UNDERWRITING AGREEMENT

CONCHO RESOURCES INC.

20,887,107 Shares of Common Stock

Underwriting Agreement

August 2, 2007

J.P. Morgan Securities Inc.
Banc of America Securities LLC

As Representatives of the
several Underwriters listed
in Schedule 1 hereto

c/o J.P. Morgan Securities Inc.
277 Park Avenue
New York, New York 10172

Ladies and Gentlemen:

     Concho Resources Inc., a Delaware corporation (“the Company”) proposes to issue and sell to the several Underwriters listed in Schedule 1 hereto (the “Underwriters”), for whom you are acting as representatives (collectively, the “Representatives”), an aggregate of 13,332,851 shares of Common Stock, par value $0.001 per share, of the Company, and Chase Oil Corporation and Caza Energy LLC (together, the “Chase Stockholders”) and certain other stockholders (collectively, the “Non-Chase Stockholders,” and together with Chase Stockholders, the “Selling Stockholders”) of the Company named in Schedules 3 and 4 hereto propose to sell to the Underwriters an aggregate of 7,554,256 shares of Common Stock of the Company. At the option of the Underwriters, the Company proposes to sell up to an additional 3,133,066 shares of Common Stock of the Company. The aggregate of 20,887,107 shares which may be sold by the Company and the Selling Stockholders is herein called the “Underwritten Shares,” and the aggregate of 3,133,066 additional shares to be sold by the Company is herein called the “Option Shares.” The Underwritten Shares and the Option Shares are herein referred to as the “Shares”. The shares of Common Stock of the Company to be outstanding after giving effect to the sale of the Shares are herein referred to as the “Stock”.

     The Company hereby confirms its agreement with the several Underwriters concerning the purchase and sale of the Underwritten Shares to be sold by the Company, the Selling Stockholders hereby confirm their agreement with the several Underwriters concerning the purchase and sale of the Underwritten Shares to be sold by the Selling Stockholders, and the Company hereby confirms its agreement with the several Underwriters concerning the purchase and sale of the Option Shares which may be sold by the Company as follows:

     1.  Registration Statement . The Company has prepared and filed with the Securities and Exchange Commission (the “Commission”) under the Securities Act of 1933, as amended, and the rules and regulations of the Commission thereunder (collectively, the “Securities Act”), a registration statement on Form S-1(File No. 333-142315) including a prospectus, relating to the Shares. Such registration statement, as amended at the time it becomes effective, including the information, if any, deemed pursuant to Rule 430A, 430B or 430C under the Securities Act to be part of the registration statement at the time of its effectiveness (“Rule 430 Information”), is referred to herein as the “Registration Statement”; and as used herein, the term “Preliminary Prospectus” means each prospectus included in such registration statement (and any amendments thereto) before it becomes effective, any prospectus filed with the Commission pursuant to Rule 424(a) under the Securities Act and the prospectus included in the Registration

Statement at the time of its effectiveness that omits Rule 430 Information, and the term “Prospectus” means the prospectus in the form first used (or made available upon the request of purchasers pursuant to Rule 173 under the Securities Act) in connection with confirmation of sales of the Shares. If the Company has filed an abbreviated registration statement pursuant to Rule 462(b) under the Securities Act (the “Rule 462 Registration Statement”), then any reference herein to the term “Registration Statement” shall be deemed to include such Rule 462 Registration Statement. Capitalized terms used but not defined herein shall have the meanings given to such terms in the Registration Statement and the Prospectus.

     At or prior to the time when sales of the Shares were first made (the “Time of Sale”), the Company had prepared the following information (collectively with the pricing information set forth on Annex D hereto, the “Time of Sale Information”): a Preliminary Prospectus dated July 18, 2007 (the “Marketing Preliminary Prospectus”), and each “free-writing prospectus” (as defined pursuant to Rule 405 under the Securities Act) listed on Annex C hereto.

     2.  Purchase of the Shares by the Underwriters .

     (a) The Company and each Selling Stockholder agrees, severally and not jointly, to sell the Underwritten Shares to the several Underwriters as provided in this Agreement, and each Underwriter, on the basis of the representations, warranties and agreements set forth herein and subject to the conditions set forth herein, agrees, severally and not jointly, to purchase from the Company and from each Selling Stockholder at a price per share of $10.7812 (the “Purchase Price”) the number of Underwritten Shares (to be adjusted by you so as to eliminate fractional shares) determined by multiplying the aggregate number of Underwritten Shares to be sold by the Company or such Selling Stockholder, as the case may be, as set forth opposite their respective names in Schedule 2 hereto by a fraction, the numerator of which is the aggregate number of Underwritten Shares to be purchased by such Underwriter as set forth opposite the name of such Underwriter in Schedule 1 hereto and the denominator of which is the aggregate number of Underwritten Shares to be purchased by all the Underwriters from the Company and all the Selling Stockholders hereunder.

     In addition, the Company, as and to the extent indicated in Schedule 1 hereto, agrees, to sell the Option Shares to the several Underwriters and the Underwriters shall have the option to purchase at their election all or any portion of the Option Shares at the Purchase Price. The Underwriters, on the basis of the representations and warranties and agreements herein contained and subject to the conditions set forth herein, shall have the option to purchase, severally and not jointly, from the Company all or any portion of the Option Shares at the Purchase Price. If any Option Shares are to be purchased, the number of Option Shares to be purchased by each Underwriter shall be the number of Option Shares which bears the same ratio to the aggregate number of Option Shares being purchased as the number of Underwritten Shares set forth opposite the name of such Underwriter in Schedule 1 hereto (or such number increased as set forth in Section 12 hereof) bears to the aggregate number of Underwritten Shares being purchased from the Company and the Selling Stockholders by the several Underwriters, subject, however, to such adjustments to eliminate any fractional Shares as the Representatives in their sole discretion shall make. Any such election to purchase Option Shares shall be made accordance with the percentages of the total amount of Option Shares to be sold by the Company as set forth in Schedule 1 hereto.

     The Underwriters may exercise the option to purchase the Option Shares at any time in whole, or from time to time in part, on or before the thirtieth day following the date of this Agreement, by written notice from the Representatives to the Company. Such notice shall set forth the aggregate number of Option Shares as to which the option is being exercised and the date and time when the Option Shares are to be delivered and paid for which may be the same date and time as the Closing Date (as hereinafter defined) but shall not be earlier than the Closing Date nor later than the tenth full business day (as hereinaf-

ter defined) after the date of such notice (unless such time and date are postponed in accordance with the provisions of Section 12 hereof). Any such notice shall be given at least two Business Days prior to the date and time of delivery specified therein.

     (b) The Company and the Selling Stockholders understand that the Underwriters intend to make a public offering of the Shares as soon after the effectiveness of this Agreement as in the judgment of the Representatives is advisable, and initially to offer the Shares on the terms set forth in the Prospectus. The Company and the Selling Stockholders acknowledge and agree that the Underwriters may offer and sell Shares to or through any affiliate of an Underwriter and that any such affiliate may offer and sell Shares purchased by it to or through any Underwriter.

     (c) Payment for the Shares shall be made by wire transfer in immediately available funds to the accounts specified by the Company and the Selling Stockholders to the Representatives in the case of the Underwritten Shares, at the offices of Vinson & Elkins L.L.P., 1001 Fannin Street, Houston, Texas, 77002 at 10:00 A.M. Houston time on August 7, 2007, or at such other time or place on the same or such other date, not later than the fifth business day thereafter, as the Representatives, the Company and the Selling Stockholders may agree upon in writing or, in the case of the Option Shares, on the date and at the time and place specified by the Representatives in the written notice of the Underwriters’ election to purchase such Option Shares. The time and date of such payment for the Underwritten Shares is referred to herein as the “Closing Date” and the time and date for such payment for the Option Shares, if other than the Closing Date, is herein referred to as the “Additional Closing Date”.

     Payment for the Shares to be purchased on the Closing Date or the Additional Closing Date, as the case may be, shall be made against delivery through the facilities of the Depository Trust Company (“DTC”) to the Representatives for the respective accounts of the several Underwriters of the Shares to be purchased on such date in definitive form registered in such names and in such denominations as the Representatives shall request in writing not later than two full business days prior to the Closing Date or the Additional Closing Date, as the case may be, with any transfer taxes payable in connection with the sale of the Shares duly paid by the Company or the Selling Stockholders. Any certificates for the Shares will be made available for inspection and packaging by the Representatives at the office of DTC or its designated custodian not later than 1:00 P.M., Houston time, on the business day prior to the Closing Date or the Additional Closing Date, as the case may be.

     (d) The Company and the Selling Stockholders acknowledge and agree that the Underwriters are acting solely in the capacity of an arm’s length contractual counterparty to the Company and the Selling Stockholders with respect to the offering of Shares contemplated hereby (including in connection with determining the terms of the offering) and not as a financial advisor or a fiduciary to, or an agent of, the Company, the Selling Stockholders or any other person. Additionally, neither the Representatives nor any other Underwriter is advising the Company, the Selling Stockholders or any other person as to any legal, tax, investment, accounting or regulatory matters in any jurisdiction. The Company and the Selling Stockholders shall consult with their own advisors concerning such matters and shall be responsible for making their own independent investigation and appraisal of the transactions contemplated hereby, and the Underwriters shall have no responsibility or liability to the Company or the Selling Stockholders with respect thereto. Any review by the Underwriters of the Company or the Selling Stockholders, the transactions contemplated hereby or other matters relating to such transactions will be performed solely for the benefit of the Underwriters and shall not be on behalf of the Company or the Selling Stockholders.

     3.  Representations and Warranties of the Company . The Company represents and warrants to each Underwriter and each Selling Stockholder that:

     (a)  Preliminary Prospectus . No order preventing or suspending the use of any Preliminary Prospectus has been issued by the Commission, and the Marketing Preliminary Prospectus, at the time of filing thereof, complied in all material respects with the Securities Act and did not contain any untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading; provided that the Company makes no representation and warranty with respect to any statements or omissions made in reliance upon and in conformity with information relating to any Underwriter furnished to the Company in writing by such Underwriter through the Representatives expressly for use in the Marketing Preliminary Prospectus.

     (b)  Time of Sale Information . The Time of Sale Information, at the Time of Sale did not, and at the Closing Date and as of the Additional Closing Date, as the case may be, will not, contain any 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 that the Company makes no representation and warranty with respect to any statements or omissions made in reliance upon and in conformity with information relating to any Underwriter furnished to the Company in writing by such Underwriter through the Representatives expressly for use in such Time of Sale Information. No statement of material fact included in the Prospectus has been omitted from the Time of Sale Information and no statement of material fact included in the Time of Sale Information that is required to be included in the Prospectus has been omitted therefrom.

     (c)  Issuer Free Writing Prospectus . Other than the Preliminary Prospectus and the Prospectus, the Company (including its agents and representatives) has not made, used, prepared, authorized, approved or referred to and will not prepare, make, use, authorize, approve or refer to any “written communication” (as defined in Rule 405 under the Securities Act) that constitutes an offer to sell or solicitation of an offer to buy the Shares (each such communication by the Company or its agents and representatives (other than a communication referred to in clause (i) below) an “Issuer Free Writing Prospectus”) other than (i) any document not constituting a prospectus pursuant to Section 2(a)(10)(a) of the Securities Act or Rule 134 under the Securities Act or (ii) the documents listed on Annex C hereto and other written communications approved in writing in advance by the Representatives. Each such Issuer Free Writing Prospectus complied in all material respects with the Securities Act, has been filed in accordance with the Securities Act (to the extent required thereby) and, when taken together with the Preliminary Prospectus accompanying, or delivered prior to delivery of, such Issuer Free Writing Prospectus, did not, and at the Closing Date and as of the Additional Closing Date, as the case may be, will not, contain any 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 that the Company makes no representation and warranty with respect to any statements or omissions made in each such Issuer Free Writing Prospectus in reliance upon and in conformity with information relating to any Underwriter furnished to the Company in writing by such Underwriter through the Representatives expressly for use in any Issuer Free Writing Prospectus.

     (d)  Registration Statement and Prospectus . The Registration Statement has been declared effective by the Commission. No order suspending the effectiveness of the Registration Statement has been issued by the Commission and no proceeding for that purpose or pursuant to Section 8A of the Securities Act against the Company or related to the offering has been initiated or threatened by the Commission; as of the applicable effective date of the Registration Statement and any amendment thereto, the Registration Statement complied and will comply in all material respects with the Securities Act, and did not and will not contain any untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary in order to make the statements therein not misleading; and as of the date of the Prospectus and any amendment or supplement thereto and as of the Closing Date and as of the Addi-

tional Closing Date, as the case may be, the Prospectus will not contain any untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading; provided that the Company makes no representation and warranty with respect to any statements or omissions made in reliance upon and in conformity with information relating to any Underwriter furnished to the Company in writing by such Underwriter through the Representatives expressly for use in the Registration Statement and the Prospectus and any amendment or supplement thereto.

     (e)  Financial Statements . (i) The financial statements and the related notes thereto of the Company and its consolidated subsidiaries included in the Registration Statement, the Time of Sale Information and the Prospectus comply in all material respects with the applicable requirements of the Securities Act and the Securities Exchange Act of 1934, as amended, and the rules and regulations of the Commission thereunder (collectively, the “Exchange Act”), as applicable, except to the extent relief therefrom has been granted in writing by the Staff of the SEC and present fairly in all material respects the financial position of the Company and its 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 in the Registration Statement present fairly in all material respects the information required to be stated therein; the other financial information included in the Registration Statement, the Time of Sale Information and the Prospectus has been derived from the accounting records of the Company and its subsidiaries and presents fairly in all material respects the information shown thereby; and the pro forma financial information and the related notes thereto included in the Registration Statement, the Time of Sale Information and the Prospectus have been prepared in all material respects consistently with the applicable requirements of the Securities Act and the Exchange Act, as applicable, and give effect to assumptions made on a reasonable basis as set forth in the Registration Statement, the Time of Sale Information and the Prospectus;

     (ii) The statements of revenue and direct operating expenses and the related notes thereto of the Lowe Properties included in the Registration Statement, the Time of Sale Information and the Prospectus comply in all material respects with the applicable requirements of the Securities Act and the Securities Exchange Act, as applicable, and present fairly in all material respects the revenues and direct operating expenses of the Lowe Properties 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; the other financial information included in the Registration Statement, the Time of Sale Information and the Prospectus of the Lowe Properties has been derived from the accounting records of the Lowe Properties and presents fairly in all material respects the information shown thereby; and

     (iii) The financial statements and the related notes thereto of the Chase Group Properties included in the Registration Statement, the Time of Sale Information and the Prospectus (and as defined therein) 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 Chase Group Properties 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, the other financial information of the Chase Group Properties included in the Registration Statement, the Time of Sale Information and the Prospectus has been derived from the accounting records of the Chase Group Properties and presents fairly in all material respects the information shown thereby.

     (f)  No Material Adverse Change . Since the date of the most recent financial statements of the Company included in the Registration Statement, the Time of Sale Information and the Prospectus, except in each case as otherwise disclosed in the Registration Statement, the Time of Sale Information and the Prospectus, (i) there has not been any change in the capital stock or material change in the long-term debt of the Company or any of its subsidiaries, or any dividend or distribution of any kind declared, set aside for payment, paid or made by the Company on any class of capital stock, or any material adverse change, or any development involving a prospective material adverse change, in or affecting the business, properties, management, financial position, stockholders’ equity, results of operations or prospects of the Company and its subsidiaries taken as a whole; (ii) neither the Company nor any of its subsidiaries has entered into any transaction or agreement that is material to the Company and its subsidiaries taken as a whole or incurred any liability or obligation, direct or contingent, that is material to the Company and its subsidiaries taken as a whole; and (iii) neither the Company nor any of its subsidiaries has sustained 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 disturbance or dispute or any action, order or decree of any court or arbitrator or governmental or regulatory authority, except in each case as otherwise disclosed in the Registration Statement, the Time of Sale Information and the Prospectus.

     (g)  Organization and Good Standing . The Company and each of its subsidiaries have been duly organized and are validly existing and in good standing under the laws of their respective jurisdictions of organization, are duly qualified to do business and are in good standing in each jurisdiction in which their respective ownership or lease of property or the conduct of their respective businesses requires such qualification, and have all power and authority necessary to own or hold their respective properties and to conduct the businesses in which they are engaged, except where the failure to be so qualified or have such power or authority would not, individually or in the aggregate, have a material adverse effect on the business, properties, management, financial position, stockholders’ equity, results of operations, cash flows or prospects of the Company and its subsidiaries taken as a whole (a “Material Adverse Effect”). The Company does not own or control, directly or indirectly, any corporation, association or other entity other than the subsidiaries listed in Exhibit 21.1 to the Registration Statement.

     (h)  Capitalization . The Company has authorized capital stock as set forth in the Registration Statement, the Time of Sale Information and the Prospectus under the heading “Capitalization”; all the outstanding shares of capital stock of the Company have been duly and validly authorized and issued and are fully paid and non-assessable and are not subject to any pre-emptive or similar rights; except as described in or expressly contemplated by the Time of Sale Information and the Prospectus, there are no outstanding rights (including, without limitation, pre-emptive rights), warrants or options to acquire, or instruments convertible into or exchangeable for, any shares of capital stock or other equity interest in the Company or any of its subsidiaries, or any contract, commitment, agreement, understanding or arrangement of any kind relating to the issuance of any capital stock of the Company or any such subsidiary, any such convertible or exchangeable securities or any such rights, warrants or options; the capital stock of the Company conforms in all material respects to the description thereof contained in the Registration Statement, the Time of Sale Information and the Prospectus; and all the outstanding shares of capital stock or other equity interests of each subsidiary of the Company have been duly and validly authorized and issued, are fully paid and non-assessable (except as otherwise described in the Registration Statement, the Time of Sale Information and the Prospectus) and are owned directly or indirectly by the Company, free and clear of any lien, charge, encumbrance, security interest, restriction on voting or transfer or any other claim of any third party, other than those arising under the Company’s Credit Agreement dated February 24, 2006 and Second Lien Credit Agreement dated March 27, 2007.

     (i) Due Authorization . The Company has full corporate, power and authority to execute and deliver this Agreement and to perform its obligations hereunder; and all corporate action required to be

taken for the due and proper authorization, execution and delivery by it of this Agreement and the consummation by it of the transactions contemplated hereby has been duly and validly taken.

     (j)  Underwriting Agreement . This Agreement has been duly authorized, executed and delivered by the Company.

     (k)  The Shares . The Shares to be issued and sold by the Company hereunder have been duly authorized by the Company and, when issued and delivered and paid for as provided herein, will be duly and validly issued and will be fully paid and nonassessable and will conform to the descriptions thereof in the Registration Statement, the Time of Sale Information and the Prospectus; and the issuance of the Shares to be sold by the Company hereunder is not subject to any preemptive or similar rights.

     (l)  No Violation or Default . Neither the Company nor any of its subsidiaries is (i) in violation of its charter or by-laws or similar organizational documents; (ii) in default, and no event has occurred that, with notice or lapse of time or both, would constitute such a default, in the due performance or observance of any term, covenant or condition contained in 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; or (iii) in violation of any law or statute or any judgment, order, rule or regulation of any court or arbitrator or governmental or regulatory authority, except, in the case of clauses (ii) and (iii) above, for any such default or violation that would not, individually or in the aggregate, have a Material Adverse Effect.

     (m)  No Conflicts . The execution, delivery and performance by the Company of this Agreement, the issuance and sale of the Shares and the consummation of the transactions contemplated by this Agreement 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 or any of its subsidiaries 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, (ii) result in any violation of the provisions of the charter or by-laws or similar organizational documents of the Company or any of its subsidiaries or (iii) result in the violation of any law or statute or any judgment, order, rule or regulation of any court or arbitrator or governmental or regulatory authority, except, in the case of clauses (i) and (iii) above, for any such conflict, breach or violation that would not, individually or in the aggregate, have a Material Adverse Effect.

     (n)  No Consents Required . No consent, approval, authorization, order, registration or qualification of or with any court or arbitrator or governmental or regulatory authority is required for the execution, delivery and performance by the Company of this Agreement, the issuance and sale of the Shares and the consummation of the transactions contemplated by this Agreement, except for the registration of the Shares under the Securities Act and such consents, approvals, authorizations, orders and registrations or qualifications as may be required under applicable state securities laws in connection with the purchase and distribution of the Shares by the Underwriters and any consent, approval, authorization, order, registration or qualification that either has been, or prior to the Closing Date will have been, obtained or made, or which if not obtained or made, would not, individually or in the aggregate, have a Material Adverse Effect and would not adversely affect the Company’s ability to fulfill its obligations under this Agreement.

     (o)  Legal Proceedings . Except as described in the Registration Statement, the Time of Sale Information and the Prospectus, there are no legal, governmental or regulatory investigations, actions,

suits or proceedings pending to which the Company or any of its subsidiaries is or may be a party or to which any property of the Company or any of its subsidiaries is or may be the subject that, individually or in the aggregate, if determined adversely to the Company or any of its subsidiaries, could reasonably be expected to have a Material Adverse Effect or materially and adversely affect the ability of the Company to perform its obligations under this Agreement; to the knowledge of the Company, no such investigations, actions, suits or proceedings are threatened or contemplated by any governmental or regulatory authority or others; and (i) there are no current or pending legal, governmental or regulatory actions, suits or proceedings that are required under the Securities Act to be described in the Registration Statement that are not so described in the Registration Statement, the Time of Sale Information and the Prospectus and (ii) there are no statutes, regulations or contracts or other documents that are required under the Securities Act to be filed as exhibits to the Registration Statement or described in the Registration Statement or the Prospectus that are not so filed as exhibits to the Registration Statement or described in the Registration Statement, the Time of Sale Information and the Prospectus.

     (p)  Independent Accountants . Grant Thornton LLP, who has certified certain financial statements of the Company and its subsidiaries, is an independent registered public accounting firm with respect to the Company and its subsidiaries within the applicable rules and regulations adopted by the Commission and the Public Company Accounting Oversight Board (United States) and as required by the Securities Act.

     (q)  Title to Real and Personal Property . The Company and its subsidiaries have good and marketable title to all real and other property they own, in each case free and clear of all liens, encumbrances and defects except those (i) described in the Registration Statement, the Time of Sale Information and the Prospectus or (ii) that could not reasonably be expected, individually or in the aggregate, to have a Material Adverse Effect. Except as described in the Registration Statement, the Time of Sale Information and the Prospectus, all items of real and other property leased by the Company and its subsidiaries are leased under valid and enforceable leases, except as could not reasonably be expected, individually or in the aggregate, to have a Material Adverse Effect.

     (r)  Title to Intellectual Property . The Company and its subsidiaries own or possess adequate rights to use any and all material patents, patent applications, trademarks, service marks, trade names, trademark registrations, service mark registrations, copyrights, licenses and know-how (including trade secrets and other unpatented and/or unpatentable proprietary or confidential information, systems or procedures) necessary for the conduct of their respective businesses, and the Company and its subsidiaries have not received any notice of any claim of infringement or conflict with any such rights of others.

     (s)  No Undisclosed Relationships . No relationship, direct or indirect, exists between or among the Company or any of its subsidiaries, on the one hand, and the directors, officers, stockholders, customers or suppliers of the Company or any of its subsidiaries, on the other, that is required by the Securities Act to be described in the Registration Statement and the Prospectus and that is not so described in such documents and in the Time of Sale Information.

     (t)  Investment Company Act . The Company is not and, after giving effect to the offering and sale of the Shares and the application of the proceeds thereof as described in the Registration Statement, the Time of Sale Information and the Prospectus, will not be required to register as an “investment company” or an entity “controlled” by an “investment company” within the meaning of the Investment Company Act of 1940, as amended, and the rules and regulations of the Commission thereunder (collectively, “Investment Company Act”).

     (u)  Taxes . The Company and its subsidiaries have paid all federal, state, local and foreign taxes and filed all tax returns required to be paid or filed through the date hereof; and except as otherwise

disclosed in the Registration Statement, the Time of Sale Information and the Prospectus or as would not, individually or in the aggregate, have a Material Adverse Effect, 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.

     (v)  Licenses and Permits . 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 federal, state, local or foreign 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 Registration Statement, the Time of Sale Information and the Prospectus, except where the failure to possess or make the same would not, individually or in the aggregate, have a Material Adverse Effect; and except as described in the Registration Statement, the Time of Sale Information and the Prospectus or as would not, individually or in the aggregate, have a Material Adverse Effect, neither the Company nor any of its subsidiaries has received notice of any revocation or modification of any such license, certificate, permit or authorization or has any reason to believe that any such license, certificate, permit or authorization will not be renewed in the ordinary course.

     (w)  No Labor Disputes . 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 contemplated or threatened and the Company is not aware of any existing or imminent labor disturbance by, or dispute with, the employees of any of its or its subsidiaries’ principal suppliers, contractors or customers, except as would not have a Material Adverse Effect.

     (x)  Compliance With Environmental Laws . (i) The Company and its subsidiaries (x) are in compliance with any and all applicable federal, state, local and foreign laws, rules, regulations, requirements, decisions and orders relating to the protection of human health and safety, the environment or hazardous or toxic substances or wastes, pollutants or contaminants (collectively, “Environmental Laws”); (y) have received and are in compliance with all permits, licenses, certificates or other authorizations or approvals required of them under applicable Environmental Laws to conduct their respective businesses; and (z) except as described in the Registration Statement, the Time of Sale Information and the Prospectus, 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, and (ii) there are no costs or liabilities associated with Environmental Laws of or relating to the Company or its subsidiaries, except in the case of each of (i) and (ii) above, for any such failure to comply, or failure to receive required permits, licenses or approvals, or cost or liability, as would not, individually or in the aggregate, have a Material Adverse Effect.

     (y)  Compliance With ERISA . 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”); 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 transactions which, individually or in the aggregate, would not have a Material Adverse Effect, and no such plan is subject to the funding rules of Section 412 of the Code or Section 302 of ERISA.

     (z)  Disclosure Controls . The Company and its subsidiaries maintain an effective system of “disclosure controls and procedures” (as defined in Rule 13a-15(e) of the Exchange Act) that is designed

to ensure that information which will be required to be disclosed by the Company in reports that it files or submits under the Exchange Act will be recorded, processed, summarized and reported within the time periods specified in the Commission’s rules and forms, including controls and procedures designed to ensure that such information will be accumulated and communicated to the Company’s management as appropriate to allow timely decisions regarding required disclosure.

     (aa)  Accounting Controls . The Company and its subsidiaries maintain a system of “internal control over financial reporting” (as defined in Rule 13a-15(f) of the Exchange Act) that comply with the requirements of the Exchange Act and have been designed by, or under the supervision of, the Company’s principal executive and principal financial officers, and effected by the Company’s board of directors, management and other personnel to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles, including those policies and procedures that (i) pertain to the maintenance of records that in reasonable detail accurately and fairly reflect the transactions and dispositions of the assets of the Company; (ii) provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in accordance with generally accepted accounting principles and that receipts and expenditures of the Company are being made in accordance with and authorizations of management and directors of the Company; and (iii) provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use or disposition of the Company’s assets that could have a material effect on the Company’s financial statements. Except as disclosed in the Registration Statement, the Time of Sale Information and the Prospectus, there are no material weaknesses in the Company’s internal control over financial reporting.

     (bb)  Insurance . The Company and its subsidiaries have insurance covering their respective properties, operations, personnel and businesses, which insurance is in reasonable amounts and insures against such losses and risks as are reasonably adequate to protect the Company and its subsidiaries and their respective businesses; and neither the Company nor any of its subsidiaries has (i) received notice from any insurer or agent of such insurer that capital improvements or other expenditures are required or necessary to be made in order to continue such insurance or (ii) 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.

     (cc)  No Unlawful Payments . Neither the Company nor any of its subsidiaries nor, to the knowledge of the Company, any director, officer, agent, employee or other person associated with or acting on behalf of the Company or any of its subsidiaries has (i) used any corporate funds for any unlawful contribution, gift, entertainment or other unlawful expense relating to political activity; (ii) made any direct or indirect unlawful payment to any foreign or domestic government official or employee from corporate funds; (iii) violated or is in violation of any provision of the Foreign Corrupt Practices Act of 1977; or (iv) made any bribe, rebate, payoff, influence payment, kickback or other unlawful payment.

     (dd)  Compliance with Money Laundering Laws . The operations of the Company and its subsidiaries are and have been conducted at all times in compliance with applicable financial recordkeeping and reporting requirements of the Currency and Foreign Transactions Reporting Act of 1970, as amended, the money laundering statutes of all jurisdictions, the rules and regulations thereunder and any related or similar rules, regulations or guidelines, issued, administered or enforced by any governmental agency (collectively, the “Money Laundering Laws”) and no action, suit or proceeding by or before any court or governmental agency, authority or body or any arbitrator involving the Company or any of its subsidiaries with respect to the Money Laundering Laws is pending or, to the knowledge of the Company, threatened.

     (ee)  Compliance with OFAC . None of the Company, any of its subsidiaries or, to the knowledge of the Company, any director, officer, agent, employee or Affiliate of the Company or any of its subsidiaries is currently subject to any U.S. sanctions administered by the Office of Foreign Assets Control of the U.S. Department of the Treasury (“OFAC”); and the Company will not directly or indirectly use the proceeds of the offering of the Shares hereunder, or lend, contribute or otherwise make available such proceeds to any subsidiary, joint venture partner or other person or entity, for the purpose of financing the activities of any person currently subject to any U.S. sanctions administered by OFAC.

     (ff)  No Restrictions on Subsidiaries . 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.

     (gg)  No Broker’s Fees . Neither the Company nor any of its subsidiaries is a party to any contract, agreement or understanding with any person (other than this Agreement) that would give rise to a valid claim against the Company or any of its subsidiaries or any Underwriter for a brokerage commission, finder’s fee or like payment in connection with the offering and sale of the Shares.

     (hh)  No Registration Rights . Except as disclosed in the Registration Statement, the Time of Sale Information and the Prospectus, no person has the right to require the Company or any of its subsidiaries to register any securities for sale under the Securities Act by reason of the filing of the Registration Statement with the Commission or the issuance and sale of the Shares.

     (ii)  No Stabilization . The Company has not taken, directly or indirectly, any action designed to or that could reasonably be expected to cause or result in any stabilization or manipulation of the price of the Shares.

     (jj)  Forward-Looking Statements . No forward-looking statement (within the meaning of Section 27A of the Securities Act and Section 21E of the Exchange Act) contained in the Registration Statement, the Time of Sale Information and the Prospectus has been made or reaffirmed without a reasonable basis or has been disclosed other than in good faith.

     (kk)  Statistical and Market Data . 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 Registration Statement, the Time of Sale Information and the Prospectus is not based on or derived from sources that are reliable and accurate in all material respects.

     (ll)  Sarbanes-Oxley Act . 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 with any applicable provision of the Sarbanes-Oxley Act of 2002 and any applicable rules and regulations promulgated in connection therewith (the “Sarbanes-Oxley Act”), including Section 402 related to loans.

     (mm)  Status under the Securities Act . The Company is not an ineligible issuer as defined under the Securities Act, at the times specified in the Securities Act in connection with the offering of the Shares.

     (nn)  Reserve Data . (i) The oil and natural gas reserve estimates of the Company and its subsidiaries as of December 31, 2004, 2005 and 2006 contained in the Registration Statement, the Time of Sale Information and the Prospectus are derived from reports that have been prepared by, or have been

audited by, either (a) Netherland, Sewell & Associates, Inc. or (b) Cawley, Gillespie & Associates, Inc., as set forth and to the extent indicated therein, and such estimates fairly reflect the oil and natural gas reserves of the Company and its subsidiaries, as applicable, at the dates indicated therein and are in accordance, in all material respects, with Commission guidelines applied on a consistent basis throughout the periods involved; and

     (oo) The oil and natural gas reserve estimates of the Chase Group Properties as of December 31, 2003, 2004 and 2005 contained in the Registration Statement, the Time of Sale Information and the Prospectus are derived from reports that have been prepared by, or have been audited by Cawley, Gillespie & Associates, Inc., as set forth therein, and such estimates fairly reflect the oil and natural gas reserves of the Chase Group Properties, at the dates indicated therein and are in accordance, in all material respects, with Commission guidelines applied on a consistent basis throughout the periods involved.

     (pp)  Independent Petroleum Engineers . Each of Netherland, Sewell & Associates, Inc. and Cawley, Gillespie & Associates, Inc. have represented to the Company that they are, and the Company believes them to be, independent petroleum engineers with respect to the Company and its subsidiaries and for the periods set forth in the Registration Statement, the Time of Sale Information and the Prospectus.

     4.  Representations and Warranties of the Selling Stockholders . (i) The Chase Stockholders represent and warrant, jointly and severally, to each Underwriter and the Company that:

     (a)  Required Consents; Authority . All consents, approvals, authorizations and orders necessary for the execution and delivery by such Chase Stockholder of this Agreement and the Power of Attorney (the “Power of Attorney”) and the Custody Agreement (the “Custody Agreement”) hereinafter referred to, and for the sale and delivery of the Shares to be sold by such Chase Stockholder hereunder, have been obtained; and such Chase Stockholder has full right, power and authority to enter into this Agreement, the Power of Attorney and the Custody Agreement and to sell, assign, transfer and deliver the Shares to be sold by such Chase Stockholder hereunder; this Agreement, the Power of Attorney and the Custody Agreement have each been duly authorized, executed and delivered by such Chase Stockholder.

     (b)  No Conflicts . The execution, delivery and performance by such Chase Stockholder of this Agreement, the Power of Attorney and the Custody Agreement, the sale of the Shares to be sold by such Chase Stockholder and the consummation by such Chase Stockholder 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 such Chase Stockholder pursuant to, any indenture, mortgage, deed of trust, loan agreement or other agreement or instrument to which such Chase Stockholder is a party or by which such Chase Stockholder is bound or to which any of the property or assets of such Chase Stockholder is subject, (ii) result in any violation of the provisions of the charter or by-laws or similar organizational documents of such Chase Stockholder or (iii) result in the violation of any law or statute or any judgment, order, rule or regulation of any court or arbitrator or governmental or regulatory agency.

     (c)  Title to Shares. Such Chase Stockholder has good and valid title to the Shares to be sold at the Closing Date or the Additional Closing Date, as the case may be, by such Chase Stockholder hereunder, free and clear of all liens, encumbrances, equities or adverse claims; such Chase Stockholder will have, immediately prior to the Closing Date or the Additional Closing Date, as the case may be, good and valid title to the Shares to be sold at the Closing Date or the Additional Closing Date, as the case may be, by such Chase Stockholder, free and clear of all liens, encumbrances, equities or adverse claims; and, upon delivery of the certificates representing such Shares and payment therefor pursuant hereto, good and

valid title to such Shares, free and clear of all liens, encumbrances, equities or adverse claims, will pass to the several Underwriters.

     (d)  No Stabilization. Such Chase Stockholder has not taken and will not take, directly or indirectly, any action designed to or that could reasonably be expected to cause or result in any stabilization or manipulation of the price of the Shares.

     (e)  Time of Sale Information . The Time of Sale Information, at the Time of Sale did not, and at the Closing Date and as of the Additional Closing Date, as the case may be, will not, contain any 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 the representations and warranties set forth in this paragraph are limited to statements or omissions made in reliance upon information relating to Chase Oil Corporation, Caza Energy LLC, their stockholders and affiliates (other than the Company and its subsidiaries), the Chase Group Properties and the Chase Group Properties financial statements (collectively, the “Time of Sale Chase Information”).

     (f)  Issuer Free Writing Prospectus. Other than the Preliminary Prospectus and the Prospectus, such Chase Stockholder (including its agents and representatives) has not made, used, prepared, authorized, approved or referred to and will not prepare, make, use, authorize, approve or refer to any Issuer Free Writing Prospectus, other than (i) any document not constituting a prospectus pursuant to Section 2(a)(10)(a) of the Securities Act or Rule 134 under the Securities Act or (ii) the documents listed on Annex C hereto and other written communications approved in writing in advance by the Company and the Representatives.

     (g)  Registration Statement and Prospectus. As of the applicable effective date of the Registration Statement and any amendment thereto, the Registration Statement complied and will comply in all material respects with the Securities Act, and did not and will not contain any untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary in order to make the statements therein not misleading; and as of the date of the Prospectus and any amendment or supplement thereto and as of the Closing Date and as of the Additional Closing Date, as the case may be, the Prospectus will not contain any untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading; provided , however , that the representations and warranties set forth in this paragraph are limited to information contained in the Registration Statement, Prospectus (or any amendment or supplement thereto) or any Issuer Free Writing Prospectus relating to Chase Oil Corporation, Caza Energy LLC, their stockholders and affiliates, the Chase Group Properties and the Chase Group Properties financial statements included in the Prospectus (collectively, the “Registration Statement Chase Information,” and together with the Time of Sale Chase Information, the “Chase Information”).

     (h)  Material Information . As of the date hereof, as of the Closing Date and as of the Additional Closing Date, as the case may be, the sale of the Shares by such Chase Stockholder is not and will not be prompted by any material information concerning the Company which is not set forth in the Registration Statement, the Time of Sale Information or the Prospectus.

     (ii) Each Chase Stockholder represents and warrants to each Underwriter and the Company that certificates in negotiable form representing all of the Shares to be sold by such Chase Stockholder hereunder have been placed in custody under a Custody Agreement relating to such Shares, in the form heretofore furnished to you, duly executed and delivered by such Chase Stockholder to American Stock Transfer & Trust Company, as custodian (the “Custodian”), and that such Chase Stockholder has duly

executed and delivered a Power of Attorney, in the form heretofore furnished to you, appointing the person or persons indicated in Schedule 3 hereto, and each of them, as such Chase Stockholder’s Attorneys-in-fact (the “Chase Attorneys-in-Fact” or any one of them, the “Chase Attorney-in-Fact”) with authority to execute and deliver this Agreement on behalf of such Chase Stockholder, to determine the purchase price to be paid by the Underwriters to the Chase Stockholders as provided herein, to authorize the delivery of the Shares to be sold by such Chase Stockholder hereunder and otherwise to act on behalf of such Chase Stockholder in connection with the transactions contemplated by this Agreement and the Custody Agreement.

     (iii) Each Chase Stockholder specifically agrees that the Shares represented by the certificates held in custody for such Chase Stockholder under the Custody Agreement are subject to the interests of the Underwriters hereunder, and that the arrangements made by such Chase Stockholder for such custody, and the appointment by such Chase Stockholder of the Chase Attorneys-in-Fact by the Power of Attorney, are to that extent irrevocable. Each Chase Stockholder specifically agrees that the obligations of such Chase Stockholder hereunder shall not be terminated by operation of law, whether by the death or incapacity of any individual Chase Stockholder, or, in the case of an estate or trust, by the death or incapacity of any executor or trustee or the termination of such estate or trust, or in the case of a partnership, corporation or similar organization, by the dissolution of such partnership, corporation or organization, or by the occurrence of any other event. If any individual Chase Stockholder or any such executor or trustee should die or become incapacitated, or if any such estate or trust should be terminated, or if any such partnership, corporation or similar organization should be dissolved, or if any other such event should occur, before the delivery of the Shares hereunder, certificates representing such Shares shall be delivered by or on behalf of such Chase Stockholder in accordance with the terms and conditions of this Agreement and the Custody Agreement, and actions taken by the Chase Attorneys-in-Fact pursuant to the Powers of Attorney shall be as valid as if such death, incapacity, termination, dissolution or other event had not occurred, regardless of whether or not the Custodian, the Chase Attorneys-in-Fact, or any of them, shall have received notice of such death, incapacity, termination, dissolution or other event.

     (iv) Each Non-Chase Stockholder represents and warrants severally and not jointly to each Underwriter and the Company that:

     (a)  Required Consents; Authority . All consents, approvals, authorizations and orders necessary for the execution and delivery by such Non-Chase Stockholder of this Agreement and the Power of Attorney (the “Power of Attorney”) and the Custody Agreement (the “Custody Agreement”) hereinafter referred to, and for the sale and delivery of the Shares to be sold by such Non-Chase Stockholder hereunder, have been obtained; and such Non-Chase Stockholder has full right, power and authority to enter into this Agreement, the Power of Attorney and the Custody Agreement and to sell, assign, transfer and deliver the Shares to be sold by such Non-Chase Stockholder hereunder; this Agreement, the Power of Attorney and the Custody Agreement have each been duly authorized, executed and delivered by such Non-Chase Stockholder.

     (b)  No Conflicts . The execution, delivery and performance by such Non-Chase Stockholder of this Agreement, the Power of Attorney and the Custody Agreement, the sale of the Shares to be sold by such Non-Chase Stockholder and the consummation by such Non-Chase Stockholder 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 such Non-Chase Stockholder pursuant to, any indenture, mortgage, deed of trust, loan agreement or other agreement or instrument to which such Non-Chase Stockholder is a party or by which such Non-Chase Stockholder is bound or to which any of the property or assets of such Non-Chase Stockholder is subject or (ii) result in the violation of any law or

statute or any judgment, order, rule or regulation of any court or arbitrator or governmental or regulatory agency applicable to such Non-Chase Stockholder, except, in the case of clauses (i) and (ii) above, for any such conflict, breach or violation that would not, individually or in the aggregate, have a Material Adverse Effect.

     (c)  Title to Shares. Such Non-Chase Stockholder has good and valid title to the Shares to be sold at the Closing Date or the Additional Closing Date, as the case may be, by such Non-Chase Stockholder hereunder, free and clear of all liens, encumbrances, equities or adverse claims; such Non-Chase Stockholder will have, immediately prior to the Closing Date or the Additional Closing Date, as the case may be, good and valid title to the Shares to be sold at the Closing Date or the Additional Closing Date, as the case may be, by such Non-Chase Stockholder, free and clear of all liens, encumbrances, equities or adverse claims; and, upon delivery of the certificates representing such Shares and payment therefor pursuant hereto, good and valid title to such Shares, free and clear of all liens, encum