terms of
any security into which it is convertible or for which it is exchangeable) or
otherwise (including upon the happening of any event), is or could become
required to be redeemed for cash or other property or is or could become
redeemable for cash or other property at the option of the holder thereof, in
whole or in part, or is or could become exchangeable at the option of the holder
thereof for Indebtedness at any time, in whole or in part, in each case on or
prior to the first anniversary of the Stated Maturity (as defined in the
Indenture) for the payment of principal of the Subordinated Debt permitted by
clause (p) of Section 7.2.2, but "Capital Stock" shall not exclude any equity
security by virtue of the fact that it may be converted or exchanged at the
option of the holder for Capital Stock of the Borrower having no preference as
to dividends or liquidation over any other Capital Stock of the Borrower.

     "Capitalized Lease Liabilities" means all monetary obligations of the
Borrower or any of its Subsidiaries under any leasing or similar arrangement
which, in accordance with GAAP, would be 

                                       4
<PAGE>
 
classified as capitalized leases, and, for purposes of this Agreement and each
other Loan Document, the amount of such obligations shall be the capitalized
amount thereof, determined in accordance with GAAP, and the stated maturity
thereof shall be the date of the last payment of rent or any other amount due
under such lease prior to the first date upon which such lease may be terminated
by the lessee without payment of a penalty.

     "CERCLA" means the Comprehensive Environmental Response, Compensation and
Liability Act of 1980, as amended.

     "CERCLIS" means the Comprehensive Environmental Response Compensation
Liability Information System List.

     "Change of Control" means the occurrence of any of the following events:
(i) any "person" or "group" (within the meaning of Sections 13(d)(3) and
14(d)(2) of the Exchange Act or any successor provision to either of the
foregoing, including any group acting for the purpose of acquiring, holding or
disposing of securities within the meaning of Rule 13d-5(b)(1) under the
Exchange Act), other than any one or more of the Permitted Holders, becomes the
"beneficial owner" (as defined in Rule 13d-3 under the Exchange Act) of 50% or
more of the total voting power of all classes of the Voting Stock of the
Borrower and/or warrants or options to acquire such Voting Stock, calculated on
a fully diluted basis, (ii) the sale, lease, conveyance or transfer of all or
substantially all of the assets of the Borrower (other than to any Restricted
Subsidiary which is wholly-owned by the Borrower or another wholly-owned
Restricted Subsidiary) shall have occurred, (iii) the stockholders of the
Borrower shall have approved any plan of liquidation or dissolution of the
Borrower, (iv) the Borrower consolidates with or merges into another Person or
any Person consolidates with or merges into the Borrower in any such event
pursuant to a transaction in which the outstanding Voting Stock of the Borrower
is reclassified into or exchanged for cash, securities or other property, other
than any such transaction where (A) the outstanding Voting Stock of the Borrower
is reclassified into or exchanged for Voting Stock of the surviving corporation
that is Capital Stock and (B) the holders of the Voting Stock of the Borrower
immediately prior to such transaction own, directly or indirectly, not less than
a majority of the Voting Stock of the surviving corporation immediately after
such transaction in substantially the same proportion as before the transaction,
or (v) during any period of two consecutive years, individuals who at the
beginning of such period constituted the Borrower's Board of Directors (together
with any new directors whose election or appointment by such board or whose
nomination for election by the stockholders of the Borrower was approved by a
vote of a majority of the directors then still in office who were either
directors at the beginning of such period or whose election or nomination for
election was previously so approved) cease for any reason to constitute a
majority of the Borrower's Board of Directors then in office.  For purposes of
this definition, a wholly-owned Subsidiary means any Subsidiary all of the
Voting Stock of which (except for director's qualifying shares) is owned
directly or indirectly by the Borrower and its other wholly-owned Subsidiaries.
Nothing set forth in this definition shall be construed to permit any
transaction which is prohibited by this Agreement, including any transaction not
permitted by Section 7.2.6.

     "Code" means the Internal Revenue Code of 1986, as amended, reformed or
otherwise modified from time to time.

                                       5
<PAGE>
 
     "Commitment" means, as the context may require, a Lender's Revolving Loan
Commitment or Term Loan Commitment.

     "Commitment Amount" means, as the context may require, either the Revolving
Period Commitment Amount or the Term Period Commitment Amount.

     "Commitment Increase Effective Date" is defined in Section 2.1.6.

     "Commitment Termination Date" means, as the context may require, either the
Revolving Period Commitment Termination Date or the Term Period Commitment
Termination Date.

     "Commitment Termination Event" means (a) the occurrence of any Default
described in clauses (a) through (d) of Section 8.1.9 with respect to the
Borrower or any of its Subsidiaries; or (b) the occurrence and continuance of
any other Event of Default and either (i) the declaration of the Loans to be due
and payable pursuant to Section 8.3 or the demand by an Issuer that the Borrower
deliver cash collateral pursuant to Section 2.8.7, or (ii) in the absence of
such declaration or demand, the giving of notice by the Agent, acting at the
direction of the Required Lenders, to the Borrower that the Commitments have
been terminated.

     "Contingent Liability" means any agreement, undertaking or arrangement by
which any Person guarantees, endorses or otherwise becomes or is contingently
liable upon (by direct or indirect agreement, contingent or otherwise, to
provide funds for payment, to supply funds to, or otherwise to invest in, a
debtor, or otherwise to assure a creditor against loss) the indebtedness,
obligation or any other liability of any other Person (other than by
endorsements of instruments in the course of collection), or guarantees the
payment of dividends or other distributions upon the shares of any other Person.
The amount of any Person's obligation under any Contingent Liability shall
(subject to any limitation set forth therein) be deemed to be the outstanding
principal amount (or maximum principal amount, if larger) of the debt,
obligation or other liability guaranteed thereby.

     "Continuation/Conversion Notice" means a notice of continuation or
conversion and certificate duly executed by an Authorized Officer of the
Borrower, substantially in the form of Exhibit C hereto.

     "Controlled Group" means all members of a controlled group of corporations
and all members of a controlled group of trades or businesses (whether or not
incorporated) under common control which, together with the Borrower, are
treated as a single employer under Section 414(b) or 414(c) of the Code or
Section 4001 of ERISA.

     "Current Ratio" means the ratio of (a) consolidated current assets of the
Borrower and its Subsidiaries to (b) consolidated current liabilities (excluding
the current portion of Senior Debt) of the Borrower and its Subsidiaries.  For
purposes of the definition of "Current Ratio", any unused portion of the
Revolving Period Commitment Amount is deemed to be a current asset of the
Borrower.

     "Default" means any Event of Default or any condition, occurrence or event
which, after notice or lapse of time or both, would constitute an Event of
Default.

                                       6
<PAGE>
 
     "Disbursement" is defined in Section 2.8.5.

     "Disbursement Date" is defined in Section 2.8.5.

     "Disclosure Schedule" means the Disclosure Schedule attached hereto as
Schedule I, as it may be amended, supplemented or otherwise modified from time
to time by the Borrower with the written consent of the Agent and the Required
Lenders.

     "Documentary Letter of Credit" means a letter of credit which is a short
term, self-liquidating trade-related contingency.

     "Dollar" and the sign "$" mean lawful money of the United States.

     "Domestic Office" means, relative to any Lender, the office of such Lender
designated as such below its signature hereto or designated in the Lender
Assignment Agreement, or such other office of a Lender (or any successor or
assign of such Lender) within the United States as may be designated from time
to time by notice from such Lender, as the case may be, to each other Person
party hereto.

     "Effective Date" means the date this Agreement becomes effective pursuant
to Section 10.8.

     "Environmental Laws" means all applicable Argentina, U.S. federal, or state
or local statutes, laws, ordinances, codes, rules and regulations (including
consent decrees and administrative orders) relating to public health and safety
and protection of the environment.

     "ERISA" means the Employee Retirement Income Security Act of 1974, as
amended, and any successor statute of similar import, together with the
regulations thereunder, in each case as in effect from time to time.  References
to sections of ERISA also refer to any successor sections.

     "Event of Default" is defined in Section 8.1.

     "Exchange Act" means the United States Securities Exchange Act of 1934 and
any successor statute thereto, in each case as amended from time to time.

     "Federal Funds Rate" means, for any period, a fluctuating interest rate per
annum equal for each day during such period to (a) the weighted average of the
rates on overnight federal funds transactions with members of the Federal
Reserve System arranged by federal funds brokers, as published for such day (or,
if such day is not a Business Day, for the next preceding Business Day) by the
Federal Reserve Bank of New York; or (b) if such rate is not so published for
any day which is a Business Day, the average of the quotations for such day on
such transactions received by Bank of Montreal from three federal funds brokers
of recognized standing selected by it.

     "Fiscal Quarter" means any quarter of a Fiscal Year.

                                       7
<PAGE>
 
     "Fiscal Year" means any period of twelve consecutive calendar months ending
on December 31st; references to a Fiscal Year with a number corresponding to any
calendar year (e.g., the "1998 Fiscal Year") refer to the Fiscal Year ending on
December 31st, occurring during such calendar year.

     "F.R.S. Board" means the Board of Governors of the Federal Reserve System
or any successor thereto.

     "GAAP" is defined in Section 1.4.

     "Hazardous Material" means (a) any "hazardous substance", as defined by
CERCLA; (b) any "hazardous waste", as defined by the Resource Conservation and
Recovery Act, as amended; (c) any petroleum product; or (d) any pollutant or
contaminant or hazardous, dangerous or toxic chemical, material or substance
within the meaning of any other applicable Argentina, U.S. federal, or state or
local law, regulation, ordinance or requirement (including consent decrees and
administrative orders) relating to or imposing liability or standards of conduct
concerning any hazardous, toxic or dangerous waste, substance or material, all
as amended or hereafter amended.

     "Hedging Obligations" means, with respect to any Person, all liabilities of
such Person under interest rate swap agreements, interest rate cap agreements
and interest rate collar agreements, and all other agreements or arrangements
designed to protect such Person against fluctuations in interest rates, currency
exchange rates or commodity prices.

     "herein", "hereof", "hereto", "hereunder" and similar terms contained in
this Agreement or any other Loan Document refer to this Agreement or such other
Loan Document, as the case may be, as a whole and not to any particular Section,
paragraph or provision of this Agreement or such other Loan Document.

     "Impermissible Qualification" means, relative to the opinion or
certification of any independent public accountant as to any financial statement
of the Borrower, any qualification or exception to such opinion or certification
(a) which is of a "going concern" or similar nature; (b) which relates to the
limited scope of examination of matters relevant to such financial statement; or
(c) which relates to the treatment or classification of any item in such
financial statement and which, as a condition to its removal, would require an
adjustment to such item the effect of which would be to cause the Borrower to be
in default of any of its obligations under Section 7.2.4.

     "including" means including without limiting the generality of any
description preceding such term, and, for purposes of this Agreement and each
other Loan Document, the parties hereto agree that the rule of ejusdem generis
shall not be applicable to limit a general statement, which is followed by or
referable to an enumeration of specific matters, to matters similar to the
matters specifically mentioned.

     "Increasing Lender" is defined in Section 2.1.6.

     "Indebtedness" of any Person means, without duplication:  (a) all
obligations of such Person for borrowed money and all obligations of such Person
evidenced by bonds, debentures, notes or other similar instruments; (b) all
obligations, contingent or otherwise, relative to the face amount of 

                                       8
<PAGE>
 
all letters of credit, whether or not drawn, and banker's acceptances issued for
the account of such Person; (c) all obligations of such Person as lessee under
leases which have been or should be, in accordance with GAAP, recorded as
Capitalized Lease Liabilities; (d) all other items which, in accordance with
GAAP, would be included as liabilities on the liability side of the balance
sheet of such Person as of the date at which Indebtedness is to be determined;
(e) net liabilities of such Person under all Hedging Obligations; (f) whether or
not so included as liabilities in accordance with GAAP, all obligations of such
Person to pay the deferred purchase price of property or services, and
indebtedness (excluding prepaid interest thereon) secured by a Lien on property
owned or being purchased by such Person (including indebtedness arising under
conditional sales or other title retention agreements), whether or not such
indebtedness shall have been assumed by such Person or is limited in recourse;
and (g) all Contingent Liabilities of such Person in respect of any of the
foregoing. For all purposes of this Agreement, the Indebtedness of any Person
shall include the Indebtedness of any partnership or joint venture in which such
Person is a general partner or a joint venturer.

     "Indemnified Liabilities" is defined in Section 10.4.

     "Indemnified Parties" is defined in Section 10.4.

     "Indenture" means that certain Indenture of the Borrower to The Chase
Manhattan Bank (formerly Chemical Bank) as Trustee entered into with respect to
the Subordinated Debt permitted by clause (p) of Section 7.2.2, as such
Indenture may from time to time be amended, supplemented or otherwise modified.

     "Interest Period" means, relative to any LIBO Rate Loans, the period
beginning on (and including) the date on which such LIBO Rate Loan is made or
continued as, or converted into, a LIBO Rate Loan pursuant to Section 2.3 or 2.4
and shall end on (but exclude) the day which numerically corresponds to such
date one, two, three or six months thereafter (or, if such month has no
numerically corresponding day, on the last Business Day of such month), in
either case as the Borrower may select in its relevant notice pursuant to
Section 2.3 or 2.4; provided, however, that (a) the Borrower shall not be
permitted to select Interest Periods to be in effect at any one time which have
expiration dates occurring on more than five different dates; (b) Interest
Periods commencing on the same date for Loans comprising part of the same
Borrowing shall be of the same duration; (c) if such Interest Period would
otherwise end on a day which is not a Business Day, such Interest Period shall
end on the next following Business Day (unless such next following Business Day
is the first Business Day of a calendar month, in which case such Interest
Period shall end on the Business Day next preceding such numerically
corresponding day); and (d) no Interest Period for a Revolving Loan may end
later than the date six months after the Revolving Period Commitment Termination
Date, and no Interest Period for a Term Loan may end after the Stated Maturity
Date for Term Loans.

     "Issuance Request" means a request and certificate duly executed by the
chief executive, accounting, or financial Authorized Officer of the Borrower,
substantially in the form of Exhibit G attached hereto (with such changes
thereto as may be agreed from time to time by the Agent and the Borrower).

                                       9
<PAGE>
 
     "Issuer" means any affiliate, unit or agency of Bank of Montreal or any
other Lender which has agreed to issue one or more Letters of Credit at the
request of the Borrower.

     "Lender Assignment Agreement" means a Lender Assignment Agreement
substantially in the form of Exhibit D hereto.

     "Lenders" is defined in the preamble.

     "Letter of Credit" means a Revolving Loan Letter of Credit or the Bolivian
Letter of Credit or both, as the case may be.

     "Letter of Credit Collateral Account" is defined in Section 2.8.10.

     "Letter of Credit Commitment" means, relative to any Lender, such Lender's
obligation to issue (in the case of an Issuer) or participate in (in the case of
all Lenders) Letters of Credit pursuant to Section 2.1.3 or Section 2.1.4.

     "Letter of Credit Outstandings" means the Revolving Loan Letter of Credit
Outstandings, the Bolivian Letter of Credit Outstandings, or both, as the case
may be.

     "LIBO Rate" is defined in Section 3.2.1.

     "LIBO Rate Applicable Margin" means (a) on any date for which it is
determined prior to the Revolving Period Commitment Termination Date and on
which the ratio (expressed as a percentage) of the outstanding principal of
Senior Debt, including any Revolving Loans outstanding, to the Borrowing Base
then in effect shall equal those ratios set forth below, the percentage set
forth opposite such ratio:

         Ratio of Senior Debt                        LIBO Rate
          to Borrowing Base                      Applicable Margin
     --------------------------                  -----------------

     Greater than 95%                                  1.500%
                                                     
     Greater than 75% and less than or               
       equal to 95%                                    1.250%
                                                     
     Greater than 60% and less than or               
       equal to 75%                                    1.000%
                                                     
     Greater than 40% and less than or               
       equal to 60%                                     .750%
                                                     
     Less than or equal to 40%                          .625%

(b) on any date for which it is determined on or after the Revolving Period
Commitment Termination Date and on which the outstanding principal balance of
Senior Debt, including any Term Loans, shall 

                                       10
<PAGE>
 
be less than or equal to the Borrowing Base then in effect, one and one-half of
one percent (1.500%); and (c) on any date on which the aggregate outstanding
principal balance of Senior Debt, including all Loans, exceeds the Borrowing
Base then in effect, one and three-quarters of one percent (1.750%). Changes in
the LIBO Rate Applicable Margin shall occur automatically with a change in such
ratio of the Senior Debt to the Borrowing Base.

     "LIBO Rate Loan" means a Loan bearing interest, at all times during an
Interest Period applicable to such Loan, at a fixed rate of interest determined
by reference to the LIBO Rate (Reserve Adjusted).

     "LIBO Rate (Reserve Adjusted)" is defined in Section 3.2.1.

     "LIBOR Office" means, relative to any Lender, the office of such Lender
designated as such below its signature hereto or designated in the Lender
Assignment Agreement or such other office of a Lender as designated from time to
time by notice from such Lender to the Borrower and the Agent, whether or not
outside the United States, which shall be making or maintaining LIBO Rate Loans
of such Lender hereunder.

     "LIBOR Reserve Percentage" is defined in Section 3.2.1.

     "Lien" means any security interest, mortgage, pledge, hypothecation,
assignment, deposit arrangement, encumbrance, lien (statutory or otherwise),
charge against or interest in property to secure payment of a debt or
performance of an obligation or other priority or preferential arrangement of
any kind or nature whatsoever.

     "Loan" means, as the context may require, either a Revolving Loan or a Term
Loan of either type; notwithstanding the foregoing, Loan does not include
participations in Letters of Credit, except to the extent that a Loan is deemed
made pursuant to Section 2.8.

     "Loan Document" means this Agreement, the Notes, each Issuance Request and
each other document or instrument executed and delivered in connection with this
Agreement, the Notes and the Letters of Credit.

     "Maximum Commitment Amount" means an amount equal to $575,000,000 as such
amount may be increased pursuant to Section 2.1.6.

     "New Funds Amount" means the amount by which a New Lender's or an
Increasing Lender's outstanding Revolving Loans increase as of a Commitment
Increase Effective Date (without regard to any such increase as a result of
Revolving Loans made on such Commitment Increase Effective Date).

     "New Lender" is defined in Section 2.1.6.

     "Non-Recourse Indebtedness" shall mean any Indebtedness of the Borrower and
its Subsidiaries with respect to which the holder thereof agrees that (i) the
Borrower and its Subsidiaries are not personally liable and (ii) such holder may
require payment only to the extent specifically 

                                       11
<PAGE>
 
identified properties of the Borrower and its Subsidiaries are available to
provide therefor, such matters to be set forth in an agreement or other
instrument in form and substance reasonably satisfactory to the Required
Lenders, and shall include such Indebtedness of partnerships and joint ventures
with respect to which the Borrower or any of its Subsidiaries is a partner or
joint venturer which is identified in Item 7.2.2(c) ("Ongoing Indebtedness") of
the Disclosure Schedule.

     "Note" means a promissory note of the Borrower payable to any Lender, in
the form of Exhibit A hereto (as such promissory note may be amended, endorsed
or otherwise modified from time to time), evidencing the aggregate Indebtedness
of the Borrower to such Lender resulting from outstanding Loans, and also means
all other promissory notes accepted from time to time in substitution therefor
or renewal thereof.

     "Notice of Commitment Increase" is defined in Section 2.1.6.

     "Obligations" means all obligations (monetary or otherwise) of the Borrower
arising under or in connection with this Agreement, the Notes, the Letters of
Credit and each other Loan Document.

     "Oil and Gas Properties" means oil, gas and other liquid or gaseous
hydrocarbon properties and interests of the Borrower and its Subsidiaries,
whether now owned or hereafter acquired.

     "Organic Document" means, relative to the Borrower, its certificate of
incorporation, its by-laws and all shareholder agreements, voting trusts and
similar arrangements applicable to any of its authorized shares of capital
stock.

     "Original Credit Agreement" is defined in the second recital.

     "Original Lenders" is defined in the second recital.

     "Original Loans" is defined in the second recital.

     "Other Letter of Credit" means a Documentary Letter of Credit or a Standby
Letter of Credit or similar instrument for which the Borrower or one or more of
its Subsidiaries is liable and which is not issued pursuant to this Agreement.

     "Partially Increasing Lenders" is defined in Section 2.1.6.

     "Participant" is defined in Section 10.11.2.

     "PBGC" means the Pension Benefit Guaranty Corporation and any entity
succeeding to any or all of its functions under ERISA.

     "Pension Plan" means a "pension plan", as such term is defined  in section
3(2) of ERISA, which is subject to Title IV of ERISA (other than a multiemployer
plan as defined in section 4001(a)(3) of ERISA), and to which the Borrower or
any corporation, trade or business that is, along with the Borrower, a member of
a Controlled Group, may have liability, including any liability by 

                                       12
<PAGE>
 
reason of having been a substantial employer within the meaning of section 4063
of ERISA at any time during the preceding five years, or by reason of being
deemed to be a contributing sponsor under section 4069 of ERISA.

     "Percentage" means, relative to any Lender, the percentage set forth
opposite the name of such Lender in Exhibit F to this Agreement as such
percentage may be adjusted from time to time pursuant to Lender Assignment
Agreements executed by a Lender and its Assignee Lenders and delivered pursuant
to Section 10.11 or as a result of an increase of the Maximum Commitment Amount
as provided in Section 2.1.6.

     "Permitted Designee" means (i) a spouse or a child of a Permitted Holder,
(ii) trusts for the benefit of a Permitted Holder or a spouse or child of a
Permitted Holder, (iii) in the event of the death or incompetence of a Permitted
Holder, his estate, heirs, executor, administrator, committee or other personal
representative, or (iv) any Person so long as a Permitted Holder owns at least
51% of the voting power of all classes of the Voting Stock of such Person.

     "Permitted Holders" means Charles C. Stephenson, Jr., Jo Bob Hille, S.
Craig George, William C. Barnes and their Permitted Designees.

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

     "Plan" means any Pension Plan or Welfare Plan.

     "Prior Indebtedness" is defined in the seventh recital.

     "Quarterly Payment Date" means the first day of each March, June, September
and December or, if any such day is not a Business Day, the next succeeding
Business Day.

     "Reducing Lender" is defined in Section 2.1.6.

     "Reduction Amount" means the amount by which a Reducing Lender's or a
Partially Increasing Lender's outstanding Revolving Loans decrease as of a
Commitment Increase Effective Date (without regard to any such increase as a
result of Revolving Loans made on such Commitment Increase Effective Date).

     "Reimbursement Obligations" is defined in Section 2.8.6.

     "Release" means a "release", as such term is defined in CERCLA.

     "Required Lenders" means, at any time, Lenders (including the Agent)
holding at least 66-2/3% of the then aggregate outstanding principal amount of
the Notes then held by the Lenders, or, if no such principal amount is then
outstanding, Lenders (including the Agent) having at least 66-2/3% of the
Commitments.

                                       13
<PAGE>
 
     "Resource Conservation and Recovery Act" means the Resource Conservation
and Recovery Act, 42 U.S.C. Section 6901, et seq., as in effect from time to
time.

     "Restricted Subsidiary" means any Subsidiary of the Borrower that has not
been designated an "Unrestricted Subsidiary" pursuant to the Indenture.

     "Revolving Loan" is defined in Section 2.1.1.

     "Revolving Loan Commitment" is defined in Section 2.1.1.

     "Revolving Loan Letter of Credit" means a Standby Letter of Credit (other
than the Bolivian Letter of Credit) or a Documentary Letter of Credit in such
form as may be mutually agreed upon by Borrower and the applicable Issuer and
issued pursuant to Section 2.1.3.

     "Revolving Loan Letter of Credit Applicable Margin" means (a) on any date
for which it is determined prior to the Revolving Period Commitment Termination
Date and on which the ratio (expressed as a percentage) of the outstanding
principal of Senior Debt, including any Revolving Loans outstanding, to the
Borrowing Base then in effect shall equal those ratios set forth below, the
percentage set forth opposite such ratio:

       Ratio of Senior Debt                     Letter of Credit 
        to Borrowing Base                       Applicable Margin
    --------------------------                  ----------------- 

     Greater than 95%                                 1.500%
                                                      
     Greater than 75% and less than or                
       equal to 95%                                   1.250%
                                                      
     Greater than 60% and less than or                
       equal to 75%                                   1.000%
                                                      
     Greater than 40% and less than or                
       equal to 60%                                    .750%
                                                      
     Less than or equal to 40%                         .625%

(b) on any date for which it is determined on or after the Revolving Period
Commitment Termination Date and on which the outstanding principal balance of
Senior Debt, including any Term Loans, shall be less than or equal to the
Borrowing Base then in effect, one and one-half of one percent (1.500%); and (c)
on any date on which the aggregate outstanding principal balance of Senior Debt,
including all Loans, exceeds the Borrowing Base then in effect, one and three-
quarters of one percent (1.750%).  Changes in the Revolving Loan Letter of
Credit Applicable Margin shall occur automatically with a change in such ratio
of the Senior Debt to the Borrowing Base.

     "Revolving Loan Letter of Credit Outstandings" means, at any time, an
amount equal to the sum of (a) the aggregate face amount at such time of all
Revolving Loan Letters of Credit then 

                                       14
<PAGE>
 
outstanding and undrawn (as such aggregate face amount shall be adjusted, from
time to time, as a result of drawings, the issuance of Revolving Loan Letters of
Credit, or otherwise), plus (b) the then aggregate amount of all unpaid and
outstanding Reimbursement Obligations relating to Revolving Loan Letters of
Credit.

     "Revolving Loan Letter of Credit Sublimit" is defined in Section 2.8.3.

     "Revolving Period Commitment Amount" means, on any date, the lowest of (i)
the Borrowing Base then in effect, (ii) the Maximum Commitment Amount, as such
amount may be reduced from time to time pursuant to Section 2.2 or increased
pursuant to Section 2.1.6 and (iii) the amount (not less than the then
outstanding principal amount of the Loans) from time to time designated by the
Borrower in writing to the Agent provided that if the Borrower has reduced the
Maximum Commitment Amount pursuant to Section 2.2.1 or has designated pursuant
to this clause (iii) a Revolving Period Commitment Amount which is less than the
amount provided by the lesser of the amount permitted pursuant to the foregoing
clause (i) or clause (ii), then the Borrower will not designate an amount
pursuant to this clause (iii) which is an increase over the then Revolving
Period Commitment Amount without the consent of all of the Lenders except to the
extent of any increase of the Maximum Commitment Amount pursuant to Section
2.1.6.

     "Revolving Period Commitment Termination Date" means the earliest of (a)
September 11, 2001; (b) the date on which the Revolving Period Commitment Amount
is terminated in full or reduced to zero pursuant to Section 2.2; and (c) the
date on which any Commitment Termination Event occurs.  Upon the occurrence of
any event described in clause (b) or (c), the Revolving Loan Commitments shall
terminate automatically and without any further action.

     "Senior Debt" means all Indebtedness for borrowed money (including the
Loans under this Agreement) and all obligations, contingent or otherwise,
relative to the face amount of all Letters of Credit and Other Letters of
Credit, whether or not drawn, of the Borrower and its Subsidiaries other than
Subordinated Debt, Non-Recourse Indebtedness, Bolivian Letter of Credit,
Indebtedness of any Subject Subsidiary and any Contingent Liability of the
Borrower (other than for borrowed money) permitted by clause (n) of Section
7.2.2.

     "Standby Letter of Credit" means a letter of credit (other than a
Documentary Letter of Credit).

     "Stated Amount" of each Letter of Credit and each Other Letter of Credit
means, on any date for which it is determined, the face amount of such Letter of
Credit or Other Letter of Credit as is in effect on such date.

     "Stated Expiry Date" is defined in Section 2.8.1.

     "Stated Maturity Date" means (a) in the case of any Revolving Loan,
September 11, 2001; and (b) in the case of any Term Loan, September 11, 2003.

                                       15
<PAGE>
 
     "Subject Subsidiary" means Cadipsa, or any Subsidiary designated by the
Borrower and approved by Lenders with an aggregate Percentage of at least 75%;
such Subsidiaries are sometimes collectively called herein the "Subject
Subsidiaries."

     "Subordinated Debt" means all unsecured Indebtedness of the Borrower for
money borrowed which is subordinated, upon terms satisfactory to the Agent and
the Required Lenders, in right of payment to the payment in full in cash of all
Obligations, and includes Borrower's $150,000,000 Senior Subordinated Notes Due
2005 and Borrower's $100,000,000 Senior Subordinated Notes Due 2009.

     "Subsidiary" means, with respect to any Person, any corporation of which
more than 50% of the outstanding capital stock having ordinary voting power to
elect a majority of the board of directors of such corporation (irrespective of
whether at the time capital stock of any other class or classes of such
corporation shall or might have voting power upon the occurrence of any
contingency) is at the time directly or indirectly owned by such Person, by such
Person and one or more other Subsidiaries of such Person, or by one or more
other Subsidiaries of such Person provided that, notwithstanding the foregoing,
Subsidiaries of the Borrower shall not include, for the purposes of Article VI
(except Sections 6.7 and 6.8), Section 7.1 (except for the purposes of
consolidated financial statements delivered pursuant to Section 7.1.1) and
Article VIII and the definitions referred to therein, the Subject Subsidiaries.

     "Tangible Net Worth" means the consolidated net worth of the Borrower and
its Subsidiaries after subtracting therefrom the aggregate amount of any
intangible assets of the Borrower and its Subsidiaries, including goodwill,
franchises, licenses, patents, trademarks, trade names, copyrights, service
marks and brand names.

     "Taxes" is defined in Section 4.6.

     "Term Loan" is defined in Section 2.1.2.

     "Term Loan Commitment" is defined in Section 2.1.2.

     "Term Period Commitment Amount" means the least of (i) the aggregate
principal amount of all Revolving Loans outstanding to all Lenders plus all
Revolving Loan Letter of Credit Outstandings as of the Revolving Period
Commitment Termination Date, (ii) the Commitment Amount in effect with respect
to Revolving Loans plus all Revolving Loan Letter of Credit Outstandings as of
the Revolving Period Commitment Termination Date, or (iii) the Borrowing Base in
effect as of the Revolving Period Commitment Termination Date minus the
outstanding principal amount of all Senior Debt other than the Loans and all
Revolving Loan Letter of Credit Outstandings.

     "Term Period Commitment Termination Date" means the earlier of (a) the
Business Day after the Stated Maturity Date of the Revolving Loans; and (b) the
date on which any Commitment Termination Event occurs.  Upon the occurrence of
any event described in clause (b), the Term Loan Commitments shall terminate
automatically and without any further action.

                                       16
<PAGE>
 
     "type" means, relative to any Loan, the portion thereof, if any, being
maintained as a Base Rate Loan or a LIBO Rate Loan.

     "United States" or "U.S." means the United States of America, its fifty
States and the District of Columbia.

     "Voting Stock" of any Person means Capital Stock of such Person which
ordinarily has voting power for the election of directors (or persons performing
similar functions) of such Person whether at all times or only so long as no
senior class of securities has such voting power by reason of any contingency.

     "Welfare Plan" means a "welfare plan", as such term is defined in section
3(1) of ERISA.

     SECTION  1.2     Use of Defined Terms.  Unless otherwise defined or the
context otherwise requires, terms for which meanings are provided in this
Agreement shall have such meanings when used in the Disclosure Schedule and in
each Note, Issuance Request,  Borrowing Request, Continuation/Conversion Notice,
Loan Document, notice and other communication delivered from time to time in
connection with this Agreement or any other Loan Document.

     SECTION  1.3     Cross-References. Unless otherwise specified, references
in this Agreement and in each other Loan Document to any Article or Section are
references to such Article or Section of this Agreement or such other Loan
Document, as the case may be, and, unless otherwise specified, references in any
Article, Section or definition to any clause are references to such clause of
such Article, Section or definition.

     SECTION  1.4     Accounting and Financial Determinations. Unless otherwise
specified, all accounting terms used herein or in any other Loan Document shall
be interpreted, all accounting determinations and computations hereunder or
thereunder (including under Section 7.2.4) shall be made, and all financial
statements required to be delivered hereunder or thereunder shall be prepared,
in accordance with those generally accepted accounting principles ("GAAP")
applied in the preparation of the financial statements referred to in Section
6.5.


                                  ARTICLE  II

                  COMMITMENTS, BORROWING PROCEDURES AND NOTES

     SECTION  2.1     Commitments. On the terms and subject to the conditions
of this Agreement (including Article V), each Lender severally agrees to make
Loans and issue or participate in Letters of Credit pursuant to the commitments
described in this Section 2.1.

     SECTION  2.1.1.  Revolving Loan Commitment.  From time to time on any
Business Day occurring prior to the Revolving Period Commitment Termination
Date, each Lender will make loans (relative to such Lender, its "Revolving
Loans") to the Borrower equal to such Lender's Percentage of the aggregate
amount of the Borrowing of Revolving Loans requested by the Borrower to be made
on such day.  The Commitment of each Lender described in this Section 2.1.1 is
herein 

                                       17
<PAGE>
 
referred to as its "Revolving Loan Commitment". On the terms and subject to the
conditions hereof, the Borrower may from time to time borrow, prepay and
reborrow Revolving Loans.

     SECTION  2.1.2.   Term Loan Commitment.  On the Revolving Period Commitment
Termination Date (unless such date shall occur as a result of clause (c) of the
definition thereof), each Lender will make one term loan (relative to such
Lender, its "Term Loan") to the Borrower equal to the lesser of its Revolving
Loan and its Percentage of the Term Period Commitment Amount.  The Commitment of
each Lender described in this Section 2.1.2 is herein referred to as its "Term
Loan Commitment".  No amounts paid or prepaid with respect to the Term Loans may
be reborrowed.  LIBO Rate Loans for which the Interest Period shall not have
terminated as of the Revolving Period Commitment Termination Date shall be
continued as LIBO Rate Loans for the applicable Interest Period and Base Rate
Loans shall be continued as Base Rate Loans after the Revolving Period
Commitment Termination Date, unless the Borrower shall have elected otherwise by
delivery of a Continuation/Conversion Notice pursuant to Section 2.4; provided
that such LIBO Rate Loans which shall have converted to Term Loans shall be in a
minimum amount of $5,000,000 and an integral multiple of $1,000,000.  Any
principal repayments received on the Revolving Period Commitment Termination
Date for Revolving Loans not converted into Term Loans shall be applied first to
Base Rate Loans and, after Base Rate Loans have been paid in full, to LIBO Rate
Loans, unless the Borrower shall have otherwise instructed the Agent in writing.
Upon a Lender making such Term Loan, its Term Loan Commitment shall terminate
and it shall have no further Commitment to make Loans.

     SECTION  2.1.3.   Commitment to Issue Revolving Loan Letters of Credit.
From time to time on any Business Day prior to the Revolving Period Commitment
Termination Date, each Issuer will issue, and each Lender will participate in,
to the extent of each Lender's Percentage, the Revolving Loan Letters of Credit,
in accordance with the terms of Section 2.8.

     SECTION  2.1.4.   Bolivian Letter of Credit.  Issuer has issued and each
Lender possesses a participation in, to the extent of each Lender's Percentage,
the Bolivian Letter of Credit, in accordance with the terms of Section 2.8.

     SECTION  2.1.5.   Lenders Not Permitted or Required To Make Loans or Issue
or Participate in Revolving Letters of Credit Under Certain Circumstances. No
Lender shall be permitted or required to (A) make any Revolving Loan if, after
giving effect thereto (i) (a) the aggregate outstanding principal amount of all
Revolving Loans of all Lenders, plus all Revolving Loan Letter of Credit
Outstandings would exceed the Revolving Period Commitment Amount or (b) the
Senior Debt would exceed the Borrowing Base then in effect or (ii) the aggregate
outstanding principal amount of all Loans of such Lender, together with its
Percentage of all Revolving Loan Letter of Credit Outstandings, would exceed
such Lender's Percentage of the Revolving Period Commitment Amount; or (B) issue
(in the case of any Issuer) or participate in (in the case of each Lender) any
Revolving Loan Letter of Credit if, after giving effect thereto (i) (a) all
Revolving Loan Letter of Credit Outstandings plus the aggregate outstanding
principal amount of all Loans of all Lenders would exceed the Revolving Period
Commitment Amount, (b) the Senior Debt would exceed the Borrowing Base then in
effect, or (c) all Revolving Loan Letter of Credit Outstandings would exceed the
Revolving Loan Letter of Credit Sublimit or (ii) such Lender's Percentage of all
Revolving Loan Letter of Credit Outstandings together with the aggregate
outstanding principal

                                       18
<PAGE>
 
amount of all Loans of such Lender would exceed such Lender's Percentage of the
Revolving Period Commitment Amount; or (C) make any Term Loan if, after giving
effect thereto (i) the aggregate original principal amount of all Term Loans
would exceed the Term Period Commitment Amount or (ii) the Term Loans of such
Lender would exceed such Lender's Percentage of the Term Period Commitment
Amount.

     SECTION  2.1.6.   Procedures with respect to the Maximum Commitment Amount.
So long as no Default or Event of Default has occurred and is continuing, the
Borrower may request from time to time, and subject to the terms and conditions
hereinafter set forth, that the Maximum Commitment Amount be increased by giving
written notice thereof to the Agent; provided, however, that any such notice
must be given no later than 60 days prior to the then Revolving Period
Commitment Termination Date.  Each such notice (a "Notice of Commitment
Increase") shall be in the form of Exhibit I and specify therein:

          (i)    the effective date of such increase, which date (the requested
     "Commitment Increase Effective Date") shall be no earlier than five
     Business Days after receipt by the Agent of such notice;

          (ii)   the amount of the requested increase; provided, however, that
     after giving effect to such requested increase, the Maximum Commitment
     Amount shall not exceed $625,000,000;

          (iii)  the identity of the then Lenders, if any, which have agreed
     with the Borrower to increase their respective Commitments in an amount
     such that their respective Percentages after giving effect to such
     requested increase will be the same or greater than their respective
     Percentages prior to giving effect to such requested increase (each such
     then Lender being a then "Increasing Lender"), each other Lender which has
     agreed to increase its Commitment in an amount such that its Lender's
     Percentage after giving effect to such a requested increase will be less
     than its Lender's Percentage prior to giving effect to such requested
     increase (each such Lender being a "Partially Increasing Lender") and the
     identity of each financial institution not already a Lender, if any, which
     has agreed with the Borrower to

                                       19
<PAGE>
 
     become a Lender to effect such requested increase in the Maximum Commitment
     Amount (each such assignee shall be reasonably acceptable to the Agent and
     the Issuer and each such assignee being a then "New Lender" and each Lender
     which has not agreed to increase its Commitment being a "Reducing Lender"),
     provided that in no case shall the dollar amount or the Percentage of a
     Lender's share of the Maximum Commitment Amount be increased without the
     express written consent of such Lender; and

          (iv)   the dollar amounts of the respective shares of the Maximum
     Commitment Amount and the dollar amounts of the respective shares of the
     Bolivian Letter of Credit of the then existing Lenders and such New Lenders
     from and after the effective date of such increase.

     On or before each Commitment Increase Effective Date:

          (i)    the Borrower, each Increasing Lender, each Partially Increasing
     Lender and each then New Lender shall execute and deliver to the Agent for
     its acceptance, as to form, documentation embodying the provisions of the
     Notice of Commitment Increase relating to the increase in the Maximum
     Commitment Amount to be effected on such Commitment Increase Effective
     Date; and

          (ii)   upon acceptance of such documentation by the Agent, which
     acceptance shall not be unreasonably withheld, and so long as no Default or
     Event of Default has occurred and is continuing, (A) the Agent shall give
     prompt notice of such acceptance to each Lender, (B) it shall become
     effective, and the Maximum Commitment Amount shall be increased to the
     amount specified therein, on such Commitment Increase Effective Date, (C)
     the Borrower shall execute and deliver a Note payable to the order of each
     then New Lender in the face principal amount equal to such New Lender's
     Percentage multiplied by the Maximum Commitment Amount and (D) upon the
     surrender of an existing Note by a Lender, the Borrower shall execute and
     deliver to each such Increasing Lender and each such Partially Increasing
     Lender, a new Note in the face principal amount equal to such Lender's
     Percentage multiplied by the Maximum Commitment Amount after giving effect
     to such increase.

     On each Commitment Increase Effective Date:

          (i)    each then New Lender and each then Increasing Lender shall, by
     wire transfer of immediately available funds, deliver to the Agent such
     Lenders' New Funds Amount for such Commitment Increase Effective Date,
     which amount, for each such Lender, shall constitute Revolving Loans made
     by such Lender to the Borrower pursuant to Section 2.1 on such Commitment
     Increase Effective Date; and

          (ii)   the Agent shall, by wire transfer of immediately available
     funds, pay to each then Reducing Lender and to each Partially Increasing
     Lender its Reduction Amount for such Commitment Increase Effective Date,
     which amount, for each such Lender, shall constitute a prepayment by the
     Borrower pursuant to Section 3.1.4, ratably in accordance with the
     respective principal amounts thereof, of the principal amounts of all then
     outstanding Revolving Loans of such Lender.

     Effective as of each Commitment Increase Effective Date, each then New
Lender and each then Increasing Lender shall be deemed to have purchased and had
transferred to it, and each then Reducing Lender and each Partially Increasing
Lender shall be deemed to have sold and transferred 

                                       20
<PAGE>
 
to such New Lenders and Increasing Lenders, such undivided interest and
participation in such Reducing Lender's and such Partially Increasing Lender's
interest and participation in all then outstanding Letters of Credit, the
obligations of the Borrower with respect thereto and any security therefor and
any guaranty pertaining thereto at any time existing as is necessary so that
such undivided interests and participations of all Lenders (including each then
New Lender) shall accord with their respective Lender's Percentages after giving
effect to the increase in the Maximum Commitment Amount on such Commitment
Increase Effective Date.

     SECTION  2.2.     Termination and Reduction of Commitment Amounts.  Each of
the Commitment Amounts is subject to reduction from time to time pursuant to
this Section 2.2.

     SECTION  2.2.1.   Optional.  The Borrower may, from time to time on any
Business Day occurring after the time of the initial Borrowing hereunder,
voluntarily reduce the amount of either Commitment Amount; provided, however,
that all such reductions shall require at least three Business Days' prior
notice to the Agent and be permanent, and any partial reduction of any
Commitment Amount shall be in a minimum amount of $1,000,000 and in an integral
multiple of $1,000,000.

     SECTION  2.2.2.   Mandatory as to Revolving Loans.  The Revolving Period
Commitment Amount shall be reduced or terminated as described below:

          (a)    Each Lender's Revolving Loan Commitment shall be automatically
     terminated on the Revolving Period Commitment Termination Date.

          (b)    Each reduction in the Revolving Period Commitment Amount shall
     be made ratably among the Lenders in accordance with their respective
     Percentages. The Borrower shall pay to the Agent for the account of the
     Lenders, on the date of each termination or voluntary reduction, the
     Commitment Fees accrued pursuant to Section 3.3.1 on the amount of
     Commitments so terminated or reduced through the date of such termination
     or reduction.

     SECTION  2.2.3.   Mandatory as to Term Loans.  The Term Period Commitment
Amount shall be reduced or terminated as described below:

          (a)    Each Lender's Term Loan Commitment shall be automatically
     terminated on the Term Period Commitment Termination Date.

          (b)    Each reduction in the Term Period Commitment Amount hereunder
     shall be made ratably among the Lenders in accordance with their respective
     Percentages.

     SECTION  2.2.4.   Mandatory as to Bolivian Letter of Credit.

          Each Lender's participation in, and its rights and obligations with
     respect to, the Bolivian Letter of Credit shall be automatically terminated
     on January 15, 2001.

     SECTION  2.3.     Borrowing Procedure.  The Borrower may from time to time
irrevocably request that a Borrowing be made in (a) for Base Rate Loans, a
minimum amount of 

                                       21
<PAGE>
 
$300,000 and integral multiple of $100,000, (b) for LIBO Rate Loans a minimum
amount of $5,000,000 and an integral multiple of $1,000,000, or (c) in the case
of Revolving Loans, in the unused amount of the Revolving Period Commitment
Amount. Such request shall be made by delivering a Borrowing Request to the
Agent on or before 11:00 a.m. U.S. Central time, (x) on the Business Day of such
Borrowing in the case of a Base Rate Borrowing and (y) on a Business Day not
less than three nor more than five Business Days in advance of a LIBO Rate
Borrowing. On the terms and subject to the conditions of this Agreement, each
Borrowing shall be comprised of the type of Loans, and shall be made on the
Business Day, specified in such Borrowing Request. On or before 12:00 Noon (U.S.
Central time) on such Business Day each Lender shall deposit with the Agent same
day funds in an amount equal to such Lender's Percentage of the requested
Borrowing. Such deposit will be made to an account which the Agent shall specify
from time to time by notice to the Lenders. To the extent funds are received
from the Lenders, the Agent shall make such funds available to the Borrower by
wire transfer to the accounts the Borrower shall have specified in its Borrowing
Request. No Lender's obligation to make any Loan shall be affected by any other
Lender's failure to make any Loan.

     SECTION  2.4.     Continuation and Conversion Elections.  By delivering a
Continuation/Conversion Notice to the Agent on or before 11:00 a.m., U.S.
Central time, on a Business Day, the Borrower may from time to time irrevocably
elect, on not less than three nor more than five Business Days' notice that all,
or any portion in an aggregate minimum amount of $5,000,000 and an integral
multiple of $1,000,000, of any Loans be, in the case of Base Rate Loans,
converted into LIBO Rate Loans or, in the case of LIBO Rate Loans, converted
into a Base Rate Loan or continued as a LIBO Rate Loan (in the absence of
delivery of a Continuation/Conversion Notice with respect to any LIBO Rate Loan
at least three Business Days before the last day of the then current Interest
Period with respect thereto, such LIBO Rate Loan shall, on such last day,
automatically convert to a Base Rate Loan); provided, however, that (a) each
such conversion or continuation shall be pro rated among the applicable
outstanding Loans of all Lenders, and (b) no portion of the outstanding
principal amount of any Loans may be continued as, or be converted into, LIBO
Rate Loans when any Default has occurred and is continuing.

     SECTION  2.5.     Funding.  Each Lender may, if it so elects, fulfill its
obligation to make, continue or convert LIBO Rate Loans hereunder by causing one
of its foreign branches or Affiliates (or an international banking facility
created by such Lender) to make or maintain such LIBO Rate Loan; provided,
however, that such LIBO Rate Loan shall nonetheless be deemed to have been made
and to be held by such Lender, and the obligation of the Borrower to repay such
LIBO Rate Loan shall nevertheless be to such Lender for the account of such
foreign branch, Affiliate or international banking facility.  In addition, the
Borrower hereby consents and agrees that, for purposes of any determination to
be made for purposes of Sections 4.1, 4.2, 4.3 or 4.4, it shall be conclusively
assumed that each Lender elected to fund all LIBO Rate Loans by purchasing
Dollar deposits in its LIBOR Office's interbank eurodollar market.

     SECTION  2.6.     Notes. Each Lender's Loans under its Commitment initially
shall be evidenced by a Note payable to the order of such Lender in a maximum
principal amount equal to such Lender's Percentage of the original Maximum
Commitment Amount. The Borrower hereby irrevocably authorizes each Lender to
make (or cause to be made) appropriate notations on the grid attached to such
Lender's Notes (or on any continuation of such grid), which notations, if made,
shall

                                       22
<PAGE>
 
evidence, inter alia, the date of, the outstanding principal of, and the
interest rate and Interest Period applicable to the Loans evidenced thereby.
Such notations shall be conclusive and binding on the Borrower absent manifest
error; provided, however, that the failure of any Lender to make any such
notations shall not limit or otherwise affect any Obligations of the Borrower.

     SECTION  2.7.     Determination of the Borrowing Base. During the period
from the date hereof to the date of the first determination of the Borrowing
Base pursuant to the further provisions of this Section 2.7, the amount of the
Borrowing Base shall be as set forth in a letter agreement between the Borrower
and the Agent dated September 11, 1998.

     SECTION  2.7.1.   Annual Scheduled Determinations of the Borrowing Base.
Promptly after December 31 of each calendar year commencing December 31, 1998,
and in any event prior to April 1 of the following calendar year, the Borrower
shall furnish to the Agent and each Lender a report in form and substance
satisfactory to the Agent, prepared or audited by Netherland, Sewell and
Associates, Inc. or such other engineering firm as may be selected by the
Borrower with the prior approval of the Required Lenders, which report shall be
dated as of December 31st of such calendar year and shall set forth the proven
and producing oil and gas reserves attributable to the Oil and Gas Properties
and a projection of the rate of production and net operating income with respect
thereto, as of such date, and a projection of the rate of production and net
operating income with respect thereto, as of such date.  Upon receipt of such
report relating to the Oil and Gas Properties, the Agent shall make a
determination within 25 days of the receipt of such report of the amount of
Senior Debt which the Borrower may maintain (herein as determined and
redetermined from time to time and in effect on any date called the "Borrowing
Base") on account of such reserves as of such December 31st, subject to the
approval of the Applicable Lenders as provided in this Section, and upon such
determination the Agent shall promptly notify the Lenders in writing of its
determination of the Borrowing Base.  The determination of the Borrowing Base
made by the Agent shall be so made by the Agent in the exercise of its sole
discretion in accordance with the Agent's customary practices and standards for
oil and gas loans.  The Applicable Lenders may approve the Agent's determination
of the Borrowing Base by written notice to the Agent within 10 days of the
Agent's notification of its determination of the new Borrowing Base.  If the
Applicable Lenders fail to approve the determination of the Borrowing Base made
by the Agent hereunder within such 10 days then, within an additional 5 days,
the Applicable Lenders in their sole discretion shall determine the Borrowing
Base in accordance with their respective customary practices and standards for
oil and gas loans.

     SECTION  2.7.2.   Semi-Annual Scheduled Determination of the Borrowing
Base. In addition, within ninety (90) days after each June 30 (commencing June
30, 1999) the Borrower will make available for review by the Agent monthly
production data for each property included within the Oil and Gas Properties for
the six (6) month period preceding such date together with the Borrower's
projection of the rate of production and net operating income for such
properties (in the aggregate). Also to be made available are the reserves,
projected rate of income and net operating income on (i) any Oil and Gas
Properties which were developed by the Borrower subsequent to the preceding
December 31 and which are to be included in the Borrowing Base. Upon the receipt
of a report relating to the Oil and Gas Properties, the Agent shall make a
determination within 25 days of the receipt of such report of the Borrowing Base
as of the preceding June 30. The determinations of the Borrowing Base shall be
made in the same manner and be subject to the same approvals as prescribed above
with respect to the annual review, and likewise the Agent shall communicate the

                                       23
<PAGE>
 
results of each such determination to the Lenders.  The Applicable Lenders 
may approve the determination of the Borrowing Base by written notice to the
Agent within 10 days of the giving of notice of the determination by the Agent
to such Lenders and the Agent will thereupon notify the Borrower of the
Borrowing Base approved by the Applicable Lenders. If the Applicable Lenders
fail to approve a determination of the Borrowing Base made by the Agent pursuant
to this Section 2.7.2 within such 10 days, then the Applicable Lenders shall,
within an additional 5 days, make a determination of the Borrowing Base based on
their sole discretion in accordance with their respective customary practices
and standards for oil and gas loans.

     SECTION  2.7.3.   Discretionary Determination of the Borrowing Base. If, in
addition to the foregoing scheduled annual and semi-annual determinations of the
Borrowing Base, the Lenders (or the Applicable Lenders) shall be requested by
the Borrower to redetermine the Borrowing Base, in their sole discretion based
on their respective customary practices and standards for oil and gas loans,
then the Borrower shall pay to the Agent a fee of $25,000 and to each Lender
(other than the Agent) a fee of $12,500 in connection with such redetermination.

     SECTION  2.7.4.   Reduction of the Borrowing Base Upon Sales of Oil and Gas
Properties.  In the event of a sale, transfer, lease, contribution or other
conveyance of an Oil and Gas Property as permitted pursuant to Section 7.2.7,
the Borrowing Base may be automatically reduced by an amount to be determined by
the Agent with the approval of the Applicable Lenders in accordance with their
respective customary standards for oil and gas loans on account of such sale,
transfer, assignment, lease, contribution or other conveyance.

     SECTION  2.8.     Letters of Credit.

     SECTION  2.8.1.   Issuance Requests.  By delivering to the Agent and the
applicable Issuer an Issuance Request on or before 11:30 a.m. (U.S. Central
time), the Borrower may request, from time to time prior to the Revolving Period
Commitment Termination Date, Revolving Loan Letters of Credit and on not less
than three nor more than ten Business Days' notice, that such Issuer issue an
irrevocable Standby Letter of Credit or Documentary Letter of Credit in such
form as may be mutually agreed to by the Borrower and such Issuer, in support of
obligations of the Borrower incurred in the Borrower's ordinary course of
business and which are described in such Issuance Request.  Upon receipt of an
Issuance Request, the Agent shall promptly notify the Lenders thereof. Each
Revolving Loan Letter of Credit shall by its terms be stated to expire on a date
(its "Stated Expiry Date") no later than five Business Days before the Stated
Maturity Date of any Term Loan .

     SECTION  2.8.2.   Issuances.  On the terms and subject to the conditions of
this Agreement (including Article V), the Issuer shall issue Revolving Loan
Letters of Credit in accordance with the Issuance Requests made therefor.  Each
Issuer will make available the original of each Revolving Loan Letter of Credit
which it issues in accordance with the Issuance Request therefor to the
beneficiary thereof (and will promptly provide each of the Lenders and the
Borrower with a copy of such Revolving Loan Letter of Credit).  The Borrower
will provide the Agent with a copy of each Other Letter of Credit on the day
such Other Letter of Credit is issued.

     SECTION  2.8.3.   Aggregate Amount Available Under Revolving Loan Letters
of Credit. The aggregate Stated Amount of all Revolving Loan Letters of Credit
outstanding at any one time

                                       24
<PAGE>
 
shall not exceed $60,000,000 (the "Revolving Loan Letter of Credit Sublimit")
and after issuance of any Revolving Loan Letter of Credit, the aggregate
Revolving Loan Letter of Credit Outstandings of all Revolving Loan Letters of
Credit plus the aggregate principal amount of outstanding Loans shall not exceed
the Commitment Amount.

     SECTION  2.8.4.   Other Lenders' Participation. Each Revolving Loan Letter
of Credit issued pursuant to Section 2.8.2 shall, effective upon its issuance
and without further action, be issued on behalf of all Lenders (including the
Issuer thereof) pro rata according to their respective Percentages. Each Lender
shall, to the extent of its Percentage, be deemed irrevocably to have
participated in the issuance of any such Revolving Loan Letter of Credit and is
hereby deemed to have participated (effective the date hereof) in the issuance
of the Bolivian Letter of Credit and shall be responsible to reimburse promptly
the Issuer thereof for Reimbursement Obligations which have not been reimbursed
by the Borrower in accordance with Section 2.8.5, or which have been reimbursed
by the Borrower but must be returned, restored or disgorged by such Issuer for
any reason, and each Lender shall, to the extent of its Percentage, be entitled
to receive from the Agent a ratable portion of the letter of credit fees
received by the Agent pursuant to Section 3.3.3, with respect to each Letter of
Credit. In the event that the Borrower shall fail to reimburse any Issuer, or if
for any reason Revolving Loans shall not be made to fund any Reimbursement
Obligation, all as provided in Section 2.8.5 and in an amount equal to the
amount of any drawing honored by such Issuer under a Letter of Credit issued by
it (including without limitation, the Bolivian Letter of Credit), or in the
event such Issuer must for any reason return or disgorge such reimbursement,
such Issuer shall promptly notify each Lender of the unreimbursed amount of such
drawing and of such Lender's respective participation therein. Each Lender shall
make available to such Issuer, whether or not any Default shall have occurred
and be continuing, an amount equal to its respective participation in same day
or immediately available funds at the office of such Issuer specified in such
notice if the Issuer shall notify the Agent on or before 11:30 a.m. (U.S.
Central time) of any Business Day by the close of business on such Business Day
or if the Issuer shall notify the Agent after 11:30 a.m. (U.S. Central time) of
any Business Day not later than 11:30 a.m. (U.S. Central time) on the Business
Day (under the laws of the jurisdiction of such Issuer) after the date notified
by such Issuer. In the event that any Lender fails to make available to such
Issuer the amount of such Lender's participation in such Letter of Credit as
provided herein, such Issuer shall be entitled to recover such amount on demand
from such Lender together with interest at the daily average Federal Funds Rate
for three Business Days (together with such other compensatory amounts as may be
required to be paid by such Lender to the Agent pursuant to the Rules for
Interbank Compensation of the council on International Banking or the
Clearinghouse Compensation Committee, as the case may be, as in effect from time
to time) and thereafter at the LIBO Rate plus the Applicable Margin. Nothing in
this Section 2.8.4 shall be deemed to prejudice the right of any Lender to
recover from any Issuer any amounts made available by such Lender to such Issuer
pursuant to this Section 2.8.4 in the event that it is determined by a court of
competent jurisdiction that the payment with respect to a Letter of Credit by
such Issuer in respect of which payment was made by such Lender constituted
gross negligence or wilful misconduct on the part of such Issuer. Each Issuer
shall distribute to each other Lender which has paid all amounts payable by it
under this Section 2.8.4 with respect to any Letter of Credit issued by such
Issuer such other Lender's Percentage of all payments received by such Issuer
from the Borrower in reimbursement of drawings honored by such Issuer under such
Letter of Credit when such payments are received.

                                       25
<PAGE>
 
     SECTION  2.8.5.     Disbursements.  Each Issuer will notify the Borrower
and the Agent promptly of the presentment for payment of any Letter of Credit,
together with notice of the date (the "Disbursement Date") such payment shall be
made. Subject to the terms and provisions of such Letter of Credit, the
applicable Issuer shall make such payment (the "Disbursement") to the
beneficiary (or its designee) of such Letter of Credit. Prior to 11:30 a.m.
(U.S. Central time) on the Disbursement Date, the Borrower will reimburse the
applicable Issuer for all amounts which it has disbursed under the Letter of
Credit. In the event the applicable Issuer is not reimbursed by the Borrower on
the Disbursement Date, or if such Issuer must for any reason return or disgorge
such reimbursement, the Lenders (including such Issuer) shall, on the terms and
subject to the conditions of this Agreement, fund the Reimbursement Obligation
therefor by making, on the next Business Day, Revolving Loans which are Base
Rate Loans as provided in Section 2.1.1 (the Borrower being deemed to have given
a timely Borrowing Request therefor for such amount); provided, however, for the
purpose of determining the availability of the Commitments to make Loans
immediately prior to giving effect to the application of the proceeds of such
Loans, such Reimbursement Obligation shall be deemed not to be outstanding at
such time. To the extent the applicable Issuer is not reimbursed in full in
accordance with the preceding sentences, the Borrower's Reimbursement Obligation
shall accrue interest at a fluctuating rate determined by reference to the LIBO
Rate, plus a margin of 2% per annum, payable on demand.

     SECTION  2.8.6.     Reimbursement.  The Borrower's obligation (a
"Reimbursement Obligation") under Section 2.8.5 to reimburse an Issuer with
respect to each Disbursement (including interest thereon), and each Lender's
obligation to make participation payments in each drawing which has not been
reimbursed by the Borrower, shall be absolute and unconditional under any and
all circumstances and irrespective of any setoff, counterclaim, or defense to
payment which the Borrower may have or have had against any Lender or any
beneficiary of a Letter of Credit, including any defense based upon the
occurrence of any Default, any draft, demand or certificate or other document
presented under a Letter of Credit proving to be forged, fraudulent, invalid or
insufficient, the failure of any disbursement to conform to the terms of the
applicable Letter of Credit (if, in the applicable Issuer's good faith opinion,
such disbursement is determined to be appropriate) or any non-application or
misapplication by the beneficiary of the proceeds of such disbursement, or the
legality, validity, form, regularity, or enforceability of such Letter of
Credit; provided, however, that nothing herein shall adversely affect the right
of the Borrower or any Lender to commence any proceeding against the applicable
Issuer for any wrongful disbursement made by such Issuer under a Letter of
Credit as a result of acts or omissions constituting gross negligence or wilful
misconduct on the part of such Issuer.

     SECTION  2.8.7.     Deemed Disbursements.  Upon either (i) the occurrence
and during the continuation of an Event of Default pursuant to Section 8.1.9 or
the occurrence of the Revolving Period Commitment Termination Date or (ii) the
declaration by the Agent of all or any portion of the outstanding principal
amount of the Loans and other Obligations to be due and payable and/or the
commitments (if not theretofore terminated) to be terminated as provided in
Section 8.3, an amount equal to that portion of Letter of Credit Outstandings
attributable to outstanding and undrawn Letters of Credit shall, at the election
of the applicable Issuer acting on instructions from the Required Lenders, and
without demand upon or notice to the Borrower, be deemed to have been paid or
disbursed by such Issuer under such Letters of Credit (notwithstanding that such
amount may not in fact have been so paid or disbursed), and, upon notification
by such Issuer to the Agent and

                                       26
<PAGE>
 
the Borrower of its obligations under this Section, the Borrower shall be
immediately obligated to reimburse such Issuer the amount deemed to have been so
paid or disbursed by such Issuer. Any amounts so received by such Issuer from
the Borrower pursuant to this Section shall be delivered to the Agent to be held
as collateral security for the repayment of the Borrower's obligations in
connection with the Letters of Credit. All amounts on deposit pursuant to this
Section 2.8.7 shall, until their application to any Obligation or their return
to the Borrower, as the case may be, at the Borrower's written request, be
invested in high grade short-term liquid investments acceptable to Agent and
designated by the Borrower, which investments shall be held by the Agent as
additional collateral security for the repayment of the Borrower's Obligations
under and in connection with the Letters of Credit and all other Obligations.
Any losses, net of earnings, and reasonable fees and expenses of such
investments shall be charged against the principal amount invested. The Agent,
the Issuer and the Lenders shall not be liable for any loss resulting from any
investment made by the Agent at the Borrower's request. The Agent is not
obligated hereby, or by any other Loan Document, to make or maintain any
investment, except upon written request by the Borrower. At any time when such
Letters of Credit shall terminate and all Obligations to each Issuer are either
terminated or paid or reimbursed to each Issuer in full, the Obligations of the
Borrower under this Section 2.8.7 shall be reduced accordingly (subject,
however, to reinstatement in the event any payment in respect of any of such
Letters of Credit is recovered in any manner from such Issuer), and the Agent
will return to the Borrower the excess, if any, of the aggregate amount held by
the Agent and not theretofore applied to any Reimbursement Obligation. At such
time when all Events of Default shall have been cured or waived, if the
Revolving Period Commitment Termination Date shall not have occurred for any
reason, the Agent shall return to the Borrower all amounts then on deposit with
the Agent pursuant to this Section 2.8.7.

     SECTION  2.8.8.     Nature of Reimbursement Obligations.  The Borrower
shall assume all risks of the acts, omissions, or misuse of any Letter of Credit
by the beneficiary thereof. Neither any Issuer, the Agent nor any Lender (except
to the extent of its own gross negligence or wilful misconduct) shall be
responsible for: (a) the form, validity, sufficiency, accuracy, genuineness, or
legal effect of any Letter of Credit or any document submitted by any party in
connection with the application for and issuance of a Letter of Credit, even if
it should in fact prove to be in any or all respects invalid, insufficient,
inaccurate, fraudulent, or forged; (b) the form, validity, sufficiency,
accuracy, genuineness, or legal effect of any instrument transferring or
assigning or purporting to transfer or assign a Letter of Credit or the rights
or benefits thereunder or proceeds thereof in whole or in part, which may prove
to be invalid or ineffective for any reason; (c) failure of the beneficiary to
comply fully with conditions required in order to demand payment under a Letter
of Credit; (d) errors, omissions, interruptions, or delays in transmission or
delivery of any messages, by mail, cable, telegraph, telex, facsimile or
otherwise; or (e) any loss or delay in the transmission or otherwise of any
document or draft required in order to make a Disbursement under a Letter of
Credit or of the proceeds thereof. None of the foregoing shall affect, impair,
or prevent the vesting of any of the rights or powers granted any Issuer or any
Lender hereunder. In furtherance and extension, and not in limitation or
derogation, of any of the foregoing, any action taken or omitted to be taken by
any Issuer in good faith shall be binding upon the Borrower and shall not put
such Issuer under any resulting liability to the Borrower.

                                       27
<PAGE>
 
     SECTION  2.8.9.     Increased Costs; Indemnity.  If by reason of (a) any
change in applicable law, regulation, rule, decree or regulatory requirement or
any change in the interpretation or application by any judicial or regulatory
authority of any law, regulation, rule, decree or regulatory requirement, or (b)
compliance by any Issuer or any Lender with any direction, or requirement of any
governmental or monetary authority, including Regulation D of the F.R.S. Board:
(i) any Issuer or any Lender shall be subject to any tax (other than taxes on
net income and franchises), levy, charge or withholding of any nature or to any
variation thereof or to any penalty with respect to the maintenance or
fulfillment of its obligations under this Section 2.8, whether directly or by
such being imposed on or suffered by such Issuer or such Lender; (ii) any
reserve, deposit or similar requirement is or shall be applicable, increased,
imposed or modified in respect of any Letters of Credit issued by any Issuer or
participations therein purchased by any Lender; or (iii) there shall be imposed
on any Issuer or any Lender any other condition regarding this Section 2.8, any
Letter of Credit or any participation therein, and the result of the foregoing
is directly to increase the cost to such Issuer or such Lender of issuing or
maintaining any Letter of Credit or of purchasing or maintaining any
participation therein, or to reduce any amount receivable in respect thereof by
such Issuer or such Lender, then and in any such case such Issuer or such Lender
may, at any time after the additional cost is incurred or the amount received is
reduced, notify the Agent and the Borrower thereof, and the Borrower shall pay
within 10 days of demand such amounts as such Issuer or Lender may in good faith
specify to be necessary to compensate such Issuer or Lender for such additional
cost or reduced receipt, together with interest on such amount from the date
demanded until payment in full thereof at a rate equal at all times to the
Alternate Base Rate per annum. The determination by such Issuer or Lender, as
the case may be, of any amount due pursuant to this Section 2.8.9, as set forth
in a statement setting forth the calculation thereof in reasonable detail,
shall, in the absence of manifest error, be conclusive and binding on the
Borrower.

     In addition to amounts payable as elsewhere provided in this Section 2.8,
the Borrower hereby indemnifies, exonerates and holds each Issuer, the Agent and
each Lender harmless from and against any and all actions, causes of action,
suits, losses, costs, liabilities and damages, and expenses incurred in
connection therewith (irrespective of whether such Issuer, the Agent or such
Lender is a party to the action for which indemnification is sought), including
reasonable attorneys' fees and disbursements, which such Issuer, the Agent or
such Lender may incur or be subject to as a consequence, direct or indirect, of
the issuance of the Letters of Credit, other than as a result of the gross
negligence or wilful misconduct of such Issuer as determined by a court of
competent jurisdiction, or the failure of such Issuer to honor a drawing under
any Letter of Credit as a result of any act or omission, whether rightful or
wrongful, of any present or future government or governmental authority.

     SECTION  2.8.10     Letter of Credit Collateral Account.  The Borrower
hereby agrees that it will, until the final expiration date of any Letter of
Credit and thereafter as long as any amount is payable to the Lenders in respect
of any Letter of Credit, maintain a special collateral account (the "Letter of
Credit Collateral Account") with the Agent, in the name of the Borrower but
under the sole dominion and control of the Agent, for the benefit of the Lenders
and in which the Borrower shall have no interest other than as set forth in
Section 3.1.2. The Agent will invest any funds on deposit from time to time in
the Letter of Credit Collateral Account in short term investments, having a
maturity not exceeding 30 days. Nothing in this Section 2.8.10 shall (i)
obligate the Borrower to deposit any funds in the Letter of Credit Collateral
Account, (ii) obligate the Agent to

                                       28
<PAGE>
 
require the Borrower to deposit any funds in the Letter of Credit Collateral
Account or (iii) limit the right of the Agent to release any funds held in the
Letter of Credit Collateral Account, other than as required by Section 3.1.2.
The Borrower hereby grants to the Agent for the benefit of the Lenders a
security interest in the Letter of Credit Collateral Account and any funds or
investments in such account.

                                 ARTICLE  III

                  REPAYMENTS, PREPAYMENTS, INTEREST AND FEES

     SECTION  3.1        Repayments and Prepayments.  The Borrower shall make
mandatory repayments and prepayments and may also make voluntary prepayments
from time to time pursuant to this Section 3.1.  Each prepayment made pursuant
to this Section shall be without premium or penalty, except as may be required
by Section 4.4.

     SECTION  3.1.1.     Repayments.  To the extent that Term Loans are made to
the Borrower on the Revolving Period Commitment Termination Date, such Term
Loans shall be deemed to be for repayment of the principal of Revolving Loans
outstanding as of the Revolving Period Commitment Termination Date. The Borrower
shall repay in full the unpaid aggregate principal amount of each Loan upon the
Stated Maturity Date therefor. Prior thereto, the Borrower shall, on each
Quarterly Payment Date occurring after the Revolving Period Commitment
Termination Date, make a scheduled repayment of the outstanding principal amount
of the Term Loans in an amount equal to one eighth (1/8) of the original
aggregate principal amount of the Term Loans; provided, that the final scheduled
repayment on the Stated Maturity Date for Term Loans shall be in an amount
necessary to repay in full the unpaid principal of the Term Loans.

     SECTION  3.1.2.     Mandatory Prepayments on Loans.  If at any time, the
aggregate principal amount of all Senior Debt outstanding shall exceed the
Borrowing Base then in effect, the Borrower shall, at the Borrower's option,
either (a) forthwith repay a portion of the Loans in an aggregate principal
amount equal to such excess or (b) pay an amount equal to such excess in no more
than six substantially equal monthly installments, the first such payment to be
due within five days after the date on which it is first determined that such
principal amount of Senior Debt exceeds the Borrowing Base, and the remaining
payments due on the numerically corresponding day of each of the subsequent
months so that, upon the conclusion of such mandatory prepayments, the aggregate
principal amount of all outstanding Senior Debt does not exceed the Borrowing
Base; provided that if the aggregate principal amount of all Senior Debt
outstanding shall exceed the Borrowing Base (i) as a result of the reduction of
the Borrowing Base pursuant to Section 7.2.7 or (ii) without any reduction in
the Borrowing Base, then the foregoing clause (b) shall not apply.  If a
subsequent month does not contain a numerically corresponding day, the Borrower
shall make such payment on the last Business Day of such month, or if the
numerically corresponding day is not a Business Day, such payment will be due on
the preceding Business Day.  In the event the aggregate of all Revolving Loan
Letter of Credit Outstandings exceeds the Revolving Loan Letter of Credit
Sublimit, the Borrower shall reduce the Revolving Loan Letter of Credit
Outstandings by an amount equal to such excess or deposit cash collateral into
the Letter of Credit Collateral Account on account of and to secure its
Obligations with respect to Revolving Loan Letters of Credit then in effect and
not otherwise fully collateralized, such cash deposits to be in an amount equal
to such excess.  In 

                                       29
<PAGE>
 
addition, in the event the sum of the aggregate Revolving Loan Letter of Credit
Outstandings of all Revolving Loan Letters of Credit plus the aggregate
principal amount of outstanding Loans exceeds the Commitment Amount, the
Borrower shall first make a mandatory prepayment of the outstanding principal
amount of the Loans, and second, deposit cash collateral in the Letter of Credit
Collateral Account, such prepayments and/or cash deposits to be in an aggregate
amount equal to such excess. Mandatory prepayments pursuant to this Section
3.1.2 shall be in addition to and not in lieu of principal payments required
pursuant to Section 3.1.1; provided, that such mandatory prepayments shall be
applied against the next scheduled repayment or repayments required pursuant to
Section 3.1.1 if, as of the date for such scheduled repayment, after giving
effect to such scheduled repayment, the Senior Debt shall be less than or equal
to the Borrowing Base then in effect.

     The Borrower shall, on each date when any reduction in the Revolving Period
Commitment Amount shall become effective pursuant to Section 2.2.1, make a
mandatory prepayment of all Revolving Loans equal to the excess, if any, of the
aggregate, outstanding principal amount of all Revolving Loans over the
Revolving Period Commitment Amount as so reduced and/or deposit cash collateral
in the Letter of Credit Collateral Account, such prepayments and or cash
deposits to be in an aggregate amount equal to such excess.

     SECTION  3.1.3.     Repayment Upon Acceleration.  The Borrower shall,
immediately upon any acceleration of the Stated Maturity Date of any Loans
pursuant to Section 8.2 or 8.3, repay all Loans.

     SECTION  3.1.4.    Voluntary Repayments.  The Borrower may, from time to
time on any Business Day prior to the Stated Maturity Date, make a voluntary
prepayment, in whole or in part, of the outstanding principal amount of any
Loans; provided, however, that (i) any such prepayment (other than a prepayment
pursuant to Section 2.1.6) shall be made pro rata among Loans of the same type
and, if applicable, having the same Interest Period of all Lenders; (ii no such
prepayment of any LIBO Rate Loan (other than a prepayment pursuant to Section
2.1.6) may be made on any day other than the last day of the Interest Period for
such Loan; and (ii all such voluntary partial prepayments (other than a
prepayment pursuant to Section 2.1.6) shall be in an aggregate minimum amount of
$300,000 for Base Rate Loans and $1,000,000 for LIBO Rate Loans and an integral
multiple of $100,000; provided that after giving effect to such partial
prepayment, any outstanding LIBO Rate Loans with the same Interest Period, if
any, shall be in a minimum aggregate principal amount of at least $5,000,000.
Each voluntary prepayment of Term Loans made pursuant to this Section 3.1.4
shall be applied, to the extent of such prepayment, in the inverse order of the
scheduled repayments of Term Loans set forth in Section 3.1.1. Each prepayment
of any Loans made pursuant to this Section shall be without premium or penalty,
except as may be required by Section 4.4. No voluntary prepayment of principal
of any Revolving Loans shall cause a reduction in the Revolving Period
Commitment Amount. No voluntary prepayment of principal of any Term Loan may be
reborrowed.

     SECTION  3.2        Interest Provisions.  Interest on the outstanding
principal amount of Loans shall accrue and be payable in accordance with this
Section 3.2.

     SECTION  3.2.1.     Rates.  Pursuant to an appropriately delivered
Borrowing Request or Continuation/Conversion Notice, the Borrower may elect that
Loans comprising a Borrowing accrue 

                                       30
<PAGE>
 
interest at a rate per annum: (a) on that portion maintained from time to time
as a Base Rate Loan, equal to the sum of the Alternate Base Rate from time to
time in effect plus the Base Rate Applicable Margin; and (b) on that portion
maintained as a LIBO Rate Loan, during each Interest Period applicable thereto,
equal to the sum of the LIBO Rate (Reserve Adjusted) for such Interest Period
plus the LIBO Rate Applicable Margin.

     The "LIBO Rate (Reserve Adjusted)" means, relative to any Loan to be made,
continued or maintained as, or converted into, a LIBO Rate Loan for any Interest
Period, a rate per annum (rounded upwards, if necessary, to the nearest 1/16 of
1%) determined pursuant to the following formula:

          LIBO Rate            =                   LIBO Rate
                                         -------------------------------
      (Reserve Adjusted)                 1.00 - LIBOR Reserve Percentage

     The LIBO Rate (Reserve Adjusted) for any Interest Period for LIBO Rate
Loans will be determined by the Agent on the basis of the LIBOR Reserve
Percentage in effect on, and the applicable rates furnished to and received by
the Agent from Bank of Montreal, two Business Days before the first day of such
Interest Period.

     "LIBO Rate" means, relative to any Interest Period for LIBO Rate Loans, the
rate of interest equal to the average (rounded upwards, if necessary, to the
nearest 1/16 of 1%) of the rates per annum at which Dollar deposits in
immediately available funds are offered to Bank of Montreal's LIBOR Office in
the London interbank market as at or about 10:00 a.m. U.S. Central time two
Business Days prior to the beginning of such Interest Period for delivery on the
first day of such Interest Period, and in an amount approximately equal to the
amount of Bank of Montreal's LIBO Rate Loan and for a period approximately equal
to such Interest Period.

     "LIBOR Reserve Percentage" means, relative to any Interest Period for LIBO
Rate Loans, the reserve percentage (expressed as a decimal) equal to the maximum
aggregate reserve requirements (including all basic, emergency, supplemental,
marginal and other reserves and taking into account any transitional adjustments
or other scheduled changes in reserve requirements) specified under regulations
issued from time to time by the F.R.S. Board and then applicable to assets or
liabilities consisting of and including "Eurocurrency Liabilities", as currently
defined in Regulation D of the F.R.S. Board, having a term approximately equal
or comparable to such Interest Period.

     All LIBO Rate Loans shall bear interest from and including the first day of
the applicable Interest Period to (but not including) the last day of such
Interest Period at the interest rate deter  mined as applicable to such LIBO
Rate Loan.

     SECTION  3.2.2.     Post-Maturity Rates.  After the date any principal
amount of any Loan is due and payable (whether on the Stated Maturity Date, upon
acceleration or otherwise), or after any other monetary Obligation of the
Borrower shall have become due and payable, the Borrower shall pay, but only to
the extent permitted by law, interest (after as well as before judgment) on such
amounts at a rate per annum equal to the Alternate Base Rate plus a margin of
2%.

                                       31
<PAGE>
 
     SECTION  3.2.3.     Payment Dates.  Interest accrued on each Loan shall be
payable, without duplication:  (a) on the Stated Maturity Date therefor; (b)
except in the case of voluntary prepayment of Base Rate Loans, on the date of
any payment or prepayment, in whole or in part, of principal outstanding on such
Loan; (c) with respect to Base Rate Loans, on each Quarterly Payment Date
occurring after the date of the initial Borrowing hereunder; (d) with respect to
LIBO Rate Loans, the last day of each applicable Interest Period (and, if such
Interest Period shall exceed 90 days, on the 90th day of such Interest Period);
and (e) on that portion of any Loans the Stated Maturity Date of which is
accelerated pursuant to Section 8.2 or Section 8.3, immediately upon such
acceleration.  Interest accrued on Loans or other monetary Obligations arising
under this Agreement or any other Loan Document after the date such amount is
due and payable (whether on the Stated Maturity Date, upon acceleration or
otherwise) shall be payable upon demand.  Notwithstanding clauses (a) and (b)
above, except as otherwise provided in this Section 3.2.3, no accrued interest
shall be due and payable on the Revolving Period Commitment Termination Date on
those Revolving Loans the principal of which is deemed to have been repaid by
Term Loans to the Borrower pursuant to Section 3.1.1.

     SECTION  3.3        Fees.  The Borrower agrees to pay the fees set forth in
this Section 3.3.  All such fees shall be non-refundable.

     SECTION  3.3.1.     Commitment Fee.  The Borrower agrees to pay to the
Agent for the account of each Lender, for the period (including any portion
thereof when any of its Commitments are suspended by reason of the Borrower's
inability to satisfy any condition of Article V) commencing on the Effective
Date and continuing through the Revolving Period Commitment Termination Date, a
commitment fee at the rate of (i) during any period when the ratio (expressed as
a percentage) of the outstanding principal of Senior Debt, including any Loans
outstanding, to the Borrowing Base then in effect is greater than 60%, 3/8 of 1%
per annum and (ii) during all other periods 1/4 of 1% per annum, on such
Lender's Percentage of the average daily unused portion of the Revolving Period
Commitment Amount. Such commitment fees shall be payable by the Borrower in
arrears on each Quarterly Payment Date, commencing on December 1, 1998, and
ending on the Revolving Period Commitment Termination Date.

     SECTION  3.3.2.     Agent's Fees.  To the Agent for its own account, the
fees as set forth in the letter agreement between the Borrower and the Agent
dated September 3, 1998.

     SECTION  3.3.3.     Letter of Credit Face Amount Fee.  The Borrower agrees
to pay to the Agent, for the account of each Lender, a fee for each Letter of
Credit for the period from and including the date of the issuance of such Letter
of Credit to (but not including) the date upon which such Letter of Credit
expires, at a per annum rate equal to (i) the Revolving Loan Letter of Credit
Applicable Margin on the outstanding face amount of each Letter of Credit in the
case of Revolving Loan Letters of Credit and (ii) 1.500% on the outstanding face
amount of the Bolivian Letter of Credit. Such fee shall be payable by the
Borrower in arrears on each Quarterly Payment Date, and on the Stated Maturity
Date of any Term Loan for any period then ending for which such fee shall not
theretofore have been paid, commencing on the first such date after the issuance
of such Letter of Credit.

                                       32
<PAGE>
 
                                  ARTICLE  IV

                    CERTAIN LIBO RATE AND OTHER PROVISIONS

     SECTION  4.1.       If LIBO Rate Lending Unlawful.  If any Lender shall
determine (which determination shall, upon notice thereof to the Borrower and
the Lenders, be conclusive and binding on the Borrower) that the introduction of
or any change in or in the interpretation of any law makes it unlawful, or any
central bank or other governmental authority asserts that it is unlawful, for
such Lender to make, continue or maintain any Loan as, or to convert any Loan
into, a LIBO Rate Loan, the obligations of all Lenders to make, continue,
maintain or convert any such Loans shall, upon such determination, forthwith be
suspended until such Lender shall notify the Agent that the circumstances
causing such suspension no longer exist, and all LIBO Rate Loans shall
automatically convert into Base Rate Loans at the end of the then current
Interest Periods with respect thereto or sooner, if required by such law or
assertion.

     SECTION  4.2.       If  Deposits Unavailable.  If the Agent shall have
determined that (a) Dollar deposits in the relevant amount and for the relevant
Interest Period are not available to Bank of Montreal in its relevant market; or
(b) by reason of circumstances affecting Bank of Montreal's relevant market,
adequate means do not exist for ascertaining the interest rate applicable
hereunder to LIBO Rate Loans, then, upon notice from the Agent to the Borrower
and the Lenders, the obligations of all Lenders under Section 2.3 and Section
2.4 to make or continue any Loans as, or to convert any Loans into, LIBO Rate
Loans shall forthwith be suspended until the Agent shall notify the Borrower and
the Lenders that the circumstances causing such suspension no longer exist.

     SECTION  4.3.       Increased LIBO Rate Loan Costs, etc.  The Borrower
agrees to reimburse each Lender for any increase in the cost to such Lender of,
or any reduction in the amount of any sum receivable by such Lender in respect
of, making, continuing or maintaining (or of its obligation to make, continue or
maintain) any Loans as, or of converting (or of its obligation to convert) any
Loans into, LIBO Rate Loans; provided, the Borrower shall only be obligated to
reimburse a Lender in respect of such increases or reductions if such Lender is
generally seeking such reimbursement from similar borrowers under similar
circumstances and Borrower shall not be obligated to reimburse a Lender in
respect of such increases or reductions in respect of any period prior to notice
thereof to Borrower. Such Lender shall promptly notify the Agent and the
Borrower in writing of the occurrence of any such event, such notice to state,
in reasonable detail, the reasons therefor and the additional amount required
fully to compensate such Lender for such increased cost or reduced amount. Such
additional amounts shall be payable by the Borrower directly to such Lender
within five days of its receipt of such notice, and such notice shall, in the
absence of manifest error, be conclusive and binding on the Borrower.

     SECTION  4.4.       Funding Losses.  In the event any Lender shall incur
any loss or expense (including any loss or expense incurred by reason of the
liquidation or reemployment of deposits or other funds acquired by such Lender
to make, continue or maintain any portion of the principal amount of any Loan
as, or to convert any portion of the principal amount of any Loan into, a LIBO
Rate Loan) as a result of (a) any conversion or repayment or prepayment of the
principal amount of any LIBO Rate Loan on a date other than the scheduled last
day of the Interest Period applicable thereto, whether pursuant to Section 3.1
or otherwise; (b) any Loans not being made as

                                       33
<PAGE>
 
LIBO Rate Loans in accordance with the Borrowing Request therefor; or (c) any
Loans not being continued as, or converted into, LIBO Rate Loans in accordance
with the Continuation/ Conversion Notice therefor; then, upon the written notice
of such Lender to the Borrower (with a copy to the Agent), the Borrower shall,
within five days of its receipt thereof, pay directly to such Lender such amount
as will (in the reasonable determination of such Lender) reimburse such Lender
for such loss or expense. Such written notice (which shall include calculations
in reasonable detail) shall, in the absence of manifest error, be conclusive and
binding on the Borrower.

     SECTION  4.5.       Increased Capital Costs.  If any change in, or the
introduction, adoption, effectiveness, interpretation, reinterpretation or
phase-in of, any law or regulation, directive, guideline, decision or request
(whether or not having the force of law) of any court, central bank, regulator
or other governmental authority affects or would affect the amount of capital
required or expected to be maintained by any Lender or any Person controlling
such Lender, and such Lender determines (in its sole and absolute discretion)
that the rate of return on its or such controlling Person's capital as a
consequence of its Commitments or the Borrowings made by such Lender is reduced
to a level below that which such Lender or such controlling Person could have
achieved but for the occurrence of any such circumstance, then, in any such case
upon notice from time to time by such Lender to the Borrower, the Borrower
shall, within 5 days of its receipt of such notice, pay directly to such Lender
additional amounts sufficient to compensate such Lender or such controlling
Person for such reduction in rate of return; provided, the Borrower shall only
be obligated to pay such amounts to a Lender if such Lender is generally seeking
payment in respect of such amounts from similar borrowers under similar
circumstances and Borrower shall not be obligated to reimburse a Lender in
respect of such amounts in respect of any period prior to such notice to the
Borrower.  A statement of such Lender as to any such additional amount or
amounts (including calculations thereof in reasonable detail) shall, in the
absence of manifest error, be conclusive and binding on the Borrower.  In
determining such amount, such Lender may use any reasonable method of averaging
and attribution that it (in its sole and absolute discretion) shall deem
applicable.

     SECTION  4.6.       Taxes.  In the event that any withholding or deduction
from any payment to be made by the Borrower hereunder is required in respect of
any present or future income, excise, stamp or franchise taxes and other taxes,
fees, duties, withholdings or other charges of any nature whatsoever imposed by
any taxing authority, but excluding franchise taxes and taxes imposed on or
measured by any Lender's or Issuer's net income or receipts (such non-excluded
items being called "Taxes") pursuant to any applicable law, rule or regulation,
then the Borrower will (a) pay directly to the relevant authority the full
amount required to be so withheld or deducted; and (b) promptly forward to the
Agent an official receipt or other documentation satisfactory to the Agent
evidencing such payment to such authority.

     If the Borrower fails to pay any Taxes when due to the appropriate taxing
authority or fails to remit to the Agent, for the account of the respective
Lenders or the Issuer, the required receipts or other required documentary
evidence, the Borrower shall indemnify the Lenders or the Issuer, as the case
may be, for any incremental Taxes, interest or penalties that may become payable
by any Lender as a result of any such failure.  For purposes of this Section
4.6, a distribution hereunder by the Agent or any Lender or Issuer to or for the
account of any Lender or Issuer shall be deemed a payment by the Borrower.

                                       34
<PAGE>
 
     Upon the request of the Borrower or the Agent, each Lender and Issuer  that
is organized under the laws of a jurisdiction other than the United States
shall, prior to the due date of any payments under the Notes, execute and
deliver to the Borrower and the Agent, on or about the first scheduled payment
date in each Fiscal Year, one or more (as the Borrower or the Agent may
reasonably request) United States Internal Revenue Service Forms 4224 or Forms
1001 or such other forms or documents (or successor forms or documents),
appropriately completed, as may be applicable to establish the extent, if any,
to which a payment to such Lender or Issuer is exempt from withholding or
deduction of Taxes.

     SECTION  4.7.       Payments, Computations, etc.  Unless otherwise
expressly provided, all payments by the Borrower pursuant to this Agreement, the
Notes or any other Loan Document shall be made by the Borrower to the Agent for
the pro rata account of the Lenders or the Issuer entitled to receive such
payment. All such payments required to be made to the Agent shall be made,
without setoff, deduction or counterclaim, not later than 12:00 Noon, United
States Central time, on the date due, in same day or immediately available
funds, to such account as the Agent shall specify from time to time by notice to
the Borrower. Funds received after that time shall be deemed to have been
received by the Agent on the next succeeding Business Day. The Agent shall
promptly remit in same day funds to each Lender or Issuer its share, if any, of
such payments received by the Agent for the account of such Lender or Issuer.
All interest and fees shall be computed on the basis of the actual number of
days (including the first day but excluding the last day) occurring during the
period for which such interest or fee is payable over a year comprised of 360
days (or, in the case of interest on a Base Rate Loan, 365 days or, if
appropriate, 366 days). Whenever any payment to be made shall otherwise be due
on a day which is not a Business Day, such payment shall (except as otherwise
required by clause (c) of the definition of the term "Interest Period" with
respect to LIBO Rate Loans) be made on the next succeeding Business Day and such
extension of time shall be included in computing interest and fees, if any, in
connection with such payment.

     SECTION  4.8.       Sharing of Payments.  If any Lender shall obtain any
payment or other recovery (whether voluntary, involuntary, by application of
setoff or otherwise) on account of any Loan or participation in a Letter of
Credit (other than pursuant to the terms of Sections 4.3, 4.4 and 4.5) in excess
of its pro rata share of payments then or therewith obtained by all Lenders,
such Lender shall purchase from the other Lenders such participations in Loans
made by them and participations in Letters of Credit held by them as shall be
necessary to cause such purchasing Lender to share the excess payment or other
recovery ratably with each of them; provided, however, that if all or any
portion of the excess payment or other recovery is thereafter recovered from
such purchasing Lender, the purchase shall be rescinded and each Lender which
has sold a participation to the purchasing Lender shall repay to the purchasing
Lender the purchase price to the ratable extent of such recovery together with
an amount equal to such selling Lender's ratable share (according to the
proportion of (a) the amount of such selling Lender's required repayment to the
purchasing Lender to (b) the total amount so recovered from the purchasing
Lender) of any interest or other amount paid or payable by the purchasing Lender
in respect of the total amount so recovered.  The Borrower agrees that any
Lender so purchasing a participation from another Lender pursuant to this
Section 4.8 may, to the fullest extent permitted by law, exercise all its rights
of payment (including pursuant to Section 4.9) with respect to such
participation as fully as if such Lender were the direct creditor of the
Borrower in the amount of such participation.  If under any applicable
bankruptcy, insolvency or other similar law, any Lender receives a secured claim
in lieu of a setoff to which this 

                                       35
<PAGE>
 
Section 4.8 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 4.8 to share in the benefits of any
recovery on such secured claim.

     SECTION  4.9.       Setoff.  Each Lender and Issuer shall, upon the
occurrence of any Default described in clauses (a) through (d) of Section 8.1.9
with respect to the Borrower or any of its Subsidiaries or any other Event of
Default, have the right to appropriate and apply to the payment of the
Obligations owing to it (whether or not then due), and (as security for such
Obligations) the Borrower hereby grants to each Lender and Issuer a continuing
security interest in, any and all balances, credits, deposits, accounts or
moneys of the Borrower then or thereafter maintained with such Lender or Issuer;
provided, however, that any such appropriation and application shall be subject
to the provisions of Section 4.8. Each Lender and Issuer agrees promptly to
notify the Borrower and the Agent after any such setoff and application made by
such Lender or Issuer; provided, however, that the failure to give such notice
shall not affect the validity of such setoff and application. The rights of each
Lender and Issuer under this Section 4.9 are in addition to other rights and
remedies (including other rights of setoff under applicable law or otherwise)
which such Lender or Issuer may have.

     SECTION  4.10.      Use of Proceeds. The Borrower shall apply the proceeds
of each Borrowing in accordance with the fifth recital; provided that the
Borrower will not and will not permit any Subsidiary to use any proceeds to fund
an Acquisition not approved by the board of directors or other governing body of
the target or selling company or to acquire any "margin stock" (as defined in
F.R.S. Regulation U) in violation of Regulation T, X or U of the Board of
Governors of the Federal Reserve System.

                                  ARTICLE  V

                            CONDITIONS TO BORROWING

     SECTION  5.1.       Initial Borrowing.  The obligations of the Lenders to
fund the initial Borrowing and to issue the initial Letter of Credit shall be
subject to the prior or concurrent satisfaction of each of the conditions
precedent set forth in this Section 5.1.

     SECTION  5.1.1.     Resolutions, etc.  The Agent shall have received from
the Borrower a certificate, dated the date of the initial Borrowing or the
issuance of the initial Letter of Credit, of its Secretary or Assistant
Secretary as to (a) resolutions of its Board of Directors then in full force and
effect authorizing the execution, delivery and performance of this Agreement,
the Notes and each other Loan Document to be executed by it; and (b) the
incumbency and signatures of those of its officers authorized to act with
respect to this Agreement, the Notes and each other Loan Document executed by
it, upon which certificate each Lender may conclusively rely until it shall have
received a further certificate of the Secretary or Assistant Secretary of the
Borrower canceling or amending such prior certificate.

     SECTION  5.1.2.     Delivery of Notes.  The Agent shall have received, for
the account of each Lender, its Note duly executed and delivered by the
Borrower.

                                       36
<PAGE>
 
     SECTION  5.1.3.     [Reserved].

     SECTION  5.1.4.     Compliance with Representations and Warranties.  The
Agent shall have received a certificate from an Authorized Officer confirming
compliance with Section 5.2.1 and stating that, after giving effect to Loans or
Letters of Credit comprising the initial Borrowings, Senior Debt shall not
exceed the Borrowing Base then in effect.

     SECTION  5.1.5.     Opinions of Counsel.  The Agent shall have received an
opinion, dated the date of the initial Borrowing and addressed to the Agent and
all Lenders and Issuers, from Conner & Winters, a Professional Corporation,
counsel to the Borrower, substantially in the form of Exhibit E-1 hereto and the
Agent shall be satisfied that it will receive within 30 days of the initial
Borrowing an opinion from Conner & Winters, a Professional Corporation, counsel
to the Borrower, substantially in the form of Exhibit E-2 hereto.

     SECTION  5.1.6.     Closing Fees, Expenses, etc.  The Agent shall have
received for its own account, or for the account of each Lender, as the case may
be, all fees, costs and expenses due and payable pursuant to Sections 3.3 and
10.3, if then invoiced.

     SECTION  5.1.7.     [Reserved].

     SECTION  5.2.       Conditions Precedent to Revolving Loans.  The
obligation of each Lender to fund any Revolving Loan and of each Issuer to issue
a Letter of Credit on the occasion of any Borrowing (including the initial
Borrowing) shall be subject to the satisfaction of each of the conditions
precedent set forth in this Section 5.2.

     SECTION  5.2.1.     Compliance with Warranties, No Default, etc.  Both
before and after giving effect to any Borrowing (but, if any Default of the
nature referred to in Section 8.1.5 shall have occurred with respect to any
other Indebtedness, without giving effect to the application, directly or
indirectly, of the proceeds thereof) the following statements shall be true and
correct: (a) the representations and warranties set forth in Article VI
(excluding, however, those contained in Section 6.7) shall be true and correct
with the same effect as if then made (unless stated to relate solely to an early
date, in which case such representations and warranties shall be true and
correct as of such earlier date); (b) except as disclosed by the Borrower to the
Agent and the Lenders pursuant to Section 6.7 (i) no labor controversy,
litigation, arbitration or governmental investigation or proceeding shall be
pending or, to the knowledge of the Borrower, threatened against the Borrower or
any of its Subsidiaries which might materially adversely affect the Borrower's
consolidated business, operations, assets, revenues, properties or prospects or
which purports to affect the legality, validity or enforceability of this
Agreement, the Notes or any other Loan Document; and (ii no development shall
have occurred in any labor controversy, litigation, arbitration or governmental
investigation or proceeding disclosed pursuant to Section 6.7 which might
materially adversely affect the consolidated businesses, operations, assets,
revenues, properties or prospects of the Borrower and its Subsidiaries; (c) no
Default shall have then occurred and be continuing, and neither the Borrower nor
any of its Subsidiaries are in material violation of any law or governmental
regulation or court order or decree; (d) the Borrower is in compliance with the
Current Ratio and Tangible Net Worth tests required by Section 7.2.4, and,
immediately after giving effect to the proposed Borrowing, the Senior Debt of
the Borrower shall not exceed the Borrowing

                                       37
<PAGE>
 
Base and (e) the Loans and Letters of Credit requested will constitute
"Designated Senior Indebtedness" pursuant to the Indenture, as defined therein.

     SECTION  5.2.2.     Borrowing Request.  The Agent shall have received a
Borrowing Request for such Borrowing of a Loan and an Issuance Request for each
Borrowing which is in the form of the issuance of a Letter of Credit.  Each of
the delivery of a Borrowing Request or Issuance Request shall constitute a
representation and warranty by the Borrower that, on the date of such Borrowing
(both immediately before and after giving effect to such Borrowing and the
application of the proceeds thereof), the statements made in Section 5.2.1 are
true and correct.

     SECTION  5.2.3.     Satisfactory Legal Form.  All documents executed or
submitted pursuant hereto by or on behalf of the Borrower or any of its
Subsidiaries shall be satisfactory in form and substance to the Agent and its
counsel; the Agent and its counsel shall have received all information,
approvals, opinions, documents or instruments as the Agent or its counsel may
reasonably request.

     SECTION  5.3.       Conditions Precedent to the Making of the Term Loans.  
The obligation of each Lender to make its Term Loan is subject to (a) the
condition precedent that the principal of all Revolving Loans and accrued
interest on all Revolving Loans, except those Revolving Loans the principal of
which shall be deemed to have been repaid by Term Loans pursuant to Section
3.1.1 and for which such interest is not otherwise due and payable, shall have
been paid in full prior to or concurrently with the making of such Term Loan;
and (b) the conditions precedent set forth in Section 5.2.1. The acceptance by
the Borrower of the proceeds of the Term Loans shall constitute a representation
and warranty that, on the Revolving Period Commitment Termination Date (both
before and after giving effect to such Term Loans and the application of the
proceeds thereof), the statements made in Section 5.2.1 are true and correct.

                                  ARTICLE  VI

                        REPRESENTATIONS AND WARRANTIES

     In order to induce the Lenders and the Agent to enter into this Agreement
and to make Loans hereunder, and the Issuer to issue Letters of Credit and the
Lenders to participate in Letters of Credit, the Borrower represents and
warrants unto the Agent and each Lender and Issuer as set forth in this Article
VI.

     SECTION  6.1.       Organization, etc.  The Borrower and each of its
Subsidiaries is a corporation validly organized and existing and in good
standing under the laws of the jurisdiction of its incorporation, is duly
qualified to do business and is in good standing as a foreign corporation in
each jurisdiction where the nature of its business requires such qualification,
and has full power and authority and holds all requisite governmental licenses,
permits and other approvals to enter into and perform its Obligations under this
Agreement, the Notes and each other Loan Document and to own and hold under
lease its property and to conduct its business substantially as currently
conducted by it.

                                       38
<PAGE>
 
     SECTION  6.2.       Due Authorization, Non-Contravention, etc.  The
execution, delivery and performance by the Borrower of this Agreement, the Notes
and each other Loan Document executed or to be executed by it, are within the
Borrower's corporate powers, have been duly authorized by all necessary
corporate action, and do not (a) contravene the Borrower's Organic Documents;
(b) contravene any contractual restriction, law or governmental regulation or
court decree or order binding on or affecting the Borrower; or (c) result in, or
require the creation or imposition of, any Lien on any of the Borrower's
properties.

     SECTION  6.3.       Government Approval, Regulation, etc.  No authorization
or approval or other action by, and no notice to or filing with, any
governmental authority or regulatory body or other Person is required for the
due execution, delivery or performance by the Borrower of this Agreement, the
Notes or any other Loan Document. Neither the Borrower nor any of its
Subsidiaries is an "investment company" within the meaning of the Investment
Company Act of 1940, as amended, or a "holding company", or a "subsidiary
company" of a "holding company", or an "affiliate" of a "holding company" or of
a "subsidiary company" of a "holding company", within the meaning of the Public
Utility Holding Company Act of 1935, as amended.

     SECTION  6.4.       Validity, etc.  This Agreement constitutes, and the
Notes and each other Loan Document executed by the Borrower will, on the due
execution and delivery thereof, constitute, the legal, valid and binding
obligations of the Borrower enforceable in accordance with their respective
terms except as enforceability may be limited by applicable bankruptcy,
insolvency, reorganization, moratorium or similar laws affecting the enforcement
of creditors' rights generally.

     SECTION  6.5.       Financial Information.  The consolidated balance sheet
of the Borrower and its Subsidiaries as at June 30, 1998, and the related
consolidated statements of earnings and cash flows of the Borrower and its
Subsidiaries, copies of which have been furnished to the Agent and each Lender,
have been prepared in accordance with GAAP consistently applied, and present
fairly the consolidated financial condition of the Borrower and its Subsidiaries
as at the date thereof and the results of their operations for the period then
ended.

     SECTION  6.6.       No Material Adverse Change.  Since the date of the
financial statements described in Section 6.5, other than changes resulting from
fluctuations in oil and gas prices, there has been no material adverse change in
the financial condition, operations, assets, business, properties or prospects
of the Borrower and its Subsidiaries, taken as a whole, except as disclosed in
Item 6.6 of the Disclosure Schedule.

     SECTION  6.7.       Litigation, Labor Controversies, etc.  There is no
pending or, to the knowledge of the Borrower, threatened litigation, action,
proceeding, or labor controversy affecting the Borrower or any of its
Subsidiaries, or any of their respective properties, businesses, assets or
revenues, which may materially adversely affect the financial condition,
operations, assets, business, properties or prospects of the Borrower and its
Subsidiaries, taken as a whole, or which purports to affect the legality,
validity or enforceability of this Agreement, the Notes or any other Loan
Document, except as disclosed in Item 6.7 ("Litigation") of the Disclosure
Schedule.

                                       39
<PAGE>
 
     SECTION  6.8.       Subsidiaries.  The Borrower has no Subsidiaries, except
those Subsidiaries which are identified in Item 6.8 ("Existing Subsidiaries") of
the Disclosure Schedule.

     SECTION  6.9.       Ownership of Properties.  The Borrower and each of its
Subsidiaries owns good and defensible title to all of its properties and assets,
real and personal, tangible and intangible, of any nature whatsoever (including
patents, trademarks, trade names, service marks and copyrights), free and clear
of all Liens, charges or claims (including infringement claims with respect to
patents, trademarks, copyrights and the like), except those which would not have
a material adverse effect on the financial conditions, operations, assets,
business, properties or prospects of the Borrower and its Subsidiaries, taken as
a whole, and except as permitted pursuant to Section 7.2.3. For the purposes of
this representation, good and defensible title shall mean record title which may
be subject to minor defects and irregularities which (a) do not materially
reduce Borrower's net revenue interests or increase Borrower's working interests
(without a corresponding and proportional increase in Borrower's net revenue
interests) therein, and (b) are not likely to interfere materially with the
benefit and enjoyment of production from such properties.

     SECTION  6.10.      Taxes.  To the best of the Borrower's knowledge,
Borrower and each of its Subsidiaries has filed all tax returns and reports
required by law to have been filed by it and has paid all taxes and governmental
charges thereby shown to be owing, except any such taxes or charges which are
being diligently contested in good faith by appropriate proceedings and for
which adequate reserves in accordance with GAAP shall have been set aside on its
books.

     SECTION  6.11.      Pension and Welfare Plans.  No steps have been taken to
terminate any Pension Plan, and no contribution failure has occurred with
respect to any Pension Plan sufficient to give rise to a Lien under section
302(f) of ERISA.  No condition exists or event or transaction has occurred with
respect to any Pension Plan which might result in the incurrence by the Borrower
or any member of the Controlled Group of any material liability, fine or
penalty. Neither the Borrower nor any member of the Controlled Group has any
contingent liability with respect to any post-retirement benefit under a Welfare
Plan, other than liability for continuation coverage described in Part 6 of
Title I of ERISA.

     SECTION  6.12.      Environmental Warranties.  To the best of Borrower's
knowledge after reasonable investigation, except as set forth in Item 6.12
("Environmental Matters") of the Disclosure Schedule:  (a) all facilities and
property (including underlying groundwater) owned or leased by the Borrower or
any of its Subsidiaries have been, and continue to be, owned or leased by the
Borrower and its Subsidiaries in material compliance with all Environmental
Laws; (b) there have been no past, and there are no pending or threatened (i)
claims, complaints, notices or requests for information received by the Borrower
or any of its Subsidiaries with respect to any alleged violation of any
Environmental Law, or (ii) complaints, notices or inquiries to the Borrower or
any of its Subsidiaries regarding potential liability under any Environmental
Law; (c) there have been no Releases (or, in Argentina, release) of Hazardous
Materials at, on or under any property now or previously owned or leased by the
Borrower or any of its Subsidiaries that, singly or in the aggregate, have, or
may reasonably be expected to have, a material adverse effect on the financial
condition, operations, assets, business, properties or prospects of the Borrower
and its Subsidiaries, taken as a whole; (d) the Borrower and its Subsidiaries
have been issued and are in material compliance with all permits, certificates,
approvals, licenses and other authorizations relating to environmental 

                                       40
<PAGE>
 
matters and necessary or desirable for their businesses; (e) no property now or
previously owned or leased by the Borrower or any of its Subsidiaries is listed
or proposed for listing (with respect to owned property only) on the National
Priorities List pursuant to CERCLA, on the CERCLIS or on any similar state list
of sites requiring investigation or clean-up; (f) there are no underground
storage tanks, active or abandoned, including petroleum storage tanks, on or
under any property now or previously owned or leased by the Borrower or any of
its Subsidiaries that, singly or in the aggregate, have, or may reasonably be
expected to have, a material adverse effect on the financial condition,
operations, assets, business, properties or prospects of the Borrower and its
Subsidiaries, taken as a whole; (g) neither Borrower nor any Subsidiary of the
Borrower has directly transported or directly arranged for the transportation of
any Hazardous Material to any location which is listed or proposed for listing
on the National Priorities List pursuant to CERCLA, on the CERCLIS or on any
similar state list or which is the subject of federal, state or local
enforcement actions or other investigations which may lead to material claims
against the Borrower or such Subsidiary thereof for any remedial work, damage to
natural resources or personal injury, including claims under CERCLA; (h) there
are no polychlorinated biphenyls or friable asbestos present at any property now
or previously owned or leased by the Borrower or any Subsidiary of the Borrower
that, singly or in the aggregate, have, or may reasonably be expected to have, a
material adverse effect on the financial condition, operations, assets,
business, properties or prospects of the Borrower and its Subsidiaries, taken as
a whole; and (i) no conditions exist at, on or under any property now or
previously owned or leased by the Borrower or any Subsidiary which, with the
passage of time, or the giving of notice or both, would give rise to liability
under any Environmental Law which singly or in the aggregate have, or may
reasonably be expected to have, a material adverse effect on the financial
condition, operations, assets, business, properties or prospects of the Borrower
and its Subsidiaries, taken as a whole.

     SECTION  6.13.      Regulations  U and X.  The Borrower is not engaged in
the business of extending credit for the purpose of purchasing or carrying
margin stock, and no proceeds of any Loans will be used for a purpose which
violates, or would be inconsistent with, F.R.S. Board Regulation U or X. Terms
for which meanings are provided in F.R.S. Board Regulation U or X or any
regulations substituted therefor, as from time to time in effect, are used in
this Section with such meanings.

     SECTION  6.14.      Accuracy of Information.  All factual information
heretofore or contemporaneously furnished by or on behalf of the Borrower in
writing to the Agent or any Lender or Issuer for purposes of or in connection
with this Agreement or any transaction contemplated hereby is, and all other
such factual information hereafter furnished by or on behalf of the Borrower to
the Agent or any Lender or Issuer will be, true and accurate in every material
respect on the date as of which such information is dated or certified and as of
the date of execution and delivery of this Agreement by the Agent and such
Lender or Issuer, and such information is not, or shall not be, as the case may
be, incomplete by omitting to state any material fact necessary to make such
information not misleading.

     SECTION  6.15.      No Default.  Neither the Borrower nor any Subsidiary is
in default in any respect materially and adversely affecting the business,
property, assets, operations or condition, financial or otherwise, of the
Borrower and its Subsidiaries, taken as a whole, with respect to any indenture,
mortgage, deed of trust or other agreement or instrument to which the Borrower
is a party or by which the Borrower or its properties is/are bound or affected.

                                       41
<PAGE>
 
     SECTION  6.16.      No Violation of Applicable Law.  To the best of the
Borrower's knowledge, neither the Borrower nor any of its Subsidiaries has
violated any applicable statute, regulation or ordinance of the United States of
America or any foreign country, or any state, municipality or other
jurisdiction, or of any agency thereof in any respect materially and adversely
affecting the business, property, assets, operations or condition, financial or
otherwise, of Borrower and its Subsidiaries, taken as a whole, and the Borrower
has not received any notice of probable violation from the Department of Energy
or the Environmental Protection Agency.  The Borrower is using the Borrower's
best efforts to comply or cause its Subsidiaries to comply with all statutes,
rules and regulations relating to environmental standards and controls in all
jurisdictions where the Borrower and its Subsidiaries are presently doing
business.

     SECTION  6.17.      Permits.  The Borrower and its Subsidiaries have all
governmental and private permits, certificates, consents and franchises which in
any respect are material to the business, property, assets, operations or
condition, financial or otherwise, of the Borrower and its Subsidiaries to carry
on the Borrower's and such Subsidiaries' business as now being conducted, and to
own or lease and operate the Borrower's and such Subsidiaries' properties as now
owned or leased.  All such governmental and private permits, certificates,
consents and franchises are valid and subsisting, and the Borrower and its
Subsidiaries are not in violation thereof in a manner which would have a
material and adverse effect thereon.

     SECTION  6.18.      Year 2000 Matters.  In order to avoid a material
adverse effect on the Borrower and its Subsidiaries taken as a whole, any
reprogramming required to permit the proper functioning in all material respects
(but only to the extent that such proper functioning would otherwise be impaired
by the occurrence of the year 2000) in and following the year 2000, of computer
systems and other equipment containing embedded microchips, in either case owned
or operated by Borrower or any Subsidiaries or used or relied upon in the
conduct of their business (including, to the Borrower's knowledge, any such
systems and other equipment supplied by others or with which the computer
systems of Borrower or any of its Subsidiaries interface), and the testing of
all such systems and other equipment as so reprogrammed, will be completed by
December 31, 1999. The costs to the Borrower and its Subsidiaries that have not
been incurred as of the date hereof for such reprogramming and testing and for
the other reasonably foreseeable consequences to them of any improper
functioning of other computer systems and equipment containing embedded
microchips due to the occurrence of the year 2000 could not reasonably be
expected to result in a Default or Event of Default or to have a material
adverse effect on the Borrower and its Subsidiaries taken as a whole. Except for
any reprogramming referred to above, the computer systems of the Borrower and
its Subsidiaries are and, with ordinary course upgrading and maintenance, will
continue for the term of this Agreement to be in all material respects,
sufficient for the conduct of their business as currently conducted.

                                       42
<PAGE>
 
                                 ARTICLE  VII

                                   COVENANTS

     SECTION  7.1.       Affirmative Covenants.  The Borrower agrees with the
Agent and each Lender that, until all Commitments have terminated and all
Obligations have been paid and performed in full, the Borrower will perform the
obligations set forth in this Section 7.1.

     SECTION  7.1.1.     Financial Information, Reports, Notices, etc.  The
Borrower will furnish, or will cause to be furnished, to each Lender and the
Agent copies of the following financial statements, reports, notices and
information: (a) as soon as available and in any event within 45 days after the
end of each of the first three Fiscal Quarters of each Fiscal Year of the
Borrower, consolidated balance sheets of the Borrower and its Subsidiaries as of
the end of such Fiscal Quarter and consolidated statements of earnings and cash
flows of the Borrower and its Subsidiaries for such Fiscal Quarter and for the
period commencing at the end of the previous Fiscal Year and ending with the end
of such Fiscal Quarter, certified by the chief accounting or financial
Authorized Officer of the Borrower; (b) as soon as available and in any event
within 120 days after the end of each Fiscal Year of the Borrower, a complete
copy of the annual audit report for such Fiscal Year for the Borrower and its
Subsidiaries, including therein consolidated balance sheets of the Borrower and
its Subsidiaries as of the end of such Fiscal Year and consolidated statements
of earnings and cash flows of the Borrower and its Subsidiaries for such Fiscal
Year, in each case certified (without any Impermissible Qualification) by Arthur
Andersen LLP or other independent public accountants selected by the Borrower
and reasonably acceptable to the Agent and the Required Lenders, together with a
certificate from such accountants (i) containing a computation of, and showing
compliance with, each of the financial ratios and restrictions contained in
Section 7.2.4 and (ii) containing a computation of the Consolidated Interest
Coverage Ratio (as defined in the Indenture) as of the date of such statements
and to the effect that, in making the examination necessary for the signing of
such annual report by such accountants, they have not become aware of any
Default or Event of Default that has occurred and is continuing, or, if they
have become aware of such Default or Event of Default, describing such Default
or Event of Default and the steps, if any, being taken to cure it; (c) as soon
as available and in any event within 45 days after the end of each Fiscal
Quarter, a certificate, executed by the chief accounting or financial Authorized
Officer of the Borrower, showing (in reasonable detail and with appropriate
calculations and computations in all respects satisfactory to the Agent) (i)
compliance with the financial covenants set forth in Section 7.2.4 and (ii)
containing a computation of the Consolidated Interest Coverage Ratio (as defined
in the Indenture) as of the date of such statements; (d) forthwith upon the
occurrence of each Default, a statement of the chief accounting or financial
Authorized Officer of the Borrower setting forth details of such Default and the
action which the Borrower has taken and proposes to take with respect thereto;
(e) as soon as possible and in any event within three days after (i) the
occurrence of any adverse development with respect to any litigation, action,
proceeding, or labor controversy described in Section 6.7, or (ii) the
commencement of any labor controversy, litigation, action or proceeding of the
type described in Section 6.7, notice thereof and copies of all documentation
relating thereto; (f) promptly after the sending or filing thereof, copies of
all reports which the Borrower sends to any of its security holders, and all
reports and registration statements which the Borrower or any of its
Subsidiaries files with the Securities and Exchange Commission or any national
securities exchange; (g) immediately

                                       43
<PAGE>
 
upon becoming aware of the institution of any steps by the Borrower or any other
Person to terminate any Pension Plan, or the failure to make a required
contribution to any Pension Plan, if such failure is sufficient to give rise to
a Lien under section 302(f) of ERISA, or the taking of any action with respect
to a Pension Plan which could result in the requirement that the Borrower
furnish a bond or other security to the PBGC or such Pension Plan, or the
occurrence of any event with respect to any Pension Plan which could result in
the incurrence by the Borrower of any material liability, fine or penalty, or
any material increase in the contingent liability of the Borrower with respect
to any post-retirement Welfare Plan benefit, notice thereof and copies of all
documentation relating thereto; and (h) such other information respecting the
condition or operations, financial or otherwise, of the Borrower or any of its
Subsidiaries as any Lender through the Agent may from time to time reasonably
request.

     SECTION  7.1.2.     Compliance with Laws, etc.  The Borrower will, and will
cause each of its Subsidiaries to, comply in all material respects with all
applicable laws, rules, regulations and orders, such compliance to include
(without limitation) the payment, before the same become delinquent, of all
taxes, assessments and governmental charges imposed upon it or upon its property
except to the extent being diligently contested in good faith by appropriate
proceedings and for which adequate reserves in accordance with GAAP shall have
been set aside on its books.  The Borrower will maintain and preserve its
corporate existence and qualification as a foreign corporation.

     SECTION  7.1.3.     Maintenance of Properties.  The Borrower will, and will
cause each of its Subsidiaries to, maintain, preserve, protect and keep its
material properties in good repair, working order and condition, and make
necessary and proper repairs, renewals and replacements so that its business
carried on in connection therewith may be properly conducted at all times, all
in accordance with approved practices of prudent operators and standards
prevailing in the oil and gas industry and within limits imposed by joint
operating agreements.

     SECTION  7.1.4.     Insurance.  The Borrower will, and will cause each of
its Subsidiaries to, maintain or cause to be maintained, with responsible
insurance companies insurance with respect to its properties and business
against such casualties and contingencies and of such types and in such amounts
as is customary in the case of similar businesses and will, upon request of the
Agent, furnish to each Lender at reasonable intervals a certificate of an
Authorized Officer of the Borrower setting forth the nature and extent of all
insurance maintained by the Borrower and its Subsidiaries in accordance with
this Section.

     SECTION  7.1.5.     Books and Records.  The Borrower will, and will cause
each of its Subsidiaries to, keep books and records which accurately reflect all
of its business affairs and transactions and permit the Agent and each Lender
and Issuer or any of their respective representatives, at reasonable times and
intervals, to visit all of its offices, to discuss its financial matters with
its officers and to examine any of its books or other corporate records.

     SECTION  7.1.6.     Environmental Covenant.  The Borrower will, and will
cause each of its Subsidiaries to (a) use and operate all of its facilities and
properties in material compliance with all Environmental Laws, keep all
necessary permits, approvals, certificates, licenses and other authorizations
relating to environmental matters in effect and remain in material compliance

                                       44
<PAGE>
 
therewith, and handle all Hazardous Materials in material compliance with all
applicable Environmental Laws; (b) immediately notify the Agent and provide
copies upon receipt of all written claims, complaints, notices or inquiries
relating to the condition of its facilities and properties or compliance with
Environmental  Laws, and shall promptly cure and have dismissed with prejudice
any actions and proceedings relating to compliance with Environmental Laws; and
(c) provide such information and certifications which the Agent may reasonably
request from time to time to evidence compliance with this Section 7.1.6.

     SECTION  7.1.7.     Employee Benefit Plans.  With respect to each Plan of
Borrower, if any:  (a) at all times make prompt payments of contributions with
respect to each such Plan, so as to meet the minimum funding standards required
by sections 302 through 305 of ERISA; (b) upon the receipt of reasonable written
request from the Lenders, promptly furnish the Lenders with copies of each
report required to be filed pursuant to (S)103 of ERISA in connection with such
Plan for each plan-year, including any certified financial statements or
actuarial statements required under said (S)103; (c) immediately notify the
Lenders of any fact, including, but not limited to, any "Reportable Event" (as
that term is defined in (S)4043 of ERISA) arising in connection with any such
Plan which might constitute grounds for the termination thereof or for the
appointment by the appropriate United States District Court of a trustee to
administer such Plan, and, within thirty (30) days after the occurrence of any
Reportable Event, deliver to the Lenders a statement from Borrower's President
detailing such Reportable Event and Borrower's proposed action with respect
thereto; and (d) promptly upon their request therefor, furnish the Lenders such
additional information concerning any such Plan as the Lenders may reasonably
request.

     SECTION  7.1.8      Designated Senior Indebtedness.  The Borrower and the
Lenders hereby agree that all Obligations of the Borrower pursuant to this
Agreement and each other Loan Document constitute Designated Senior Indebtedness
(as defined in the Indenture) for purposes of the Indenture.  The Borrower
furthermore agrees that it shall deliver all notices and take such other action
as may be required by the Indenture such that the Obligations of the Borrower
under this Agreement shall at all times constitute Designated Senior
Indebtedness.

     SECTION  7.2.       Negative Covenants.  The Borrower agrees with the Agent
and each Lender and Issuer that, until all Commitments have terminated and all
Obligations have been paid and performed in full, the Borrower will perform the
obligations set forth in this Section 7.2.

     SECTION  7.2.1.     Business Activities.  The Borrower will not, and will
not permit any of its Subsidiaries to, engage in any business activity, except
those described in the first recital and such activities as may be incidental or
related thereto.

     SECTION  7.2.2.     Indebtedness.  The Borrower will not, and will not
permit any of its Subsidiaries to, create, incur, assume or suffer to exist or
otherwise become or be liable in respect of any Indebtedness, other than,
without duplication, the following: (a) Indebtedness in respect of the Loans and
other Obligations; (b) Indebtedness existing as of the Effective Date which is
identified in Item 7.2.2(c) ("Ongoing Indebtedness") of the Disclosure Schedule;
(c) unsecured trade debt incurred in the ordinary course of business (including
open accounts extended by suppliers on normal trade terms in connection with
purchases of goods and services, but excluding Indebtedness incurred through the
borrowing of money or Contingent Liabilities); (d) lease obligations under

                                       45
<PAGE>
 
leases covering Borrower's or any of its Subsidiary's business premises (which
shall include storage yard facilities); (e) lease obligations arising from the
leasing of equipment located upon the Borrower's properties and utilized in the
production of oil and gas therefrom; (f) lease obligations, not to exceed
$1,000,000 in any Fiscal Year arising from the lease of equipment used in the
ordinary course of business of the Borrower and its Subsidiaries; (g) current
indebtedness to operators under joint operating agreements or compulsory pooling
orders; (h) advances made as operator on behalf of non-operators pursuant to
joint operating agreements or pooling orders; (i) Other Letters of Credit of the
Borrower, provided such reimbursement obligations in respect thereof are not in
excess of $50,000,000 at any time outstanding in the aggregate; (j) funds held
for and payments due to third parties from production from properties; (k)
Indebtedness of the Borrower's Subsidiaries owing to the Borrower or to other
Subsidiaries of the Borrower and unsecured Indebtedness of the Borrower owing to
its Subsidiaries; (l) deferred tax liability; (m) Indebtedness of the Borrower
in an outstanding amount not to exceed $50,000,000 in the aggregate, plus
interest and premium, if any; (n) the guaranties by the Borrower of the
obligations of its Subsidiaries otherwise permitted by the terms of this
Agreement, provided that the aggregate outstanding principal amount of
Indebtedness and other obligations of Subject Subsidiaries guaranteed by the
Borrower shall not exceed $25,000,000 at any time; (o) Indebtedness of any
Subject Subsidiary, provided that such Indebtedness shall not be a direct
obligation or Contingent Liability of the Borrower or any other Subsidiary of
the Borrower except as permitted by clause (n) above; (p) the Borrower's
outstanding $150,000,000 9% Senior Subordinated Notes Due 2005; (q) Indebtedness
in respect of Hedging Obligations, provided that such Hedging Obligations in
respect of oil and gas do not exceed volumes with respect to any year in excess
of 80% of the projected production attributable to the Borrower's and its
Subsidiaries' then proved developed oil and gas properties in respect of such
year; and (r) the Borrower's outstanding $100,000,000 8-5/8% Senior Subordinated
Notes Due 2009.

     SECTION  7.2.3.     Liens.  The Borrower will not, and will not permit any
of its Subsidiaries (other than any Subject Subsidiary) to, create, incur,
assume or suffer to exist any Lien upon any of its property, revenues or assets,
whether now owned or hereafter acquired, except: (a) Liens granted prior to the
Effective Date to secure payment of Indebtedness of the type permitted and
described in clause (b) of Section 7.2.2; (b) Liens for taxes, assessments or
other governmental charges or levies not at the time delinquent or thereafter
payable without penalty or being diligently contested in good faith by
appropriate proceedings and for which adequate reserves in accordance with GAAP
shall have been set aside on its books; (c) Liens of carriers, warehousemen,
mechanics, materialmen and landlords incurred in the ordinary course of business
for sums not overdue or being diligently contested in good faith by appropriate
proceedings and for which adequate reserves in accordance with GAAP shall have
been set aside on its books; (d) encumbrances created by production sales
contracts, joint operating agreements and other contracts entered into in the
normal course of Borrower's business for exploration, development and/or
operation of the Borrower's properties; (e) easements, servitudes and other
rights of user which do not materially interfere with the use of such assets;
(f) other minor burdens and defects of or in title which do not secure the
payment of money, other than as described in clause (a); (g) those and only
those lease burdens previously disclosed to the Lenders in writing and existing
operating agreements, farmout agreements and other agreements and contractual
obligations related to the Borrower's properties; (h) Liens incurred in the
ordinary course of business in connection with workmen's compensation,
unemployment insurance or other forms of governmental insurance or benefits, or
to secure performance of tenders, statutory obligations, leases and contracts
(other than for borrowed money)

                                       46
<PAGE>
 
entered into in the ordinary course of business or to secure obligations on
surety or appeal bonds; (i) judgment Liens in existence less than 15 days after
the entry thereof or with respect to which execution has been stayed or the
payment of which is covered in full (subject to a customary deductible) by
insurance maintained with responsible insurance companies; (j) Liens affecting
the property of the Subject Subsidiaries only securing Indebtedness permitted by
clause (o) of Section 7.2.2; (k) the Lien granted to Exxon Company, U.S.A. prior
to the Effective Date covering property described in Exhibit H; (l) Liens on
cash collateral delivered pursuant to Section 2.8.7; and (m) Liens granted
pursuant to Section 4.9.

     SECTION  7.2.4.     Financial Condition.  The Borrower will not permit: (a)
its Tangible Net Worth to be less than the sum of $250,000,000 plus 75% of the
proceeds from third parties of the sale by the Borrower and its Subsidiaries of
securities (other than securities constituting Indebtedness) net of reasonable
incidental, brokerage, underwriting and legal costs actually paid to third
parties in connection therewith, less any impairment writedowns required by GAAP
or by the Securities and Exchange Commission; and (b) its Current Ratio as of
the end of any Fiscal Quarter to be less than 1:1; provided that for purposes
hereof, any unused portion of the Revolving Period Commitment Amount will be
deemed a current asset.

     SECTION  7.2.5.     Take or Pay Contracts.  The Borrower will not, and will
not permit any of its Subsidiaries to, enter into or be a party to any
arrangement for the purchase of materials, supplies, other property or services
if such arrangement by its express terms requires that payment be made by the
Borrower or such Subsidiary regardless of whether such materials, supplies,
other property or services are delivered or furnished to it.

     SECTION  7.2.6.     Consolidation, Merger, etc.  The Borrower will not, and
will not permit any of its Subsidiaries to, liquidate or dissolve, consolidate
with, or merge into or with, any other corporation, or purchase or otherwise
acquire all or substantially all of the assets of any Person (or of any division
thereof) except (a) any such Subsidiary may liquidate or dissolve voluntarily
into, and may merge with and into, the Borrower or any other Subsidiary of the
Borrower, and the assets or stock of any Subsidiary of the Borrower may be
purchased or otherwise acquired by the Borrower or any other Subsidiary of the
Borrower; provided, that no Subsidiary of the Borrower which is not a Subject
Subsidiary may dissolve or liquidate voluntarily into, and neither the Borrower
nor any Subsidiary of the Borrower which is not a Subject Subsidiary may merge
with or into, any Subject Subsidiary unless the Borrower or such Subsidiary
which is not a Subject Subsidiary is the surviving entity, and the assets or
stock of any Subsidiary of the Borrower which is not a Subject Subsidiary may
not be purchased or otherwise acquired by any Subject Subsidiary; and (b) so
long as no Default has occurred and is continuing or would occur after giving
effect thereto, the Borrower or any of its Subsidiaries may purchase all or
substantially all of the assets of any Person, or acquire such Person by merger.

     SECTION  7.2.7.     Asset Dispositions, etc.  The Borrower will not, and
will not permit any of its Subsidiaries to, sell, transfer, lease, contribute or
otherwise convey, exchange or lease, or grant options, warrants or other rights
with respect to, all or any substantial part of its assets (including accounts
receivable and capital stock of Subsidiaries) to any Person (including any
Subject Subsidiary), unless it has either given Lenders 15 Business Days prior
written notice thereof or the aggregate consideration for all such sales,
transfers, conveyances, exchanges or leases made

                                       47
<PAGE>
 
in any six month period ending June 30 or December 31 is less than Twenty-five
Million Dollars ($25,000,000). Notwithstanding anything to the contrary in this
Agreement, the Borrower will not, and will not permit any of its Subsidiaries
(other than a Subject Subsidiary) to, sell, transfer, lease, contribute or
otherwise convey, exchange or lease, or grant options, warrants or other rights
with respect to, all or any substantial part of its assets (including accounts
receivable and capital stock of Subsidiaries) to any Subject Subsidiary. In the
event that the Borrower and its Subsidiaries shall sell, transfer, lease,
contribute or otherwise convey, exchange or lease properties in excess of 
Twenty-five Million Dollars ($25,000,000) in the aggregate in any six month
period ending June 30 or December 31, the Applicable Lenders shall have the
option to reduce the Borrowing Base.

     SECTION  7.2.8.     Guaranties, Loans or Advances.  Other than Borrower's
Indebtedness hereunder and other than pursuant to Borrower's current and future
employees' stock option plans, the Borrower will not become or be a guarantor or
surety of, or otherwise become or be responsible in any manner (whether by
agreement to purchase or repurchase any obligation, stock, assets, goods or
services, or to supply or advance any funds, assets, goods or services, or
otherwise, whether directly or indirectly) with respect to, any undertaking of
any other person or entity, nor make or permit to exist any loans or advances to
any other Persons which in the aggregate exceed the amount of $500,000 at any
time outstanding, except for (a) the endorsement, in the ordinary course of
collection, of instruments payable to Borrower, or its order; (b) advances made
and liabilities existing under joint operating agreements and compulsory pooling
orders; (c) the liability to account to third persons for their share of
production proceeds received by Borrower; (d) loans and advances to employees
for the sole purpose of permitting such employees to purchase shares of
Borrower's capital stock; (e) loans and advances to employees of the Borrower
and its Subsidiaries for travel and other business expenses; (f)loans and
advances by the Borrower to any of its Subsidiaries or by any Subsidiary of the
Borrower to the Borrower or any other Subsidiary of the Borrower; and (g)
guaranties by the Borrower of obligations of its Subsidiaries otherwise
permitted pursuant to this Agreement, provided that the aggregate outstanding
principal amount of Indebtedness and other obligations of Subject Subsidiaries
so guaranteed shall not at any time exceed $25,000,000 in the aggregate.

     SECTION  7.2.9.     Other Agreements.  The Borrower will not enter into any
agreement containing any provision which would be violated or breached by the
performance of its obligations hereunder or under any instrument or document
delivered or to be delivered by it hereunder or in connection herewith.

     SECTION  7.2.10.    Transactions with Affiliates.  The Borrower will not,
and will not permit any of its Subsidiaries to, enter into, or cause, suffer or
permit to exist any arrangement or contract with any of its other Affiliates
unless such arrangement or contract is determined by the Board of Directors of
the Borrower to be (a) fair and equitable to the Borrower or such Subsidiary and
(b) an arrangement or contract of the kind which would be entered into by a
prudent Person in the position of the Borrower or such Subsidiary with a Person
which is not one of its Affiliates.

     SECTION  7.2.11.    Negative Pledges, Restrictive Agreements, etc.  The
Borrower will not, and will not permit any of its Subsidiaries to, enter into
any agreement (excluding this Agreement, any other Loan Document, and any
agreement governing any Indebtedness permitted by clause (b), (p) or (r) of
Section 7.2.2) prohibiting (a) the creation or assumption of any Lien upon

                                       48
<PAGE>
 
its properties, revenues or assets (other than the properties, revenues or
assets of the Subject Subsidiaries) whether now owned or hereafter acquired, or
the ability of the Borrower to amend or otherwise modify this Agreement or any
other Loan Document; or (b) the ability of any Subsidiary (other than a Subject
Subsidiary) to make any payments, directly or indirectly, to the Borrower by way
of dividends, advances, repayments of loans or advances, reimbursements of
management and other intercompany charges, expenses and accruals or other
returns on investments, or any other agreement or arrangement which restricts
the ability of any such Subsidiary (other than a Subject Subsidiary) to make any
payment, directly or indirectly, to the Borrower. Notwithstanding the foregoing,
any agreement governing any Indebtedness permitted by clause (p) or (r) of
Section 7.2.2 shall not prohibit the creation or assumption of any Lien upon the
properties, revenues or assets of the Borrower or any Subsidiary (other than a
Subject Subsidiary), whether now owned or hereafter acquired securing any Senior
Debt, and no agreement governing any Indebtedness permitted by clause (p) or (r)
of Section 7.2.2 shall prohibit the ability of any Subsidiary (other than a
Subject Subsidiary) to make any payments, directly or indirectly, to the
Borrower or the ability of the Borrower to amend or otherwise modify this
Agreement or any other Loan Document.

     SECTION  7.2.12.    Investment in Subsidiaries.  If any Default or Event of
Default shall have occurred and is continuing or during any period in which the
aggregate principal amount of Senior Debt shall exceed the Borrowing Base then
in effect, the Borrower shall not, and shall not permit any of its Subsidiaries
which are not Subject Subsidiaries to, incur any Contingent Liabilities for any
Indebtedness or other obligations of any Subject Subsidiary, make any loan or
advance to, or assume, redeem, purchase, defease, pay or forgive any
Indebtedness or other obligation of, or make any equity investment in, or incur
any Indebtedness on behalf of, any Subsidiary and the Borrower shall not, and
shall not permit any of its Subsidiaries which are not Subject Subsidiaries to,
apply any of its funds, property or assets to the purchase, redemption, sinking
fund for or other retirement of any shares of any class of capital stock of a
Subsidiary or warrants, options or other rights with respect to any shares of
any class of such capital stock or any Indebtedness or obligations of any
Subsidiary.

     SECTION  7.2.13.    Acquisition of Capital Stock.  The Borrower will not,
and will not permit any of its Subsidiaries to, purchase, redeem or otherwise
acquire for value any shares of the capital stock in the Borrower or any
warrants, rights or options to acquire such shares now or hereafter outstanding
(other than in connection with employee benefit plans of Borrower or redemption
or exchange of preferred share purchase rights under a stockholder rights plan
of Borrower) if, immediately after giving effect to such purchase, redemption or
acquisition, the Borrower's and its Subsidiaries' outstanding Senior Debt plus
the Bolivian Letter of Credit Outstandings exceed the Borrowing Base in effect
at the time.

                                 ARTICLE  VII

                               EVENTS OF DEFAULT

     SECTION  8.1.       Listing of Events of Default.  Each of the following
events or occurrences described in this Section 8.1 shall constitute an "Event
of Default".

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<PAGE>
 
     SECTION  8.1.1      Non-Payment of Obligations.  The Borrower shall default
in the payment or prepayment when due of any principal of or interest on any
Loan or any Reimbursement Obligations, or the Borrower shall default in the
payment when due of any commitment fee or any letter of credit fees or of any
other Obligation.

     SECTION  8.1.2.     Breach of Warranty.  Any representation or warranty of
the Borrower made or deemed to be made hereunder or in any other Loan Document
or any other writing or certificate furnished by or on behalf of the Borrower to
the Agent or any Lender for the purposes of or in connection with this Agreement
or any such other Loan Document (including any certificates delivered pursuant
to Article V) is or shall be incorrect when made in any material respect.

     SECTION  8.1.3.     Non-Performance of Certain Covenants and Obligations.  
The Borrower shall default in the due performance and observance of any of its
obligations under Sections 7.2.4 or 7.2.8.

     SECTION  8.1.4.     Non-Performance of Other Covenants and Obligations.  
The Borrower shall default in the due performance and observance of any other
agreement contained herein or in any other Loan Document, and such default shall
continue unremedied for a period of 15 days after the Borrower shall become
aware of such default, whether by notice thereof given to the Borrower by the
Agent or any Lender or otherwise.

     SECTION  8.1.5.     Default on Other Indebtedness.  A default shall occur
in the payment when due (subject to any applicable grace period), whether by
acceleration or otherwise, of any Indebtedness for borrowed money (other than
Indebtedness described in Section 8.1.1) or Contingent Liability of the Borrower
or any of its Subsidiaries, or a default shall occur in the performance or
observance of any obligation or condition with respect to such Indebtedness if
the effect of such default is to accelerate the maturity of any such
Indebtedness or such default shall continue unremedied for any applicable period
of time sufficient to permit the holder or holders of such Indebtedness, or any
trustee or agent for such holders, to cause such Indebtedness to become due and
payable prior to its expressed maturity.

     SECTION  8.1.6.     Other Material Obligations.  Default in the payment for
a period in excess of sixty (60) days of when due, or in the performance or
observance of any material obligation of, or condition agreed to by, the
Borrower or any Subsidiary with respect to any material purchase or lease of
goods or services (except those which would not have a material adverse effect
on the financial conditions, operations, assets, business, properties or
prospects of the Borrower and its Subsidiaries, taken as a whole, and except
only to the extent that the existence of any such default is being contested by
the Borrower or such Subsidiary in good faith by appropriate proceedings).

     SECTION  8.1.7.     Judgments.  Any judgment or order for the payment of
money in excess of $20,000,000 (or its equivalent) shall be rendered against the
Borrower or any of its Subsidiaries and either (a) enforcement proceedings shall
have been commenced by any creditor upon such judgment or order; or (b) there
shall be any period of 10 consecutive days during which a stay of enforcement of
such judgment or order, by reason of a pending appeal or otherwise, shall not be
in effect.

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<PAGE>
 
     SECTION  8.1.8.     Pension Plans.  Any of the following events shall occur
with respect to any Pension Plan: (a) the institution of any steps by the
Borrower, any member of its Controlled Group or any other Person to terminate a
Pension Plan if, as a result of such termination, the Borrower or any such
member could be required to make a contribution to such Pension Plan, or could
reasonably expect to incur a liability or obligation to such Pension Plan, in
excess of $1,000,000; or (b) a contribution failure occurs with respect to any
Pension Plan sufficient to give rise to a Lien under section 302(f) of ERISA.

     SECTION  8.1.9.     Bankruptcy, Insolvency, etc.  The Borrower or any of
its Subsidiaries shall (a) become insolvent or generally fail to pay, or admit
in writing its inability or unwillingness to pay, debts as they become due; (b)
apply for, consent to, or acquiesce in, the appointment of a trustee, receiver,
sequestrator or other custodian for the Borrower or any of its Subsidiaries or
any property of any thereof, or make a general assignment for the benefit of
creditors; (c) in the absence of such application, consent or acquiescence,
permit or suffer to exist the appointment of a trustee, receiver, sequestrator
or other custodian for the Borrower or any of its Subsidiaries or for a
substantial part of the property of any thereof, and such trustee, receiver,
sequestrator or other custodian shall not be discharged within 60 days, provided
that the Borrower, for itself and each of its Subsidiaries, hereby expressly
authorizes the Agent and each Lender to appear in any court conducting any
relevant proceeding during such 60-day period to preserve, protect and defend
their rights under the Loan Documents; (d) permit or suffer to exist the
commencement of any bankruptcy, reorganization, debt arrangement or other case
or proceeding under any bankruptcy or insolvency law, or any dissolution,
winding up or liquidation proceeding, in respect of the Borrower or any of its
Subsidiaries, and, if any such case or proceeding is not commenced by the
Borrower or such Subsidiary, such case or proceeding shall be consented to or
acquiesced in by the Borrower or such Subsidiary or shall result in the entry of
an order for relief or shall remain for 60 days undismissed, provided that the
Borrower, for itself and each of its Subsidiaries, hereby expressly authorizes
the Agent and each Lender to appear in any court conducting any such case or
proceeding during such 60-day period to preserve, protect and defend their
rights under the Loan Documents; or (e) take any corporate action authorizing,
or in furtherance of, any of the foregoing.

     SECTION  8.1.10.    Change of Control.  A Change of Control shall occur.

     SECTION  8.2.       Action if Bankruptcy.  If any Event of Default
described in clauses (a) through (d) of Section 8.1.9 shall occur with respect
to the Borrower or any of its Subsidiaries, the Commitments (if not theretofore
terminated) shall automatically terminate and the outstanding principal amount
of all outstanding Loans and all other Obligations shall automatically be and
become immediately due and payable, without notice (including notice of intent
to accelerate and notice of acceleration) or demand and notice and demand, are
hereby waived.

     SECTION  8.3.       Action if Other Event of Default.  If any Event of
Default (other than any Event of Default described in clauses (a) through (d) of
Section 8.1.9 (with respect to the Borrower or any of its Subsidiaries) shall
occur for any reason, whether voluntary or involuntary, and be continuing, the
Agent, upon the direction of the Required Lenders, shall by notice to the
Borrower declare all or any portion of the outstanding principal amount of the
Loans and other Obligations to be due and payable and/or the Commitments (if not
theretofore terminated) to be terminated, whereupon the full unpaid amount of
such Loans and other Obligations which shall be so declared

                                       51
<PAGE>
 
due and payable shall be and become immediately due and payable, without further
notice (including notice of intent to accelerate and notice of acceleration),
demand or presentment, and/or, as the case may be, the Commitments shall
terminate, all of which notice, demand and presentment are hereby waived.


                                  ARTICLE  IX

                                   THE AGENT

     SECTION  9.1.       Actions.  Each Lender hereby appoints Bank of Montreal
as its Agent under and for purposes of this Agreement, the Notes, the Letters of
Credit and each other Loan Document. Each Lender authorizes the Agent and each
Issuer to act on behalf of such Lender under this Agreement, the Notes, the
Letters of Credit and each other Loan Document and, in the absence of other
written instructions from the Required Lenders received from time to time by the
Agent (with respect to which the Agent agrees that it will comply, except as
otherwise provided in this Section or as otherwise advised by counsel), to
exercise such powers hereunder and thereunder as are specifically delegated to
or required of the Agent or such Issuer by the terms hereof and thereof,
together with such powers as may be reasonably incidental thereto. Each Lender
hereby indemnifies (which indemnity shall survive any termination of this
Agreement) the Agent, pro rata according to such Lender's Percentage, from and
against any and all liabilities, obligations, losses, damages, claims, costs or
expenses of any kind or nature whatsoever which may at any time be imposed on,
incurred by, or asserted against, the Agent or such Issuer in any way relating
to or arising out of its services as Agent under this Agreement, the Notes, the
Letters of Credit and any other Loan Document, including reasonable attorneys'
fees, and as to which the Agent or such Issuer is not reimbursed by the
Borrower; provided, however, that no Lender shall be liable for the payment of
any portion of such liabilities, obligations, losses, damages, claims, costs or
expenses which are determined by a court of competent jurisdiction in a final
proceeding to have resulted solely from the Agent's gross negligence or wilful
misconduct. The Agent or any Issuer shall not be required to take any action
hereunder, under the Notes under the Letters of Credit or under any other Loan
Document, or to prosecute or defend any suit in respect of this Agreement, the
Notes, the Letters of Credit or any other Loan Document, unless it is
indemnified hereunder to its satisfaction. If any indemnity in favor of the
Agent or any Issuer shall be or become, in the Agent's determination,
inadequate, the Agent or such Issuer may call for additional indemnification
from the Lenders and cease to do the acts indemnified against hereunder until
such additional indemnity is given.

     SECTION  9.2.       Funding Reliance, etc.  Unless the Agent shall have
been notified by telephone, confirmed in writing, by any Lender by (i) 5:00
p.m., United States Central time, on the day prior to a Borrowing in the case of
LIBO Rate Loans and (ii) 12:00 Noon United States Central time on the day of any
Borrowing in the case of Base Rate Loans that such Lender will not make
available the amount which would constitute its Percentage of such Borrowing on
the date specified therefor, the Agent may assume that such Lender has made such
amount available to the Agent and, in reliance upon such assumption, make
available to the Borrower a corresponding amount. If and to the extent that such
Lender shall not have made such amount available to the Agent, such Lender and
the Borrower severally agree to repay the Agent forthwith on demand such
corresponding amount together with interest thereon, for each day from the date
the Agent made such amount

                                       52
<PAGE>
 
available to the Borrower to the date such amount is repaid to the Agent, at the
interest rate applicable at the time to Loans comprising such Borrowing.

     SECTION  9.3.       Exculpation.  Neither the Agent, any Issuer nor any of
their respective directors, officers, employees or agents shall be liable to any
Lender for any action taken or omitted to be taken by it or them under this
Agreement or any other Loan Document, or in connection herewith or therewith,
except for its or their own wilful misconduct or gross negligence, nor
responsible for any recitals or warranties herein or therein, nor for the
effectiveness, enforceability, validity or due execution of this Agreement or
any other Loan Document, nor to make any inquiry respecting the performance by
the Borrower of its obligations hereunder or under any other Loan Document.  Any
such inquiry which may be made by the Agent or any Issuer shall not obligate it
to make any further inquiry or to take any action.  The Agent and each Issuer
shall be entitled to rely upon advice of counsel concerning legal matters and
upon any notice, consent, certificate, statement or writing which the Agent
believes to be genuine and to have been presented by a proper Person.

     SECTION  9.4.       Successor.  The Agent may resign as such at any time
upon at least 30 days' prior notice to the Borrower and all Lenders. If the
Agent at any time shall resign, the Required Lenders may appoint another Lender
as a successor Agent which shall thereupon become the Agent hereunder. If no
successor Agent shall have been so appointed by the Required Lenders, and shall
have accepted such appointment, within 30 days after the retiring Agent's giving
notice of resignation, then the retiring Agent may, on behalf of the Lenders,
appoint a successor Agent, which shall be one of the Lenders or a commercial
banking institution organized under the laws of the U.S. (or any State thereof)
or a U.S. branch or agency of a commercial banking institution, and having a
combined capital and surplus of at least $500,000,000. Upon the acceptance of
any appointment as Agent hereunder by a successor Agent, such successor Agent
shall be entitled to receive from the retiring Agent such documents of transfer
and assignment as such successor Agent may reasonably request, and shall
thereupon succeed to and become vested with all rights, powers, privileges and
duties of the retiring Agent, and the retiring Agent shall be discharged from
its duties and obligations under this Agreement. After any retiring Agent's
resignation hereunder as the Agent, the provisions of (a) this Article IX shall
inure to its benefit as to any actions taken or omitted to be taken by it while
it was the Agent under this Agreement; and (b) Section 10.3 and Section 10.4
shall continue to inure to its benefit.

     SECTION  9.5.       Loans by Bank of Montreal.  Bank of Montreal shall have
the same rights and powers with respect to (x) the Loans made by it or any of
its Affiliates, and (y) the Notes held by it or any of its Affiliates as any
other Lender and may exercise the same as if it were not the Agent. Bank of
Montreal and its Affiliates may accept deposits from, lend money to, and
generally engage in any kind of business with the Borrower or any Subsidiary or
Affiliate of the Borrower as if Bank of Montreal were not the Agent hereunder.
Each Issuer shall have the same rights and powers hereunder as the other Lenders
and may exercise the same rights and powers as though it were not an Issuer.

     SECTION  9.6.       Credit Decisions.  Each Lender acknowledges that it
has, independently of the Agent and each other Lender, and based on such
Lender's review of the financial information of the Borrower, this Agreement,
the other Loan Documents (the terms and provisions of which being satisfactory
to such Lender) and such other documents, information and

                                       53
<PAGE>
 
investigations as such Lender has deemed appropriate, made its own credit
decision to extend its Commitments. Each Lender also acknowledges that it will,
independently of the Agent and each other Lender, and based on such other
documents, information and investigations as it shall deem appropriate at any
time, continue to make its own credit decisions as to exercising or not
exercising from time to time any rights and privileges available to it under
this Agreement or any other Loan Document.

     SECTION  9.7.       Copies, etc.  The Agent shall give prompt notice to
each Lender of each notice or request required or permitted to be given to the
Agent by the Borrower pursuant to the terms of this Agreement (unless
concurrently delivered to the Lenders by the Borrower). The Agent will
distribute to each Lender each document or instrument received for its account
and copies of all other communications received by the Agent from the Borrower
for distribution to the Lenders by the Agent in accordance with the terms of
this Agreement.

     SECTION  9.8.       Syndication Agent, Documentation Agent.  Neither
NationsBank, N.A., as syndication agent, nor Societe Generale, Southwest Agency,
as documentation agent, shall have any right, power, obligation, liability,
responsibility or duty under this Agreement or the other Loan Documents other
than those applicable to Lenders as Lenders.

                                  ARTICLE  X

                           MISCELLANEOUS PROVISIONS

     SECTION  10.1.      Waivers, Amendments, etc.  The provisions of this
Agreement and of each other Loan Document may from time to time be amended,
modified or waived, if such amendment, modification or waiver is in writing and
consented to by the Borrower and the Required Lenders; provided, however, that
no such amendment, modification or waiver which would: (a) modify any
requirement hereunder that any particular action be taken by all the Lenders or
by the Required Lenders or by the Applicable Lenders shall be effective unless
consented to by each Lender; (b) modify this Section 10.1, change the definition
of "Required Lenders" or "Applicable Lenders", increase any Commitment Amount or
the Percentage of any Lender (except as contemplated by Section 2.1.6), reduce
any fees described in Article III, or extend any Commitment Termination Date
shall be made without the consent of each Lender and each holder of a Note; (c)
(1) extend the due date for or increase the face amount of the Bolivian Letter
of Credit shall be made without the consent of each Lender or (2) extend the due
date for, or reduce the amount of, any scheduled repayment or prepayment of
principal of or interest on any Loan (or reduce the principal amount of or rate
of interest on any Loan) shall be made without the consent of the Lenders; or
(d) affect adversely the interests, rights or obligations of the Agent as the
Agent shall be made without consent of the Agent.

     No failure or delay on the part of the Agent, any Lender, any Issuer or the
holder of any Note in exercising any power or right under this Agreement or any
other Loan Document shall operate as a waiver thereof, nor shall any single or
partial exercise of any such power or right preclude any other or further
exercise thereof or the exercise of any other power or right.  No notice to or
demand on the Borrower in any case shall entitle it to any notice or demand in
similar or other circumstances. No waiver or approval by the Agent, any Lender,
any Issuer or the holder of any Note under this 

                                       54
<PAGE>
 
Agreement or any other Loan Document shall, except as may be otherwise stated in
such waiver or approval, be applicable to subsequent transactions. No waiver or
approval hereunder shall require any similar or dissimilar waiver or approval
thereafter to be granted hereunder.

     SECTION  10.2.      Notices.  All notices and other communications provided
to any party hereto under this Agreement or any other Loan Document shall be in
writing or by facsimile and addressed, delivered or transmitted to such party at
its address or facsimile number set forth below its signature hereto or set
forth in the Lender Assignment Agreement or at such other address or facsimile
number as may be designated by such party in a notice to the other parties. Any
notice, if mailed and properly addressed with postage prepaid or if properly
addressed and sent by pre-paid courier service, shall be deemed given when
received; any notice, if transmitted by facsimile, shall be deemed given when
transmitted.

     SECTION  10.3.      Payment of Costs and Expenses.  The Borrower agrees to
pay on demand all reasonable expenses of the Agent (including the reasonable
fees and out-of-pocket expenses of counsel to the Agent and of local counsel, if
any, who may be retained by counsel to the Agent) in connection with (a) the
negotiation, preparation, execution and delivery of this Agreement and of each
other Loan Document, including schedules and exhibits, and any amendments,
waivers, consents, supplements or other modifications to this Agreement or any
other Loan Document as may from time to time hereafter be required, whether or
not the transactions contemplated hereby are consummated, and (b) the
preparation and review of the form of any document or instrument relevant to
this Agreement or any other Loan Document.

     The Borrower further agrees to pay, and to save the Agent and the Lenders
and Issuers harmless from all liability for, any stamp or other taxes which may
be payable in connection with the execution or delivery of this Agreement, the
borrowings hereunder, or the issuance of the Notes or any other Loan Documents.
The Borrower also agrees to reimburse the Agent and each Lender and Issuer upon
demand for all reasonable out-of-pocket expenses (including attorneys' fees and
legal expenses) incurred by the Agent or such Lender in connection with (x) the
negotiation of any restructuring or "work-out", whether or not consummated, of
any Obligations, and (y) the enforcement of any Obligations.

     SECTION  10.4.      Indemnification.  In consideration of the execution and
delivery of this Agreement by each Lender and the extension of the Commitments
and the issuance of Letters of Credit, the Borrower hereby indemnifies,
exonerates and holds the Agent, each Issuer and each Lender and each of their
respective officers, directors, employees and agents (collectively, the
"Indemnified Parties") free and harmless from and against any and all actions,
causes of action, suits, losses, costs, liabilities and damages, and expenses
incurred in connection therewith (irrespective of whether any such Indemnified
Party is a party to the action for which indemnification hereunder is sought),
including reasonable attorneys' fees and disbursements (collectively, the
"Indemnified Liabilities"), incurred by the Indemnified Parties or any of them
as a result of, or arising out of, or relating to (a) any transaction financed
or to be financed in whole or in part, directly or indirectly, with the proceeds
of any Loan or Letter of Credit; (b) the entering into and performance of this
Agreement and any other Loan Document by any of the Indemnified Parties (except,
with respect to any action brought by or on behalf of the Borrower, to the
extent such Indemnified Party shall be found liable to the Borrower pursuant to
a finding by a court of competent jurisdiction, not subject 

                                       55
<PAGE>
 
to appeal); (c) any investigation, litigation or proceeding related to any
environmental cleanup, audit, compliance or other matter relating to the
protection of the environment or the Release by the Borrower or any of its
Subsidiaries of any Hazardous Material; or (d) the presence on or under, or the
escape, seepage, leakage, spillage, discharge, emission, discharging or releases
from, any real property owned or operated by the Borrower or any Subsidiary
thereof of any Hazardous Material (including any losses, liabilities, damages,
injuries, costs, expenses or claims asserted or arising under any Environmental
Law), regardless of whether caused by, or within the control of, the Borrower or
such Subsidiary, except for any such Indemnified Liabilities arising for the
account of a particular Indemnified Party by reason of the relevant Indemnified
Party's gross negligence or wilful misconduct. If and to the extent that the
foregoing undertaking may be unenforceable for any reason, the Borrower hereby
agrees to make the maximum contribution to the payment and satisfaction of each
of the Indemnified Liabilities which is permissible under applicable law.

     SECTION  10.5.      Survival.  The obligations of the Borrower under
Sections 4.3, 4.4, 4.5, 4.6, 10.3 and 10.4, and the obligations of the Lenders
under Section 9.1, shall in each case survive any termination of this Agreement,
the payment in full of all Obligations and the termination of all Commitments.
The representations and warranties made by the Borrower in this Agreement and in
each other Loan Document shall survive the execution and delivery of this
Agreement and each such other Loan Document.

     SECTION  10.6.      Severability.  Any provision of this Agreement or any
other Loan Document which is prohibited or unenforceable in any jurisdiction
shall, as to such provision and such jurisdiction, be ineffective to the extent
of such prohibition or unenforceability without invalidating the remaining
provisions of this Agreement or such Loan Document or affecting the validity or
enforceability of such provision in any other jurisdiction.

     SECTION  10.7.      Headings.  The various headings of this Agreement and
of each other Loan Document are inserted for convenience only and shall not
affect the meaning or interpretation of this Agreement or such other Loan
Document or any provisions hereof or thereof.

     SECTION  10.8.      Execution in Counterparts, Effectiveness, etc.  This
Agreement may be executed by the parties hereto in several counterparts, each of
which shall be executed by the Borrower and the Agent and be deemed to be an
original and all of which shall constitute together but one and the same
agreement.  This Agreement shall become effective when counterparts hereof
executed on behalf of the Borrower and each Lender (or notice thereof
satisfactory to the Agent) shall have been received by the Agent and notice
thereof shall have been given by the Agent to the Borrower and each Lender.

     SECTION  10.9.      Governing Law; Entire Agreement.  THIS AGREEMENT, THE
NOTES AND EACH OTHER LOAN DOCUMENT SHALL EACH BE DEEMED TO BE A CONTRACT MADE
UNDER AND GOVERNED BY THE INTERNAL LAWS OF THE STATE OF ILLINOIS. This
Agreement, the Notes and the other Loan Documents constitute the entire
understanding among the parties hereto with respect to the subject matter hereof
and supersede any prior agreements, written or oral, with respect thereto.

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<PAGE>
 
     THIS WRITTEN LOAN AGREEMENT REPRESENTS THE FINAL AGREEMENT AMONG THE
PARTIES AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS, OR
SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES.

     THERE ARE NO UNWRITTEN ORAL AGREEMENTS AMONG THE PARTIES.

     SECTION  10.10.    Successors and Assigns.  This Agreement shall be binding
upon and shall inure to the benefit of the parties hereto and their respective
successors and assigns; provided, however, that:  (a) the Borrower may not
assign or transfer its rights or obligations hereunder without the prior written
consent of the Agent and all Lenders; and (b) the rights of sale, assignment and
transfer of the Lenders are subject to Section 10.11.

     SECTION  10.11.    Sale and Transfer of Loans and Notes; Participations in
Loans and Notes.  Each Lender may assign, or sell participations in, its Loans
and Commitments to one or more other Persons in accordance with this Section
10.11.

     SECTION  10.11.1.  Assignments.  Any Lender,

          (a) with the written consent of the Borrower (in its sole discretion)
     and the Agent (which consent shall not be unreasonably delayed or withheld)
     and each Issuer, may at any time assign and delegate to one or more
     commercial banks or other financial institutions, and

          (b) with notice to the Borrower and the Agent and each Issuer, but
     without the consent of the Borrower or the Agent or any Issuer, may assign
     and delegate to any of its Affiliates or to any other Lender

(each Person described in either of the foregoing clauses as being the Person to
whom such assignment and delegation is to be made, being hereinafter referred to
as an "Assignee Lender"), all or any fraction of such Lender's total Loans,
Commitments and participations in Letters of Credit (which assignment and
delegation shall be of a constant, and not a varying, percentage of all the
assigning Lender's Loans and Commitments and participations in Letters of
Credit) in a minimum aggregate amount of $20,000,000 or such Lender's Percentage
of the Commitment Amount, if less; provided, however, that any such Assignee
Lender will comply, if applicable, with the provisions contained in the last
sentence of Section 4.6; and further, provided, however, that, the Borrower and
the Agent shall be entitled to continue to deal solely and directly with such
Lender in connection with the interests so assigned and delegated to an Assignee
Lender until

          (c) written notice of such assignment and delegation, together with
     payment instructions, addresses and related information with respect to
     such Assignee Lender, shall have been given to the Borrower and the Agent
     and each Issuer by such Lender and such Assignee Lender,

          (d) such Assignee Lender shall have executed and delivered to the
     Borrower, the Agent and each Issuer a Lender Assignment Agreement, accepted
     by the Borrower, the Agent and each Issuer, and

                                       57
<PAGE>
 
          (e) the processing fees described below shall have been paid.

From and after the date that the Borrower and the Agent and each Issuer accepts
such Lender Assignment Agreement, (x) the Assignee Lender thereunder shall be
deemed automatically to have become a party hereto and to the extent that rights
and obligations hereunder have been assigned and delegated to such Assignee
Lender in connection with such Lender Assignment Agreement, shall have the
rights and obligations of a Lender hereunder and under the other Loan Documents,
and (y) the assignor Lender, to the extent that rights and obligations hereunder
have been assigned and delegated by it in connection with such Lender Assignment
Agreement, shall be released from its obligations hereunder and under the other
Loan Documents.  Within five Business Days after its receipt of notice that the
Agent has received an executed Lender Assignment Agreement, the Borrower shall
execute and deliver to the Agent (for delivery to the relevant Assignee Lender)
new Notes evidencing such Assignee Lender's assigned Loans and Commitments and,
if the assignor Lender has retained Loans and Commitments hereunder, replacement
Notes in the principal amount of the Loans and Commitments retained by the
assignor Lender hereunder (such Notes to be in exchange for, but not in payment
of, those Notes then held by such assignor Lender).  Each such Note shall be
dated the date of the predecessor Notes.  The assignor Lender shall mark the
predecessor Notes "exchanged" and deliver them to the Borrower.  Accrued
interest on that part of the predecessor Notes evidenced by the new Notes, and
accrued fees, shall be paid as provided in the Lender Assignment Agreement.
Accrued interest on that part of the predecessor Notes evidenced by the
replacement Notes shall be paid to the assignor Lender.  Accrued interest and
accrued fees shall be paid at the same time or times provided in the predecessor
Notes and in this Agreement. Such assignor Lender or such Assignee Lender must
also pay a processing fee to the Agent upon delivery of any Lender Assignment
Agreement in the amount of $2,500.  Any attempted assignment and delegation not
made in accordance with this Section 10.11.1 shall be null and void.

     SECTION  10.11.2.  Participations.  Any Lender, with the prior written
consent of the Borrower in its sole discretion, may at any time sell to one or
more trusts, financial institutions or commercial banks (each of such trust,
financial institution or commercial bank being herein called a "Participant")
participating interests in any of the Loans, Commitments, or other interests of
such Lender hereunder; provided, however, that (a) no participation contemplated
in this Section 10.11 shall relieve such Lender from its Commitments or its
other obligations hereunder or under any other Loan Document, (b) such Lender
shall remain solely responsible for the performance of its Commitments and such
other obligations, (c) the Borrower and each other Obligor and the Agent shall
continue to deal solely and directly with such Lender in connection with such
Lender's rights and obligations under this Agreement and each of the other Loan
Documents, (d) no Participant, unless such Participant is an Affiliate of such
Lender, or is itself a Lender, shall be entitled to require such Lender to take
or refrain from taking any action hereunder or under any other Loan Document,
except that such Lender may agree with any Participant that such Lender will
not, without such Participant's consent, take any actions of the type described
in clause (b) or (c) of Section 10.1, and (e) the Borrower shall not be required
to pay any amount under Section 4.6 that is greater than the amount which it
would have been required to pay had no participating interest been sold.

     SECTION  10.11.3   Pledges to Federal Reserve Banks.  Any Lender may at any
time pledge or assign a security interest in all or any portion of its rights
under this Agreement to secure obligations of such Lender to a Federal Reserve
Bank or, in the case of a Lender organized in a 

                                       58
<PAGE>
 
jurisdiction outside of the United States, a comparable Person; provided that no
such pledge or assignment of a security interest shall release a Lender from any
of its obligations hereunder or substitute any such pledgee or assignee for such
Lender as a party hereto.

     SECTION  10.12.    Other Transactions.  Nothing contained herein shall
preclude the Agent or any other Lender from engaging in any transaction, in
addition to those contemplated by this Agreement or any other Loan Document,
with the Borrower or any of its Affiliates in which the Borrower or such
Affiliate is not restricted hereby from engaging with any other Person.  The
parties hereto agree that if at any time the Borrower or its Subsidiaries shall
grant to the Lenders Liens securing the obligations of the Borrower to the
Lenders and Issuers hereunder, such Liens shall also secure obligations to any
Lender in respect of any letter of credit reimbursement obligations permitted by
Section 7.2.2.(i) hereof owing to one or more Lenders.

     SECTION  10.13.    Sale and Purchase of Loans. Bank of Montreal hereby
sells, assigns, transfers and conveys, and Lenders hereby purchase and accept so
much of the Prior Indebtedness and all of the rights, titles, benefits,
interests, privileges, claims, liens, security interests, and obligations
existing and to exist (collectively the "Interests") such that each Lender's
Percentage of the outstanding loans and commitments under the Original Credit
Agreement as amended and restated by this Agreement shall be as set forth in
Exhibit F as of the Effective Date. The foregoing assignment, transfer and
conveyance are without recourse to Bank of Montreal and without any warranties
whatsoever as to title, enforceability, collectibility, documentation or freedom
from liens or encumbrances, in whole or in part, other than the warranty by Bank
of Montreal that it has not sold, transferred, conveyed or encumbered such
Interests. Each Lender so acquiring a part of such outstanding loans assumes its
Percentage of the outstanding Loans, Commitments, rights, titles, interests,
privileges, claims, liens, security interests, benefits and obligations under
this Agreement and the other Loan Documents and any Lender so acquiring an
interest in such outstanding Loans may be paid a cost of funds with respect
thereto as mutually agreed between the Borrower and such Lender. Bank of
Montreal is released from the obligations assumed by Lenders so acquiring such
obligations. The Borrower hereby represents and warrants that it has no
defenses, offsets or counterclaims to the Prior Indebtedness or its obligations
or rights under this Agreement, including, without limitation, the Interests
being assigned pursuant to this Section 10.13. Any loans outstanding under the
Original Credit Agreement on the Effective Date shall be deemed continued as
Loans under this Agreement, any loans outstanding under the Original Credit
Agreement, on the Effective Date, bearing interest at a LIBO Rate (as defined
therein) shall be deemed continued as Loans under this Agreement at such LIBO
Rate and for the Interest Period with respect thereto under the Original Credit
Agreement and any letters of credit outstanding under the Original Credit
Agreement on the Effective Date shall be deemed continued as Revolving Loan
Letters of Credit and the Bolivian Letter of Credit, as the case may be, under
this Agreement. The Commitments, outstanding Notes, and Loans under the Original
Credit Agreement shall become Commitments, Notes, and Loans, respectively,
hereunder. Interest accrued on the Loans and Commitment fees accrued under the
Original Credit Agreement through the Effective Date hereof shall be deemed due
and payable hereunder. The Lenders hereunder shall be deemed to have purchased
participations in the outstanding Letters of Credit, pro rata according to their
respective Percentages.

     SECTION  10.14.    Forum Selection and Consent to Jurisdiction.  ANY
LITIGATION BASED HEREON, OR ARISING OUT OF, UNDER, OR IN CONNECTION WITH, THIS

                                       59
<PAGE>
 
AGREEMENT OR ANY OTHER LOAN DOCUMENT, OR ANY COURSE OF CONDUCT, COURSE OF
DEALING, STATEMENTS (WHETHER VERBAL OR WRITTEN) OR ACTIONS OF THE AGENT, THE
LENDERS, ANY ISSUER, OR THE BORROWER MAY BE BROUGHT AND MAINTAINED IN THE COURTS
OF THE STATE OF ILLINOIS OR IN THE UNITED STATES DISTRICT COURT FOR THE NORTHERN
DISTRICT OF ILLINOIS.  THE BORROWER HEREBY EXPRESSLY AND IRREVOCABLY SUBMITS TO
THE JURISDICTION OF THE COURTS OF THE STATE OF ILLINOIS AND OF THE UNITED STATES
DISTRICT COURT FOR THE NORTHERN DISTRICT OF ILLINOIS FOR THE PURPOSE OF ANY SUCH
LITIGATION AS SET FORTH ABOVE AND IRREVOCABLY AGREES TO BE BOUND BY ANY JUDGMENT
RENDERED THEREBY IN CONNECTION WITH SUCH LITIGATION.  THE BORROWER FURTHER
IRREVOCABLY CONSENTS TO THE SERVICE OF PROCESS BY REGISTERED MAIL, POSTAGE
PREPAID, OR BY PERSONAL SERVICE WITHIN OR WITHOUT THE STATE OF ILLINOIS.  THE
BORROWER HEREBY EXPRESSLY AND IRREVOCABLY WAIVES, TO THE FULLEST EXTENT
PERMITTED BY LAW, ANY OBJECTION WHICH IT MAY HAVE OR HEREAFTER MAY HAVE TO THE
LAYING OF VENUE OF ANY SUCH LITIGATION BROUGHT IN ANY SUCH COURT REFERRED TO
ABOVE AND ANY CLAIM THAT ANY SUCH LITIGATION HAS BEEN BROUGHT IN AN INCONVENIENT
FORUM.  TO THE EXTENT THAT THE BORROWER HAS OR HEREAFTER MAY ACQUIRE ANY
IMMUNITY FROM JURISDICTION OF ANY COURT OF FROM ANY LEGAL PROCESS (WHETHER
THROUGH SERVICE OR NOTICE, ATTACHMENT PRIOR TO JUDGMENT, ATTACHMENT IN AID OF
EXECUTION OR OTHERWISE) WITH RESPECT TO ITSELF OR ITS PROPERTY, THE BORROWER
HEREBY IRREVOCABLY WAIVES SUCH IMMUNITY IN RESPECT OF ITS OBLIGATIONS UNDER THIS
AGREEMENT AND THE OTHER LOAN DOCUMENTS.

     SECTION  10.15.    Waiver of Jury Trial. THE AGENT, THE LENDERS, EACH
ISSUER AND THE BORROWER HEREBY KNOWINGLY, VOLUNTARILY AND INTENTIONALLY WAIVE
ANY RIGHTS THEY MAY HAVE TO A TRIAL BY JURY IN RESPECT OF ANY LITIGATION BASED
HEREON, OR ARISING OUT OF, UNDER, OR IN CONNECTION WITH, THIS AGREEMENT OR ANY
OTHER LOAN DOCUMENT, OR ANY COURSE OF CONDUCT, COURSE OF DEALING, STATEMENTS
(WHETHER VERBAL OR WRITTEN) OR ACTIONS OF THE AGENT, THE LENDERS OR THE
BORROWER. THE BORROWER ACKNOWLEDGES AND AGREES THAT IT HAS RECEIVED FULL AND
SUFFICIENT CONSIDERATION FOR THIS PROVISION (AND EACH OTHER PROVISION OF EACH
OTHER LOAN DOCUMENT TO WHICH IT IS A PARTY) AND THAT THIS PROVISION IS A
MATERIAL INDUCEMENT FOR THE AGENT, EACH ISSUER AND THE LENDERS ENTERING INTO
THIS AGREEMENT AND EACH SUCH OTHER LOAN DOCUMENT.

                                       60
<PAGE>
 
     IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
executed by their respective officers thereunto duly authorized as of the day
and year first above written.

                             VINTAGE PETROLEUM, INC.


                             By:     /s/  William C. Barnes
                                ---------------------------------------
                                William C. Barnes,
                                Executive Vice President and
                                Chief Financial Officer

                             Address:  4200 One Williams Center
                                       Tulsa, Oklahoma 74172

                             Facsimile No.: (918) 584-7282

                             Attention:  William C. Barnes,
                                           Executive Vice President
                                           and Chief Financial Officer

                                       61
<PAGE>
 
                             BANK OF MONTREAL
                               acting through its U.S. branches
                               and agencies, including initially
                               its Chicago, Illinois branch,
                               as Agent


                             By:     /s/  Robert L. Roberts
                                ---------------------------------------
                             Name:     Robert L. Roberts
                             Title:    Director, U.S. Corporate Banking

                             Address:  115 South LaSalle Street, 11th Floor West
                                       Chicago, Illinois  60603

                             Facsimile No.: (312) 750-3456


                             Attention:  Terri Perez-Ford, Specialist
 

                             with copy to:

                             Bank of Montreal
                             Houston Agency
                             700 Louisiana Street
                             4400 NationsBank Center
                             Houston, Texas  77002

                             Facsimile No.:  (713) 223-4007


                             Attention:  Brian Otis, Associate
 

                                       62
<PAGE>
 
                                LENDERS:

                                BANK OF MONTREAL, as Lender


                                By:    /s/  Robert L. Roberts
                                ---------------------------------------
                                Name:    Robert L. Roberts
                                Title:   Director, U.S. Corporate Banking

                                Domestic
                                Office:  115 South LaSalle Street
                                         11th Floor West
                                         Chicago, Illinois  60603

                                Facsimile No. (312) 750-3456


                                Attention: Terri Perez-Ford, Specialist
 

                                LIBOR
                                Office:  115 South LaSalle Street
                                         Chicago, Illinois  60603

                                Facsimile No.:
                                              -------------------------


                                Attention:
                                           ----------------------------
 
                                              -------------------------


                                with copy to:

                                Bank of Montreal
                                Houston Agency
                                700 Louisiana Street
                                4400 NationsBank Center
                                Houston, Texas  77002

                                Facsimile No.:  (713) 223-4007


                                Attention: Brian Otis, Associate
 

                                       63
<PAGE>
 
                                ABN AMRO BANK, N.V.,
                                as Lender and Co-Agent


                                By:   /s/  Jamie A. Conn
                                   ---------------------------------------
                                Name:  Jamie A. Conn
                                Title: Vice President


                                By:   /s/  Deanna B. Breland
                                   ---------------------------------------
                                Name:  Deanna B. Breland
                                Title: Vice President

                                Domestic
                                Office:    Three Riverway
                                           Suite 1700
                                           Houston, TX 77056

                                Facsimile No. (713) 621-5801

                                Attention: Robert Cunningham
                                           Chuck Randall

                                LIBOR
                                Office:    Three Riverway
                                           Suite 1700
                                           Houston, TX 77056

                                Facsimile No.: (713) 621-5801

                                Attention: Robert Cunningham
                                           Chuck Randall

                                with a copy to:

                                ABN Amro Bank
                                135 S. LaSalle, Suite 2805
                                Chicago, IL 60603

                                Attention: Karen MacAllister
 

                                       64
<PAGE>
 
                                BANKBOSTON, N.A.,
                                as Lender and Co-Agent


                                By:   /s/  George Passela
                                   ---------------------------------------
                                Name:    George Passela
                                Title:   Managing Director

                                Domestic
                                Office:  100 Federal Street
                                         MS 01-08-04
                                         Boston, MA 02110

                                Facsimile No. (617) 434-3652

                                Attention: Allison Rossi
 
                                LIBOR
                                Office:  100 Federal Street
                                         MS 01-08-04
                                         Boston, MA 02110

                                Facsimile No.: (617) 434-3652

                                Attention: Allison Rossi

 
 

                                       65
<PAGE>
 
                                THE BANK OF NEW YORK,
                                as Lender


                                By:   /s/  Raymond J. Palmer
                                   ---------------------------------------
                                Name:    Raymond J. Palmer
                                Title:   Vice President

                                Domestic
                                Office:     One Wall Street
                                            New York, NY 10286
 
                                Facsimile No.:  (212) 635-7923

                                Attention:  Ray Palmer
 
                                LIBOR
                                Office:     One Wall Street
                                            New York, NY 10286
 
                                Facsimile No.: (212)

                                Attention:   Ray Palmer

 
 

                                       66
<PAGE>
 
                                THE BANK OF NOVA SCOTIA,
                                as Lender and Lead Manager


                                By:   /s/  F.C.H. Ashby
                                   ---------------------------------------
                                Name:    F.C.H. Ashby
                                Title:   Senior Manager Loan Operations

                                Domestic
                                Office:    The Bank of Nova Scotia, Atlanta
                                             Office
                                           600 Peachtree Street, N.E.
                                           Suite 2700
                                           Atlanta, GA  30308
 
                                Facsimile No. (404) 888-8998
                                Attention: Cleve Bushey
 
                                LIBOR
                                Office:    The Bank of Nova Scotia, Atlanta 
                                             Office
                                           600 Peachtree Street, N.E.
                                           Suite 2700
                                           Atlanta, GA  30308

                                Facsimile No.: (404) 888-8998
                                Attention: Cleve Bushey
 
                                with a copy to:

                                The Bank of Nova Scotia
                                1100 Louisiana Street, Suite 3000
                                Houston, TX  77002

                                Attention:  Greg Smith

                                       67
<PAGE>
 
                                BANK OF OKLAHOMA,
                                NATIONAL ASSOCIATION, as Lender



                                By:   /s/  Kevin A. Humphrey
                                   ---------------------------------------
                                Name:    Kevin A. Humphrey
                                Title:   Vice-President

                                Domestic
                                Office:    One Williams Center, 8th Floor
                                           Tulsa, OK  74172

                                Facsimile No.:  (918) 588-6880

                                Attention: Michael Coats
 
                                LIBOR
                                Office:    One Williams Center, 8th Floor
                                           Tulsa, OK  74172
 
                                Facsimile No.: (918) 588-6880

                                Attention: Michael Coats

 

                                       68
<PAGE>
 
                                PARIBAS,
                                as Lender and Co-Agent


                                By:   /s/  Marian Livingston
                                   ---------------------------------------
                                Name:    Marian Livingston
                                Title:   Vice President


                                By:   /s/  A. David Dodd
                                   ---------------------------------------
                                Name:    A. David Dodd
                                Title:   Vice President

                                Domestic
                                Office:    1200 Smith Street, Suite 3100
                                           Houston, TX  77002

                                Facsimile No. (713) 659-3832

                                Attention: Leah Evans-Hughes
 
                                LIBOR
                                Office:    1200 Smith Street, Suite 3100
                                           Houston, TX  77002

                                Facsimile No. (713) 659-3832

                                Attention: Leah Evans-Hughes

 

                                       69
<PAGE>
 
                                THE CHASE MANHATTAN BANK,
                                as Lender and Co-Agent


                                By:   /s/  Peter Ling
                                   ---------------------------------------
                                Name:    Peter M. Ling
                                Title:   Vice President

                                Domestic
                                Office:    270 Park Avenue, 32nd Floor
                                           New York, NY 10017
 
                                Facsimile No. (212) 270-3897

                                Attention: Peter Ling
 
                                LIBOR
                                Office:    270 Park Avenue, 32nd Floor
                                           New York, NY  10017

                                Facsimile No.: (212)

                                Attention: LuAnn DeStephano

                                       70
<PAGE>
 
                        CHRISTIANIA BANK OG KREDITKASSE ASA,
                        as Lender

 
 
                        By:   /s/  Peter M. Dodge  /s/  William S. Phillips
                           -----------------------------------------------------
                        Name:  Peter M. Dodge            William S. Phillips
                        Title: Senior Vice President     First Vice President

                        Domestic
                        Office:     New York Branch
                                    11 West 42nd Street
                                    New York, NY 10036

                        Facsimile No.  (212) 827-4888

                        Attention:  Peter Dodge
 
                        LIBOR
                        Office:     New York Branch
                                    11 West 42nd Street
                                    New York, NY 10036

                        Facsimile No.: (212) 827-4888

                        Attention:  Peter Dodge

 

                                       71
<PAGE>
 
                        CREDIT LYONNAIS,
                        as Lender


                        By:   /s/  Xavier Ratouis
                           -----------------------------------------------------
                        Name:    Xavier Ratouis
                        Title:   Senior Vice President

                        Domestic
                        Office:  Credit Lyonnais New York Branch
                                 1301 Avenue of the Americas
                                 New York, NY  10019

                        Facsimile No. (713) 751-0307

                        Attention: Christine Smith-Byerly
                                   Credit Lyonnais Houston
                                   Representative Office

                        LIBOR
                        Office:  Credit Lyonnais New York Branch
                                 1301 Avenue of the Americas
                                 New York, NY  10019

                        Facsimile No.: (713) 751-0307

                        Attention: Christine Smith-Byerly
                                   Credit Lyonnais Houston
                                   Representative Office
 

                                       72
<PAGE>
 
                        THE FIRST NATIONAL BANK OF CHICAGO,
                        as Lender and Co-Agent
 

                        By:   /s/  Dixon P. Schultz
                           -----------------------------------------------------
                        Name:    Dixon P. Schultz
                        Title:   First Vice President

                        Domestic
                        Office:  1100 Louisiana, 32nd Floor
                                 Houston, TX 77002
 
                        Facsimile No. (713) 654-7370

                        Attention: Dixon Schultz
 
                        LIBOR
                        Office:  One First National Plaza
                                 Chicago, IL  60670

                        Facsimile No.:  (312) 732-4840

                        Attention: Kathy Murphy

                        with copy to:

                        Mr. Robert Long
                        First Chicago NBD
                        One National Plaza
                        20th Floor, Suite 0573
                        Chicago, IL 60670

                        Facsimile No.:  (312) 732-5144

                                       73
<PAGE>
 
                        FIRST UNION NATIONAL BANK,
                        as Lender and Lead Manager


                        By:   /s/  Robert R. Wetteroff
                           -----------------------------------------------------
                        Name:    Robert R. Wetteroff
                        Title:   Senior Vice President

                        Domestic
                        Office:    301 South College Street
                                   Charlotte, NC 28288
 
                        Facsimile No. (713) 650-6354

                        Attention: David E. Humphreys
 
                        LIBOR
                        Office:    301 South College Street
                                   Charlotte, NC 28288
 
                        Facsimile No.: (713) 650-6354

                        Attention: David E. Humphreys

 

                                       74
<PAGE>
 
                        MEES PIERSON CAPITAL CORP.,
                        as Lender and Lead Manager


                        By:   /s/  Darrell W. Holley
                           -----------------------------------------------------
                        Name:    Darrell W. Holley
                        Title:   Senior Vice President
 
                        By:   /s/  Karel Louman
                           -----------------------------------------------------
                        Name:     Karel Louman
                        Title:    Managing Director

                        Domestic Office:
                        MeesPierson Capital Corp.
                        300 Crescent Court
                        Suite 1750
                        Dallas, Texas  75201
 
                        Telephone:  214/ 754-0009
                        Telefax:    214/ 754-5981
 
                        Address for Operational Notices:
                        MeesPierson Capital Corp.
                        300 Crescent Court
                        Suite 1750
                        Dallas, Texas  75201
 
                        Yolanda Dittmar/Angela Pross
                        Telephone:  214/ 754-0009
                        Telefax:    214/ 754-5981

                        Wiring Instructions:
                        Chase Manhattan Bank
                        ABA#021000021
                        Credit to:  MeesPierson New York Agency
                        Acct.#:  001-1-624418
                        For further Credit:  MeesPierson Capital Corp.
                        Ref:  Vintage Petroleum, Inc.
                        Acct.#:  100980360

                                       75
<PAGE>
 
                        NATEXIS Banque BFCE,
                        as Lender


                        By:   /s/  Mark A. Harrington
                           -----------------------------------------------------
                        Name:    Mark A. Harrington
                        Title:   Vice President and Regional Manager


                        By:   /s/  N. Eric Ditges
                           -----------------------------------------------------
                        Name:    N. Eric Ditges
                        Title:   Assistant Vice President

                        Domestic
                        Office:    NATEXIS Banque
                                   Southwest Representative Office
                                   333 Clay Street, Suite 4340
                                   Houston, TX 77002

                        Facsimile No.  (713) 759-9908

                        Attention: Eric Ditges
 
                        LIBOR
                        Office:    NATEXIS Banque
                                   Southwest Representative Office
                                   333 Clay Street, Suite 4340
                                   Houston, TX 77002

                        Facsimile No.: (713) 759-9908

                        Attention: Tanya McAllister

                        with a copy to:

                        NATEXIS Banque
                        New York Branch
                        645 5th Avenue, 20th Floor
                        New York, NY 10022

                        Facsimile No.: (212) 872-5045
                        Attention: Joan Rankine

                                       76
<PAGE>
 
                        NATIONSBANK, N.A.,
                        as Lender and Syndication Agent


                        By:   /s/  Denise A. Smith
                           -----------------------------------------------------
                        Name:      Denise A. Smith
                        Title:     Senior Vice President

                        Domestic
                        Office:    901 Main Street, 64th Floor
                                   Dallas, TX 75202
 
                        Facsimile No. (214) 508-1285

                        Attention: Denise Smith
 
                        LIBOR
                        Office:    901 Main Street, 64th Floor
                                   Dallas, TX 75202

                        Facsimile No.: (214) 508-1285

                        Attention: Denise Smith

                        with copy to:

                        901 Main Street, 14th Floor
                        Dallas, Texas 75202

                        Facsimile No.:  (214) 508-1215

                        Attention:  Betty Canales

 

                                       77
<PAGE>
 
                        THE SANWA BANK LIMITED,
                        as Lender and Lead Manager


                        By:   /s/  C. Lawrence Murphy
                           -----------------------------------------------------
                        Name:          C. Lawrence Murphy
                        Title:

                        Domestic
                        Office:        55 East 52nd Street
                                       New York, NY 10055
 

                        Facsimile No.
                                     -------------------------------------------

                        Attention:     T. Ojima
 
                        LIBOR
                        Office:        55 East 52nd Street
                                       New York, NY 10055
 
                        Facsimile No.: 
                                      ------------------------------------------

                        Attention:     T. Ojima

 

                                       78
<PAGE>
 
                        SOCIETE GENERALE, SOUTHWEST AGENCY,
                        as Lender and Documentation Agent


                        By:   /s/  Richard Erbert
                           -----------------------------------------------------
                        Name:         Richard A. Erbert
                        Title:        Vice President

                        Domestic
                        Office:       4800 Trammell Crow Center
                                      2001 Ross Avenue
                                      Dallas, Texas 75201

                        Facsimile No. (214) 754-0171

                        Attention: Loan Operations
 
                        LIBOR
                        Office:       4800 Trammell Crow Center
                                      2001 Ross Avenue
                                      Dallas, Texas 75201

                        Facsimile No.: (214) 754-0171

                        Attention: Loan Operations

                        with copy to:

                        Societe Generale, Southwest Agency
                        1111 Bagby, Suite 2020
                        Houston, Texas 77002

                        Facsimile No.  (713) 650-0824

                        Attention: Richard A. Erbert

                                       79
<PAGE>
 
                        UNION BANK OF CALIFORNIA, N.A.,
                        as Lender and Lead Manager
 
 
                        By:   /s/  Gary Shekerjian
                           -----------------------------------------------------
                        Name:    Gary Shekerjian
                        Title:   Assistant Vice President
 
                        Domestic
                        Office:        500 North Akard St. #4200
                                       Dallas, Texas  75201
 
                        Facsimile No.  214-922-4209

                        Attention:     Gary Shekerjian
 
                        LIBOR
                        Office:        Energy Capital Services
                                       445 S. Figueroa Street, 15/th/ fl.
                                       Los Angeles, Ca  90071

                        Facsimile No.: 213-236-4096

                        Attention:     Patricia Gonzales

 

                                       80
<PAGE>
 
                                                                       EXHIBIT A
                                     NOTE

$_____________                                               ____________, 19___

     FOR VALUE RECEIVED, the undersigned, VINTAGE PETROLEUM, INC., a Delaware
corporation (the "Borrower"), promises to pay to the order of
_______________________ (the "Lender") the principal sum of ____________________
DOLLARS ($____________) or, if less, the aggregate unpaid principal amount of
all Loans made by the Lender pursuant to that certain Amended and Restated
Credit Agreement, dated as of October 21, 1998 (together with all amendments and
other modifications, if any, from time to time thereafter made thereto, the
"Credit Agreement"), among the Borrower, BANK OF MONTREAL, as Agent, the various
financial institutions (including the Lender) as are, or may from time to time
become, parties thereto, payable in installments as set forth in the Credit
Agreement, with a final installment (in the amount necessary to pay in full this
Note) due and payable on the Stated Maturity Date set forth therein.

     The Borrower also promises to pay interest on the unpaid principal amount
hereof from time to time outstanding from the date hereof until maturity
(whether by acceleration or otherwise) and, after maturity, until paid, at the
rates per annum and on the dates specified in the Credit Agreement.

     Payments of both principal and interest are to be made in lawful money of
the United States of America in same day or immediately available funds to the
account designated by the Agent pursuant to the Credit Agreement.

     This Note is one of the Notes referred to in, and evidences Indebtedness
incurred under, the Credit Agreement, to which reference is made for a statement
of the terms and conditions on which the Borrower is permitted and required to
make prepayments and repayments of principal of the Indebtedness evidenced by
this Note and on which such Indebtedness may be declared to be immediately due
and payable.  Unless otherwise defined, terms used herein have the meanings
provided in the Credit Agreement.

     All parties hereto, whether as makers, endorsers, or otherwise, severally
waive presentment for payment, demand, protest and notice of dishonor.

     THIS NOTE HAS BEEN DELIVERED IN CHICAGO, ILLINOIS AND SHALL BE DEEMED TO BE
A CONTRACT MADE UNDER AND GOVERNED BY THE INTERNAL LAWS OF THE STATE OF
ILLINOIS.

                                                VINTAGE PETROLEUM, INC.


                                                By
                                                  ------------------------------
                                                  Title:
<PAGE>
 
                         LOANS AND PRINCIPAL PAYMENTS



<TABLE>
<CAPTION>
                                       Amount of          Unpaid
         Amount of                  Principal Repaid     Principal
         Loan Made                  ----------------      Balance
         --------                                         ------- 
                      Interest
        Base   LIBO   Period (if    Base        LIBO   Base     LIBO          Notation
Date    Rate   Rate   applicable)   Rate        Rate   Rate     Rate   Total  Made By
- ----    ----   ----   -----------   ----        ----   ----     ----   -----  -------
<S>     <C>    <C>    <C>           <C>         <C>    <C>      <C>    <C>    <C>
 
- --------------------------------------------------------------------------------------
 
- --------------------------------------------------------------------------------------
 
- --------------------------------------------------------------------------------------
 
- --------------------------------------------------------------------------------------
 
- --------------------------------------------------------------------------------------
 
- --------------------------------------------------------------------------------------
 
- --------------------------------------------------------------------------------------
 
- --------------------------------------------------------------------------------------
 
- --------------------------------------------------------------------------------------
 
- --------------------------------------------------------------------------------------
 
- --------------------------------------------------------------------------------------
 
- --------------------------------------------------------------------------------------
 
- --------------------------------------------------------------------------------------
 
</TABLE> 
 
 
                                       2
<PAGE>
 
                                                                       EXHIBIT B


                               BORROWING REQUEST


Bank of Montreal
115 South LaSalle Street
Chicago, Illinois 60603

Attention:  [Name]
            [Title]

                            VINTAGE PETROLEUM, INC.


Gentlemen and Ladies:

     This Borrowing Request is delivered to you pursuant to Section 2.3 of the
Amended and Restated Credit Agreement, dated as of October 21, 1998 (together
with all amendments, if any, from time to time thereafter made thereto, the
"Credit Agreement"), among Vintage Petroleum, Inc., a Delaware corporation (the
"Borrower"), certain financial institutions and Bank of Montreal (the "Agent").
Unless otherwise defined herein or the context otherwise requires, terms used
herein have the meanings provided in the Credit Agreement.

     The Borrower hereby requests that a Revolving Loan be made in the aggregate
principal amount of $__________ on __________, 19___ as a [LIBO Rate Loan having
an Interest Period of _______ months] [Base Rate Loan].

     The Borrower hereby acknowledges that, pursuant to Section 5.2.2 of the
Credit Agreement, each of the delivery of this Borrowing Request and the
acceptance by the Borrower of the proceeds of the Loans requested hereby
constitutes a representation and warranty by the Borrower that, on the date of
such Loans, and before and after giving effect thereto and to the application of
the proceeds therefrom, all statements set forth in Section 5.2.1 are true and
correct in all material respects.

     The Borrower certifies that the Senior Debt of the Borrower and its
Subsidiaries, other than Loans made pursuant to the Credit Agreement, is
$_____________ as of the date hereof.

     The Borrower agrees that if prior to the time of the Borrowing requested
hereby any matter certified to herein by it will not be true and correct at such
time as if then made, it will immediately so notify the Agent.  Except to the
extent, if any, that prior to the time of the Borrowing requested hereby the
Agent shall receive written notice to the contrary from the Borrower, each
matter certified to herein shall be deemed once again to be certified as true
and correct at the date of such Borrowing as if then made.
<PAGE>
 
     Please wire transfer the proceeds of the Borrowing requested hereby to the
accounts of the following persons at the financial institutions indicated
respectively:
 
                    Person to be Paid  
Amount to be    -------------------------  Name, Address, etc. 
Transferred     Name          Account No.  of Transferee Lender
- --------------  ----          -----------  --------------------
                              
$                             
 -------------  ------------  -----------  --------------------
                                           --------------------
                                           Attention: 
                                                      ---------
                              
$                             
 -------------  ------------  -----------  --------------------
                                           --------------------
                                           Attention: 
                                                      ---------

Balance of      The Borrower  -----------  -------------------- 
such proceeds                              -------------------- 
                                           Attention: 
                                                      ---------



     The Borrower has caused this Borrowing Request to be executed and
delivered, and the certification and warranties contained herein to be made, by
its duly Authorized Officer this ___ day of ___________, 19___.

                                                VINTAGE PETROLEUM, INC.



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


                                       2
<PAGE>
 
                                                                       EXHIBIT C

                        CONTINUATION/CONVERSION NOTICE


Bank of Montreal
115 South LaSalle Street
Chicago, Illinois 60603

Attention:  [Name]
            [Title]

                            VINTAGE PETROLEUM, INC.

Gentlemen and Ladies:

     This Continuation/Conversion Notice is delivered to you pursuant to Section
2.4 of the Amended and Restated Credit Agreement, dated as of October 21, 1998
(together with all amendments, if any, from time to time thereafter made
thereto, the "Credit Agreement"), among Vintage Petroleum, Inc., a Delaware
corporation (the "Borrower"), certain financial institutions and Bank of
Montreal (the "Agent").  Unless otherwise defined herein or the context
otherwise requires, terms used herein have the meanings provided in the Credit
Agreement.

     The Borrower hereby requests that on ____________, 19___,

          (1)  $___________ of the presently outstanding principal amount of the
     [Term Loans] [Revolving Loans] originally made on __________, 19___ [and
     $__________ of the presently outstanding principal amount of the [Revolving
     Loans] originally made on __________, 19___],

          (2)  and all presently being maintained as-*[Base Rate Loans]
     [LIBO Rate Loans],

          (3)  be [converted into] [continued as],

          (4)  **[LIBO Rate Loans having an Interest Period of ______ months]
     [Base Rate Loans].


- --------------------
*    Select appropriate interest rate option.

**   Insert appropriate interest rate option.
<PAGE>
 
The Borrower hereby:

          (a)  certifies and warrants that no Default has occurred and is
     continuing; and

          (b)  agrees that if prior to the time of such continuation or
     conversion any matter certified to herein by it will not be true and
     correct at such time as if then made, it will immediately so notify the
     Agent.

Except to the extent, if any, that prior to the time of the continuation or
conversion requested hereby the Agent shall receive written notice to the
contrary from the Borrower, each matter certified to herein shall be deemed to
be certified at the date of such continuation or conversion as if then made.

     The Borrower has caused this Continuation/Conversion Notice to be executed
and delivered, and the certification and warranties contained herein to be made,
by its Authorized Officer this ___ day of _________, 19___.


                                        VINTAGE PETROLEUM, INC.


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


                                       2
<PAGE>
 
                                                                       EXHIBIT D

                          LENDER ASSIGNMENT AGREEMENT

To:  Vintage Petroleum, Inc.



To:  Bank of Montreal,
     as the Agent

                            VINTAGE PETROLEUM, INC.

Gentlemen and Ladies:

     We refer to clause (d) of Section 10.11.1 of the Amended and Restated
Credit Agreement, dated as of October 21, 1998 (together with all amendments and
other modifications, if any, from time to time thereafter made thereto, the
"Credit Agreement"), among Vintage Petroleum, Inc., a Delaware corporation (the
"Borrower"), the various financial institutions (the "Lenders") as are, or shall
from time to time become, parties thereto, and Bank of Montreal, as agent (the
"Agent") for the Lenders.  Unless otherwise defined herein or the context
otherwise requires, terms used herein have the meanings provided in the Credit
Agreement.

     This Agreement is delivered to you pursuant to clause (d) of Section
10.11.1 of the Credit Agreement and also constitutes notice to each of you,
pursuant to clause (c) of Section 10.11.1 of the Credit Agreement, of the
assignment and delegation to _______________ (the "Assignee") of ___% of the
Loans and Commitments of _____________ (the "Assignor") outstanding under the
Credit Agreement on the date hereof.  After giving effect to the foregoing
assignment and delegation, the Assignor's and the Assignee's Percentages for the
purposes of the Credit Agreement are set forth opposite such Person's name on
the signature pages hereof.

     [Add paragraph dealing with accrued interest and fees with respect to Loans
and participations in Letters of Credit being assigned.]

     The Assignee hereby acknowledges and confirms that it has received a copy
of the Credit Agreement and the exhibits related thereto, together with copies
of the documents which were required to be delivered under the Credit Agreement
as a condition to the making of the Loans thereunder.  The Assignee further
confirms and agrees that in becoming a Lender and in making its Commitments and
Loans and in participating in Letters of Credit under the Credit Agreement, such
actions have and will be made without recourse to, or representation or warranty
by the Agent.

     Except as otherwise provided in the Credit Agreement, effective as of the
date of acceptance hereof by the Agent

          (a)  the Assignee
<PAGE>
 
               (i)  shall be deemed automatically to have become a party to the
          Credit Agreement, have all the rights and obligations of a "Lender"
          under the Credit Agreement and the other Loan Documents as if it were
          an original signatory thereto to the extent specified in the second
          paragraph hereof; and

               (ii) agrees to be bound by the terms and conditions set forth in
          the Credit Agreement and the other Loan Documents as if it were an
          original signatory thereto; and

          (b)  the Assignor shall be released from its obligations under the
     Credit Agreement and the other Loan Documents to the extent specified in
     the second paragraph hereof.

     The Assignor and the Assignee hereby agree that the [Assignor] [Assignee]
will pay to the Agent the processing fee referred to in Section 10.11.1 of the
Credit Agreement upon the delivery hereof.

     The Assignee hereby advises each of you of the following administrative
details with respect to the assigned Loans and Commitments and requests the
Agent to acknowledge receipt of this document:

          (A)  Address for Notices:

                    Institution Name:

                    Attention:

                    Domestic Office:

                    Telephone:

                    Facsimile:

                    LIBOR Office:

                    Telephone:

                    Facsimile:

          (B)  Payment Instructions:

     The Assignee agrees to furnish the tax form required by the last sentence
of Section 4.6 (if so required) of the Credit Agreement no later than the date
of acceptance hereof by the Agent.

     This Agreement may be executed by the Assignor and Assignee in separate
counterparts, each of which when so executed and delivered shall be deemed to be
an original and all of which taken together shall constitute one and the same
agreement.

Adjusted Percentage                             [ASSIGNOR]
- -------------------                                       

                                       2
<PAGE>
 
Term Loan Commitment
      and
Term Loans:             __%

Revolving Loan
  Commitment
      and
Revolving Loans:        __%

Letter of Credit
  participations:       __%

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

Percentage                                      [ASSIGNEE]
- ----------                                                

Term Loan Commitment
     and
Term Loans:             __%

Revolving Loan
  Commitment
     and
Revolving Loans:        __%

Letter of Credit
  participations:       __%
                                        By:
                                           -------------------------------------
                                           Title:
Accepted and Acknowledged
this __ day of _______, 19__

BANK OF MONTREAL,
  as Agent

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

[VINTAGE PETROLEUM, INC.,
  as Borrower

By:
   ----------------------------------
   Title:]

[add signature blocks for each Issuer]


                                       3
<PAGE>
 
                                                                       EXHIBIT G


                            FORM OF ISSUANCE REQUEST


                                Issuance Request


Bank of Montreal
115 S. LaSalle Street
Chicago, IL 60603

Attention:

     Re:  Vintage Petroleum, Inc.

Gentlemen and Ladies:

     This Issuance Request is delivered to you pursuant to Section 2.8.1 of the
Amended and Restated Credit Agreement, dated as of October 21, 1998 (together
with all amendments and other modifications, if any, from time to time
thereafter made thereto, the "Credit Agreement"), among Vintage Petroleum, Inc.,
a Delaware corporation (the "Borrower"), the various financial institutions as
are, or may from time to time become, parties thereto (collectively, the
"Lenders"), and Bank of Montreal, acting through certain of its U.S. branches or
agencies ("BMO") as agent (in such capacity, together with any successor(s)
thereto in such capacity, the "Agent") for the Lenders. Terms used herein have
the meanings provided in the Credit Agreement unless otherwise defined herein or
the context otherwise requires.

     The Borrower hereby requests that __________________________ as the Issuer
issue a Letter of Credit on [Date] in the aggregate initial face amount of
________________ [and in the form attached hereto].*

     The beneficiary of the requested Letter of Credit will be
_________________________, and such Letter of Credit will be in support of the
[Provide Description] and will have a stated expiry date of [Date].  [The
following documents will be required upon presentation:  [Provide Description]

     Attached hereto is an executed copy of an [Application for Letter of
Credit].


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

*    Include where the Borrower is providing the form of Letter of Credit
     requested to be issued.
<PAGE>
 
     The Borrower hereby acknowledges that, pursuant to Section 5.2.2 of the
Credit Agreement, each of the delivery of this Issuance Request and the issuance
of the Letter of Credit requested hereby constitutes a representation and
warranty by the Borrower that, on the date of such Borrowing, and before and
after giving effect thereto, all statements set forth in Section 5.2.1 are true
and correct in all material respects.

     IN WITNESS WHEREOF, the Borrower has caused this Issuance Request to be
executed and delivered by its duly Authorized Officer this _____ day of
_____________________, 19__.


                                    VINTAGE PETROLEUM, INC.


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


                                       2
<PAGE>
 
                                                                       EXHIBIT I


Bank of Montreal
Houston Agency
700 Louisiana Street
4400 NationsBank Center
Houston, Texas 77002
Telecopier: (713) 223-4007

Date:
     -----------------------------------

                         Notice of Commitment Increase

     Reference is made to the Amended and Restated Credit Agreement, dated as of
October 21, 1998, among Vintage Petroleum, Inc., a Delaware corporation, (the
"Borrower"), certain financial institutions and the Bank of Montreal (the
"Agent") (as amended, modified and supplemented to the date hereof, the
"Agreement").  Capitalized terms used herein but not otherwise defined have the
meanings assigned to them in the Agreement.  The undersigned hereby gives notice
pursuant to Section 2.1.6 of the Agreement of its intent to increase the
Commitment Amount by the amount of $______________, effective _________________
(the "Commitment Increase Effective Date"). The existing Lenders agreeing to
increase their Commitments and the assignees agreeing to become New Lenders to
effect such requested increase are identified below.

     From and after the Commitment Increase Effective Date, the respective
Commitments of the existing Lenders agreeing to increase their Commitments and
the New Lenders will be as set forth below:

Existing Lenders:        Share of         Share of       Percentage
                         Maximum       Bolivian Letter
                        Commitment        of Credit
                         Amount

                     $                 $
- ------------------    --------------    --------------   ----------
                     $                 $
- ------------------    --------------    --------------   ----------
                     $                 $
- ------------------    --------------    --------------   ----------
                     $                 $
- ------------------    --------------    --------------   ----------
                     $                 $
- ------------------    --------------    --------------   ----------
                     $                 $
- ------------------    --------------    --------------   ----------
<PAGE>
 
New Lenders:             Share of          Share of      Percentage
                         Maximum       Bolivian Letter
                       Commitment         of Credit
                         Amount

                     $                 $
- ------------------    --------------    --------------   ----------
                     $                 $
- ------------------    --------------    --------------   ----------
                     $                 $
- ------------------    --------------    --------------   ----------
                     $                 $
- ------------------    --------------    --------------   ----------
                     $                 $
- ------------------    --------------    --------------   ----------
                     $                 $
- ------------------    --------------    --------------   ----------
                     $                 $
- ------------------    --------------    --------------   ----------


     The undersigned Authorized Officer represents and warrants that (a) the
increase requested hereby complies with the requirements of Section 2.1.6 of the
Agreement and (b) except [as set forth on Annex A hereto, and]* to the extent
the undersigned gives notice to the Agent to the contrary prior to 5:00 p.m.,
(U.S. central time) on the Business Day before the Commitment Increase Effective
Date, no Default or Event of Default exists as of the date hereof and no Default
will exist on the Commitment Increase Effective Date.


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

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



- --------------------
*    If the representation and warranty in clause (b) would be incorrect,
     include the material in the brackets and set forth the reasons such
     representation and warranty would be incorrect on an attachment labeled
     Annex A.


                                       2

<TABLE> <S> <C>

<PAGE>
<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM 
SEPTEMBER 30, 1998 FORM 10-Q AND IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO
SUCH FINANCIAL STATEMENTS.
</LEGEND>
<MULTIPLIER> 1,000
       
<S>                             <C>
<PERIOD-TYPE>                   9-MOS
<FISCAL-YEAR-END>                          DEC-31-1998
<PERIOD-START>                             JAN-01-1998
<PERIOD-END>                               SEP-30-1998
<CASH>                                           2,556
<SECURITIES>                                         0
<RECEIVABLES>                                   57,053
<ALLOWANCES>                                         0
<INVENTORY>                                          0
<CURRENT-ASSETS>                                70,378
<PP&E>                                       1,315,399
<DEPRECIATION>                                 450,672
<TOTAL-ASSETS>                                 964,774
<CURRENT-LIABILITIES>                           59,613
<BONDS>                                        563,379
                                0
                                          0
<COMMON>                                           259
<OTHER-SE>                                     314,850
<TOTAL-LIABILITY-AND-EQUITY>                   964,774
<SALES>                                        253,530
<TOTAL-REVENUES>                               254,211
<CGS>                                          154,184
<TOTAL-COSTS>                                  154,184
<OTHER-EXPENSES>                               104,205
<LOSS-PROVISION>                                     0
<INTEREST-EXPENSE>                              30,795
<INCOME-PRETAX>                                (34,973)
<INCOME-TAX>                                   (13,958)
<INCOME-CONTINUING>                            (21,015)
<DISCONTINUED>                                       0
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                   (21,015)
<EPS-PRIMARY>                                     (.41)
<EPS-DILUTED>                                     (.41)
        

</TABLE>


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