SENIOR REVOLVING CREDIT AGREEMENT

Exhibit 10.18

Execution Version

S ENIOR R EVOLVING C REDIT A GREEMENT

D ATED AS OF

J ULY 7, 2005

AMONG

R OSETTA R ESOURCES I NC .,

AS B ORROWER ,

BNP P ARIBAS ,

AS A DMINISTRATIVE A GENT ,

AND

T HE L ENDERS P ARTY H ERETO

S OLE L EAD A RRANGER AND S OLE B OOKRUNNER

BNP P ARIBAS

TABLE OF CONTENTS

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ANNEXES, EXHIBITS AND SCHEDULES

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THIS SENIOR REVOLVING CREDIT AGREEMENT dated as of July 7, 2005, is among: Rosetta Resources Inc., a corporation duly formed and existing under the laws of the State of Delaware (the “ Borrower ”); each of the Lenders from time to time party hereto; and BNP Paribas (in its individual capacity, “BNP Paribas”), as administrative agent for the Lenders (in such capacity, together with its successors in such capacity, the “ Administrative Agent ”).

R E C I T A L S

A. The Borrower has requested that the Lenders provide certain loans to and extensions of credit on behalf of the Borrower.

B. The Lenders have agreed to make such loans and extensions of credit subject to the terms and conditions of this Agreement.

C. In consideration of the mutual covenants and agreements herein contained and of the loans, extensions of credit and commitments hereinafter referred to, the parties hereto agree as follows:

ARTICLE I

Definitions and Accounting Matters

Section 1.01 Terms Defined Above . As used in this Agreement, each term defined above has the meaning indicated above.

Section 1.02 Certain Defined Terms . As used in this Agreement, the following terms have the meanings specified below:

“ ABR ”, when used in reference to any Loan or Borrowing, refers to whether such Loan, or the Loans comprising such Borrowing, are bearing interest at a rate determined by reference to the Alternate Base Rate.

“ Acceptable Collateral ” means: (a) letters of credit having terms satisfactory to the Administrative Agent issued by a bank or trust company which is organized under the laws of the United States or any state thereof, has capital, surplus and undivided profits aggregating at least $100,000,000 (as of the date of such bank or trust company’s most recent financial reports) and has a short term deposit rating of no lower than A2 or P2, as such rating is set forth from time to time, by S&P or Moody’s, (b) if the counterparty to a Gas Sales Contract is a “forward contract merchant” (as defined in the United States Federal Bankruptcy Code) acting in such capacity, the posting of cash collateral to the Margin Account in accordance with Section 9.21, (c) cash prepayment for gas purchases and (d) such other forms of collateral as may be approved by the Majority Lenders.

“ Acquisition ” means the acquisition by the Borrower of all of the Equity Interests of certain Subsidiaries of Calpine pursuant to the terms and conditions of the Acquisition Documents.

“ Acquisition Documents ” means (a) the Purchase and Sale Agreement, (b) the Transfer and Assumption Agreement, (c) the Transition Services Agreement and (d) all bills of sale, assignments, agreements, instruments and documents executed and delivered in connection therewith, as amended.

“ Acquisition Properties ” means the Oil and Gas Properties and other properties acquired directly or indirectly by the Borrower or any Guarantor pursuant to the Acquisition Documents.

“ Adjusted LIBO Rate ” means, with respect to any Eurodollar Borrowing for any Interest Period, an interest rate per annum (rounded upwards, if necessary, to the next 1/100 of 1%) equal to (a) the LIBO Rate for such Interest Period multiplied by (b) the Statutory Reserve Rate.

“ Administrative Questionnaire ” means an Administrative Questionnaire in a form supplied by the Administrative Agent.

“ Affected Loans ” has the meaning assigned such term in Section 5.05.

“ Affiliate ” means, with respect to a specified Person, another Person that directly, or indirectly through one or more intermediaries, Controls or is Controlled by or is under common Control with the Person specified.

“ Agents ” means, collectively, the Administrative Agent, and any syndication agent, documentation agent or similar agent that hereafter becomes a party hereto, and “Agent” shall mean either the Administrative Agent or such other agent, as the context requires.

“ Aggregate Maximum Credit Amounts ” at any time shall equal the sum of the Maximum Credit Amounts, as the same may be reduced or terminated pursuant to Section 2.06.

“ Agreement ” means this Senior Revolving Credit Agreement, as the same may from time to time be amended, modified, supplemented or restated.

“ Alternate Base Rate ” means, for any day, a rate per annum equal to the greater of (a) the Prime Rate in effect on such day and (b) the Federal Funds Effective Rate in effect on such day plus ½ of 1%. Any change in the Alternate Base Rate due to a change in the Prime Rate or the Federal Funds Effective Rate shall be effective from and including the effective date of such change in the Prime Rate or the Federal Funds Effective Rate, respectively.

“ Applicable Margin ” means, for any day, with respect to any ABR Loan or Eurodollar Loan, or with respect to the Commitment Fee Rate, as the case may be, the rate per annum set forth in the Borrowing Base Utilization Grid below based upon the Borrowing Base Utilization Percentage then in effect:

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Each change in the Applicable Margin shall apply during the period commencing on the effective date of such change and ending on the date immediately preceding the effective date of the next such change, provided, however, that if at any time the Borrower fails to deliver a Reserve Report pursuant to Section 8.12(a), then the “ Applicable Margin ” means the rate per annum set forth on the grid when the Borrowing Base Utilization Percentage is at its highest level.

“ Applicable Percentage ” means, with respect to any Lender, the percentage of the Aggregate Maximum Credit Amounts represented by such Lender’s Maximum Credit Amount as such percentage is set forth on Annex I.

“ Approved Counterparty ” means (a) any Lender or any Affiliate of a Lender or (b) any other Person whose long term senior unsecured debt rating is A/A2 by S&P or Moody’s (or their equivalent) or higher or (c) any other Person from time to time approved by the Majority Lenders.

“ Approved Fund ” means any Person (other than a natural person) that is engaged in making, purchasing, holding or investing in bank loans and similar extensions of credit in the ordinary course of its business and that is administered or managed by (a) a Lender, (b) an Affiliate of a Lender or (c) an entity or an Affiliate of an entity that administers or manages a Lender.

“ Approved Petroleum Engineers ” means Netherland, Sewell & Associates, Inc. and any other independent petroleum engineers reasonably acceptable to the Administrative Agent and the Borrower.

“ Approved Purchaser ” means a Person whose long term senior unsecured debt rating from S&P is at least “BBB+” or whose obligations are unconditionally guaranteed pursuant to a guaranty of payment by a Person (the “ Approved Purchaser Guarantor ”) whose long term senior unsecured debt rating from S&P is at least “BBB+”, in either case at the time such Gas Sales Contract is entered into, provided that if such Person’s (or Approved Purchaser Guarantor’s, if applicable) long term senior unsecured debt rating from S&P subsequently is downgraded to “BBB with negative outlook” or to “BBB-” or below, the Person will cease to be an Approved Purchaser until such time as such Person’s (or such Approved Purchaser Guarantor’s, if applicable) long term senior unsecured debt rating is upgraded to “BBB with no negative outlook” or “BBB+” or above.

“ Arranger ” means BNP Paribas, in its capacity as the sole lead arranger and sole bookrunner hereunder.

“ Assignment and Assumption ” means an assignment and assumption entered into by a Lender and an assignee (with the consent of any party whose consent is required by Section 12.04(b)), and accepted by the Administrative Agent, in the form of Exhibit G or any other form approved by the Administrative Agent.

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“ Availability Period ” means the period from and including the Effective Date to but excluding the Termination Date.

“ Board ” means the Board of Governors of the Federal Reserve System of the United States of America or any successor Governmental Authority.

“ Borrowing ” means Loans of the same Type, made, converted or continued on the same date and, in the case of Eurodollar Loans, as to which a single Interest Period is in effect.

“ Borrowing Base ” means at any time an amount equal to the amount determined in accordance with Section 2.07, as the same may be adjusted from time to time pursuant to Section 8.13(c) or Section 9.13(e).

“ Borrowing Base Deficiency ” occurs if at any time the total Revolving Credit Exposures exceeds the Borrowing Base then in effect.

“ Borrowing Base Utilization Percentage ” means, as of any day, the fraction expressed as a percentage, the numerator of which is the total Revolving Credit Exposures of the Lenders on such day, and the denominator of which is the Borrowing Base in effect on such day.

“ Borrowing Request ” means a request by the Borrower for a Borrowing in accordance with Section 2.03.

“ Business Day ” means any day that is not a Saturday, Sunday or other day on which commercial banks in New York City or Houston, Texas are authorized or required by law to remain closed; and if such day relates to a Borrowing or continuation of, a payment or prepayment of principal of or interest on, or a conversion of or into, or the Interest Period for, a Eurodollar Loan or a notice by the Borrower with respect to any such Borrowing or continuation, payment, prepayment, conversion or Interest Period, any day which is also a day on which dealings in dollar deposits are carried out in the London interbank market.

“ Calpine ” means Calpine Corporation, a Delaware corporation.

“ Calpine Gas Contracts ” means all Gas Sales Contracts between the Borrower or any of its Subsidiaries and Calpine or any of its Subsidiaries.

“ Capital Leases ” means, in respect of any Person, all leases which shall have been, or should have been, in accordance with GAAP, recorded as capital leases on the balance sheet of the Person liable (whether contingent or otherwise) for the payment of rent thereunder.

“ Casualty Event ” means any loss, casualty or other insured damage to, or any nationalization, taking under power of eminent domain or by condemnation or similar proceeding of, any Property of the Borrower or any of its Restricted Subsidiaries having a fair market value in excess of $1,000,000.

“ Change in Control ” means (a) the acquisition of ownership, directly or indirectly, beneficially or of record, by any Person or group (within the meaning of the Securities Exchange Act of 1934 and the rules of the SEC thereunder as in effect on the date hereof) of Equity

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Interests representing more than 35% of the aggregate ordinary voting power represented by the issued and outstanding Equity Interests of the Borrower or (b) occupation of a majority of the seats (other than vacant seats) on the board of directors of the Borrower by Persons who were neither (i) nominated by the board of directors of the Borrower nor (ii) appointed by directors so nominated.

“ Change in Law ” means (a) the adoption of any law, rule or regulation after the date of this Agreement, (b) any change in any law, rule or regulation or in the interpretation or application thereof by any Governmental Authority after the date of this Agreement or (c) compliance by any Lender or the Issuing Bank (or, for purposes of Section 5.01(b)), by any lending office of such Lender or by such Lender’s or the Issuing Bank’s holding company, if any) with any request, guideline or directive (whether or not having the force of law) of any Governmental Authority made or issued after the date of this Agreement.

“ Code ” means the Internal Revenue Code of 1986, as amended from time to time, and any successor statute.

“ Commitment ” means, with respect to each Lender, the commitment of such Lender to make Loans and to acquire participations in Letters of Credit hereunder, expressed as an amount representing the maximum aggregate amount of such Lender’s Revolving Credit Exposure hereunder, as such commitment may be (a) modified from time to time pursuant to Section 2.06 and (b) modified from time to time pursuant to assignments by or to such Lender pursuant to Section 12.04(b), and “Commitments” means the aggregate amount of the Commitments of all Lenders. The amount representing each Lender’s Commitment shall at any time be the lesser of such Lender’s Maximum Credit Amount and such Lender’s Applicable Percentage of the then effective Borrowing Base.

“ Commitment Fee Rate ” has the meaning set forth in the definition of “ Applicable Margin ”.

“ Consolidated Net Income ” means with respect to the Borrower and the Consolidated Restricted Subsidiaries, for any period, the aggregate of the net income (or loss) of the Borrower and the Consolidated Restricted Subsidiaries after allowances for taxes for such period determined on a consolidated basis in accordance with GAAP; provided that there shall be excluded from such net income (to the extent otherwise included therein) the following: (a) the net income of any Person in which the Borrower or any Consolidated Restricted Subsidiary has an interest (which interest does not cause the net income of such other Person to be consolidated with the net income of the Borrower and the Consolidated Restricted Subsidiaries in accordance with GAAP), except to the extent of the amount of dividends or distributions actually paid in cash during such period by such other Person to the Borrower or to a Consolidated Restricted Subsidiary, as the case may be; (b) the net income (but not loss) during such period of any Consolidated Restricted Subsidiary to the extent that the declaration or payment of dividends or similar distributions or transfers or loans by that Consolidated Restricted Subsidiary is not at the time permitted by operation of the terms of its charter or any agreement, instrument or Governmental Requirement applicable to such Consolidated Restricted Subsidiary or is otherwise restricted or prohibited, in each case determined in accordance with GAAP; (c) any extraordinary non-cash gains or losses during such period, (d) non-cash gains or losses under

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FAS 133 resulting from the net change in Borrower’s mark-to-market portfolio of commodity price risk management activities during that period and (e) any gains or losses attributable to writeups or writedowns of assets, including ceiling test writedowns; and provided further that for purposes of calculating the financial ratio in Section 9.01(a), if the Borrower or any Consolidated Restricted Subsidiary shall acquire or dispose of any material Property or a Subsidiary shall be redesignated as either an Unrestricted Subsidiary or a Restricted Subsidiary, in any case, during the period of four fiscal quarters ending on the last day of the fiscal quarter immediately preceding the date of determination for which financial statements are available and up to and including the date of the consummation of such acquisition, disposition or redesignation, then Consolidated Net Income shall be calculated after giving pro forma effect to such acquisition (including the revenues of the Properties acquired), merger, disposition or redesignation, as if such acquisition, merger, disposition or redesignation had occurred on the first day of such period.

“ Consolidated Restricted Subsidiaries ” means any Restricted Subsidiaries that are Consolidated Subsidiaries.

“ Consolidated Subsidiaries ” means each Subsidiary of the Borrower (whether now existing or hereafter created or acquired) the financial statements of which shall be (or should have been) consolidated with the financial statements of the Borrower in accordance with GAAP.

“ Consolidated Unrestricted Subsidiaries ” means any Unrestricted Subsidiaries that are Consolidated Subsidiaries.

“ Control ” means the possession, directly or indirectly, of the power to direct or cause the direction of the management or policies of a Person, whether through the ability to exercise voting power, by contract or otherwise. “ Controlling ” and “ Controlled ” have meanings correlative thereto.

“ Control Agreement ” means the Account Control Agreement by and among the Borrower, the Administrative Agent and the depository bank named therein, granting the Administrative Agent “control” over the Margin Account, to be executed pursuant to Section 8.19.

“ Debt ” means, for any Person, the sum of the following (without duplication): (a) all obligations of such Person for borrowed money or evidenced by bonds, bankers’ acceptances, debentures, notes or other similar instruments; (b) all obligations of such Person (whether contingent or otherwise) in respect of letters of credit, surety or other bonds and similar instruments; (c) all accounts payable and all accrued expenses, liabilities or other obligations of such Person to pay the deferred purchase price of Property or services that are more than ninety (90) days past the date of invoice other than those which are being contested in good faith by appropriate action and for which adequate reserves have been maintained in accordance with GAAP; (d) all obligations under Capital Leases; (e) all obligations under Synthetic Leases; (f) all Debt (as defined in the other clauses of this definition) of others secured by (or for which the holder of such Debt has an existing right, contingent or otherwise, to be secured by) a Lien on any Property of such Person, whether or not such Debt is assumed by such Person; (g) all Debt

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(as defined in the other clauses of this definition) of others guaranteed by such Person or in which such Person otherwise assures a creditor against loss of the Debt (howsoever such assurance shall be made) to the extent of the lesser of the amount of such Debt and the maximum stated amount of such guarantee or assurance against loss; (h) all obligations or undertakings of such Person to maintain or cause to be maintained the financial position or covenants of others or to purchase the Debt or Property of others to insure a creditor against a loss; (i) obligations to deliver commodities, goods or services, including, without limitation, Hydrocarbons, in consideration of one or more advance payments made more than one month in advance of the month in which the commodities, goods or services are to be delivered, other than gas balancing arrangements in the ordinary course of business; (j) obligations to pay for goods or services even if such goods or services are not actually received or utilized by such Person; (k) any Debt of a partnership for which such Person is liable either by agreement, by operation of law or by a Governmental Requirement but only to the extent of such liability; (l) Disqualified Capital Stock; and (m) the undischarged balance of any production payment created by such Person or for the creation of which such Person directly or indirectly received payment. The Debt of any Person shall include all obligations of such Person of the character described above to the extent such Person remains legally liable in respect thereof notwithstanding that any such obligation is not included as a liability of such Person under GAAP.

“ Default ” means any event or condition which constitutes an Event of Default or which upon notice, lapse of time or both would, unless cured or waived, become an Event of Default.

“ Disqualified Capital Stock ” means any Equity Interest that, by its terms (or by the terms of any security into which it is convertible or for which it is exchangeable) or upon the happening of any event, matures or is mandatorily redeemable for any consideration other than other Equity Interests (which would not constitute Disqualified Capital Stock), pursuant to a sinking fund obligation or otherwise, or is convertible or exchangeable for Debt or redeemable for any consideration other than other Equity Interests (which would not constitute Disqualified Capital Stock) at the option of the holder thereof, in whole or in part, on or prior to the date that is one year after the earlier of (a) the Maturity Date and (b) the date on which there are no Loans, LC Exposure or other obligations hereunder outstanding and all of the Commitments are terminated.

“ dollars ” or “$” refers to lawful money of the United States of America.

“ Domestic Subsidiary ” means any Restricted Subsidiary that is organized under the laws of the United States of America or any state thereof or the District of Columbia.

“ EBITDAX ” means, for any period, the sum of Consolidated Net Income for such period plus the following expenses or charges to the extent deducted from Consolidated Net Income in such period: interest, letter of credit fees, income and franchise taxes, depreciation, depletion, amortization and other similar noncash charges and exploration expenses, minus all noncash income added to Consolidated Net Income.

“ Effective Date ” means the date on which the conditions specified in Section 6.01 are satisfied (or waived in accordance with Section 12.02).

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“ Engineering Reports ” has the meaning assigned such term in Section 2.07(c)(i).

“ Environmental Laws ” means any and all Governmental Requirements pertaining in any way to health, safety the environment or the preservation or reclamation of natural resources, in effect in any and all jurisdictions in which the Borrower or any Restricted Subsidiary is conducting or at any time has conducted business, or where any Property of the Borrower or any Restricted Subsidiary is located, including without limitation, the Oil Pollution Act of 1990 (“ OPA ”), as amended, the Clean Air Act, as amended, the Comprehensive Environmental, Response, Compensation, and Liability Act of 1980 (“ CERCLA ”), as amended, the Federal Water Pollution Control Act, as amended, the Occupational Safety and Health Act of 1970, as amended, the Resource Conservation and Recovery Act of 1976 (“ RCRA ”), as amended, the Safe Drinking Water Act, as amended, the Toxic Substances Control Act, as amended, the Superfund Amendments and Reauthorization Act of 1986, as amended, the Hazardous Materials Transportation Act, as amended, and other environmental conservation or protection Governmental Requirements. The term “oil” shall have the meaning specified in OPA, the terms “ hazardous substance ” and “ release ” (or “ threatened release ”) have the meanings specified in CERCLA, the terms “ solid waste ” and “ disposal ” (or “ disposed ”) have the meanings specified in RCRA and the term “ oil and gas waste ” shall have the meaning specified in Section 91.1011 of the Texas Natural Resources Code (“ Section 91.1011 ”); provided, however, that (a) in the event either OPA, CERCLA, RCRA or Section 91.1011 is amended so as to broaden the meaning of any term defined thereby, such broader meaning shall apply subsequent to the effective date of such amendment and (b) to the extent the laws of the state or other jurisdiction in which any Property of the Borrower or any Restricted Subsidiary is located establish a meaning for “ oil ,” “ hazardous substance ,” “ release ,” “ solid waste ,” “ disposal ” or “ oil and gas waste ” which is broader than that specified in either OPA, CERCLA, RCRA or Section 91.1011, such broader meaning shall apply.

“ Equity Interests ” means shares of capital stock, partnership interests, membership interests in a limited liability company, beneficial interests in a trust or other equity ownership interests in a Person, and any warrants, options or other rights entitling the holder thereof to purchase or acquire any such Equity Interest.

“ ERISA ” means the Employee Retirement Income Security Act of 1974, as amended, and any successor statute.

“ ERISA Affiliate ” means each trade or business (whether or not incorporated) which together with the Borrower or a Subsidiary would be deemed to be a “single employer” within the meaning of section 4001(b)(1) of ERISA or subsections (b), (c), (m) or (o) of section 414 of the Code.

“ ERISA Event ” means (a) a “Reportable Event” described in section 4043 of ERISA and the regulations issued thereunder, (b) the withdrawal of the Borrower, a Subsidiary or any ERISA Affiliate from a Plan during a plan year in which it was a “substantial employer” as defined in section 4001(a)(2) of ERISA, (c) the filing of a notice of intent to terminate a Plan or the treatment of a Plan amendment as a termination under section 4041 of ERISA, (d) the institution of proceedings to terminate a Plan by the PBGC, (e) receipt of a notice of withdrawal liability pursuant to Section 4202 of ERISA or (f) any other event or condition which might constitute grounds under section 4042 of ERISA for the termination of, or the appointment of a trustee to administer, any Plan.

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“ Eurodollar ”, when used in reference to any Loan or Borrowing, refers to whether such Loan, or the Loans comprising such Borrowing, are bearing interest at a rate determined by reference to the Adjusted LIBO Rate.

“ Event of Default ” has the meaning assigned such term in Section 10.01.

“ Excepted Liens ” means: (a) Liens for Taxes, assessments or other governmental charges or levies which are not delinquent or which are being contested in good faith by appropriate action and for which adequate reserves have been maintained in accordance with GAAP; (b) Liens in connection with workers’ compensation, unemployment insurance or other social security, old age pension or public liability obligations which are not delinquent or which are being contested in good faith by appropriate action and for which adequate reserves have been maintained in accordance with GAAP; (c) statutory landlord’s liens, operators’, vendors’, carriers’, warehousemen’s, repairmen’s, mechanics’, suppliers’, workers’, materialmen’s, construction or other like Liens arising by operation of law in the ordinary course of business or incident to the exploration, development, operation and maintenance of Oil and Gas Properties each of which is in respect of obligations that are not delinquent or which are being contested in good faith by appropriate action and for which adequate reserves have been maintained in accordance with GAAP; (d) contractual Liens which arise in the ordinary course of business under real property leases, operating agreements, joint venture agreements, oil and gas partnership agreements, oil and gas leases, farm-out agreements, division orders, contracts for the sale, transportation or exchange of oil and natural gas, unitization and pooling declarations and agreements, area of mutual interest agreements, overriding royalty agreements, marketing agreements, processing agreements, net profits agreements, development agreements, gas balancing or deferred production agreements, injection, repressuring and recycling agreements, salt water or other disposal agreements, seismic or other geophysical permits or agreements, and other agreements which are usual and customary in the oil and gas business and are for claims which are not delinquent or which are being contested in good faith by appropriate action and for which adequate reserves have been maintained in accordance with GAAP, provided that any such Lien referred to in this clause does not materially impair the use of the Property covered by such Lien for the purposes for which such Property is held by the Borrower or any Restricted Subsidiary or materially impair the value of such Property subject thereto; (e) Liens relating to banker’s liens, rights of set-off or similar rights and remedies and burdening only deposit accounts or other funds maintained with a creditor depository institution, provided that no such deposit account is a dedicated cash collateral account or is subject to restrictions against access by the depositor in excess of those set forth by regulations promulgated by the Board and no such deposit account is intended by Borrower or any of its Restricted Subsidiaries to provide collateral to the depository institution; (f) easements, restrictions, servitudes, permits, conditions, covenants, exceptions or reservations in any Property of the Borrower or any Restricted Subsidiary that do not secure any Debt and which in the aggregate do not materially impair the use of such Property for the purposes of which such Property is held by the Borrower or any Restricted Subsidiary or materially impair the value of such Property subject thereto; (g) Liens on cash or securities pledged to secure performance of tenders, surety and appeal bonds, government contracts, performance and return of money bonds, bids, trade contracts, leases,

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statutory obligations, regulatory obligations and other obligations of a like nature incurred in the ordinary course of business; (h) Liens arising under Uniform Commercial Code financing filings regarding operating leases which are not Synthetic Leases entered into by Borrower and Restricted Subsidiaries in the ordinary course of business covering only the Property under such lease and (i) judgment and attachment Liens not giving rise to an Event of Default, provided that any appropriate legal proceedings which may have been duly initiated for the review of such judgment shall not have been finally terminated or the period within which such proceeding may be initiated shall not have expired and no action to divest title to such Lien has been commenced; provided, further that Liens described in clauses (a) through (e) shall remain “Excepted Liens” only for so long as no action to divest title to such Lien has been commenced and no intention to subordinate the first priority Lien granted in favor of the Administrative Agent and the Lenders is to be hereby implied or expressed by the permitted existence of such Excepted Liens.

“ Excluded Taxes ” means, with respect to the Administrative Agent, any Lender, the Issuing Bank or any other recipient of any payment to be made by or on account of any obligation of the Borrower or any Guarantor hereunder or under any other Loan Document, (a) income or franchise taxes imposed on (or measured by) its net income by the United States of America or such other jurisdiction under the laws of which such recipient is organized or in which its principal office is located or, in the case of any Lender, in which its applicable lending office is located, (b) any branch profits taxes imposed by the United States of America or any similar tax imposed by any other jurisdiction in which the Borrower or any Guarantor is located and (c) in the case of a Foreign Lender (other than an assignee pursuant to a request by the Borrower under Section 5.04(b)), any withholding tax that is imposed on amounts payable to such Foreign Lender at the time such Foreign Lender becomes a party to this Agreement (or designates a new lending office) or is attributable to such Foreign Lender’s failure to comply with Section 5.03(e), except to the extent that such Foreign Lender (or its assignor, if any) was entitled, at the time of designation of a new lending office (or assignment), to receive additional amounts with respect to such withholding tax pursuant to Section 5.03 or Section 5.03(c).

“ FAS 133 ” means Statement of Financial Accounting Standard 133 (and any statements replacing, modifying or superceding such statement) adopted by the Financial Accounting Standards Board.

“ Federal Funds Effective Rate ” means, for any day, the weighted average (rounded upwards, if necessary, to the next 1/100 of 1%) of the rates on overnight Federal funds transactions with members of the Federal Reserve System arranged by Federal funds brokers, as published on the next succeeding Business Day by the Federal Reserve Bank of New York, or, if such rate is not so published for any day that is a Business Day, the average (rounded upwards, if necessary, to the next 1/100 of 1%) of the quotations for such day for such transactions received by the Administrative Agent from three Federal funds brokers of recognized standing selected by it.

“ Financial Officer ” means, for any Person, the chief financial officer, principal accounting officer, treasurer or controller of such Person. Unless otherwise specified, all references herein to a Financial Officer means a Financial Officer of the Borrower.

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“ Financial Statements ” means the financial statement or statements of the Borrower and its Consolidated Subsidiaries referred to in Section 7.04(a).

“ Foreign Lender ” means any Lender that is organized under the laws of a jurisdiction other than that in which the Borrower is located. For purposes of this definition, the United States of America, each State thereof and the District of Columbia shall be deemed to constitute a single jurisdiction.

“ Foreign Subsidiary ” means any Restricted Subsidiary that is not a Domestic Subsidiary.

“ GAAP ” means generally accepted accounting principles in the United States of America as in effect from time to time subject to the terms and conditions set forth in Section 1.05.

“ Gas Sales Contract ” means any contract for the purchase and sale of gas.

“ Governmental Authority ” means the government of the United States of America, any other nation or any political subdivision thereof, whether state or local, and any agency, authority, instrumentality, regulatory body, court, central bank or other entity exercising executive, legislative, judicial, taxing, regulatory or administrative powers or functions of or pertaining to government over the Borrower, any Restricted Subsidiary, any of their Properties, any Agent, the Issuing Bank or any Lender.

“ Governmental Requirement ” means any law, statute, code, ordinance, order, determination, rule, regulation, judgment, decree, injunction, franchise, permit, certificate, license, authorization or other directive or requirement, whether now or hereinafter in effect, including, without limitation, Environmental Laws, energy regulations and occupational, safety and health standards or controls, of any Governmental Authority.

“ Guarantors ” means, collectively:

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“ Guaranty Agreement ” means an agreement executed by the Guarantors in substantially the form of Exhibit F-2 unconditionally guarantying on a joint and several basis, payment of the Indebtedness, as the same may be amended, modified or supplemented from time to time.

“ Highest Lawful Rate ” means, with respect to each Lender, the maximum nonusurious interest rate, if any, that at any time or from time to time may be contracted for, taken, reserved, charged or received on the Notes or on other Indebtedness under laws applicable to such Lender which are presently in effect or, to the extent allowed by law, under such applicable laws which may hereafter be in effect and which allow a higher maximum nonusurious interest rate than applicable laws allow as of the date hereof.

“ Hydrocarbon Interests ” means all rights, titles, interests and estates now or hereafter acquired in and to oil and gas leases, oil, gas and mineral leases, or other liquid or gaseous hydrocarbon leases, mineral fee interests, overriding royalty and royalty interests, net profit interests and production payment interests, including any reserved or residual interests of whatever nature. Unless otherwise indicated herein, each reference to the term “Hydrocarbon Interests” shall mean Hydrocarbon Interests of the Borrower and the Restricted Subsidiaries.

“ Hydrocarbons ” means oil, gas, casinghead gas, drip gasoline, natural gasoline, condensate, distillate, liquid hydrocarbons, gaseous hydrocarbons and all products refined or separated therefrom. Unless otherwise indicated herein, each reference to the term “Hydrocarbons” shall mean Hydrocarbons of the Borrower and the Restricted Subsidiaries.

“ Indebtedness ” means any and all amounts owing or to be owing by the Borrower, any Restricted Subsidiary or any Guarantor whether direct or indirect (including those acquired by assumption), absolute or contingent, due or to become due, now existing or hereafter arising: (a) to the Administrative Agent, the Issuing Bank or any Lender under any Loan Document, (b) to any Lender or any Affiliate of a Lender under any Swap Agreement between the Borrower or any Restricted Subsidiary and such Lender or Affiliate of a Lender while such Person (or in the case of its Affiliate, the Person affiliated therewith) is a Lender hereunder and (c) all renewals, extensions and/or rearrangements of any of the above.

“ Indemnified Taxes ” means Taxes other than Excluded Taxes.

“ Initial Borrowing Base ” has the meaning assigned such term in Section 2.07(a).

“ Initial Reserve Report ” means the report of Netherland, Sewell & Associates, Inc. dated as of January 26, 2005, with respect to certain Oil and Gas Properties of Calpine and its Subsidiaries as of December 31, 2004, as rolled forward to April 30, 2005 by the report of Netherland, Sewell & Associates, Inc. dated as of June 5, 2005.

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“ Intercreditor Agreement ” means in respect of the Second Lien Term Loan Agreement, the terms of subordination as attached as Annex II to the Second Lien Term Loan Agreement, as the same may from time to time be amended, modified, supplemented or restated.

“ Interest Election Request ” means a request by the Borrower to convert or continue a Borrowing in accordance with Section 2.04.

“ Interest Expense ” means, for any period, the sum (determined without duplication) of (a) all cash dividends paid on the Borrower’s preferred Equity Interests and (b) the aggregate gross interest expense of the Borrower and the Consolidated Restricted Subsidiaries for such period, including to the extent included in interest expense under GAAP: (i) amortization of debt discount, (ii) capitalized interest and (iii) the portion of any payments or accruals under Capital Leases allocable to interest expense, plus the portion of any payments or accruals under Synthetic Leases allocable to interest expense whether or not the same constitutes interest expense under GAAP.

“ Interest Payment Date ” means (a) with respect to any ABR Loan, the last day of each March, June, September and December and (b) with respect to any Eurodollar Loan, the last day of the Interest Period applicable to the Borrowing of which such Loan is a part and, in the case of a Eurodollar Borrowing with an Interest Period of more than three months’ duration, each day prior to the last day of such Interest Period that occurs at intervals of three months’ duration after the first day of such Interest Period.

“ Interest Period ” means with respect to any Eurodollar Borrowing, the period commencing on the date of such Borrowing and ending on the numerically corresponding day in the calendar month that is one, two, three or six months (or, with the consent of each Lender, nine or twelve months) thereafter, as the Borrower may elect; provided, that (a) if any Interest Period would end on a day other than a Business Day, such Interest Period shall be extended to the next succeeding Business Day unless such next succeeding Business Day would fall in the next calendar month, in which case such Interest Period shall end on the next preceding Business Day and (b) any Interest Period pertaining to a Eurodollar Borrowing that commences on the last Business Day of a calendar month (or on a day for which there is no numerically corresponding day in the last calendar month of such Interest Period) shall end on the last Business Day of the last calendar month of such Interest Period. For purposes hereof, the date of a Borrowing initially shall be the date on which such Borrowing is made and thereafter shall be the effective date of the most recent conversion or continuation of such Borrowing.

“ Interim Redetermination ” has the meaning assigned such term in Section 2.07(b).

“ Interim Redetermination Date ” means the date on which a Borrowing Base that has been redetermined pursuant to an Interim Redetermination becomes effective as provided in Section 2.07(d).

“ Investment ” means, for any Person: (a) the acquisition (whether for cash, Property, services or securities or otherwise) of Equity Interests of any other Person or any agreement to make any such acquisition (including, without limitation, any “short sale” or any sale of any securities at a time when such securities are not owned by the Person entering into such short

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sale); (b) the making of any deposit with, or advance, loan or capital contribution to, assumption of Debt of, purchase or other acquisition of any other Debt or equity participation or interest in, or other extension of credit to, any other Person (including the purchase of Property from another Person subject to an understanding or agreement, contingent or otherwise, to resell such Property to such Person, but excluding any such advance, loan or extension of credit having a term not exceeding ninety (90) days representing the purchase price of inventory or supplies sold by such Person in the ordinary course of business) or (c) the entering into of any guarantee of, or other contingent obligation (including the deposit of any Equity Interests to be sold) with respect to, Debt of any other Person and (without duplication) any amount committed to be advanced, lent or extended to such Person.

“ Issuing Bank ” means BNP Paribas, in its capacity as the issuer of Letters of Credit hereunder, and its successors in such capacity as provided in Section 2.08(i). The Issuing Bank may, in its discretion, arrange for one or more Letters of Credit to be issued by Affiliates of the Issuing Bank, in which case the term “ Issuing Bank ” shall include any such Affiliate with respect to Letters of Credit issued by such Affiliate.

“ LC Commitment ” at any time means Fifty Million Dollars ($50,000,000).

“ LC Disbursement ” means a payment made by the Issuing Bank pursuant to a Letter of Credit.

“ LC Exposure ” means, at any time, the sum of (a) the aggregate undrawn amount of all outstanding Letters of Credit at such time plus (b) the aggregate amount of all LC Disbursements that have not yet been reimbursed by or on behalf of the Borrower at such time. The LC Exposure of any Lender at any time shall be its Applicable Percentage of the total LC Exposure at such time.

“ Lenders ” means the Persons listed on Annex I and any Person that shall have become a party hereto pursuant to an Assignment and Assumption, other than any such Person that ceases to be a party hereto pursuant to an Assignment and Assumption.

“ Letter of Credit ” means any letter of credit issued pursuant to this Agreement.

“ Letter of Credit Agreements ” means all letter of credit applications and other agreements (including any amendments, modifications or supplements thereto) submitted by the Borrower, or entered into by the Borrower, with the Issuing Bank relating to any Letter of Credit.

“ LIBO Rate ” means, with respect to any Eurodollar Borrowing for any Interest Period, the rate appearing on Page 3750 of the Dow Jones Market Service (or on any successor or substitute page of such Service, or any successor to or substitute for such Service, providing rate quotations comparable to those currently provided on such page of such Service, as determined by the Administrative Agent from time to time for purposes of providing quotations of interest rates applicable to dollar deposits in the London interbank market) at approximately 11:00 a.m., London time, two Business Days prior to the commencement of such Interest Period, as the rate for dollar deposits with a maturity comparable to such Interest Period. In the event that such rate is not available at such time for any reason, then the “ LIBO Rate ” with respect to such Eurodollar Borrowing for such Interest Period shall be the rate (rounded upwards, if necessary,

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to the next 1/16 of 1%) at which dollar deposits of $5,000,000 and for a maturity comparable to such Interest Period are offered by the principal London office of the Administrative Agent in immediately available funds in the London interbank market at approximately 11:00 a.m., London time, two Business Days prior to the commencement of such Interest Period.

“ Lien ” means any interest in Property securing an obligation owed to, or a claim by, a Person other than the owner of the Property, whether such interest is based on the common law, statute or contract, and whether such obligation or claim is fixed or contingent, and including but not limited to (a) the lien or security interest arising from a mortgage, encumbrance, pledge, security agreement, conditional sale or trust receipt or a lease, consignment or bailment for security purposes or (b) production payments and the like payable out of Oil and Gas Properties. For the purposes of this Agreement, the Borrower and its Restricted Subsidiaries shall be deemed to be the owner of any Property which it has acquired or holds subject to a conditional sale agreement, or leases under a financing lease or other arrangement pursuant to which title to the Property has been retained by or vested in some other Person in a transaction intended to create a financing.

“ Loan Documents ” means this Agreement, the Notes, the Letter of Credit Agreements, the Letters of Credit, the Security Instruments and the Intercreditor Agreement.

“ Loans ” means the loans made by the Lenders to the Borrower pursuant to this Agreement.

“ Majority Lenders ” means, at any time while no Loans or LC Exposure is outstanding, Lenders having at least sixty-six and two-thirds percent (66-2/3%) of the Aggregate Maximum Credit Amounts; and at any time while any Loans or LC Exposure is outstanding, Lenders holding at least sixty-six and two-thirds percent (66-2/3%) of the outstanding aggregate principal amount of the Loans or participation interests in Letters of Credit (without regard to any sale by a Lender of a participation in any Loan under Section 12.04(c)).

“ Margin Account ” has the meaning assigned to such term in Section 9.21.

“ Marketing Agreement ” means the Service Agreement between Calpine Producer Services, L.P. and the Borrower.

“ Material Adverse Effect ” means a material adverse change in, or material adverse effect on (a) the business, operations, Property, condition (financial or otherwise) or prospects of the Borrower and the Restricted Subsidiaries taken as a whole, (b) the ability of the Borrower, any Restricted Subsidiary or any Guarantor to perform any of its obligations under any Loan Document, (c) the validity or enforceability of any Loan Document or (d) the rights and remedies of or benefits available to the Administrative Agent, any other Agent, the Issuing Bank or any Lender under any Loan Document.

“ Material Indebtedness ” means Debt (other than the Loans and Letters of Credit), or obligations in respect of one or more Swap Agreements, of any one or more of the Borrower and its Restricted Subsidiaries in an aggregate principal amount exceeding $5,000,000. For purposes of determining Material Indebtedness, the “principal amount” of the obligations of the Borrower or any Restricted Subsidiary in respect of any Swap Agreement at any time shall be the Swap Termination Value.

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“ Maturity Date ” means July 7, 2009.

“ Maximum Credit Amount ” means, as to each Lender, the amount set forth opposite such Lender’s name on Annex I under the caption “Maximum Credit Amounts”, as the same may be (a) reduced or terminated from time to time in connection with a reduction or termination of the Aggregate Maximum Credit Amounts pursuant to Section 2.06(b) or (b) modified from time to time pursuant to any assignment permitted by Section 12.04(b).

“ Moody’s ” means Moody’s Investors Service, Inc. and any successor thereto that is a nationally recognized rating agency.

“ Mortgaged Property ” means any Property owned by the Borrower or any Guarantor which is subject to the Liens existing and to exist under the terms of the Security Instruments.

“ Multiemployer Plan ” means a Plan which is a multiemployer plan as defined in section 3(37) or 4001 (a)(3) of ERISA.

“ New Borrowing Base Notice ” has the meaning assigned such term in Section 2.07(d).

“ Non-Recourse Debt ” means any Debt of any Unrestricted Subsidiary, in each case in respect of which: (a) the holder or holders thereof (i) shall have recourse only to, and shall have the right to require the obligations of such Unrestricted Subsidiary to be performed, satisfied, and paid only out of, the Property of such Unrestricted Subsidiary and/or one or more of its Subsidiaries (but only to the extent that such Subsidiaries are Unrestricted Subsidiaries) and/or any other Person (other than Borrower and/or any Restricted Subsidiary) and (ii) shall have no direct or indirect recourse (including by way of guaranty, support or indemnity) to the Borrower or any Restricted Subsidiary or to any of the Property of Borrower or any Restricted Subsidiary, whether for principal, interest, fees, expenses or otherwise; and (b) the terms and conditions relating to the non-recourse nature of such Debt are in form and substance reasonably acceptable to the Administrative Agent.

“ Notes ” means the promissory notes of the Borrower described in Section 2.02(d) and being substantially in the form of Exhibit A, together with all amendments, modifications, replacements, extensions and rearrangements thereof.

“ Offering Memorandum ” means that certain Offering Memorandum dated June 30, 2005 from the Borrower related to the offering of 45,312,500 shares of its common stock.

“ Oil and Gas Properties ” means (a) Hydrocarbon Interests; (b) the Properties now or hereafter pooled or unitized with Hydrocarbon Interests; (c) all presently existing or future unitization, pooling agreements and declarations of pooled units and the units created thereby (including without limitation all units created under orders, regulations and rules of any Governmental Authority) which may affect all or any portion of the Hydrocarbon Interests; (d) all operating agreements, contracts and other agreements, including production sharing contracts and agreements, which relate to any of the Hydrocarbon Interests or the production,

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sale, purchase, exchange or processing of Hydrocarbons from or attributable to such Hydrocarbon Interests; (e) all Hydrocarbons in and under and which may be produced and saved or attributable to the Hydrocarbon Interests, including all oil in tanks, and all rents, issues, profits, proceeds, products, revenues and other incomes from or attributable to the Hydrocarbon Interests; (f) all tenements, hereditaments, appurtenances and Properties in any manner appertaining, belonging, affixed or incidental to the Hydrocarbon Interests and (g) all Properties, rights, titles, interests and estates described or referred to above, including any and all Property, real or personal, now owned or hereinafter acquired and situated upon, used, held for use or useful in connection with the operating, working or development of any of such Hydrocarbon Interests or Property (excluding drilling rigs, automotive equipment, rental equipment or other personal Property which may be on such premises for the purpose of drilling a well or for other similar temporary uses) and including any and all oil wells, gas wells, injection wells or other wells, buildings, structures, fuel separators, liquid extraction plants, plant compressors, pumps, pumping units, field gathering systems, tanks and tank batteries, fixtures, valves, fittings, machinery and parts, engines, boilers, meters, apparatus, equipment, appliances, tools, implements, cables, wires, towers, casing, tubing and rods, surface leases, rights-of-way, easements and servitudes together with all additions, substitutions, replacements, accessions and attachments to any and all of the foregoing. Unless otherwise indicated herein, each reference to the term “Oil and Gas Properties” shall mean Oil and Gas Properties of the Borrower and the Restricted Subsidiaries.

“ Other Taxes ” means any and all present or future stamp or documentary taxes or any other excise or Property taxes, charges or similar levies arising from any payment made hereunder or from the execution, delivery or enforcement of, or otherwise with respect to, this Agreement and any other Loan Document.

“ Participant ” has the meaning set forth in Section 12.04(c)(i).

“ PBGC ” means the Pension Benefit Guaranty Corporation, or any successor thereto.

“ Person ” means any natural person, corporation, limited liability company, trust, joint venture, association, company, partnership, Governmental Authority or other entity.

“ Plan ” means any employee pension benefit plan, as defined in section 3(2) of ERISA, which (a) is currently or hereafter sponsored, maintained or contributed to by the Borrower, a Subsidiary or an ERISA Affiliate or (b) was at any time during the six calendar years preceding the date hereof, sponsored, maintained or contributed to by the Borrower or a Subsidiary or an ERISA Affiliate.

“ Prime Rate ” means the rate of interest per annum publicly announced from time to time by the Administrative Agent as its prime rate in effect at its principal office in New York City; each change in the Prime Rate shall be effective from and including the date such change is publicly announced as being effective. Such rate is set by the Administrative Agent as a general reference rate of interest, taking into account such factors as the Administrative Agent may deem appropriate; it being understood that many of the Administrative Agent’s commercial or other loans are priced in relation to such rate, that it is not necessarily the lowest or best rate actually charged to any customer and that the Administrative Agent may make various commercial or other loans at rates of interest having no relationship to such rate.

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“ Private Placement ” means the issuance and sale of common stock of the Borrower pursuant to the Offering Memorandum.

“ Property ” means any interest in any kind of property or asset, whether real, personal or mixed, or tangible or intangible, including, without limitation, cash, securities, accounts and contract rights.

“ Proposed Borrowing Base ” has the meaning assigned to such term in Section 2.07(c)(i).

“ Proposed Borrowing Base Notice ” has the meaning assigned to such term in Section 2.07(c)(ii).

“ Purchase and Sale Agreement ” means the Purchase and Sale Agreement among Calpine, Calpine Gas Holdings LLC, Calpine Fuels Corporation, and the Borrower, dated July 7, 2005.

“ Purchaser ” has the meaning assigned such term in Section 9.21.

“ Redemption ” means with respect to any Debt, the repurchase, redemption, prepayment, repayment, defeasance or any other acquisition or retirement for value (or the segregation of funds with respect to any of the foregoing) of such Debt. “ Redeem ” has the correlative meaning thereto.

“ Redetermination Date ” means, with respect to any Scheduled Redetermination or any Interim Redetermination, the date that the redetermined Borrowing Base related thereto becomes effective pursuant to Section 2.07(d).

“ Register ” has the meaning assigned such term in Section 12.04(b)(iv).

“ Regulation D ” means Regulation D of the Board, as the same may be amended, supplemented or replaced from time to time.

“ Related Parties ” means, with respect to any specified Person, such Person’s Affiliates and the respective directors, officers, employees, agents and advisors (including attorneys, accountants and experts) of such Person and such Person’s Affiliates.

“ Remedial Work ” has the meaning assigned such term in Section 8.10(a).

“ Required Lenders ” means, at any time while no Loans or LC Exposure is outstanding, Lenders having in excess of seventy-five percent (75%) of the Aggregate Maximum Credit Amounts; and at any time while any Loans or LC Exposure is outstanding, Lenders holding in excess of seventy-five percent (75%) of the outstanding aggregate principal amount of the Loans or participation interests in such Letters of Credit (without regard to any sale by a Lender of a participation in any Loan under Section 12.04(c)).

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“ Reserve Report ” means a report, in form and substance reasonably satisfactory to the Administrative Agent, setting forth, as of each January 1st or July 1st (or such other date in the event of an Interim Redetermination) the oil and gas reserves attributable to the Oil and Gas Properties of the Borrower and the Restricted Subsidiaries, together with a projection of the rate of production and future net income, taxes, operating expenses and capital expenditures with respect thereto as of such date, based upon the pricing assumptions consistent with SEC reporting requirements at the time.

“ Responsible Officer ” means, as to any Person, the Chief Executive Officer, the President, any Financial Officer or any Executive Vice President or other Vice President of such Person. Unless otherwise specified, all references to a Responsible Officer herein shall mean a Responsible Officer of the Borrower.

“ Restricted Payment ” means any dividend or other distribution (whether in cash, securities or other Property) with respect to any Equity Interests in the Borrower or any of its Subsidiaries, or any payment (whether in cash, securities or other Property), including any sinking fund or similar deposit, on account of the purchase, redemption, retirement, acquisition, cancellation or termination of any such Equity Interests in the Borrower or any of its Subsidiaries or any option, warrant or other right to acquire any such Equity Interests in the Borrower.

“ Restricted Subsidiary ” means any Subsidiary of the Borrower that is not an Unrestricted Subsidiary.

“ Revolving Credit Exposure ” means, with respect to any Lender at any time, the sum of the outstanding principal amount of such Lender’s Loans and its LC Exposure at such time.

“ Scheduled Redetermination ” has the meaning assigned such term in Section 2.07(b).

“ Scheduled Redetermination Date ” means the date on which a Borrowing Base that has been redetermined pursuant to a Scheduled Redetermination becomes effective as provided in Section 2.07(d).

“ SEC ” means the Securities and Exchange Commission or any successor Governmental Authority.

“ Second Lien Notes ” means the $100,000,000 Second Lien Term Notes issued pursuant to the Second Lien Term Loan Agreement, together with all amendments, modifications, replacements, extensions and rearrangements thereof permitted by Section 9.04(b).

“ Second Lien Term Loan Agreement ” means that certain Second Lien Term Loan Credit Agreement dated as of the date hereof among the Borrower, BNP Paribas, as the Second Lien Administrative Agent, and the lenders party thereto, together with all amendments, modifications and supplements thereto permitted by Section 9.04(b).

“ Second Lien Term Loan Documents ” means the Second Lien Term Loan Agreement, the Second Lien Notes and any “Loan Documents” (as defined therein), in each case, together with all amendments, modifications and supplements thereto permitted by Section 9.04(b).

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“ Security Instruments ” means the Guaranty Agreement, the Control Agreement, mortgages, deeds of trust and other agreements, instruments or certificates described or referred to in Exhibit F-1, and any and all other agreements, instruments, consents or certificates now or hereafter executed and delivered by the Borrower or any other Person (other than Swap Agreements with the Lenders or any Affiliate of a Lender or participation or similar agreements between any Lender and any other lender or creditor with respect to any Indebtedness pursuant to this Agreement) in connection with, or as security for the payment or performance of the Indebtedness, the Notes, this Agreement, or reimbursement obligations under the Letters of Credit, as such agreements may be amended, modified, supplemented or restated from time to time.

“ Seller ” has the meaning assigned such term in Section 9.21.

“ Separation ” means the following transactions:

(a) STEP I: Calpine causes the formation of new indirect subsidiaries and enters into the Transfer and Assumption Agreement;

(b) STEP II: Calpine, the Borrower and the other parties thereto enter into the Purchase and Sale Agreement;

(c) STEP III: Calpine causes the domestic oil and gas assets subject of the Transfer and Assumption Agreement to be transferred to the newly formed subsidiaries;

(d) STEP IV: The following fundings occur:

(i) the Private Placement is completed and net proceeds therefrom in the amount of not less than $550,000,000 are applied to the purchase price of the Acquisition and other Transaction costs and expenses;

(ii) funding occurs hereunder in the principal amount of not more than $247,500,000 and the proceeds thereof are applied to the purchase price of the Acquisition and other Transaction costs and expenses; and

(iii) funding occurs under the Senior Term Loan Agreement in the principal amount of $100,000,000 and the proceeds thereof are applied to the purchase price of the Acquisition and other Transaction costs and expenses;

(e) STEP V: the Acquisition is consummated and the Borrower acquires the Equity Interests of Rosetta Resources California, LLC, Rosetta Resources Offshore, LLC, Rosetta Resources Rockies, LLC, Rosetta Resources Texas GP, LLC and Rosetta Resources Texas LP, LLC; and

(f) STEP VI: The Borrower enters into the Transition Services Agreement and such other documents referenced therein.

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“ Separation Documents ” means the following agreements as such documents exist on the date hereof, in each case, together with all amendments, modifications and supplements thereto permitted by Section 9.20:

(a) Purchase and Sale Agreement;

(b) Transfer and Assumption Agreement;

(c) Transition Services Agreement;

(d) Marketing Agreement; and

(e) all other agreements, instruments and documents executed in connection with the Separation.

“ September Reserve Report ” has the meaning assigned to such term in Section 2.07(b).

“ S&P ” means Standard & Poor’s Ratings Group, a division of The McGraw-Hill Companies, Inc., and any successor thereto that is a nationally recognized rating agency.

“ Statutory Reserve Rate ” means a fraction (expressed as a decimal), the numerator of which is the number one and the denominator of which is the number one minus the aggregate of the maximum reserve percentages (including any marginal, special, emergency or supplemental reserves) expressed as a decimal established by the Board to which the Administrative Agent is subject with respect to the Adjusted LIBO Rate, for eurocurrency funding (currently referred to as “Eurocurrency Liabilities” in Regulation D of the Board). Such reserve percentages shall include those imposed pursuant to such Regulation D. Eurodollar Loans shall be deemed to constitute eurocurrency funding and to be subject to such reserve requirements without benefit of or credit for proration, exemptions or offsets that may be available from time to time to any Lender under such Regulation D or any comparable regulation. The Statutory Reserve Rate shall be adjusted automatically on and as of the effective date of any change in any reserve percentage.

“ Subsidiary ” means: (a) any Person of which at least a majority of the outstanding Equity Interests having by the terms thereof ordinary voting power to elect a majority of the board of directors, manager or other governing body of such Person (irrespective of whether or not at the time Equity Interests of any other class or classes of such Person shall have or might have voting power by reason of the happening of any contingency) is at the time directly or indirectly owned or controlled by the Borrower or one or more of its Subsidiaries or by the Borrower and one or more of its Subsidiaries and (b) any partnership of which the Borrower or any of its Subsidiaries is a general partner. Unless otherwise indicated herein, each reference to the term “ Subsidiary ” shall mean a Subsidiary of the Borrower.

“ Swap Agreement ” means any agreement with respect to any swap, forward, future or derivative transaction, collar or option or similar agreement, whether exchange traded, “over-the-counter” or otherwise, involving, or settled by reference to, one or more rates, currencies, commodities, equity or debt instruments or securities, or economic, financial or pricing indices or measures of economic, financial or pricing risk or value or any similar transaction or any

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combination of these transactions; provided that no phantom stock or similar plan providing for payments only on account of services provided by current or former directors, officers, employees or consultants of the Borrower or the Subsidiaries shall be a Swap Agreement; provided further, that no options to purchase tangible Property for cash (other than currency options) shall be a Swap Agreement.

“ Swap Termination Value ” means, in respect of any one or more Swap Agreements, after taking into account the effect of any legally enforceable netting agreement relating to such Swap Agreements, (a) for any date on or after the date such Swap Agreements have been closed out and termination value(s) determined in accordance therewith, such termination value(s) and (b) for any date prior to the date referenced in clause (a), the amount(s) determined as the mark-to-market value(s) for such Swap Agreements, as determined by the counterparties to such Swap Agreements.

“ Synthetic Leases ” means, in respect of any Person, all leases which shall have been, or should have been, in accordance with GAAP, treated as operating leases on the financial statements of the Person liable (whether contingently or otherwise) for the payment of rent thereunder and which were properly treated as indebtedness for borrowed money for purposes of U.S. federal income taxes, if the lessee in respect thereof is obligated to either purchase for an amount in excess of, or pay upon early termination an amount in excess of, 80% of the residual value of the Property subject to such operating lease upon expiration or early termination of such lease.

“ Taxes ” means any and all present or future taxes, levies, imposts, duties, deductions, charges or withholdings imposed by any Governmental Authority.

“ Termination Date ” means the earlier of the Maturity Date and the date of termination of the Commitments.

“ Total Debt ” means, at any date, all Debt of the Borrower and the Consolidated Restricted Subsidiaries on a consolidated basis, excluding non-cash obligations under FAS 133.

“ Transactions ” means, with respect to (a) the Borrower, the execution, delivery and performance by the Borrower of this Agreement and each other Loan Document, Acquisition Document and Separation Document to which it is a party, the Acquisition, the Separation, the borrowing of Loans, the use of the proceeds thereof and the issuance of Letters of Credit hereunder, and the Borrower’s grant of the security interests and provision of collateral under the Security Instruments and (b) each Guarantor, the execution, delivery and performance by such Guarantor of each Loan Document, Acquisition Document and Separation Document to which it is a party, the Acquisition, the Separation, the guaranteeing of the Indebtedness and the other obligations under the Guaranty Agreement by such Guarantor and such Guarantor’s grant of the security interests and provision of collateral under the Security Instruments, and the grant of Liens by such Guarantor on Mortgaged Properties and other Properties pursuant to the Security Instruments.

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“ Transfer and Assumption Agreement ” means the Transfer and Assumption Agreement dated July 7, 2005 by and among Calpine, and the subsidiaries of Calpine Gas Holdings LLC identified therein.

“ Transition Services Agreement ” means the Transition Services Agreement dated July 7, 2005 by and among Calpine, Calpine Fuels Corporation, the Borrower and Calpine Natural Gas, L.P.

“ Type ”, when used in reference to any Loan or Borrowing, refers to whether the rate of interest on such Loan, or on the Loans comprising such Borrowing, is determined by reference to the Alternate Base Rate or the Adjusted LIBO Rate.

“ Unrestricted Subsidiary ” means any Subsidiary of the Borrower designated as such on Schedule 7.15 or which the Borrower has designated in writing to the Administrative Agent to be an Unrestricted Subsidiary pursuant to Section 9.06.

“ Wholly-Owned Subsidiary ” means any Restricted Subsidiary of which all of the outstanding Equity Interests (other than any directors’ qualifying shares mandated by applicable law), on a fully-diluted basis, are owned by the Borrower or one or more of the Wholly-Owned Subsidiaries or by the Borrower and one or more of the Wholly-Owned Subsidiaries.

Section 1.03 Types of Loans and Borrowings . For purposes of this Agreement, Loans and Borrowings, respectively, may be classified and referred to by Type (e.g., a “ Eurodollar Loan ” or a “ Eurodollar Borrowing ”).

Section 1.04 Terms Generally; Rules of Construction . The definitions of terms herein shall apply equally to the singular and plural forms of the terms defined. Whenever the context may require, any pronoun shall include the corresponding masculine, feminine and neuter forms. The words “include”, “includes” and “including” shall be deemed to be followed by the phrase “without limitation”. The word “will” shall be construed to have the same meaning and effect as the word “shall”. Unless the context requires otherwise (a) any definition of or reference to any agreement, instrument or other document herein shall be construed as referring to such agreement, instrument or other document as from time to time amended, supplemented or otherwise modified (subject to any restrictions on such amendments, supplements or modifications set forth in the Loan Documents), (b) any reference herein to any law shall be construed as referring to such law as amended, modified, codified or reenacted, in whole or in part, and in effect from time to time, (c) any reference herein to any Person shall be construed to include such Person’s successors and assigns (subject to the restrictions contained in the Loan Documents), (d) the words “herein”, “hereof” and “hereunder”, and words of similar import, shall be construed to refer to this Agreement in its entirety and not to any particular provision hereof, (e) with respect to the determination of any time period, the word “from” means “from and including” and the word “to” means “to and including” and (f) any reference herein to Articles, Sections, Annexes, Exhibits and Schedules shall be construed to refer to Articles and Sections of, and Annexes, Exhibits and Schedules to, this Agreement. No provision of this Agreement or any other Loan Document shall be interpreted or construed against any Person solely because such Person or its legal representative drafted such provision.

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Section 1.05 Accounting Terms and Determinations; GAAP . Unless otherwise specified herein, all accounting terms used herein shall be interpreted, all determinations with respect to accounting matters hereunder shall be made, and all financial statements and certificates and reports as to financial matters required to be furnished to the Administrative Agent or the Lenders hereunder shall be prepared, in accordance with GAAP as in effect at such time; provided that upon the occurrence of any change in GAAP after the Effective Date, Borrower shall disclose to Administrative Agent on the next date on which financial statements are required to be delivered to the Lenders pursuant to Section 8.01(a) any such change, and no such change shall modify or affect the manner in which compliance with the covenants contained herein is computed such that all such computations shall be conducted utilizing financial information presented consistently with prior periods, unless the Borrower and the Majority Lenders shall otherwise agree in writing.

ARTICLE II

The Credits

Section 2.01 Commitments . Subject to the terms and conditions set forth herein, each Lender agrees to make Loans to the Borrower during the Availability Period in an aggregate principal amount that will not result in (a) such Lender’s Revolving Credit Exposure exceeding such Lender’s Commitment or (b) the total Revolving Credit Exposures exceeding the total Commitments. Within the foregoing limits and subject to the terms and conditions set forth herein, the Borrower may borrow, repay and reborrow the Loans.

Section 2.02 Loans and Borrowings .

(a) Borrowings; Several Obligations . Each Loan shall be made as part of a Borrowing consisting of Loans made by the Lenders ratably in accordance with their respective Commitments. The failure of any Lender to make any Loan required to be made by it shall not relieve any other Lender of its obligations hereunder; provided that the Commitments are several and no Lender shall be responsible for any other Lender’s failure to make Loans as required.

(b) Types of Loans . Subject to Section 3.03, each Borrowing shall be comprised entirely of ABR Loans or Eurodollar Loans as the Borrower may request in accordance herewith. Each Lender at its option may make any Eurodollar Loan by causing any domestic or foreign branch or Affiliate of such Lender to make such Loan; provided that any exercise of such option shall not affect the obligation of the Borrower to repay such Loan in accordance with the terms of this Agreement.

(c) Minimum Amounts; Limitation on Number of Borrowings . At the commencement of each Interest Period for any Eurodollar Borrowing, such Borrowing shall be in an aggregate amount that is an integral multiple of $100,000 and not less than $1,000,000. At the time that each ABR Borrowing is made, such Borrowing shall be in an aggregate amount that is an integral multiple of $100,000 and not less than $1,000,000; provided that an ABR Borrowing may be in an aggregate amount that is equal to the entire unused balance of the total Commitments or that is required to finance the reimbursement of an LC Disbursement as contemplated by Section 2.08(e). Borrowings of more than one Type may be outstanding at the same time, provided that there shall not at any time be more than a total of 8 Eurodollar

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Borrowings outstanding. Notwithstanding any other provision of this Agreement, the Borrower shall not be entitled to request, or to elect to convert or continue, any Borrowing if the Interest Period requested with respect thereto would end after the Maturity Date.

(d) Notes . The Loans made by each Lender shall be evidenced by a single promissory note of the Borrower in substantially the form of Exhibit A, dated, in the case of (i) any Lender party hereto as of the date of this Agreement, as of the date of this Agreement or (ii) any Lender that becomes a party hereto pursuant to an Assignment and Assumption, as of the effective date of the Assignment and Assumption, payable to the order of such Lender in a principal amount equal to its Maximum Credit Amount as in effect on such date, and otherwise duly completed. In the event that any Lender’s Maximum Credit Amount increases or decreases for any reason (whether pursuant to Section 2.06, Section 12.04(b) or otherwise), the Borrower shall deliver or cause to be delivered on the effective date of such increase or decrease, a new Note payable to the order of such Lender in a principal amount equal to its Maximum Credit Amount after giving effect to such increase or decrease, and otherwise duly completed. The date, amount, Type, interest rate and, if applicable, Interest Period of each Loan made by each Lender, and all payments made on account of the principal thereof, shall be recorded by such Lender on its books for its Note, and, prior to any transfer, may be endorsed by such Lender on a schedule attached to such Note or any continuation thereof or on any separate record maintained by such Lender. Failure to make any such notation or to attach a schedule shall not affect any Lender’s or the Borrower’s rights or obligations in respect of such Loans or affect the validity of such transfer by any Lender of its Note.

Section 2.03 Requests for Borrowings . To request a Borrowing, the Borrower shall notify the Administrative Agent of such request by telephone, fax (or transmit by electronic communication, if arrangements for doing so have been approved by the Administrative Agent) (a) in the case of a Eurodollar Borrowing, not later than 12:00 noon, New York City time, three Business Days before the date of the proposed Borrowing or (b) in the case of an ABR Borrowing, not later than 12:00 noon, New York City time, on the Business Day of the proposed Borrowing; provided that no such notice shall be required for any deemed request of an ABR Borrowing to finance the reimbursement of an LC Disbursement as provided in Section 2.08(e). Each such telephonic (or electronic communication) Borrowing Request shall be irrevocable and shall be confirmed promptly by hand delivery or telecopy to the Administrative Agent of a written Borrowing Request in substantially the form of Exhibit B and signed by the Borrower. Each such telephonic, electronic communication, and written Borrowing Request shall specify the following information in compliance with Section 2.02:

(i) the aggregate amount of the requested Borrowing;

(ii) the date of such Borrowing, which shall be a Business Day;

(iii) whether such Borrowing is to be an ABR Borrowing or a Eurodollar Borrowing;

(iv) in the case of a Eurodollar Borrowing, the initial Interest Period to be applicable thereto, which shall be a period contemplated by the definition of the term “Interest Period”;

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(v) the amount of the then effective Borrowing Base, the current total Revolving Credit Exposures (without regard to the requested Borrowing) and the pro form a total Revolving Credit Exposures (giving effect to the requested Borrowing); and

(vi) the location and number of the Borrower’s account to which funds are to be disbursed, which shall comply with the requirements of Section 2.05.

If no election as to the Type of Borrowing is specified, then the requested Borrowing shall be an ABR Borrowing. If no Interest Period is specified with respect to any requested Eurodollar Borrowing, then the Borrower shall be deemed to have selected an Interest Period of one month’s duration. Each Borrowing Request shall constitute a representation that the amount of the requested Borrowing shall not cause the total Revolving Credit Exposures to exceed the total Commitments (i.e., the lesser of the Aggregate Maximum Credit Amounts and the then effective Borrowing Base).

Promptly following receipt of a Borrowing Request in accordance with this Section 2.03, the Administrative Agent shall advise each Lender of the details thereof and of the amount of such Lender’s Loan to be made as part of the requested Borrowing.

Section 2.04 Interest Elections .

(a) Conversion and Continuance . Each Borrowing initially shall be of the Type specified in the applicable Borrowing Request and, in the case of a Eurodollar Borrowing, shall have an initial Interest Period as specified in such Borrowing Request. Thereafter, the Borrower may elect to convert such Borrowing to a different Type or to continue such Borrowing and, in the case of a Eurodollar Borrowing, may elect Interest Periods therefor, all as provided in this Section 2.04. The Borrower may elect different options with respect to different portions of the affected Borrowing, in which case each such portion shall be allocated ratably among the Lenders holding the Loans comprising such Borrowing, and the Loans comprising each such portion shall be considered a separate Borrowing.

(b) Interest Election Requests . To make an election pursuant to this Section 2.04, the Borrower shall notify the Administrative Agent of such election by telephone, fax (or transmit by electronic communication, if arrangements for doing so have been approved by the Issuing Bank) by the time that a Borrowing Request would be required under Section 2.03 if the Borrower were requesting a Borrowing of the Type resulting from such election to be made on the effective date of such election. Each such telephonic (or electronic communication) Interest Election Request shall be irrevocable and shall be confirmed promptly by hand delivery or telecopy to the Administrative Agent of a written Interest Election Request in substantially the form of Exhibit C and signed by the Borrower.

(c) Information in Interest Election Requests . Each telephonic, electronic communication and written Interest Election Request shall specify the following information in compliance with Section 2.02:

(i) the Borrowing to which such Interest Election Request applies and, if different options are being elected with respect to different portions thereof, the portions thereof to be allocated to each resulting Borrowing (in which case the information to be specified pursuant to Section 2.04(c)(iii) and (iv) shall be specified for each resulting Borrowing);

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(ii) the effective date of the election made pursuant to such Interest Election Request, which shall be a Business Day;

(iii) whether the resulting Borrowing is to be an ABR Borrowing or a Eurodollar Borrowing; and

(iv) if the resulting Borrowing is a Eurodollar Borrowing, the Interest Period to be applicable thereto after giving effect to such election, which shall be a period contemplated by the definition of the term “Interest Period”.

If any such Interest Election Request requests a Eurodollar Borrowing but does not specify an Interest Period, then the Borrower shall be deemed to have selected an Interest Period of one month’s duration.

(d) Notice to Lenders by the Administrative Agent . Promptly following receipt of an Interest Election Request, the Administrative Agent shall advise each Lender of the details thereof and of such Lender’s portion of each resulting Borrowing.

(e) Effect of Failure to Deliver Timely Interest Election Request; Effect of Events of Default and Borrowing Base Deficiencies on Interest Election . If the Borrower fails to deliver a timely Interest Election Request with respect to a Eurodollar Borrowing prior to the end of the Interest Period applicable thereto, then, unless such Borrowing is repaid as provided herein, at the end of such Interest Period such Borrowing shall be converted to an ABR Borrowing. Notwithstanding any contrary provision hereof, if an Event of Default or a Borrowing Base Deficiency has occurred and is continuing: (i) no outstanding Borrowing may be converted to or continued as a Eurodollar Borrowing (and any Interest Election Request that requests the conversion of any Borrowing to, or continuation of any Borrowing as, a Eurodollar Borrowing shall be ineffective) and (ii) unless repaid, each Eurodollar Borrowing shall be converted to an ABR Borrowing at the end of the Interest Period applicable thereto.

Section 2.05 Funding of Borrowings .

(a) Funding by Lenders . Each Lender shall make each Loan to be made by it hereunder on the proposed date thereof by wire transfer of immediately available funds by 1:00 p.m., New York City time, to the account of the Administrative Agent most recently designated by it for such purpose by notice to the Lenders. The Administrative Agent will make such Loans available to the Borrower by promptly crediting the amounts so received, in like funds, to an account of the Borrower maintained with the Administrative Agent in New York, New York and designated by the Borrower in the applicable Borrowing Request; provided that ABR Loans made to finance the reimbursement of an LC Disbursement as provided in Section 2.08(e) shall be remitted by the Administrative Agent to the Issuing Bank. Nothing herein shall be deemed to obligate any Lender to obtain the funds for its Loan in any particular place or manner or to constitute a representation by any Lender that it has obtained or will obtain the funds for its Loan in any particular place or manner.

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(b) Presumption of Funding by the Lenders . Unless the Administrative Agent shall have received notice from a Lender prior to the proposed date of any Borrowing that such Lender will not make available to the Administrative Agent such Lender’s share of such Borrowing, the Administrative Agent may assume that such Lender has made such share available on such date in accordance with Section 2.05(a) and may, in reliance upon such assumption, make available to the Borrower a corresponding amount. In such event, if a Lender has not in fact made its share of the applicable Borrowing available to the Administrative Agent, then the applicable Lender and the Borrower severally agree to pay to the Administrative Agent forthwith on demand such corresponding amount with interest thereon, for each day from and including the date such amount is made available to the Borrower to but excluding the date of payment to the Administrative Agent, at (i) in the case of such Lender, the greater of the Federal Funds Effective Rate and a rate determined by the Administrative Agent in accordance with banking industry rules on interbank compensation or (ii) in the case of the Borrower, the interest rate applicable to ABR Loans. If such Lender pays such amount to the Administrative Agent, then such amount shall constitute such Lender’s Loan included in such Borrowing.

Section 2.06 Termination and Reduction of Aggregate Maximum Credit Amounts .

(a) Scheduled Termination of Commitments . Unless previously terminated, the Commitments shall terminate on the Maturity Date. If at any time the Aggregate Maximum Credit Amounts or the Borrowing Base is terminated or reduced to zero, then the Commitments shall terminate on the effective date of such termination or reduction.

(b) Optional Termination and Reduction of Aggregate Credit Amounts .

(i) The Borrower may at any time terminate, or from time to time reduce, the Aggregate Maximum Credit Amounts; provided that (A) each reduction of the Aggregate Maximum Credit Amounts shall be in an amount that is an integral multiple of $1,000,000 and not less than $5,000,000 and (B) the Borrower shall not terminate or reduce the Aggregate Maximum Credit Amounts if, after giving effect to any concurrent prepayment of the Loans in accordance with Section 3.04(c), the total Revolving Credit Exposures would exceed the total Commitments.

(ii) The Borrower shall notify the Administrative Agent of any election to terminate or reduce the Aggregate Maximum Credit Amounts under Section 2.06(b)(i) at least three Business Days prior to the effective date of such termination or reduction, specifying such election and the effective date thereof. Promptly following receipt of any notice, the Administrative Agent shall advise the Lenders of the contents thereof. Each notice delivered by the Borrower pursuant to this Section 2.06(b)(ii) shall be irrevocable; provided that a notice of termination of the Aggregate Maximum Credit Amounts delivered by the Borrower may state that such notice is conditioned upon the effectiveness of other credit facilities, in which case such notice may be revoked by the Borrower (by notice to the Administrative Agent on or prior to the specified effective date) if such condition is not satisfied. Any termination or reduction of the Aggregate Maximum Credit Amounts shall be permanent and may not be reinstated. Each reduction of the Aggregate Maximum Credit Amounts shall be made ratably among the Lenders in accordance with each Lender’s Applicable Percentage.

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Section 2.07 Borrowing Base .

(a) Initial Borrowing Base . For the period from and including the Effective Date to but excluding the first Redetermination Date, the amount of the Borrowing Base shall be $275,000,000 (the “ Initial Borrowing Base ”). Notwithstanding the foregoing, the Borrowing Base may be subject to further adjustments from time to time pursuant to Section 6.01(r), Section 8.13(c) or Section 9.13.

(b) Scheduled and Interim Redeterminations . The Borrowing Base shall be redetermined semi-annually in accordance with this Section 2.07 (a “ Scheduled Redetermination ”), and, subject to Section 2.07(d), such redetermined Borrowing Base shall become effective and applicable to the Borrower, the Agents, the Issuing Bank and the Lenders on April 1st and October 1st of each year, commencing April 1, 2006; and, on or before October 30, 2005, the Borrower shall deliver to the Administrative Agent a Reserve Report with an “as of” date of September 30, 2005 (the “ September Reserve Report ”) together with a certificate in form reasonably satisfactory to the Administrative Agent. In addition, the Borrower may, by notifying the Administrative Agent thereof, and the Administrative Agent may, at the direction of the Majority Lenders, by notifying the Borrower thereof, one time during any 12-month period, each elect to cause the Borrowing Base to be redetermined between Scheduled Redeterminations (an “ Interim Redetermination ”) in accordance with this Section 2.07.

(c) Scheduled and Interim Redetermination Procedure .

(i) Each Scheduled Redetermination and each Interim Redetermination shall be effectuated as follows: Upon receipt by the Administrative Agent of (A) the Reserve Report and the certificate required to be delivered by the Borrower to the Administrative Agent, in the case of a Scheduled Redetermination, pursuant to Section 8.12(a) and Section 8.12(c), and, in the case of an Interim Redetermination, pursuant to Section 8.12(b) and Section 8.12(c), and (B) such other reports, data and supplemental information, including, without limitation, the information provided pursuant to Section 8.12(c), as may, from time to time, be reasonably requested by the Majority Lenders (the Reserve Report, such certificate and such other reports, data and supplemental information being the “ Engineering Reports ”), the Administrative Agent shall evaluate the information contained in the Engineering Reports and shall, in its sole discretion, propose a new Borrowing Base (the “ Proposed Borrowing Base ”) based upon such information and such other information (including, without limitation, the status of title information with respect to the Oil and Gas Properties as described in the Engineering Reports and the existence of any other Debt) as the Administrative Agent deems appropriate and consistent with its normal and customary oil and gas lending criteria as it exists at the particular time. In no event shall the Proposed Borrowing Base exceed the Aggregate Maximum Credit Amounts.

(ii) The Administrative Agent shall notify the Borrower and the Lenders of the Proposed Borrowing Base (the “ Proposed Borrowing Base Notice ”):

(A) in the case of a Scheduled Redetermination (1) if the Administrative Agent shall have received the Engineering Reports required to be delivered by the Borrower pursuant to Section 8.12(a) and (c) in a timely and complete manner, then on or

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before March 15th and September 15th of such year following the date of delivery (or in the case of the September Reserve Report, 15 days after the delivery of the Engineering Reports prepared in connection with such report) or (2) if the Administrative Agent shall not have received the Engineering Reports required to be delivered by the Borrower pursuant to Section 8.12(a) and (c) in a timely and complete manner, then promptly after the Administrative Agent has received complete Engineering Reports from the Borrower and has had a reasonable opportunity to determine the Proposed Borrowing Base in accordance with Section 2.07(c)(i); and

(B) in the case of an Interim Redetermination, promptly, and in any event, within fifteen (15) days after the Administrative Agent has received the required Engineering Reports.

(iii) Any Proposed Borrowing Base that would increase the Borrowing Base then in effect must be approved or deemed to have been approved by all of the Lenders as provided in this Section 2.07(c)(iii), and any Proposed Borrowing Base that would decrease or maintain the Borrowing Base then in effect must be approved or be deemed to have been approved by the Required Lenders as provided in this Section 2.07(c)(iii). Upon receipt of the Proposed Borrowing Base Notice, each Lender shall have fifteen (15) days to agree with the Proposed Borrowing Base or disagree with the Proposed Borrowing Base by proposing an alternate Borrowing Base. If at the end of such fifteen (15) days, any Lender has not communicated its approval or disapproval in writing to the Administrative Agent, such silence shall be deemed to be an approval of the Proposed Borrowing Base. If, at the end of such 15-day period, all of the Lenders, in the case of a Proposed Borrowing Base that would increase the Borrowing Base then in effect, or the Required Lenders, in the case of a Proposed Borrowing Base that would decrease or maintain the Borrowing Base then in effect, have approved or deemed to have approved, as aforesaid, then the Proposed Borrowing Base shall become the new Borrowing Base, effective on the date specified in Section 2.07(d). If, however, at the end of such 15-day period, all of the Lenders or the Required Lenders, as applicable, have not approved or deemed to have approved, as aforesaid, then the Administrative Agent shall poll, (A) in the case of an increase in the Borrowing Base, the Lenders to ascertain the highest Borrowing Base then acceptable to all of the Lenders, and (B) in the case of a decrease in or maintenance of the Borrowing Base, the Lenders to ascertain the highest Borrowing Base then acceptable to a number of Lenders sufficient to constitute the Required Lenders, then such amount shall become the new Borrowing Base, effective on the date specified in Section 2.07(d).

(d) Effectiveness of a Redetermined Borrowing Base . After a redetermined Borrowing Base is approved or is deemed to have been approved by all of the Lenders or the Required Lenders, as applicable, pursuant to Section 2.07(c)(iii), the Administrative Agent shall notify the Borrower and the Lenders of the amount of the redetermined Borrowing Base (the “ New Borrowing Base Notice ”), and such amount shall become the new Borrowing Base, effective and applicable to the Borrower, the Administrative Agent, the Issuing Bank and the Lenders:

(i) in the case of a Scheduled Redetermination, (A) if the Administrative Agent shall have received the Engineering Reports required to be delivered by

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the Borrower pursuant to Section 8.12(a) and (c) in a timely and complete manner, then on the April 1st or October 1st (or in the case of the September Reserve Report, 15 days after the delivery of the New Borrowing Base Notice delivered in connection with such report), as applicable, following such notice, or (B) if the Administrative Agent shall not have received the Engineering Reports required to be delivered by the Borrower pursuant to Section 8.12(a) and (c) in a timely and complete manner, then on the Business Day next succeeding delivery of such notice; and

(ii) in the case of an Interim Redetermination, on the Business Day next succeeding delivery of such notice.

Such amount shall then become the Borrowing Base until the next Scheduled Redetermination Date, the next Interim Redetermination Date or the next adjustment to the Borrowing Base under Section 8.13(c) or Section 9.13, whichever occurs first. Notwithstanding the foregoing, no Scheduled Redetermination or Interim Redetermination shall become effective until the New Borrowing Base Notice related thereto is received by the Borrower.

Section 2.08 Letters of Credit .

(a) General . Subject to the terms and conditions set forth herein, the Borrower may request the issuance of dollar denominated Letters of Credit for its own account or for the account of any of its Restricted Subsidiaries, in a form reasonably acceptable to the Administrative Agent and the Issuing Bank, at any time and from time to time during the Availability Period; provided that the Borrower may not request the issuance, amendment, renewal or extension of Letters of Credit hereunder if a Borrowing Base Deficiency exists at such time or would exist as a result thereof. In the event of any inconsistency between the terms and conditions of this Agreement and the terms and conditions of any form of letter of credit application or other agreement submitted by the Borrower to, or entered into by the Borrower with, the Issuing Bank relating to any Letter of Credit, the terms and conditions of this Agreement shall control.

(b) Notice of Issuance, Amendment, Renewal, Extension; Certain Conditions . To request the issuance of a Letter of Credit (or the amendment, renewal or extension of an outstanding Letter of Credit), the Borrower shall hand deliver or telecopy (or transmit by electronic communication, if arrangements for doing so have been approved by the Issuing Bank) to the Issuing Bank and the Administrative Agent (not less than three (3) Business Days in advance of the requested date of issuance, amendment, renewal or extension) a notice:

(i) requesting the issuance of a Letter of Credit or identifying the Letter of Credit to be amended, renewed or extended;

(ii) specifying the date of issuance, amendment, renewal or extension (which shall be a Business Day);

(iii) specifying the date on which such Letter of Credit is to expire (which shall comply with Section 2.08(c));

(iv) specifying the amount of such Letter of Credit;

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(v) specifying the name and address of the beneficiary thereof and such other information as shall be necessary to prepare, amend, renew or extend such Letter of Credit; and

(vi) specifying the amount of the then effective Borrowing Base and whether a Borrowing Base Deficiency exists at such time, the current total Revolving Credit Exposures (without regard to the requested Letter of Credit or the requested amendment, renewal or extension of an outstanding Letter of Credit) and the pro forma total Revolving Credit Exposures (giving effect to the requested Letter of Credit or the requested amendment, renewal or extension of an outstanding Letter of Credit).

Each notice shall constitute a representation that after giving effect to the requested issuance, amendment, renewal or extension, as applicable, (i) the LC Exposure shall not exceed the LC Commitment and (ii) the total Revolving Credit Exposures shall not exceed the total Commitments (i.e. the lesser of the Aggregate Maximum Credit Amounts and the then effective Borrowing Base).

If requested by the Issuing Bank, the Borrower also shall submit a letter of credit application on the Issuing Bank’s standard form in connection with any request for a Letter of Credit; provided, in the event of any conflict between such standard form and the terms of the Loan Documents, the terms of the Loan Documents shall control.

(c) Expiration Date . Each Letter of Credit shall expire at or prior to the close of business on the earlier of (i) the date one year after the date of the issuance of such Letter of Credit (or, in the case of any renewal or extension thereof, which may be provided for in such Letter of Credit, one year after such renewal or extension) and (ii) the date that is five Business Days prior to the Maturity Date.

(d) Participations . By the issuance of a Letter of Credit (or an amendment to a Letter of Credit increasing the amount thereof) and without any further action on the part of the Issuing Bank or the Lenders, the Issuing Bank hereby grants to each Lender, and each Lender hereby acquires from the Issuing Bank, a participation in such Letter of Credit equal to such Lender’s Applicable Percentage of the aggregate amount available to be drawn under such Letter of Credit. In consideration and in furtherance of the foregoing, each Lender hereby absolutely and unconditionally agrees to pay to the Administrative Agent, for the account of the Issuing Bank, such Lender’s Applicable Percentage of each LC Disbursement made by the Issuing Bank and not reimbursed by the Borrower on the date due as provided in Section 2.08(e), or of any reimbursement payment required to be refunded to the Borrower for any reason. Each Lender acknowledges and agrees that its obligation to acquire participations pursuant to this Section 2.08(d) in respect of Letters of Credit is absolute and unconditional and shall not be affected by any circumstance whatsoever, including any amendment, renewal or extension of any Letter of Credit or the occurrence and continuance of a Default, the existence of a Borrowing Base Deficiency or reduction or termination of the Commitments, and that each such payment shall be made without any offset, abatement, withholding or reduction whatsoever.

(e) Reimbursement . If the Issuing Bank shall make any LC Disbursement in respect of a Letter of Credit, the Borrower shall reimburse such LC Disbursement by paying to

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the Administrative Agent an amount equal to such LC Disbursement not later than 12:00 noon, New York City time, on the date that such LC Disbursement is made, if the Borrower shall have received notice of such LC Disbursement prior to 10:00 a.m., New York City time, on such date, or, if such notice has not been received by the Borrower prior to such time on such date, then not later than 12:00 noon, New York City time, on (i) the Business Day that the Borrower receives such notice, if such notice is received prior to 10:00 a.m., New York City time, on the day of receipt, or (ii) the Business Day immediately following the day that the Borrower receives such notice, if such notice is not received prior to such time on the day of receipt; provided that if such LC Disbursement is equal to or greater than $1,000,000, the Borrower shall, subject to the conditions to Borrowing set forth herein, be deemed to have requested, and the Borrower does hereby request under such circumstances, that such LC Disbursement be financed with an ABR Borrowing in an equivalent amount and, to the extent so financed, the Borrower’s obligation to make such payment shall be discharged and replaced by the resulting ABR Borrowing. If the Borrower fails to make such payment when due, the Administrative Agent shall notify each Lender of the applicable LC Disbursement, the payment then due from the Borrower in respect thereof and such Lender’s Applicable Percentage thereof. Promptly following receipt of such notice, each Lender shall pay to the Administrative Agent its Applicable Percentage of the payment then due from the Borrower, in the same manner as provided in Section 2.05 with respect to Loans made by such Lender (and Section 2.05 shall apply, mutatis mutandis , to the payment obligations of the Lenders), and the Administrative Agent shall promptly pay to the Issuing Bank the amounts so received by it from the Lenders. Promptly following receipt by the Administrative Agent of any payment from the Borrower pursuant to this Section 2.08(e), the Administrative Agent shall distribute such payment to the Issuing Bank or, to the extent that Lenders have made payments pursuant to this Section 2.08(e) to reimburse the Issuing Bank, then to such Lenders and the Issuing Bank as their interests may appear. Any payment made by a Lender pursuant to this Section 2.08(e) to reimburse the Issuing Bank for any LC Disbursement (other than the funding of ABR Loans as contemplated above) shall not constitute a Loan and shall not relieve the Borrower of its obligation to reimburse such LC Disbursement.

(f) Obligations Absolute . The Borrower’s obligation to reimburse LC Disbursements as provided in Section 2.08(e) shall be absolute, unconditional and irrevocable, and shall be performed strictly in accordance with the terms of this Agreement under any and all circumstances whatsoever and irrespective of (i) any lack of validity or enforceability of any Letter of Credit, any Letter of Credit Agreement or this Agreement, or any term or provision therein, (ii) any draft or other document presented under a Letter of Credit proving to be forged, fraudulent or invalid in any respect or any statement therein being untrue or inaccurate in any respect, (iii) payment by the Issuing Bank under a Letter of Credit against presentation of a draft or other document that does not comply with the terms of such Letter of Credit or any Letter of Credit Agreement, or (iv) any other event or circumstance whatsoever, whether or not similar to any of the foregoing, that might, but for the provisions of this Section 2.08(f), constitute a legal or equitable discharge of, or provide a right of setoff against, the Borrower’s obligations hereunder. Neither the Administrative Agent, the Lenders nor the Issuing Bank, nor any of their Related Parties shall have any liability or responsibility by reason of or in connection with the issuance or transfer of any Letter of Credit or any payment or failure to make any payment thereunder (irrespective of any of the circumstances referred to in the preceding sentence), or any error, omission, interruption, loss or delay in transmission or delivery of any draft, notice or other communication under or relating to any Letter of Credit (including any document required

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to make a drawing thereunder), any error in interpretation of technical terms or any consequence arising from causes beyond the control of the Issuing Bank; provided that the foregoing shall not be construed to excuse the Issuing Bank from liability to the Borrower to the extent of any direct damages (as opposed to consequential damages, claims in respect of which are hereby waived by the Borrower to the extent permitted by applicable law) suffered by the Borrower that are caused by the Issuing Bank’s failure to exercise care when determining whether drafts and other documents presented under a Letter of Credit comply with the terms thereof. The parties hereto expressly agree that, in the absence of gross negligence or willful misconduct on the part of the Issuing Bank (as finally determined by a court of competent jurisdiction), the Issuing Bank shall be deemed to have exercised all requisite care in each such determination. In furtherance of the foregoing and without limiting the generality thereof, the parties agree that, with respect to documents presented which appear on their face to be in compliance with the terms of a Letter of Credit, the Issuing Bank may, in its sole discretion, either accept and make payment upon such documents without responsibility for further investigation, regardless of any notice or information to the contrary, or refuse to accept and make payment upon such documents if such documents are not in strict compliance with the terms of such Letter of Credit.

(g) Disbursement Procedures . The Issuing Bank shall, promptly following its receipt thereof, examine all documents purporting to represent a demand for payment under a Letter of Credit. The Issuing Bank shall promptly notify the Administrative Agent and the Borrower by telephone (confirmed by telecopy) of such demand for payment and whether the Issuing Bank has made or will make an LC Disbursement thereunder; provided that any failure to give or delay in giving such notice shall not relieve the Borrower of its obligation to reimburse the Issuing Bank and the Lenders with respect to any such LC Disbursement.

(h) Interim Interest . If the Issuing Bank shall make any LC Disbursement, then, until the Borrower shall have reimbursed the Issuing Bank for such LC Disbursement (either with its own funds or a Borrowing under Section 2.08(e)), the unpaid amount thereof shall bear interest, for each day from and including the date such LC Disbursement is made to but excluding the date that the Borrower reimburses such LC Disbursement, at the rate per annum then applicable to ABR Loans. Interest accrued pursuant to this Section 2.08(h) shall be for the account of the Issuing Bank, except that interest accrued on and after the date of payment by any Lender pursuant to Section 2.08(e) to reimburse the Issuing Bank shall be for the account of such Lender to the extent of such payment.

(i) Replacement of the Issuing Bank . The Issuing Bank may be replaced at any time by written agreement among the Borrower, the Administrative Agent, the replaced Issuing Bank and the successor Issuing Bank. One or more Lenders may become issuers of Letters of Credit hereunder (each, an “ Additional Issuing Bank ”) at any time by written agreement among the Borrower and the Issuing Banks hereunder at such time. The Administrative Agent shall notify the Lenders of any such replacement or Additional Issuing Bank. At the time any such replacement shall become effective, the Borrower shall pay all unpaid fees accrued for the account of the replaced Issuing Bank pursuant to Section 3.05(b). From and after the effective date of any such replacement or addition, (i) the successor or Additional Issuing Bank shall have all the rights and obligations of the Issuing Bank under this Agreement with respect to Letters of Credit to be issued thereafter and (ii) references herein to the term “Issuing Bank” shall be deemed to refer to such Additional Issuing Bank, such successor or to any previous Issuing

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Bank, or to such Additional Issuing Bank, such successor and all previous Issuing Banks, as the context shall require. After the replacement of the Issuing Bank hereunder, the replaced Issuing Bank shall remain a party hereto and shall continue to have all the rights and obligations of the Issuing Bank under this Agreement with respect to Letters of Credit issued by it prior to such replacement, but shall not be required to issue additional Letters of Credit.

(j) Cash Collateralization . If (i) any Event of Default shall occur and be continuing and the Borrower receives notice from the Administrative Agent or the Majority Lenders demanding the deposit of cash collateral pursuant to this Section 2.08(j), or (ii) the Borrower is required to pay to the Administrative Agent the excess attributable to an LC Exposure in connection with any prepayment pursuant to Section 3.04(c), then the Borrower shall deposit, in an account with the Administrative Agent, in the name of the Administrative Agent and for the benefit of the Lenders, an amount in cash equal to, in the case of an Event of Default, the LC Exposure, and in the case of a payment required by Section 3.04(c), the amount of such excess as provided in Section 3.04(c), as of such date plus any accrued and unpaid interest thereon; provided that the obligation to deposit such cash collateral shall become effective immediately, and such deposit shall become immediately due and payable, without demand or other notice of any kind, upon the occurrence of any Event of Default with respect to the Borrower or any Restricted Subsidiary described in Section 10.01(h) or Section 10.01(i). The Borrower hereby grants to the Administrative Agent, for the benefit of the Issuing Bank and the Lenders, an exclusive first priority and continuing perfected security interest in and Lien on such account and all cash, checks, drafts, certificates and instruments, if any, from time to time deposited or held in such account, all deposits or wire transfers made thereto, any and all investments purchased with funds deposited in such account, all interest, dividends, cash, instruments, financial assets and other Property from time to time received, receivable or otherwise payable in respect of, or in exchange for, any or all of the foregoing, and all proceeds, products, accessions, rents, profits, income and benefits therefrom, and any substitutions and replacements therefor. The Borrower’s obligation to deposit amounts pursuant to this Section 2.08(j) shall be absolute and unconditional, without regard to whether any beneficiary of any such Letter of Credit has attempted to draw down all or a portion of such amount under the terms of a Letter of Credit, and, to the fullest extent permitted by applicable law, shall not be subject to any defense or be affected by a right of set-off, counterclaim or recoupment which the Borrower or any of its Subsidiaries may now or hereafter have against any such beneficiary, the Issuing Bank, the Administrative Agent, the Lenders or any other Person for any reason whatsoever. Such deposit shall be held as collateral securing the payment and performance of the Borrower’s and the Guarantor’s obligations under this Agreement and the other Loan Documents. The Administrative Agent shall have exclusive dominion and control, including the exclusive right of withdrawal. Other than any interest earned on the investment of such deposits, which investments shall be made at the direction of the Borrower in Investments of the type described in Section 9.05(c), (d), (e) or (f) at the Borrower’s risk and expense, such deposits shall not bear interest. Interest or profits, if any, on such investments shall accumulate in such account. Moneys in such account shall be applied by the Administrative Agent to reimburse the Issuing Bank for LC Disbursements for which it has not been reimbursed and, to the extent not so applied, shall be held for the satisfaction of the reimbursement obligations of the Borrower for the LC Exposure at such time or, if the maturity of the Loans has been accelerated, be applied to satisfy other obligations of the Borrower and the Guarantors under this Agreement or the other Loan Documents. If the Borrower is required to provide an amount of cash collateral hereunder

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as a result of the occurrence of an Event of Default, and the Borrower is not otherwise required to pay to the Administrative Agent the excess attributable to an LC Exposure in connection with any prepayment pursuant to Section 3.04(c), then such amount (to the extent not applied as aforesaid) shall be returned to the Borrower within three Business Days after all Events of Default have been cured or waived.

ARTICLE III

Payments of Principal and Interest; Prepayments; Fees

Section 3.01 Repayment of Loans . The Borrower hereby unconditionally promises to pay to the Administrative Agent for the account of each Lender the then unpaid principal amount of each Loan on the Termination Date.

Section 3.02 Interest .

(a) ABR Loans . The Loans comprising each ABR Borrowing shall bear interest at the Alternate Base Rate plus the Applicable Margin, but in no event to exceed the Highest Lawful Rate.

(b) Eurodollar Loans . The Loans comprising each Eurodollar Borrowing shall bear interest at the Adjusted LIBO Rate for the Interest Period in effect for such Borrowing plus the Applicable Margin, but in no event to exceed the Highest Lawful Rate.

(c) Late Payment Rate . Notwithstanding the foregoing, if any principal of or interest on any Loan or any fee or other amount payable by the Borrower or any Guarantor hereunder or under any other Loan Document is not paid when due, whether at stated maturity, upon acceleration or otherwise, such overdue amount shall bear interest, after as well as before judgment, at a rate per annum equal to two percent (2%) plus the rate applicable to ABR Loans as provided in Section 3.02(a), but in no event to exceed the Highest Lawful Rate.

(d) Interest Payment Dates . Accrued interest on each Loan shall be payable in arrears on each Interest Payment Date for such Loan and on the Termination Date; provided that (i) interest accrued pursuant to Section 3.02(c) shall be payable on demand, (ii) in the event of any repayment or prepayment of any Loan (other than an optional prepayment of an ABR Loan prior to the Termination Date), accrued interest on the principal amount repaid or prepaid shall be payable on the date of such repayment or prepayment, and (iii) in the event of any conversion of any Eurodollar Loan prior to the end of the current Interest Period therefor, accrued interest on such Loan shall be payable on the effective date of such conversion.

(e) Interest Rate Computations . All interest hereunder shall be computed on the basis of a year of 360 days, unless such computation would exceed the Highest Lawful Rate, in which case interest shall be computed on the basis of a year of 365 days (or 366 days in a leap year), except that interest computed by reference to the Alternate Base Rate at times when the Alternate Base Rate is based on the Prime Rate shall be computed on the basis of a year of 365 days (or 366 days in a leap year), and in each case shall be payable for the actual number of days elapsed (including the first day but excluding the last day). The applicable Alternate Base Rate, Adjusted LIBO Rate or LIBO Rate shall be determined by the Administrative Agent, and such determination shall be conclusive absent manifest error, and be binding upon the parties hereto.

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Section 3.03 Alternate Rate of Interest . If prior to the commencement of any Interest Period for a Eurodollar Borrowing:

(a) the Administrative Agent determines (which determination shall be conclusive absent manifest error) that adequate and reasonable means do not exist for ascertaining the Adjusted LIBO Rate or the LIBO Rate for such Interest Period; or

(b) the Administrative Agent is advised by the Majority Lenders that the Adjusted LIBO Rate or LIBO Rate, as applicable, for such Interest Period will not adequately and fairly reflect the cost to such Lenders of making or maintaining their Loans included in such Borrowing for such Interest Period;

then the Administrative Agent shall give notice thereof to the Borrower and the Lenders by telephone or telecopy as promptly as practicable thereafter and, until the Administrative Agent notifies the Borrower and the Lenders that the circumstances giving rise to such notice no longer exist, (i) any Interest Election Request that requests the conversion of any Borrowing to, or continuation of any Borrowing as, a Eurodollar Borrowing shall be ineffective, and (ii) if any Borrowing Request requests a Eurodollar Borrowing, such Borrowing shall be made as an ABR Borrowing.

Section 3.04 Prepayments .

(a) Optional Prepayments . The Borrower shall have the right at any time and from time to time to prepay any Borrowing in whole or in part, subject to prior notice in accordance with Section 3.04(b).

(b) Notice and Terms of Optional Prepayment . The Borrower shall notify the Administrative Agent by telephone (confirmed by telecopy) or telecopy of any prepayment hereunder (i) in the case of prepayment of a Eurodollar Borrowing, not later than 12:00 noon, New York City time, three Business Days before the date of prepayment, or (ii) in the case of prepayment of an ABR Borrowing, not later than 12:00 noon, New York City time, of the Business Day of prepayment. Each such notice shall be irrevocable and shall specify the prepayment date and the principal amount of each Borrowing or portion thereof to be prepaid. Promptly following receipt of any such notice relating to a Borrowing, the Administrative Agent shall advise the Lenders of the contents thereof. Each partial prepayment of any Borrowing shall be in an amount that would be permitted in the case of an advance of a Borrowing of the same Type as provided in Section 2.02. Each prepayment of a Borrowing shall be applied ratably to the Loans included in the prepaid Borrowing. Prepayments shall be accompanied by accrued interest to the extent required by Section 3.02.

(c) Mandatory Prepayments .

(i) If, after giving effect to any termination or reduction of the Aggregate Maximum Credit Amounts pursuant to Section 2.06(b), the total Revolving Credit Exposures exceeds the total Commitments, then the Borrower shall (A) prepay the Borrowings on the date of such termination or reduction in an aggregate principal amount equal to such excess, and (B) if any excess remains after prepaying all of the Borrowings as a result of an LC Exposure, pay to the Administrative Agent on behalf of the Lenders an amount equal to such excess to be held as cash collateral as provided in Section 2.08(j).

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(ii) Upon any redetermination of or adjustment to the amount of the Borrowing Base in accordance with Section 2.07 or Section 8.13(c), if the total Revolving Credit Exposures exceeds the redetermined or adjusted Borrowing Base, then the Borrower shall (A) prepay the Borrowings in an aggregate principal amount equal to such excess, and (B) if any excess remains after prepaying all of the Borrowings as a result of an LC Exposure, pay to the Administrative Agent on behalf of the Lenders an amount equal to such excess to be held as cash collateral as provided in Section 2.08(j). The Borrower shall be obligated to make such prepayment and/or deposit of cash collateral in an amount equal to at least fifty percent (50%) of such excess within sixty (60) days following its receipt of the New Borrowing Base Notice in accordance with Section 2.07(d) or the date the adjustment occurs, with the balance of such excess being due and payable within one hundred twenty (120) days following the receipt of such New Borrowing Base Notice or the date the adjustment occurs; provided that all payments required to be made pursuant to this Section 3.04(c)(ii) must be made on or prior to the Termination Date.

(iii) Upon any adjustments to the Borrowing Base pursuant to Section 9.13, if the total Revolving Credit Exposures exceeds the Borrowing Base as adjusted, then the Borrower shall (A) prepay the Borrowings in an aggregate principal amount equal to such excess, and (B) if any excess remains after prepaying all of the Borrowings as a result of an LC Exposure, pay to the Administrative Agent on behalf of the Lenders an amount equal to such excess to be held as cash collateral as provided in Section 2.08(j). The Borrower shall be obligated to make such prepayment and/or deposit of cash collateral on the date it or any Restricted Subsidiary receives cash proceeds as a result of such disposition; provided that all payments required to be made pursuant to this Section 3.04(c)(iii) must be made on or prior to the Termination Date.

(iv) Each prepayment of Borrowings pursuant to this Section 3.04(c) shall be applied, first, ratably to any ABR Borrowings then outstanding, and, second, to any Eurodollar Borrowings then outstanding, and if more than one Eurodollar Borrowing is then outstanding, to each such Eurodollar Borrowing in order of priority beginning with the Eurodollar Borrowing with the least number of days remaining in the Interest Period applicable thereto and ending with the Eurodollar Borrowing with the most number of days remaining in the Interest Period applicable thereto.

(v) Each prepayment of Borrowings pursuant to this Section 3.04(c) shall be applied ratably to the Loans included in the prepaid Borrowings. Prepayments pursuant to this Section 3.04(c) shall be accompanied by accrued interest to the extent required by Section 3.02.

(d) No Premium or Penalty . Prepayments permitted or required under this Section 3.04 shall be without premium or penalty, except as required under Section 5.02.

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Section 3.05 Fees .

(a) Commitment Fees . The Borrower agrees to pay to the Administrative Agent for the account of each Lender a commitment fee, which shall accrue at the applicable Commitment Fee Rate on the average daily amount of the unused amount of the Commitment of such Lender during the period from and including the date of this Agreement to but excluding the Termination Date. Accrued commitment fees shall be payable in arrears on the last day of March, June, September and December of each year and on the Termination Date, commencing on the first such date to occur after the date hereof. All commitment fees shall be computed on the basis of a year of 360 days, unless such computation would exceed the Highest Lawful Rate, in which case interest shall be computed on the basis of a year of 365 days (or 366 days in a leap year), and shall be payable for the actual number of days elapsed (including the first day but excluding the last day).

(b) Letter of Credit Fees . The Borrower agrees to pay (i) to the Administrative Agent for the account of each Lender a participation fee with respect to its participations in Letters of Credit, which shall accrue at the same Applicable Margin used to determine the interest rate applicable to Eurodollar Loans on the average daily amount of such Lender’s LC Exposure (excluding any portion thereof attributable to unreimbursed LC Disbursements) during the period from and including the date of this Agreement to but excluding the later of the date on which such Lender’s Commitment terminates and the date on which such Lender ceases to have any LC Exposure, (ii) to the Issuing Bank a fronting fee, which shall accrue at the rate of 0.15% per annum on the average daily amount of the LC Exposure (excluding any portion thereof attributable to unreimbursed LC Disbursements) during the period from and including the date of this Agreement to but excluding the later of the date of termination of the Commitments and the date on which there ceases to be any LC Exposure, provided that in no event shall such fee be less than $500 during any quarter, and (iii) to the Issuing Bank, for its own account, its standard fees with respect to the issuance, amendment, renewal or extension of any Letter of Credit or processing of drawings thereunder. Participation fees and fronting fees accrued through and including the last day of March, June, September and December of each year shall be payable on the third Business Day following such last day, commencing on the first such date to occur after the date of this Agreement; provided that all such fees shall be payable on the Termination Date and any such fees accruing after the Termination Date shall be payable on demand. Any other fees payable to the Issuing Bank pursuant to this Section 3.05(b) shall be payable within 10 days after demand. All participation fees and fronting fees shall be computed on the basis of a year of 360 days, unless such computation would exceed the Highest Lawful Rate, in which case interest shall be computed on the basis of a year of 365 days (or 366 days in a leap year), and shall be payable for the actual number of days elapsed (including the first day but excluding the last day).

(c) Administrative Agent Fees . The Borrower agrees to pay to the Administrative Agent, for its own account, fees payable in the amounts and at the times separately agreed upon between the Borrower and the Administrative Agent.

(d) Borrowing Base Increase Fees . The Borrower agrees to pay to the Administrative Agent, for the account of each Lender then party to this Agreement, ratably in accordance with its Applicable Percentage, a Borrowing Base increase fee to be agreed by the Lenders and the Borrower on the amount of any increase of the Borrowing Base over the highest Borrowing Base previously in effect, payable on the effective date of any such increase to the Borrowing Base.

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ARTICLE IV

Payments; Pro Rata Treatment; Sharing of Set-offs

Section 4.01 Payments Generally; Pro Rata Treatment; Sharing of Set-offs .

(a) Payments by the Borrower . The Borrower shall make each payment required to be made by it hereunder (whether of principal, interest, fees or reimbursement of LC Disbursements, or of amounts payable under Section 5.01, Section 5.02, Section 5.03 or otherwise) prior to 12:00 noon, New York City time, on the date when due, in immediately available funds, without defense, deduction, recoupment, set-off or counterclaim. Fees, once paid, shall be fully earned and shall not be refundable under any circumstances. Any amounts received after such time on any date may, in the discretion of the Administrative Agent, be deemed to have been received on the next succeeding Business Day for purposes of calculating interest thereon. All such payments shall be made to the Administrative Agent at its offices specified in Section 12.01, except payments to be made directly to the Issuing Bank as expressly provided herein and except that payments pursuant to Section 5.01, Section 5.02, Section 5.03 and Section 12.03 shall be made directly to the Persons entitled thereto. The Administrative Agent shall distribute any such payments received by it for the account of any other Person to the appropriate recipient promptly following receipt thereof. If any payment hereunder shall be due on a day that is not a Business Day, the date for payment shall be extended to the next succeeding Business Day, and, in the case of any payment accruing interest, interest thereon shall be payable for the period of such extension. All payments hereunder shall be made in dollars.

(b) Application of Insufficient Payments . If at any time insufficient funds are received by and available to the Administrative Agent to pay fully all amounts of principal, unreimbursed LC Disbursements, interest and fees then due hereunder, such funds shall be applied (i) first, towards payment of interest and fees then due hereunder, ratably among the parties entitled thereto in accordance with the amounts of interest and fees then due to such parties, and (ii) second, towards payment of principal and unreimbursed LC Disbursements then due hereunder, ratably among the parties entitled thereto in accordance with the amounts of principal and unreimbursed LC Disbursements then due to such parties.

(c) Sharing of Payments by Lenders . If any Lender shall, by exercising any right of set-off or counterclaim or otherwise, obtain payment in respect of any principal of or interest on any of its Loans or participations in LC Disbursements resulting in such Lender receiving payment of a greater proportion of the aggregate amount of its Loans and participations in LC Disbursements and accrued interest thereon than the proportion received by any other Lender, then the Lender receiving such greater proportion shall purchase (for cash at face value) participations in the Loans and participations in LC Disbursements of other Lenders to the extent necessary so that the benefit of all such payments shall be shared by the Lenders ratably in accordance with the aggregate amount of principal of and accrued interest on their respective Loans and participations in LC Disbursements; provided that (i) if any such participations are purchased and all or any portion of the payment giving rise thereto is recovered, such participations shall be rescinded and the purchase price restored to the extent of such recovery, without interest, and (ii) the provisions of this Section 4.01(c) shall not be construed to apply to any payment made by the Borrower pursuant to and in accordance with the express terms of this

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Agreement or any payment obtained by a Lender as consideration for the assignment of or sale of a participation in any of its Loans or participations in LC Disbursements to any assignee or participant, other than to the Borrower or any Subsidiary or Affiliate thereof (as to which the provisions of this Section 4.01(c) shall apply). The Borrower consents to the foregoing and agrees, to the extent it may effectively do so under applicable law, that any Lender acquiring a participation pursuant to the foregoing arrangements may exercise against the Borrower rights of set-off and counterclaim with respect to such participation as fully as if such Lender were a direct creditor of the Borrower in the amount of such participation.

Section 4.02 Presumption of Payment by the Borrower . Unless the Administrative Agent shall have received notice from the Borrower prior to the date on which any payment is due to the Administrative Agent for the account of the Lenders or the Issuing Bank that the Borrower will not make such payment, the Administrative Agent may assume that the Borrower has made such payment on such date in accordance herewith and may, in reliance upon such assumption, distribute to the Lenders or the Issuing Bank, as the case may be, the amount due. In such event, if the Borrower has not in fact made such payment, then each of the Lenders or the Issuing Bank, as the case may be, severally agrees to repay to the Administrative Agent forthwith on demand the amount so distributed to such Lender or Issuing Bank with interest thereon, for each day from and including the date such amount is distributed to it to but excluding the date of payment to the Administrative Agent, at the greater of the Federal Funds Effective Rate and a rate determined by the Administrative Agent in accordance with banking industry rules on interbank compensation.

Section 4.03 Certain Deductions by the Administrative Agent . If any Lender shall fail to make any payment required to be made by it pursuant to Section 2.05(b), Section 2.08(d), Section 2.08(e) or Section 4.02 then the Administrative Agent may, in its discretion (notwithstanding any contrary provision hereof), apply any amounts thereafter received by the Administrative Agent for the account of such Lender to satisfy such Lender’s obligations under such Sections until all such unsatisfied obligations are fully paid.

Section 4.04 Disposition of Proceeds . The Security Instruments contain an assignment by the Borrower and/or the Guarantors unto and in favor of the Administrative Agent for the benefit of the Lenders of all of the Borrower’s or each Guarantor’s interest in and to production and all proceeds attributable thereto which may be produced from or allocated to the Mortgaged Property. The Security Instruments further provide in general for the application of such proceeds to the satisfaction of the Indebtedness and other obligations described therein and secured thereby. Notwithstanding the assignment contained in such Security Instruments, until the occurrence of an Event of Default, (a) the Administrative Agent and the Lenders agree that they will neither notify the purchaser or purchasers of such production nor take any other action to cause such proceeds to be remitted to the Administrative Agent or the Lenders, but the Lenders will instead permit such proceeds to be paid to the Borrower and its Restricted Subsidiaries and (b) the Lenders hereby authorize the Administrative Agent to take such actions as may be necessary to cause such proceeds to be paid to the Borrower and/or such Restricted Subsidiaries.

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ARTICLE V

Increased Costs; Break Funding Payments; Taxes; Illegality

Section 5.01 Increased Costs .

(a) Eurodollar Changes in Law . If any Change in Law shall:

(i) impose, modify or deem applicable any reserve, special deposit or similar requirement against assets of, deposits with or for the account of, or credit extended by, any Lender (except any such reserve requirement reflected in the Adjusted LIBO Rate); or

(ii) impose on any Lender or the London interbank market any other condition affecting this Agreement or Eurodollar Loans made by such Lender;

and the result of any of the foregoing shall be to increase the cost to such Lender of making or maintaining any Eurodollar Loan (or of maintaining its obligation to make any such Loan) or to reduce the amount of any sum received or receivable by such Lender (whether of principal, interest or otherwise), then the Borrower will pay to such Lender such additional amount or amounts as will compensate such Lender for such additional costs incurred or reduction suffered.

(b) Capital Requirements . If any Lender or the Issuing Bank determines that any Change in Law regarding capital requirements has or would have the effect of reducing the rate of return on such Lender’s or the Issuing Bank’s capital or on the capital of such Lender’s or the Issuing Bank’s holding company, if any, as a consequence of this Agreement or the Loans made by, or participations in Letters of Credit held by, such Lender, or the Letters of Credit issued by the Issuing Bank, to a level below that which such Lender or the Issuing Bank or such Lender’s or the Issuing Bank’s holding company could have achieved but for such Change in Law (taking into consideration such Lender’s or the Issuing Bank’s policies and the policies of such Lender’s or the Issuing Bank’s holding company with respect to capital adequacy), then from time to time the Borrower will pay to such Lender or the Issuing Bank, as the case may be, such additional amount or amounts as will compensate such Lender or the Issuing Bank or such Lender’s or the Issuing Bank’s holding company for any such reduction suffered.

(c) Certificates . A certificate of a Lender or the Issuing Bank setting forth the amount or amounts necessary to compensate such Lender or the Issuing Bank or its holding company, as the case may be, as specified in Section 5.01(a) or (b) shall be delivered to the Borrower and shall be conclusive absent manifest error. The Borrower shall pay such Lender or the Issuing Bank, as the case may be, the amount shown as due on any such certificate within 10 days after receipt thereof.

(d) Effect of Failure or Delay in Requesting Compensation . Failure or delay on the part of any Lender or the Issuing Bank to demand compensation pursuant to this Section 5.01 shall not constitute a waiver of such Lender’s or the Issuing Bank’s right to demand such compensation; provided that the Borrower shall not be required to compensate a Lender or the Issuing Bank pursuant to this Section 5.01 for any increased costs or reductions incurred more than 180 days prior to the date that such Lender or the Issuing Bank, as the case may be, notifies the Borrower of the Change in Law giving rise to such increased costs or reductions and of such Lender’s or the Issuing Bank’s intention to claim compensation therefor; provided further that, if the Change in Law giving rise to such increased costs or reductions is retroactive, then the 180-day period referred to above shall be extended to include the period of retroactive effect thereof.

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Section 5.02 Break Funding Payments . In the event of (a) the payment of any principal of any Eurodollar Loan other than on the last day of an Interest Period applicable thereto (including as a result of an Event of Default), (b) the conversion of any Eurodollar Loan into an ABR Loan other than on the last day of the Interest Period applicable thereto, or (c) the failure to borrow, convert, continue or prepay any Eurodollar Loan on the date specified in any notice delivered pursuant hereto, or (d) the assignment of any Eurodollar Loan other than on the last day of the Interest Period applicable thereto as a result of a request by the Borrower pursuant to Section 5.04(b), then, in any such event, the Borrower shall compensate each Lender for the loss, cost and expense attributable to such event. In the case of a Eurodollar Loan, such loss, cost or expense to any Lender shall be deemed to include an amount determined by such Lender to be the excess, if any, of (i) the amount of interest which would have accrued on the principal amount of such Loan had such event not occurred, at the Adjusted LIBO Rate that would have been applicable to such Loan, for the period from the date of such event to the last day of the then current Interest Period therefor (or, in the case of a failure to borrow, convert or continue, for the period that would have been the Interest Period for such Loan), over (ii) the amount of interest which would accrue on such principal amount for such period at the interest rate which such Lender would bid were it to bid, at the commencement of such period, for dollar deposits of a comparable amount and period from other banks in the eurodollar market.

A certificate of any Lender setting forth any amount or amounts that such Lender is entitled to receive pursuant to this Section 5.02 shall be delivered to the Borrower and shall be conclusive absent manifest error. The Borrower shall pay such Lender the amount shown as due on any such certificate within 10 days after receipt thereof.

Section 5.03 Taxes .

(a) Payments Free of Taxes . Any and all payments by or on account of any obligation of the Borrower or any Guarantor under any Loan Document shall be made free and clear of and without deduction for any Indemnified Taxes or Other Taxes; provided that if the Borrower or any Guarantor shall be required to deduct any Indemnified Taxes or Other Taxes from such payments, then (i) the sum payable shall be increased as necessary so that after making all required deductions (including deductions applicable to additional sums payable under this Section 5.03), the Administrative Agent, Lender or Issuing Bank (as the case may be) receives an amount equal to the sum it would have received had no such deductions been made, (ii) the Borrower or such Guarantor shall make such deductions and (iii) the Borrower or such Guarantor shall pay the full amount deducted to the relevant Governmental Authority in accordance with applicable law.

(b) Payment of Other Taxes by the Borrower . The Borrower shall pay any Other Taxes to the relevant Governmental Authority in accordance with applicable law.

(c) Indemnification by the Borrower . The Borrower shall indemnify the Administrative Agent, each Lender and the Issuing Bank, within 10 days after written demand therefor, for the full amount of any Indemnified Taxes or Other Taxes paid by the Administrative

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Agent, such Lender or the Issuing Bank, as the case may be, on or with respect to any payment by or on account of any obligation of the Borrower hereunder (including Indemnified Taxes or Other Taxes imposed or asserted on or attributable to amounts payable under this Section 5.03) and any penalties, interest and reasonable expenses arising therefrom or with respect thereto, whether or not such Indemnified Taxes or Other Taxes were correctly or legally imposed or asserted by the relevant Governmental Authority. A certificate of the Administrative Agent, a Lender or the Issuing Bank as to the amount of such payment or liability under this Section 5.03 shall be delivered to the Borrower and shall be conclusive absent manifest error.

(d) Evidence of Payments . As soon as practicable after any payment of Indemnified Taxes or Other Taxes by the Borrower or a Guarantor to a Governmental Authority, the Borrower shall deliver to the Administrative Agent the original or a certified copy of a receipt issued by such Governmental Authority evidencing such payment, a copy of the return reporting such payment or other evidence of such payment reasonably satisfactory to the Administrative Agent.

(e) Foreign Lenders . Any Foreign Lender that is entitled to an exemption from or reduction of withholding tax under the law of the jurisdiction in which the Borrower is located, or any treaty to which such jurisdiction is a party, with respect to payments under this Agreement or any other Loan Document shall deliver to the Borrower (with a copy to the Administrative Agent), at the time or times prescribed by applicable law, such properly completed and executed documentation prescribed by applicable law or reasonably requested by the Borrower as will permit such payments to be made without withholding or at a reduced rate.

Section 5.04 Mitigation Obligations; Replacement of Lenders .

(a) Designation of Different Lending Office . If any Lender requests compensation under Section 5.01, or if the Borrower is required to pay any additional amount to any Lender or any Governmental Authority for the account of any Lender pursuant to Section 5.03, then such Lender shall use reasonable efforts to designate a different lending office for funding or booking its Loans hereunder or to assign its rights and obligations hereunder to another of its offices, branches or affiliates, if, in the judgment of such Lender, such designation or assignment (i) would eliminate or reduce amounts payable pursuant to Section 5.01 or Section 5.03, as the case may be, in the future and (ii) would not subject such Lender to any unreimbursed cost or expense and would not otherwise be disadvantageous to such Lender. The Borrower hereby agrees to pay all reasonable costs and expenses incurred by any Lender in connection with any such designation or assignment.

(b) Replacement of Lenders . If any Lender requests compensation under Section 5.01, or if the Borrower is required to pay any additional amount to any Lender or any Governmental Authority for the account of any Lender pursuant to Section 5.03, or if any Lender defaults in its obligation to fund Loans hereunder, then the Borrower may, at its sole expense and effort, upon notice to such Lender and the Administrative Agent, require such Lender to assign and delegate, without recourse (in accordance with and subject to the restrictions contained in Section 12.04(b)), all its interests, rights and obligations under this Agreement to an assignee that shall assume such obligations (which assignee may be another Lender, if a Lender accepts such assignment); provi