EX 1 Purchase Agreement

QuickLinks -- Click here to rapidly navigate through this document

Exhibit 1

Evergreen Resources, Inc.

$200,000,000
5.875% Senior Subordinated Notes due March 15, 2012

Purchase Agreement

        March 5, 2004

Goldman, Sachs & Co.,
    As representative of the several Purchasers
    named in Schedule I hereto (the "Representative")
85 Broad Street
New York, New York 10004

Ladies and Gentlemen:

        Evergreen Resources, Inc., a Colorado corporation (the "Company"), proposes, subject to the terms and conditions stated herein, to issue and sell to the Purchasers named in Schedule I hereto (the "Purchasers") an aggregate of $200,000,000 principal amount of 5.875% Senior Subordinated Notes due March 15, 2012 of the Company (the "Securities"). The Securities are to be issued pursuant to an indenture to be dated as of March 10, 2004 (the "Indenture"), between the Company and Wachovia Bank, National Association, as trustee (the "Trustee").

        1.     The Company represents and warrants to, and agrees with, each of the Purchasers that:

        (a)   A preliminary offering circular, dated February 27, 2004 (the "Preliminary Offering Circular") and an offering circular, dated March 5, 2004 (the "Offering Circular") have been prepared in connection with the offering of the Securities. Any reference to the Preliminary Offering Circular or the Offering Circular shall be deemed to refer to and include the Company's most recent Annual Report on Form 10-K and all subsequent documents filed with the United States Securities and Exchange Commission (the "Commission") pursuant to Section 13(a), 13(c) or 15(d) of the United States Securities Exchange Act of 1934, as amended (the "Exchange Act"), on or prior to the date of the Preliminary Offering Circular or the Offering Circular, as the case may be, and any reference to the Preliminary Offering Circular or the Offering Circular, as the case may be, as amended or supplemented, as of any specified date, shall be deemed to include (i) any documents filed with the Commission pursuant to Section 13(a), 13(c) or 15(d) of the Exchange Act after the date of the Preliminary Offering Circular or the Offering Circular, as the case may be, and prior to such specified date and (ii) any Additional Issuer Information (as defined in Section 5(f)) furnished by the Company prior to the completion of the distribution of the Securities; and all documents filed under the Exchange Act and so deemed to be included in the Preliminary Offering Circular or the Offering Circular, as the case may be, or any amendment or supplement thereto are hereinafter called the "Exchange Act Reports". The Exchange Act Reports, when they were or are filed with the Commission, conformed or will conform in all material respects to the applicable requirements of the Exchange Act and the applicable rules and regulations of the Commission thereunder. The Preliminary Offering Circular or the Offering Circular and any amendments or supplements thereto and the Exchange Act Reports did not and will not, as of their respective dates, contain an untrue statement of a material fact or omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading; provided , however , that this representation and warranty shall not apply to any statements or omissions made in reliance upon and in conformity with information furnished in writing to the Company by a Purchaser through Goldman, Sachs & Co. expressly for use therein;

        (b)   Neither the Company nor any of its subsidiaries that individually or collectively would constitute a "significant subsidiary" as defined in Rule 1-02(w) of Regulation S-X of the Commission, including but not limited to Primero Gas Marketing Co., Evergreen Operating Co., Carbon Energy Corporation, Evergreen Resources Canada, Ltd., Carbon Energy Corp. (USA) and Primero Gas Company, LLC (collectively, the "Material Subsidiaries") has sustained since the date of the latest audited financial statements included in the Offering Circular any material loss or interference with its business from fire, explosion, flood or other calamity, whether or not covered by insurance, or from any labor dispute or court or governmental action, order or decree, otherwise than as set forth or contemplated in the Offering Circular; and, since the respective dates as of which information is given in the Offering Circular, there has not been any change in the capital stock (except pursuant to publicly-disclosed stock-based employee benefit plans of the Company in existence on the date of this Agreement) or long-term debt of the Company or any of its subsidiaries except as set forth or contemplated in the Offering Circular or non-material changes in the ordinary course of business in outstanding indebtedness under the Company's publicly-disclosed long-term debt facilities, or any material adverse change, or any development involving a prospective material adverse change, in or affecting the general affairs, business, properties, management, financial position, stockholders' equity or results of operations or prospects of the Company and its subsidiaries, taken as a whole (a "Material Adverse Effect"), otherwise than as set forth or contemplated in the Offering Circular;

        (c)   (i) The Company and its subsidiaries have good and marketable title in fee simple to all real property and good and marketable title to all personal property owned by them and that is, individually or in the aggregate, material to the respective businesses of the Company and its subsidiaries taken as a whole, in each case free and clear of all liens, encumbrances and defects except (A) such as are described in the Offering Circular or (B) such as do not materially affect the value of such property and do not interfere with the use made and proposed to be made of such property by the Company and its subsidiaries; and any real property and buildings held under lease by the Company and its subsidiaries that are, individually or in the aggregate, material to the respective businesses of the Company and its subsidiaries taken as a whole are held by them under valid, subsisting and enforceable leases with such exceptions as are not material and do not interfere with the use made and proposed to be made of such property and buildings by the Company and its subsidiaries, subject as to enforcement, to bankruptcy, insolvency, reorganization and other laws of general applicability relating to or affecting creditors' rights and to general equity principles; and

        (ii)   There are no defects in the title to, or encumbrances upon the leasehold interests in, the oil and gas producing properties of the Company and its subsidiaries or the assets or facilities used by the Company and its subsidiaries, in each case that are, individually or in the aggregate, material to the respective businesses of the Company and its subsidiaries taken as a whole except for such defects or encumbrances that do not materially interfere with the use made and proposed to be made of such property by the Company and its subsidiaries;

        (d)   The Company has been duly incorporated and is validly existing as a corporation in good standing under the laws of Colorado, with corporate power and authority to own its properties and conduct its business as described in the Offering Circular, and has been duly qualified as a foreign entity for the transaction of business and is in good standing under the laws of each other jurisdiction in which it owns or leases properties or conducts any business so as to require such qualification, or is subject to no material liability or disability by reason of the failure to be so qualified in any such jurisdiction; and each Material Subsidiary has been duly formed and is validly existing as a corporation or limited liability company, as the case may be, in good standing under the laws of its jurisdiction of incorporation or formation, as the case may be;

        (e)   The Company has all necessary corporate power and authority to execute and deliver this Agreement and to perform its respective obligations hereunder; and all corporate action required to be taken for the due and proper authorization, execution and delivery by the Company of this Agreement and the consummation by it of the transactions contemplated hereby has been duly and validly taken;

        (f)    The Company has an authorized capitalization as set forth in the Offering Circular, and all of the issued shares of capital stock of the Company have been duly and validly authorized and issued and are fully paid and non-assessable; and all of the issued shares of capital stock of each subsidiary of the Company have been duly and validly authorized and issued, are fully paid and non-assessable and are owned directly or indirectly by the Company, free and clear of all liens, encumbrances, equities or claims;

        (g)   The Securities have been duly authorized by the Company and, when issued, executed and delivered against payment therefor pursuant to this Agreement and authenticated in accordance with the Indenture, will have been duly executed, authenticated, issued and delivered and will constitute valid and legally binding obligations of the Company, entitled to the benefits provided by the Indenture, subject, as to enforcement, to bankruptcy, insolvency, reorganization and other laws of general applicability relating to or affecting creditors' rights and to general equity principles; the Indenture has been duly authorized by the Company and, when executed and delivered by the Company and the Trustee, will constitute a valid and legally binding instrument of the Company, enforceable against the Company in accordance with its terms, subject, as to enforcement, to bankruptcy, insolvency, reorganization and other laws of general applicability relating to or affecting creditors' rights and to general equity principles; and the Securities and the Indenture will conform to the descriptions thereof in the Offering Circular and will be in substantially the form previously delivered to you;

        (h)   None of the transactions contemplated by this Agreement (including, without limitation, the use of the proceeds from the sale of the Securities) will violate or result in a violation of Section 7 of the Exchange Act, or any regulation promulgated thereunder, including, without limitation, Regulations T, U, and X of the Board of Governors of the Federal Reserve System;

        (i)    Prior to the date hereof, neither the Company nor any of its affiliates has taken any action which is designed to or which has constituted or which might have been expected to cause or result in stabilization or manipulation of the price of any security of the Company in connection with the offering of the Securities;

        (j)    The issue and sale of the Securities and the compliance by the Company with all of the provisions of the Securities, the Indenture and this Agreement and the consummation of the transactions herein and therein contemplated will not (i) conflict with or result in a breach or violation of any of the terms or provisions of, or constitute a default under, or result in the creation or imposition of any lien, charge or encumbrance upon any property or assets of the Company pursuant to, any indenture, mortgage, deed of trust, loan agreement or other agreement or instrument to which the Company or any of its subsidiaries is a party or by which the Company or any of its subsidiaries is bound or to which any of the property or assets of the Company or any of its subsidiaries is subject (except for such as would not, individually or in the aggregate, have a Material Adverse Effect), (ii) result in any violation of the provisions of the Articles of Incorporation or Bylaws or similar organizational or constituent documents of the Company or (iii) result in the violation of any statute or any order, rule or regulation of any court or governmental agency or body having jurisdiction over the Company or any of its subsidiaries or any of their properties (except for such as would not, individually or in the aggregate, have a Material Adverse Effect); and no consent, approval, authorization, order, registration or qualification of or with any such court or governmental agency or body is required for the issue and sale of the Securities or the consummation by the Company of the transactions contemplated by this Agreement or the Indenture, except for the filing of a registration statement by the Company with the Commission pursuant to the United States Securities Act of 1933, as amended (the "Securities Act") pursuant to Section 5(k) hereof and such consents, approvals, authorizations, registrations or qualifications as may be required under state securities or Blue Sky laws in connection with the purchase and distribution of the Securities by the Purchasers;

        (k)   (i) Neither the Company nor any of its Material Subsidiaries is in violation of its Articles of Incorporation or Bylaws or similar organizational or constituent documents; and

        (ii)   Neither the Company nor any of its subsidiaries is in default in the performance or observance of any obligation, covenant or condition contained in any indenture, mortgage, deed of trust, loan agreement, lease or other agreement or instrument to which it is a party or by which it or any of its properties may be bound (except for such as would not, individually or in the aggregate, have a Material Adverse Effect);

        (l)    The statements set forth in the Offering Circular under the caption "Description of the Notes", insofar as they purport to constitute a summary of the terms of the Securities and under the captions "Underwriting" and "Certain United States Federal Income Tax Considerations," insofar as they purport to describe the provisions of the laws and documents referred to therein, are accurate and complete in all material respects and present fairly the information described therein. The statements in the Offering Circular incorporated by reference from "Item 1. Business—Government Regulation of the Oil and Gas Industry" of the Company's Annual Report on Form 10-K for the year ended December 31, 2003 insofar as they purport to describe the provisions of the laws or regulations and documents referred to therein, are accurate and complete in all material respects and present fairly the information described therein;

        (m)  Other than as set forth in the Offering Circular, there are no legal, governmental or regulatory investigations, actions, suits or proceedings pending to which the Company or any of its subsidiaries is a party or of which any property of the Company or any of its subsidiaries is the subject which, if determined adversely to the Company or any of its subsidiaries, would individually or in the aggregate, have a Material Adverse Effect; and, to the best of the Company's knowledge, no such proceedings are threatened or contemplated by governmental authorities or threatened by others;

        (n)   When the Securities are issued and delivered pursuant to this Agreement, the Securities will not be of the same class (within the meaning of Rule 144A under the Securities Act) as securities which are listed on a national securities exchange registered under Section 6 of the Exchange Act or quoted in a U.S. automated inter-dealer quotation system;

        (o)   The Company is subject to Section 13 or 15(d) of the Exchange Act;

        (p)   The Company is not, and after giving effect to the offering and sale of the Securities and the application of the proceeds thereof as described in the Offering Circular, will not be, an "investment company", as such term is defined in the United States Investment Company Act of 1940, as amended (the "Investment Company Act");

        (q)   Neither the Company nor any person acting on its or their behalf has offered or sold the Securities by means of any general solicitation or general advertising within the meaning of Rule 502(c) under the Securities Act or, with respect to Securities sold outside the United States to non-U.S. persons (as defined in Rule 902 under the Securities Act), by means of any directed selling efforts within the meaning of Rule 902 under the Securities Act and the Company, any affiliate of the Company and any person acting on its or their behalf has complied with and will implement the "offering restriction" within the meaning of such Rule 902; provided, that the Company makes no representation or warranty with respect to any actions undertaken by or on behalf of the Purchasers;

        (r)   Within the preceding six months, neither the Company nor any other person acting on behalf of the Company has offered or sold to any person any Securities, or any securities of the same or a similar class as the Securities, other than Securities offered or sold to the Purchasers hereunder. The Company will take reasonable precautions designed to insure that any offer or sale, direct or indirect, in the United States or to any U.S. person (as defined in Rule 902 under the Securities Act) of any Securities or any substantially similar security issued by the Company, within six months subsequent to the date on which the distribution of the Securities has been completed (as notified to the Company by Goldman, Sachs & Co.), is made under restrictions and other circumstances reasonably designed not to affect the status of the offer and sale of the Securities in the United States and to U.S. persons contemplated by this Agreement as transactions exempt from the registration provisions of the Securities Act;

        (s)   BDO Seidman, LLP, who have certified certain financial statements of the Company and its subsidiaries, are independent public accountants as required by the Securities Act and the rules and regulations of the Commission thereunder;

        (t)    Except with respect to any taxes that are being contested in good faith by the Company or its subsidiaries, the Company and its subsidiaries have paid all United States and Canadian federal, state, provincial and local taxes (except for any taxes that are immaterial in amount) and filed all tax returns required to be paid or filed through the date hereof and there is no tax deficiency that has been, or could reasonably be expected to be, asserted against the Company or any of its subsidiaries or any of their respective properties or assets (except for any deficiencies that are immaterial in amount);

        (u)   The Company and its subsidiaries possess all licenses, certificates, permits and other authorizations issued by, and have made all declarations and filings with, the appropriate United States and Canadian federal, state, provincial or local governmental or regulatory authorities that are necessary for the ownership or lease of their respective properties or the conduct of their respective businesses as described in the Offering Circular (except where the failure to have any such licenses, certificates, permits and other authorizations or to make any declarations of filings would not, individually or in the aggregate, have a Material Adverse Effect); and neither the Company nor any of its subsidiaries has received notice of any revocation or modification adverse to the Company or its subsidiaries of any such material license, certificate, permit or authorization or has any reason to believe that any such material license, certificate, permit or authorization will not be renewed in the ordinary course;

        (v)   No labor disturbance by or dispute with employees of the Company or any of its subsidiaries exists or, to the knowledge of the Company, is threatened (except for such as would not, individually or in the aggregate, have a Material Adverse Effect);

        (w)  Except for such matters as would not, individually or in the aggregate, have a Material Adverse Effect, the Company and its subsidiaries (i) are in compliance with any and all applicable United States and Canadian federal, state, provincial and local laws, rules, regulations, decisions and orders relating to the protection of human health and safety, the environment or the use, disposal or release of hazardous or toxic substances or wastes, pollutants or contaminants (collectively, "Environmental Laws"); (ii) have received and are in compliance with all permits, licenses or other approvals required of them under applicable Environmental Laws to conduct their respective businesses as described in the Offering Circular; and (iii) have not received notice of any actual or potential liability for the investigation or remediation of any disposal or release of hazardous or toxic substances or wastes, pollutants or contaminants;

        (x)   There has been no storage, generation, transportation, handling, treatment, disposal, discharge, emission, or other release of any kind of toxic wastes or hazardous substances, including, but not limited to, any naturally occurring radioactive materials, brine, drilling mud, crude oil, natural gas liquids and other petroleum materials, by, due to or caused by the Company or any of its subsidiaries (or any other entity (including any predecessor) for whose acts or omissions the Company or any of its subsidiaries is or could reasonably be expected to be liable) upon any of the property now or previously owned or leased by the Company or any of its subsidiaries, or upon any other property, in violation of any Environmental Laws or in a manner or to a location that could reasonably be expected to give rise to any liability under any Environmental Laws (except for such as would not, individually or in the aggregate, have a Material Adverse Effect);

        (y)   (i) Each employee benefit plan, within the meaning of Section 3(3) of the Employee Retirement Income Security Act of 1974, as amended ("ERISA"), that is maintained, administered or contributed to by the Company or any of its affiliates for employees or former employees of the Company and its affiliates has been maintained in compliance in all material respects with its terms and the requirements of any applicable statutes, orders, rules and regulations, including but not limited to ERISA and the Internal Revenue Code of 1986, as amended (the "Code"); (ii) no prohibited transaction, within the meaning of Section 406 of ERISA or Section 4975 of the Code, has occurred with respect to any such plan excluding transactions effected pursuant to a statutory or administrative exemption; and (iii) for each such plan that is subject to the funding rules of Section 412 of the Code or Section 302 of ERISA, no "accumulated funding deficiency" as defined in Section 412 of the Code has been incurred, whether or not waived, and the fair market value of the assets of each such plan (excluding for these purposes accrued but unpaid contributions) exceeds the present value of all benefits accrued under such plan determined using reasonable actuarial assumptions;

        (z)   The Company and its subsidiaries maintain systems of internal accounting controls sufficient to provide reasonable assurance that (i) transactions are executed in accordance with management's general or specific authorizations; (ii) transactions are recorded as necessary to permit preparation of financial statements in conformity with generally accepted accounting principles and to maintain asset accountability; (iii) access to assets is permitted only in accordance with management's general or specific authorization; and (iv) the recorded accountability for assets is compared with the existing assets at reasonable intervals and appropriate action is taken with respect to any differences;

        (aa) (i) The Company and its subsidiaries have insurance covering their respective properties, operations, personnel and businesses, which insurance is in amounts and insures against such losses and risks to protect the Company and its subsidiaries and their respective businesses as described in the Offering Circular in a manner consistent with other businesses similarly situated; and neither the Company nor any of its subsidiaries has (ii) received notice from any insurer or agent of such insurer that capital improvements or other expenditures that are, individually or in the aggregate, material to the Company and its subsidiaries taken as a whole are required or necessary to be made in order to continue such insurance or (iii) any reason to believe that it will not be able to renew its existing insurance coverage as and when such coverage expires or to obtain similar coverage at reasonable cost from similar insurers as may be necessary to continue its business;

        (bb) Except as disclosed in the Offering Circular, no subsidiary of the Company is currently prohibited, directly or indirectly, under any agreement or other instrument to which it is a party or is subject, from paying any dividends to the Company, from making any other distribution on such subsidiary's capital stock, from repaying to the Company any loans or advances to such subsidiary from the Company or from transferring any of such subsidiary's properties or assets to the Company or any other subsidiary of the Company;

        (cc) Nothing has come to the attention of the Company that has caused the Company to believe that the statistical and market-related data included in the Offering Circular is not based on or derived from sources that are reliable and accurate in all material respects;

        (dd) The oil and gas reserve estimates of the Company and its subsidiaries contained in, incorporated by reference or attached to and made a part of the Offering Circular have been prepared by the Company and, with respect to the year-end estimates of the Company and its subsidiaries, audited or prepared by Netherland, Sewell & Associates, Inc., in accordance with the Commission guidelines applied on a consistent basis throughout the periods involved and neither the Company nor its subsidiaries has any reason to believe that such reserve estimates do not fairly reflect the oil and natural gas reserves of the Company and its subsidiaries at the dates indicated in the Offering Circular;

        (ee) Netherland, Sewell & Associates, Inc. are independent petroleum engineers with respect to the Company and its subsidiaries;

        (ff)  There is and has been no failure on the part of the Company or any of the Company's directors or officers, in their capacities as such, to comply in any material respect with any provision of the Sarbanes-Oxley Act of 2002 and the rules and regulations promulgated in connection therewith, including Section 402 related to loans and Sections 302 and 906 related to certifications; and

        (gg) The financial statements and the related notes thereto of the Company and its consolidated subsidiaries included or incorporated by reference in the Preliminary Offering Circular and the Offering Circular comply in all material respects with the applicable requirements of the Securities Act and the Exchange Act, as applicable, and present fairly in all material respects the financial position of the Company and its consolidated subsidiaries as of the dates indicated and the results of their operations and the changes in their cash flows for the periods specified; such financial statements have been prepared in conformity with generally accepted accounting principles applied on a consistent basis throughout the periods covered thereby, and the supporting schedules included or incorporated by reference in the Preliminary Offering Circular and the Offering Circular present fairly in all material respects the information required to be stated therein; and the other financial information included or incorporated by reference in the Preliminary Offering Circular and the Offering Circular has been derived from the accounting records of the Company and its consolidated subsidiaries and presents fairly in all material respects the information shown thereby.

        2.     Subject to the terms and conditions herein set forth, the Company agrees to issue and sell to each of the Purchasers, and each of the Purchasers agrees, severally and not jointly, to purchase from the Company, at an aggregate purchase price of $194,426,000 or a purchase price of $972 per Security, plus accrued interest, if any, from March 10, 2004 to the Time of Delivery (as defined below) hereunder, the principal amount of Securities set forth opposite the name of such Purchaser in Schedule I hereto.

        3.     Upon the authorization by you of the release of the Securities, the several Purchasers propose to offer the Securities for sale upon the terms and conditions set forth in this Agreement and the Offering Circular and each Purchaser hereby represents and warrants to, and agrees with the Company that:

        (a)   It will offer and sell the Securities only to : (i) persons who it reasonably believes are "qualified institutional buyers" ("QIBs") within the meaning of Rule 144A under the Securities Act in transactions meeting the requirements of Rule 144A or (ii) upon the terms and conditions set forth in Annex I to this Agreement;

        (b)   It is an Institutional Accredited Investor; and

        (c)   It will not offer or sell the Securities by any form of general solicitation or general advertising, including but not limited to the methods described in Rule 502(c) under the Securities Act.

        4.     (a) The Securities to be purchased by each Purchaser hereunder will be represented by one or more definitive global Securities in book-entry form which will be deposited by or on behalf of the Company with The Depository Trust Company ("DTC") or its designated custodian. The Company will deliver the Securities to Goldman, Sachs & Co., for the account of each Purchaser, against payment by or on behalf of such Purchaser of the purchase price therefor by wire transfer of Federal (same-day) funds to the account specified by the Company to Goldman, Sachs & Co. at least forty-eight hours in advance, by causing DTC to credit the Securities to the account of Goldman, Sachs & Co. at DTC. The Company will cause the certificates representing the Securities to be made available to Goldman, Sachs & Co. for checking at least twenty-four hours prior to the Time of Delivery (as defined below) at the office of DTC or its designated custodian (the "Designated Office"). The time and date of such delivery and payment shall be 9:30 a.m., New York City time, on March 10, 2004 or such other time and date as Goldman, Sachs & Co. and the Company may agree upon in writing. Such time and date are herein called the "Time of Delivery".

        (b)   The documents to be delivered at the Time of Delivery by or on behalf of the parties hereto pursuant to Section 7 hereof, including the cross-receipt for the Securities and any additional documents requested by the Purchasers pursuant to Section 7(i) hereof, will be delivered at such time and date at the offices of Vinson & Elkins, L.L.P., 666 Fifth Avenue, 26th Floor, New York, New York 10103 (the "Closing Location"), and the Securities will be delivered at the Designated Office, all at the Time of Delivery. A meeting will be held at the Closing Location at 3:00p.m., New York City time, on the New York Business Day next preceding the Time of Delivery, at which meeting the final drafts of the documents to be delivered pursuant to the preceding sentence will be available for review by the parties hereto. For the purposes of this Section 4, "New York Business Day" shall mean each Monday, Tuesday, Wednesday, Thursday and Friday which is not a day on which banking institutions in New York are generally authorized or obligated by law or executive order to close.

        5.     The Company agrees with each of the Purchasers:

        (a)   To prepare the Offering Circular in a form approved by you; to make no amendment or any supplement to the Offering Circular which shall be disapproved by you promptly after reasonable notice thereof; and to furnish you with copies thereof;

        (b)   Promptly from time to time to take such action as you may reasonably request to qualify the Securities for offering and sale under the securities laws of such jurisdictions as you may request and to comply with such laws so as to permit the continuance of sales and dealings therein in such jurisdictions for as long as may be necessary to complete the distribution of the Securities, provided that in connection therewith the Company shall not be required to qualify as a foreign corporation or to file a general consent to service of process in any jurisdiction or subject itself to taxation in any jurisdiction to which it is not then subject;

        (c)   To furnish the Purchasers with copies of the Offering Circular and each amendment or supplement thereto, in such quantities as you may request, with the independent accountants' report(s) in the Offering Circular, and any amendment or supplement containing amendments to the financial statements covered by such report(s) and additional written and electronic copies thereof in such quantities as you may from time to time reasonably request, and if, at any time prior to the expiration of nine months after the date of the Offering Circular, any event shall have occurred as a result of which the Offering Circular as then amended or supplemented would include an untrue statement of a material fact or omit to state any material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made when such Offering Circular is delivered, not misleading, or, if for any other reason it shall be necessary or desirable during such same period to amend or supplement the Offering Circular, to notify you and upon your request to prepare and furnish without charge to each Purchaser and to any dealer in securities as many written and electronic copies as you may from time to time reasonably request of an amended Offering Circular or a supplement to the Offering Circular which will correct such statement or omission or effect such compliance;

        (d)   During the period beginning from the date hereof and continuing until the date ninety days after the Time of Delivery, not to offer, sell, contract to sell or otherwise dispose of, except as provided hereunder, any securities of the Company that are substantially similar to the Securities;

        (e)   Not to be or become, at any time prior to the expiration of three years after the Time of Delivery, an open-end investment company, unit investment trust, closed-end investment company or face-amount certificate company that is or is required to be registered under Section 8 of the Investment Company Act;

        (f)    At any time when the Company is not subject to Section 13 or 15(d) of the Exchange Act, for the benefit of holders from time to time of Securities, to furnish at its expense, upon request, to holders of Securities and prospective purchasers of securities information (the "Additional Issuer Information") satisfying the requirements of subsection (d)(4)(i) of Rule 144A under the Securities Act, unless all the Securities no longer are "restricted securities" within the meaning of Rule 144(a)(3) under the Securities Act or may be sold under Rule 144(k) under the Securities Act;

        (g)   If requested by you, to use its best efforts to cause the Securities to be eligible for the PORTAL trading system of the National Association of Securities Dealers, Inc.;

        (h)   To the extent not otherwise available on the web site of the Commission, to furnish to the holders of the Securities as soon as practicable after the end of each fiscal year an annual report (including a balance sheet and statements of income, stockholders' equity and cash flows of the Company and its consolidated subsidiaries certified by independent public accountants) and, as soon as practicable after the end of each of the first three quarters of each fiscal year (beginning with the fiscal quarter ending after the date of the Offering Circular), to make available to its stockholders consolidated summary financial information of the Company and its subsidiaries for such quarter in reasonable detail;

        (i)    To the extent not otherwise available on the web site of the Commission, during a period of five years from the date of the Offering Circular, to furnish to you copies of all reports or other communications (financial or other) furnished to stockholders of the Company, and to deliver to you (i) as soon as they are available, copies of any reports and financial statements furnished to or filed with the Commission or any securities exchange on which the Securities or any class of securities of the Company is listed; and (ii) such additional information concerning the business and financial condition of the Company as you may from time to time reasonably request (such financial statements to be on a consolidated basis to the extent the accounts of the Company and its subsidiaries are consolidated in reports furnished to its stockholders generally or to the Commission);

        (j)    During the period of two years after the Time of Delivery, the Company will not, and will not permit any of its "affiliates" (as defined in Rule 144 under the Securities Act) to, resell any of the Securities which constitute "restricted securities" under Rule 144 that have been reacquired by any of them;

        (k)   The Company shall file and use its best efforts to cause to be declared or become effective under the Securities Act, on or prior to 180 days after the Time of Delivery, a registration statement on Form S-4 providing for the registration of (i) another series of debt securities of the Company, with terms identical to the Securities (the "Exchange Securities"), and the exchange of the Securities for the Exchange Securities, all in a manner which will permit persons who acquire the Exchange Securities to resell the Exchange Securities pursuant to Section 4(1) of the Securities Act; and

        (l)    To use the net proceeds received by the Company from the sale of the Securities pursuant to this Agreement in the manner specified in the Offering Circular under the caption "Use of Proceeds".

        6.     The Company covenants and agrees with the several Purchasers that the Company will pay or cause to be paid the following: (i) the fees, disbursements and expenses of the Company's counsel and accountants in connection with the issue of the Securities and all other expenses in connection with the preparation, printing and filing of the Preliminary Offering Circular and the Offering Circular and any amendments and supplements thereto and the mailing and delivering of copies thereof to the Purchasers and dealers; (ii) the cost of printing or producing any Agreement among Purchasers, this Agreement, the Indenture, the Blue Sky and Legal Investment Memoranda, closing documents (including any compilations thereof) and any other documents in connection with the offering, purchase, sale and delivery of the Securities; (iii) all expenses in connection with the qualification of the Securities for offering and sale under state securities laws as provided in Section 5(b) hereof, including the fees and disbursements of counsel for the Purchasers in connection with such qualification and in connection with the Blue Sky and legal investment surveys; (iv) any fees charged by securities rating services for rating the Securities; (v) the cost of preparing the Securities; (vi) the fees and expenses of the Trustee and any agent of the Trustee and the fees and disbursements of counsel for the Trustee in connection with the Indenture and the Securities; (vii) any cost incurred in connection with the designation of the Securities for trading in PORTAL and (viii) all other costs and expenses incident to the performance of its obligations hereunder which are not otherwise specifically provided for in this Section. It is understood, however, that, except as provided in this Section, and Sections 8 and 11 hereof, the Purchasers will pay all of their own costs and expenses, including the fees of their counsel, transfer taxes on resale of any of the Securities by them, and any advertising expenses connected with any offers they may make.

        7.     The obligations of the Purchasers hereunder shall be subject, in their discretion, to the condition that all representations and warranties and other statements of the Company herein are, at and as of the Time of Delivery, true and correct, the condition that the Company shall have performed all of its respective obligations hereunder theretofore to be performed, and the following additional conditions:

        (a)   Vinson & Elkins L.L.P., counsel for the Purchasers, shall have furnished to you such opinion or opinions, dated the Time of Delivery, with respect to the matters as you may reasonably request, and such counsel shall have received such papers and information as they may reasonably request to enable them to pass upon such matters;

        (b)   Womble, Carlyle, Sandridge, & Rice PLLC, counsel for the Company, shall have furnished to you their written opinion, dated the Time of Delivery, in form and substance satisfactory to you, to the effect set forth in Annex II hereto; provided, that in rendering such opinion, counsel for the Company may rely (i) as to the matters set forth in paragraphs 1-10 and 11 (clauses (i) and (ii)) and as to all other matters of Colorado law solely on the opinions of Berenbaum, Weinshienk & Eason, P.C., (ii) as to matters relating to any subsidiary incorporated under the provincial laws of Canada and all other provincial laws solely on the opinions of Burnett, Duckforth & Palmer and (iii) as to paragraph 13 relating to "Item 1. Business— Government Regulation of the Oil and Gas Industry" of the Company's Annual Report on Form 10-K for the year ended December 31, 2003 and all other matters relating to government regulation of the oil and gas industry, solely on the opinions of Barry W. Spector, or in each case such other counsel satisfactory to counsel to the Company and to your counsel; and, provided further, that in rendering opinions on matters that are governed by the laws of the State of New York, Berenbaum, Weinshienk & Eason, P.C. may assume that, for such purposes, the laws of the State of New York and the laws of the State of Colorado are identical;

        (c)   On the date of the Offering Circular prior to the execution of this Agreement and also at the Time of Delivery, BDO Seidman, LLP shall have furnished to you a letter or letters, dated the respective dates of delivery thereof, in form and substance satisfactory to you, to the effect set forth in Annex III hereto;

        (d)   (i) Neither the Company nor any of its subsidiaries shall have sustained since the date of the latest audited financial statements included in the Offering Circular any loss or interference with its business from fire, explosion, flood or other calamity, whether or not covered by insurance, or from any labor dispute or any action, order or decree of any court or arbitrator or governmental or regulatory authority, otherwise than as set forth or contemplated in the Offering Circular, and (ii) since the respective dates as of which information is given in the Offering Circular there shall not have been any change in the capital stock (except pursuant to publicly-disclosed stock-based employee benefit plans of the Company in existence on the date of this Agreement) or long-term debt of the Company or any of its subsidiaries or non-material changes in the ordinary course of business in outstanding indebtedness under the Company's publicly-disclosed long-term debt facilities, or any change, or any development involving a prospective change, in or affecting the business, properties, general affairs, management, financial position, stockholders' equity or results of operations of the Company and its subsidiaries taken as a whole, otherwise than as set forth or contemplated in the Offering Circular, the effect of which, in any such case described in clause (i) or (ii), is in the judgment of the Representative so material and adverse as to make it impracticable or inadvisable to proceed with the offering or the delivery of the Securities on the terms and in the manner contemplated in this Agreement and in the Offering Circular;

        (e)   On or after the date hereof (i) no downgrading shall have occurred in the rating accorded the Securities and any other debt of the Company, if any, by any "nationally recognized statistical rating organization", as that term is defined by the Commission for purposes of Rule 436(g)(2) under the Securities Act, and (ii) no such organization shall have publicly announced that it has under surveillance or review, with possible negative implications, its rating of any of the Company's debt securities;

        (f)    On or after the date hereof there shall not have occurred any of the following: (i) a suspension or material limitation in trading in securities generally on the New York Stock Exchange; (ii) a suspension or material limitation in trading in the Company's securities on the New York Stock Exchange; (iii) a general moratorium on commercial banking activities declared by either Federal or New York State authorities or a material disruption in commercial banking or securities settlement or clearance services in the United States; (iv) the outbreak or escalation of hostilities involving the United States or the declaration by the United States of a national emergency or war or (v) the occurrence of any other calamity or crisis or any change in financial, political or economic conditions in the United States or elsewhere, if the effect of any such event specified in clause (iv) or (v) in the judgment of the Representative makes it impracticable or inadvisable to proceed with the offering or the delivery of the Securities on the terms and in the manner contemplated in the Offering Circular;

        (g)   The Securities have been designated for trading on PORTAL;

        (h)   The Company shall have furnished or caused to be furnished to you at the Time of Delivery certificates of the chief financial officer or chief accounting officer and one additional senior executive officer of the Company satisfactory to you as to (i) the accuracy of the representations and warranties of the Company herein at and as of such Time of Delivery, (ii) the performance by the Company of all of its obligations hereunder to be performed at or prior to such Time of Delivery, (iii) the matters set forth in subsections (d) and (e) of this Section and (iv) such other matters as you may reasonably request;

        (i)    On the date of the Offering Circular prior to the execution of this Agreement, the Company and the Purchasers shall have entered into an Exchange and Registration Rights Agreement in form and substance satisfactory to you, to the effect set forth in Annex IV hereto; and

        (j)    At the Time of Delivery, Netherland, Sewell & Associates, Inc. shall have furnished to you a letter or letters, dated the respective dates of delivery thereof, in form and substance satisfactory to you.

        8.     (a) The Company will indemnify and hold harmless each Purchaser against any losses, claims, damages or liabilities, joint or several, to which such Purchaser may become subject, under the Securities Act or otherwise, insofar as such losses, claims, damages or liabilities (or actions in respect thereof) arise out of or are based upon an untrue statement or alleged untrue statement of a material fact contained in any Preliminary Offering Circular or the Offering Circular, or any amendment or supplement thereto, or arise out of or are based upon the omission or alleged omission to state therein a material fact necessary to make the statements therein not misleading, and will reimburse each Purchaser for any legal or other expenses reasonably incurred by such Purchaser in connection with investigating or defending any such action or claim as such expenses are incurred; provided , however , that the Company shall not be liable in any such case to the extent that any such loss, claim, damage or liability arises out of or is based upon an untrue statement or alleged untrue statement or omission or alleged omission made in any Preliminary Offering Circular or the Offering Circular or any such amendment or supplement in reliance upon and in conformity with written information furnished to the Company by any Purchaser through Goldman, Sachs & Co. expressly for use therein.

        (b)   Each Purchaser will, severally and jointly, indemnify and hold harmless the Company against any losses, claims, damages or liabilities to which the Company may become subject, under the Securities Act or otherwise, insofar as such losses, claims, damages or liabilities (or actions in respect thereof) arise out of or are based upon an untrue statement or alleged untrue statement of a material fact contained in any Preliminary Offering Circular or the Offering Circular, or any amendment or supplement thereto, or arise out of or are based upon the omission or alleged omission to state therein a material fact or necessary to make the statements therein not misleading, in each case to the extent, but only to the extent, that such untrue statement or alleged untrue statement or omission or alleged omission was made in any Preliminary Offering Circular or the Offering Circular or any such amendment or supplement in reliance upon and in conformity with written information furnished to the Company by such Purchaser through Goldman, Sachs & Co. expressly for use therein; and will reimburse the Company for any legal or other expenses reasonably incurred by the Company in connection with investigating or defending any such action or claim as such expenses are incurred.

        (c)   Promptly after receipt by an indemnified party under subsection (a) or (b) above of notice of the commencement of any action, such indemnified party shall, if a claim in respect thereof is to be made against the indemnifying party under such subsection, notify the indemnifying party in writing of the commencement thereof; but the omission so to notify the indemnifying party shall not relieve it from any liability which it may have to any indemnified party otherwise than under such subsection. In case any such action shall be brought against any indemnified party and it shall notify the indemnifying party of the commencement thereof, the indemnifying party shall be entitled to participate therein and, to the extent that it shall wish, jointly with any other indemnifying party similarly notified, to assume the defense thereof, with counsel satisfactory to such indemnified party (who shall not, except with the consent of the indemnified party, be counsel to the indemnifying party), and, after notice from the indemnifying party to such indemnified party of its election so to assume the defense thereof, the indemnifying party shall not be liable to such indemnified party under such subsection for any legal expenses of other counsel or any other expenses, in each case subsequently incurred by such indemnified party, in connection with the defense thereof other than reasonable costs of investigation. No indemnifying party shall, without the written consent of the indemnified party, effect the settlement or compromise of, or consent to the entry of any judgment with respect to, any pending or threatened action or claim in respect of which indemnification or contribution may be sought hereunder (whether or not the indemnified party is an actual or potential party to such action or claim) unless such settlement, compromise or judgment (i) includes an unconditional release of the indemnified party from all liability arising out of such action or claim and (ii) does not include a statement as to, or an admission of, fault, culpability or a failure to act, by or on behalf of any indemnified party.

        (d)   If the indemnification provided for in this Section 8 is unavailable to or insufficient to hold harmless an indemnified party under subsection (a) or (b) above in respect of any losses, claims, damages or liabilities (or actions in respect thereof) referred to therein, then each indemnifying party shall contribute to the amount paid or payable by such indemnified party as a result of such losses, claims, damages or liabilities (or actions in respect thereof) in such proportion as is appropriate to reflect the relative benefits received by the Company on the one hand and the Purchasers on the other from the offering of the Securities. If, however, the allocation provided by the immediately preceding sentence is not permitted by applicable law or if the indemnified party failed to give the notice required under subsection (c) above, then each indemnifying party shall contribute to such amount paid or payable by such indemnified party in such proportion as is appropriate to reflect not only such relative benefits but also the relative fault of the Company on the one hand and the Purchasers on the other in connection with the statements or omissions which resulted in such losses, claims, damages or liabilities (or actions in respect thereof), as well as any other relevant equitable considerations. The relative benefits received by the Company on the one hand and the Purchasers on the other shall be deemed to be in the same proportion as the total net proceeds from the offering (before deducting expenses) received by the Company bear to the total underwriting discounts and commissions received by the Purchasers, in each case as set forth in the Offering Circular. The relative fault shall be determined by reference to, among other things, whether the untrue or alleged untrue statement of a material fact or the omission or alleged omission to state a material fact relates to information supplied by the Company on the one hand or the Purchasers on the other and the parties' relative intent, knowledge, access to information and opportunity to correct or prevent such statement or omission. The Company and the Purchasers agree that it would not be just and equitable if contribution pursuant to this subsection (d) were determined by pro rata allocation (even if the Purchasers were treated as one entity for such purpose) or by any other method of allocation which does not take account of the equitable considerations referred to above in this subsection (d). The amount paid or payable by an indemnified party as a result of the losses, claims, damages or liabilities (or actions in respect thereof) referred to above in this subsection (d) shall be deemed to include any legal or other expenses reasonably incurred by such indemnified party in connection with investigating or defending any such action or claim. Notwithstanding the provisions of this subsection (d), no Purchaser shall be required to contribute any amount in excess of the amount by which the total price at which the Securities underwritten by it and distributed to investors were offered to investors exceeds the amount of any damages which such Purchaser has otherwise been required to pay by reason of such untrue or alleged untrue statement or omission or alleged omission. The Purchasers' obligations in this subsection (d) to contribute are several in proportion to their respective underwriting obligations and not joint.

        (e)   The obligations of the Company under this Section 8 shall be in addition to any liability which the Company may otherwise have and shall extend, upon the same terms and conditions, to each person, if any, who controls any Purchaser within the meaning of the Securities Act; and the obligations of the Purchasers under this Section 8 shall be in addition to any liability which the respective Purchasers may otherwise have and shall extend, upon the same terms and conditions, to each officer and director of the Company and to each person, if any, who controls the Company within the meaning of the Securities Act.

        9.     (a) If any Purchaser shall default in its obligation to purchase the Securities which it has agreed to purchase hereunder, you may in its discretion arrange for itself or another party or other parties to purchase such Securities on the terms contained herein. If within thirty-six hours after such default by any Purchaser you do not arrange for the purchase of such Securities, then the Company shall be entitled to a further period of thirty-six hours within which to procure another party or other parties satisfactory to you to purchase such Securities on such terms. In the event that, within the respective prescribed periods, you notify the Company that it has so arranged for the purchase of such Securities , or the Company notifies you that it has so arranged for the purchase of such Securities, you or the Company shall have the right to postpone the Time of Delivery for a period of not more than seven days, in order to effect whatever changes may thereby be made necessary in the Offering Circular, or in any other documents or arrangements, and the Company agrees to prepare promptly any amendments to the Offering Circular which in your opinion may thereby be made necessary. The term "Purchaser" as used in this Agreement shall include any person substituted under this Section with like effect as if such person had originally been a party to this Agreement with respect to such Securities.

        (b)   If, after giving effect to any arrangements for the purchase of the Securities of a defaulting Purchaser or Purchasers by you and the Company as provided in subsection (a) above, the aggregate principal amount of such Securities which remains unpurchased does not exceed one-eleventh of the aggregate principal amount of all the Securities, then the Company shall have the right to require each non-defaulting Purchaser to purchase the principal amount of Securities which such Purchaser agreed to purchase hereunder and, in addition, to require each non-defaulting Purchaser to purchase its pro rata share (based on the principal amount of Securities which such Purchaser agreed to purchase hereunder) of the Securities of such defaulting Purchaser or Purchasers for which such arrangements have not been made; but nothing herein shall relieve a defaulting Purchaser from liability for its default.

        (c)   If, after giving effect to any arrangements for the purchase of the Securities of a defaulting Purchaser or Purchasers by you and the Company as provided in subsection (a) above, the aggregate principal amount of Securities which remains unpurchased exceeds one-eleventh of the aggregate principal amount of all the Securities, or if the Company shall not exercise the right described in subsection (b) above to require non-defaulting Purchasers to purchase Securities of a defaulting Purchaser or Purchasers, then this Agreement shall thereupon terminate, without liability on the part of any non-defaulting Purchaser, the Company, except for the expenses to be borne by the Company and the Purchasers as provided in Section 6 hereof and the indemnity and contribution agreements in Section 8 hereof; but nothing herein shall relieve a defaulting Purchaser from liability for its default.

        10.   The respective indemnities, agreements, representations, warranties and other statements of the Company, and the several Purchasers, as set forth in this Agreement or made by or on behalf of them, respectively, pursuant to this Agreement, shall remain in full force and effect, regardless of any investigation (or any statement as to the results thereof) made by or on behalf of any Purchaser or any controlling person of any Purchaser, or the Company, or any officer or director or controlling person of the Company, and shall survive delivery of and payment for the Securities .

        11.   If this Agreement shall be terminated pursuant to Section 9 hereof, the Company shall not then be under any liability to any Purchaser except as provided in Sections 6 and 8 hereof; but, if for any other reason, the Securities are not delivered by or on behalf of the Company as provided herein, the Company will reimburse the Purchasers through you for all out-of-pocket expenses approved in writing by you, including fees and disbursements of counsel, reasonably incurred by the Purchasers in making preparations for the purchase, sale and delivery of the Securities, but the Company shall not then be under any further liability to any Purchaser except as provided in Sections 6 and 8 hereof.

        12.   In all dealings hereunder, you shall act on behalf of each of the Purchasers, and the parties hereto shall be entitled to act and rely upon any statement, request, notice or agreement on behalf of any Purchaser made or given by you.

        13.   All statements, requests, notices and agreements hereunder shall be in writing, and if to the Purchasers shall be delivered or sent by mail, telex or facsimile transmission to the Representative at Goldman, Sachs & Co., 85 Broad Street, New York, New York 10004, Attention: Registration Department; and if to the Company shall be delivered or sent by mail or facsimile transmission to the address of the Company set forth in the Offering Circular, Attention: Chief Financial Officer; provided , however , that any notice to a Purchaser pursuant to Section 8(c) hereof shall be delivered or sent by mail or facsimile transmission to such Purchaser at its address set forth in its Purchasers' Questionnaire, or telex constituting such Questionnaire, which address will be supplied to the Company by you upon request. Any such statements, requests, notices or agreements shall take effect upon receipt thereof.

        14.   This Agreement shall be binding upon, and inure solely to the benefit of, the Purchasers, the Company, and, to the extent provided in Sections 8 and 10 hereof, the officers and directors of the Company and each person who controls the Company or any Purchaser, and their respective heirs, executors, administrators, successors and assigns, and no other person shall acquire or have any right under or by virtue of this Agreement. No purchaser of any of the Securities from any Purchaser shall be deemed a successor or assign by reason merely of such purchase.

        15.   Time shall be of the essence of this Agreement.

        16.   This Agreement shall be governed by and construed in accordance with the laws of the State of New York.

        17.   This Agreement may be executed by any one or more of the parties hereto in any number of counterparts, each of which shall be deemed to be an original, but all such respective counterparts shall together constitute one and the same instrument.

        18.   No amendment or waiver of any provision of this Agreement, nor any consent or approval to any departure therefrom, shall in any event be effective unless the same shall be in writing and signed by each of the parties hereto.

        19.   This Agreement, including the Schedules and Annexes hereto, constitutes the entire agreement among the parties pertaining to the subject matter hereof and supercedes all other prior and contemporaneous agreements and understandings, whether oral and written, of the parties in connection therewith.

        20.   The Company is authorized, subject to applicable law, to disclose any and all aspects of this potential transaction that are necessary to support any U.S. federal income tax benefits expected to be claimed with respect to such transaction, and all materials of any kind (including tax opinions and other tax analyses) related to those benefits, without the Purchasers imposing any limitation of any kind.

        If the foregoing is in accordance with your understanding, please sign and return to us one for the Company and one for the Representative plus one for each counsel counterparts hereof, and upon the acceptance hereof by you, on behalf of each of the Purchasers, this letter and such acceptance hereof shall constitute a binding agreement between each of the Purchasers and the Company. It is understood that your acceptance of this letter on behalf of each of the Purchasers is pursuant to the authority set forth in a form of Agreement among Purchasers, the form of which shall be submitted to the Company for examination upon request, but without warranty on your part as to the authority of the signers thereof.

SCHEDULE I

ANNEX I

        (1)   The Securities have not been and will not be registered under the Securities Act and may not be offered or sold within the United States or to, or for the account or benefit of, U.S. persons except in accordance with Regulation S under the Securities Act or pursuant to an exemption from the registration requirements of the Securities Act. Each Purchaser represents that it has offered and sold the Securities, and will offer and sell the Securities (i) as part of their distribution at any time and (ii) otherwise until 40 days after the later of the commencement of the offering and the Time of Delivery, only in accordance with Rule 903 of Regulation S or, Rule 144A under the Securities Act. Accordingly, each Purchaser agrees that neither it, its affiliates nor any persons acting on its or their behalf has engaged or will engage in any directed selling efforts with respect to the Securities, and it and they have complied and will comply with the offering restrictions requirement of Regulation S. Each Purchaser agrees that, at or prior to confirmation of sale of Securities (other than a sale pursuant to Rule 144A), it will have sent to each distributor, dealer or person receiving a selling concession, fee or other remuneration that purchases Securities from it during the restricted period a confirmation or notice to substantially the following effect:

        "The Securities covered hereby have not been registered under the U.S. Securities Act of 1933 (the "Securities Act") and may not be offered and sold within the United States or to, or for the account or benefit of, U.S. persons (i) as part of their distribution at any time or (ii) otherwise until 40 days after the later of the commencement of the offering and the closing date, except in either case in accordance with Regulation S (or Rule 144A if available) under the Securities Act. Terms used above have the meaning given to them by Regulation S."

Terms used in this paragraph have the meanings given to them by Regulation S.

        Each Purchaser further agrees that it has not entered and will not enter into any contractual arrangement with respect to the distribution or delivery of the Securities, except with its affiliates or with the prior written consent of the Company.

        (2)   Notwithstanding the foregoing, Securities in registered form may be offered, sold and delivered by the Purchasers in the United States and to U.S. persons pursuant to Section 3 of this Agreement without delivery of the written statement required by paragraph (1) above.

        (3)   Each Purchaser further represents and agrees that (i) it has not offered or sold and prior to the date six months after the date of issue of the Securities will not offer or sell any Securities to persons in the United Kingdom except to persons whose ordinary activities involve them in acquiring, holding, managing or disposing of investments (as principal or agent) for the purposes of their businesses or otherwise in circumstances which have not resulted and will not result in an offer to the public in the United Kingdom within the meaning of the Public Offers of Securities Regulations 1995, (b) it has complied, and will comply, with all applicable provisions of the Financial Services Act of 1986 of Great Britain with respect to anything done by it in relation to the Securities in, from or otherwise involving the United Kingdom, and (c) it has only issued or passed on and will only issue or pass on in the United Kingdom any document received by it in connection with the issuance of the Securities to a person who is of a kind described in Article 11(3) of the Financial Services Act 1986 (Investment Advertisements) (Exemptions) Order 1996 of Great Britain or is a person to whom the document may otherwise lawfully be issued or passed on.

        (4)   Each Purchaser agrees that it will not offer, sell or deliver any of the Securities in any jurisdiction outside the United States except under circumstances that will result in compliance with the applicable laws thereof, and that it will take at its own expense whatever action is required to permit its purchase and resale of the Securities in such jurisdictions. Each Purchaser understands that no action has been taken to permit a public offering in any jurisdiction outside the United States where action would be required for such purpose. Each Purchaser agrees not to cause any advertisement of the Securities to be published in any newspaper or periodical or posted in any public place and not to issue any circular relating to the Securities, except in any such case with Goldman, Sachs & Co.'s express written consent and then only at its own risk and expense.

ANNEX II

        Pursuant to Section 7(b) of the Purchase Agreement, Womble, Carlyle, Sandridge, & Rice PLLC shall furnish letters to the Representative to the effect that:

        1.     Each of the Company, Primero Gas Marketing Co., Evergreen Operating Co., Carbon Energy Corporation, Evergreen Resources Canada, Ltd., Carbon Energy Corp. (USA) and Primero Gas Company, LLC (collectively, the "Subsidiaries") has been duly incorporated and is validly existing as a corporation in good standing under the laws of the State of Colorado and has the corporate power and authority to own its properties and to conduct its business as described in the Offering Circular.

        2.     The Company has an authorized capitalization as set forth in the Offering Circular, and all of the issued shares of capital stock of the Company have been duly and validly authorized and issued and are fully paid and non-assessable.

        3.     All of the issued shares of capital stock of each of the Subsidiaries have been duly and validly authorized and issued, are fully paid and non-assessable, and are owned directly or indirectly by the Company, free and clear of all liens, encumbrances, equities or claims.

        4.     To our knowledge, (i) there is no action, suit, proceeding, inquiry or investigation before or by any court or governmental agency or body, now pending or threatened, against the Company or any of the Subsidiaries that is reasonably likely to have a material adverse effect on the business, financial condition and results of operations of the Company and its subsidiaries taken as a whole, except as disclosed in the Offering Circular and (ii) neither the Company nor any of the Subsidiaries is in material violation of its Articles of Incorporation or Bylaws or similar organizational documents, as applicable.

        5.     The Agreement has been duly authorized, executed and delivered by the Company.

        6.     The Securities have been duly authorized, executed and delivered and, when authenticated in accordance with the Indenture and issued against payment therefor as contemplated by the Agreement, will constitute valid and legally binding obligations of the Company enforceable against the Company in accordance with their terms, subject to the effect of bankruptcy, insolvency, fraudulent conveyance, fraudulent transfer, reorganization, moratorium and other similar laws affecting the rights and remedies of creditors; and the Securities conform in all material respects to the description thereof in the Offering Circular.

        7.     The Indenture has been duly authorized, executed and delivered by the Company and constitutes a valid and legally binding obligation of the Company enforceable against the Company in accordance with its terms, subject to the effect of bankruptcy, insolvency, fraudulent conveyance, fraudulent transfer, reorganization, moratorium and other similar laws affecting the rights and remedies of creditors.

        8.     The form of global certificate representing the Securities has been duly authorized by the Company.

        9.     The Exchange and Registration Rights Agreement has been duly authorized, executed and delivered by the Company and constitutes a valid and legally binding obligation of the Company enforceable against the Company in accordance with its terms, subject to the effect of bankruptcy, insolvency, fraudulent conveyance, fraudulent transfer, reorganization, moratorium and other similar laws affecting the rights and remedies of creditors.

        10.   When executed, authenticated, issued and delivered in accordance with the Indenture and as contemplated by Section 5(k) of the Agreement, the Exchange Securities will constitute valid and legally binding obligations of the Company enforceable against the Company in accordance with their terms, subject to the effect of bankruptcy, insolvency, fraudulent conveyance, fraudulent transfer, reorganization, moratorium and other similar laws affecting the rights and remedies of creditors.