8.00%Convertible Perpetual Preferred Stock PURCHASE AGREEMENT

Exhibit 10.1

EXECUTION COPY

1,250,000

ATP Oil & Gas Corporation

8.00%Convertible Perpetual Preferred Stock

PURCHASE AGREEMENT

September 23, 2009

C REDIT S UISSE S ECURITIES (USA) LLC

J.P. M ORGAN S ECURITIES I NC .

As Representatives of the several Purchasers

c/o Credit Suisse Securities (USA) LLC (“ Credit Suisse ”)

Eleven Madison Avenue,

New York, N.Y. 10010-3629

Dear Sirs:

1. Introductory. ATP Oil & Gas Corporation, a Texas corporation (the “ Company ”), agrees with the several initial purchasers named in Schedule A hereto (the “ Purchasers ”), for whom you are acting as the representatives (the “ Representatives ”), subject to the terms and conditions stated herein, to issue and sell to the several Purchasers 1,250,000 shares of its 8.00% Convertible Perpetual Preferred Stock (the “Firm Securities ”) and also proposes to grant to the Purchasers an option, exercisable from time to time by the Representatives, to purchase an aggregate of up to an additional 350,000 shares (“ Optional Securities ”) of its 8.00% Convertible Perpetual Preferred Stock. The Firm Securities and the Optional Securities which the Purchasers may elect to purchase pursuant to Section 3 hereof are herein collectively called the “ Offered Securities ”.

The Offered Securities will be convertible, subject to certain conditions set forth in the Statement of Resolutions establishing the Offered Securities, at the option of the holder for shares of common stock, par value $0.001 per share, of the Company (the “ Common Stock ”), in accordance with the terms of the Offered Securities.

The Company hereby agrees with the several Purchasers as follows:

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

(a) Offering Circulars; Certain Defined Terms . The Company has prepared or will prepare a Preliminary Offering Circular and a Final Offering Circular.

For purposes of this Agreement:

“ Applicable Time ” means 8:00 p.m. (New York City time) on the date of this Agreement.

“ Closing Date ” has the meaning set forth in Section 3 hereof.

“ Commission ” means the Securities and Exchange Commission.

“ Exchange Act ” means the United States Securities Exchange Act of 1934.

“ Final Offering Circular ” means the final offering circular (including all documents incorporated by reference therein) relating to the Offered Securities to be offered by the Purchasers that discloses the offering price and other final terms of the Offered Securities and is dated as of the date of this Agreement (even if finalized and issued subsequent to the date of this Agreement).

“ Free Writing Communication ” means a written communication (as such term is defined in Rule 405) that constitutes an offer to sell or a solicitation of an offer to buy the Offered Securities and is made by means other than the Preliminary Offering Circular or the Final Offering Circular.

“ General Disclosure Package ” means the Preliminary Offering Circular together with any Issuer Free Writing Communication existing at the Applicable Time and the information in which is intended for general distribution to prospective investors, as evidenced by its being specified in Schedule B hereto.

“ Issuer Free Writing Communication ” means a Free Writing Communication prepared by or on behalf of the Company, used or referred to by the Company or containing a description of the final terms of the Offered Securities or of their offering, in the form retained in the Company’s records.

“ Preliminary Offering Circular ” means the preliminary offering circular (including all documents incorporated by reference therein), dated September 22, 2009, relating to the Offered Securities to be offered by the Purchasers.

“ Rules and Regulations ” means the rules and regulations of the Commission.

“ Securities Act ” means the United States Securities Act of 1933.

“ Securities Laws ” means, collectively, the Sarbanes-Oxley Act of 2002 (“ Sarbanes-Oxley ”), the Act, the Exchange Act, the Rules and Regulations, the auditing principles, rules, standards and practices applicable to auditors of “issuers” (as defined in Sarbanes-Oxley) promulgated or approved by the Public Company Accounting Oversight Board and, as applicable, the rules of the New York Stock Exchange and the NASDAQ Stock Market (“ Exchange Rules ”).

“ Supplemental Marketing Material ” means any Issuer Free Writing Communication other than any Issuer Free Writing Communication specified in Schedule B hereto. Supplemental Marketing Materials include, but are not limited to, any Issuer Free Writing Communication listed on Schedule C hereto.

“ Underlying Shares ” means shares of Common Stock into which the Offered Securities are convertible or shares of Common Stock that may be issued as dividends on the Offered Securities or may otherwise be issued in respect of the Offered Securities.

Unless otherwise specified, a reference to a “rule” is to the indicated rule under the Securities Act.

(b) Disclosure . As of the date of this Agreement, the Final Offering Circular does not, and as of each Closing Date, the Final Offering Circular will not include any 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, not misleading. At the Applicable Time neither (i) the General Disclosure Package nor (ii) any individual Supplemental Marketing Material, when considered together with the General Disclosure Package, included any untrue statement of a material fact or omitted to state any material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading. The preceding two sentences do not apply to statements in or omissions from the Preliminary or Final Offering Circular, the General Disclosure Package or any Supplemental Marketing Material based upon written information furnished to the Company by any Purchaser through the Representatives specifically for use therein, it being understood and agreed that the only such information is that described as such in Section 8(b) hereof. Except as disclosed in the General Disclosure Package, on the date of this Agreement, the Company’s Annual Report on Form 10-K

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most recently filed with the Commission and all subsequent reports (collectively, the “ Exchange Act Reports ”) which have been filed by the Company with the Commission or sent to shareholders pursuant to the Exchange Act do not include any untrue statement of a material fact or omit to state any material fact necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading. Such documents, when they were filed with the Commission, conformed in all material respects to the requirements of the Exchange Act and the Rules and Regulations.

(c) Good Standing of the Company . The Company has been duly incorporated and is existing and in good standing under the laws of the State of Texas, with power and authority (corporate and other) to own its properties and conduct its business as described in the General Disclosure Package and the Final Offering Circular; and the Company is duly qualified to do business as a foreign corporation in good standing in all other jurisdictions in which its ownership or lease of property or the conduct of its business requires such qualification.

(d) Subsidiaries . Each subsidiary of the Company has been duly incorporated and is existing and in good standing under the laws of the jurisdiction of its incorporation, with power and authority (corporate and other) to own its properties and conduct its business as described in the General Disclosure Package and the Final Offering Circular; and each subsidiary of the Company is duly qualified to do business as a foreign corporation in good standing in all other jurisdictions in which its ownership or lease of property or the conduct of its business requires such qualification, except where the failure to so qualify would not have, individually or in the aggregate, a material adverse effect on the business, financial position, or results of operations of the Company and its subsidiaries taken as a whole or on the performance by the Company of its obligations under this Agreement (“ Material Adverse Effect ”); all of the issued and outstanding capital stock of each subsidiary of the Company has been duly authorized and validly issued and is fully paid and nonassessable; and, except as disclosed in the General Disclosure Package and the Final Offering Circular, the capital stock of each subsidiary owned by the Company, directly or through subsidiaries, is owned free from liens, encumbrances and defects.

(e) Offered Securities . The Offered Securities and all other outstanding shares of capital stock of the Company have been duly authorized; and when the Offered Securities are delivered and paid for pursuant to this Agreement on each Closing Date, such Offered Securities will have been validly issued, fully paid and nonassessable, will conform to the information in the General Disclosure Package and will conform to the description of such Offered Securities contained in the Final Offering Circular; and the shareholders of the Company have no preemptive rights with respect to the Offered Securities; none of the outstanding shares of capital stock of the Company are or will have been issued in violation of any preemptive or similar rights of any security holder; and the authorized equity capitalization of the Company is as set forth in the General Disclosure Package and the Final Offering Circular.

(f) Underlying Shares . When the Offered Securities are delivered and paid for pursuant to this Agreement on each Closing Date, such Offered Securities will be convertible into the Underlying Shares of the Company in accordance with their terms; the Underlying Shares initially issuable upon conversion of such Offered Securities have been duly authorized and reserved for issuance upon such conversion and will conform to the information in the General Disclosure Package and will conform to the description of such Underlying Shares contained in the Final Offering Circular; all outstanding shares of capital stock of the Company are, and when issued upon conversion of the Offered Securities the Underlying Shares will be, validly issued, fully paid and nonassessable; and the shareholders of the Company have no preemptive rights with respect to the issuance of the Underlying Shares upon the conversion of the Offered Securities.

(g) No Finder’s Fee . 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 Purchaser for a brokerage commission, finder’s fee or like payment in connection with the offering and sale of the Offered Securities.

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(h) Absence of Further Requirements . No consent, approval, authorization, order, license, 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 Offered Securities and the Underlying Shares and the consummation of the transactions contemplated by this Agreement and described in the General Disclosure Package and Final Offering Circular.

(i) Stock Options . With respect to the stock options (the “ Stock Options ”) granted pursuant to the stock-based compensation plans of the Company and its subsidiaries (the “ Company Stock Plans ”), (A) each Stock Option intended to qualify as an “incentive stock option” under Section 422 of the Code so qualifies, (B) each grant of a Stock Option was duly authorized no later than the date on which the grant of such Stock Option was by its terms to be effective (the “ Grant Date ”) by all necessary corporate action, including, as applicable, approval by the board of directors of the Company (or a duly constituted and authorized committee thereof) and any required shareholder approval by the necessary number of votes or written consents, and the award agreement governing such grant (if any) was duly executed and delivered by each party thereto, (C) each such grant was made in accordance with the terms of the Company Stock Plans, the Exchange Act and all other applicable laws and regulatory rules or requirements, including the rules of the Nasdaq Global Select Market and any other exchange on which Company securities are traded, and (D) each such grant was properly accounted for in accordance with generally accepted accounting principles in the financial statements (including the related notes) of the Company and disclosed in the Company’s filings with the Commission in accordance with the Exchange Act and all other applicable laws. The Company has not knowingly granted, and there is no and has been no policy or practice of the Company of granting, Stock Options prior to, or otherwise coordinating the grant of Stock Options with, the release or other public announcement of material information regarding the Company or its subsidiaries or their results of operations or prospects.

(j) Title to Real and Personal Property . Except as disclosed in the General Disclosure Package and the Final Offering Circular or such as in the aggregate does not now cause nor will it in the future cause a Material Adverse Effect, the Company and its subsidiaries have title to their properties as follows: (A) with respect to their wells (including leasehold interests and appurtenant personal property) and their non-producing oil and gas properties (including undeveloped locations on leases held by production and those leases not held by production), such title is valid and defensible and free and clear of all liens, security interests, pledges, charges, encumbrances, mortgages and restrictions, (B) with respect to their non-producing properties in exploration prospects, such title was investigated in accordance with customary industry procedures prior to the Company or its subsidiaries’ acquisition thereof; (C) with respect to their real property other than oil and gas interests, such title is good and marketable free and clear of all liens, security interests, pledges, charges, encumbrances, mortgages and restrictions; and (D) with respect to their personal property other than that appurtenant to its oil and gas interests, such title is free and clear of all liens, security interests, pledges, charges, encumbrances, mortgages and restrictions. No real property owned, leased, licensed, or used by the Company or its subsidiaries lies in an area which is, or to the knowledge of the Company will be, subject to restrictions which would prohibit, and no statements of facts relating to the actions or inaction of another person or entity or his or its ownership, leasing, licensing, or use of any real or personal property exists or will exist which would prevent, the continued effective ownership, leasing, licensing, exploration, development or production or use of such real property in the business of the Company as presently conducted or as the General Disclosure Package or the Final Offering Circular indicates they contemplate conducting, except as disclosed in the General Disclosure Package and the Final Offering Circular or such as in the aggregate do not now cause and will not in the future reasonably be expected to cause a Material Adverse Effect.

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(k) Title to Intellectual Property . The Company and its subsidiaries own or possess, or can acquire on reasonable terms, adequate patents, patent rights, licenses, inventions, copyrights, know-how, confidential information, trademarks, service marks, trade names or other intellectual property (collectively, “ Intellectual Property ”) necessary to carry on the business now operated by them, except where the failure to own or possess, or have the ability to acquire on reasonable terms such Intellectual Property, would not reasonably be expected to cause, individually or in the aggregate, a Material Adverse Effect. Neither the Company nor any subsidiary has received any notice of any infringement of or conflict with asserted rights of others with respect to any Intellectual Property that if determined adversely to the Company would result in, individually or in the aggregate, a Material Adverse Effect.

(l) Absence of Defaults and Conflicts Resulting from Transaction . The execution, delivery and performance by the Company of each of this Agreement, the issuance and sale of the Offered Securities and the Underlying Shares and the consummation of the transactions contemplated by this Agreement and described in the General Disclosure Package and Final Offering Circular 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, violation or default that would not, individually or in the aggregate, have a Material Adverse Effect.

(m) Absence of Existing Defaults and Conflicts . 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.

(n) Authorization of Agreement. The Company has full right, power and authority to execute and deliver this Agreement and to perform its obligations hereunder; and all 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. This Agreement has been duly authorized, executed and delivered by the Company.

(o) Possession of Licenses and Permits . The Company and its subsidiaries possess all licenses, certificates, permits and other authorizations issued by 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 General Disclosure Package and the Final Offering Circular, except where the failure to so possess would not have, individually or in the aggregate, a Material Adverse Effect; except as described in the General Disclosure Package and the Final Offering Circular, the Company and its subsidiaries are in compliance with the terms and conditions of all such licenses, certificates, permits and authorizations, except where the failure to so comply would not have, individually or in the aggregate, a Material Adverse Effect; and except as described in the General Disclosure Package

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and the Final Offering Circular, neither the Company nor any of its subsidiaries has received notice of any revocation or modification of any such license, certificate, permit or authorization which, individually or in the aggregate, if subject to an unfavorable decision, ruling or finding would result in a Material Adverse Effect.

(p) Absence of Labor Dispute . 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 imminent, 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.

(q) Environmental Laws . (A) The Company and its subsidiaries (1) are in compliance with any and all applicable Federal, state, local and foreign laws, rules, regulations, requirements, decisions, judgments, decrees, and orders relating to pollution or the protection of the environment, natural resources or human health or safety, including those relating to the generation, storage, treatment, use, handling, transportation, Release or threat of Release of Hazardous Materials (collectively, “ Environmental Laws ”), (2) 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, (3) have not received notice of any actual or potential liability under or relating to, or actual or potential violation of, any Environmental Laws, including for the investigation or remediation of any Release or threat of Release of Hazardous Materials, and have no knowledge of any event or condition that would reasonably be expected to result in any such notice, (4) are not conducting or paying for, in whole or in part, any investigation, remediation or other corrective action pursuant to any Environmental Law at any location, and (5) are not a party to any order, decree or agreement that imposes any obligation or liability under any Environmental Law, except for any such matter as would not reasonably be expected to have, individually or in the aggregate, a Material Adverse Effect, and (B) there are no costs or liabilities associated with Environmental Laws of or relating to the Company or its subsidiaries, except for any such matter as would not reasonably be expected to have, individually or in the aggregate, a Material Adverse Effect; and (C) except as described in the General Disclosure Package and the Final Offering Circular, (1) there are no proceedings that are pending, or that are known to be contemplated, against the Company or any of its subsidiaries under any Environmental Laws in which a governmental entity is also a party, other than such proceedings regarding which it is reasonably believed no monetary sanctions of $100,000 or more will be imposed, and (2) the Company and its subsidiaries are not aware of any facts or issues regarding compliance with Environmental Laws, or liabilities or other obligations under Environmental Laws, including the Release or threat of Release of Hazardous Materials, that could reasonably be expected to have a material effect on the capital expenditures, earnings or competitive position of the Company and its subsidiaries.

(r) Hazardous Materials . There has been no storage, generation, transportation, use, handling, treatment, Release or threat of Release of Hazardous Materials by, relating to or caused by the Company or any of its subsidiaries (or, to the knowledge of the Company and its subsidiaries, 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) at, on, under or from any property or facility now or previously owned, operated or leased by the Company or any of its subsidiaries, or at, on, under or from any other property or facility, in violation of any Environmental Laws or in a manner or amount or to a location that could reasonably be expected to result in any liability of the Company or any of its subsidiaries under any Environmental Law, except for any violation or liability which would not reasonably be expected to have, individually or in the aggregate, a Material Adverse Effect. “ Hazardous Materials ” means any material, chemical, substance, waste, pollutant, contaminant, compound, mixture, or constituent thereof, in any form or amount, including petroleum (including crude oil or any fraction thereof) and petroleum products, natural gas, natural gas liquids, asbestos and asbestos containing materials, naturally occurring radioactive materials, brine, and drilling mud, regulated or which can give rise to liability under any Environmental Law. “ Release ” means any spilling, leaking, seepage,

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pumping, pouring, emitting, emptying, discharging, injecting, escaping, leaching, dumping, disposing, depositing, dispersing, or migrating in, into or through the environment, or in, into, from or through any building or structure

(s) Absence of Manipulation. Neither the Company nor any of its affiliates has, either alone or with one or more other persons, bid for or purchased for any account in which it or any of its affiliates had a beneficial interest any Offered Securities or attempted to induce any person to purchase any Offered Securities.

(t) Statistical and Market-Related Data . Any third-party statistical and market-related data included in a Preliminary Offering Circular, a Final Offering Circular, or any Issuer Free Writing Communication are based on or derived from sources that the Company believes to be reliable and accurate.

(u) 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 complies with the requirements of the Exchange Act and that has been designed to ensure that information required to be disclosed by the Company in reports that it files or submits under the Exchange Act is 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 is accumulated and communicated to the Company’s management as appropriate to allow timely decisions regarding required disclosure. The Company and its subsidiaries have carried out evaluations of the effectiveness of their disclosure controls and procedures as required by Rule 13a-15 of the Exchange Act.

(v) Accounting Controls . The Company and its subsidiaries maintain systems 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, their respective principal executive and principal financial officers, or persons performing similar functions, 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, but not limited to, internal accounting controls sufficient to provide reasonable assurance that (A) transactions are executed in accordance with management’s general or specific authorizations; (B) transactions are recorded as necessary to permit preparation of financial statements in conformity with generally accepted accounting principles and to maintain asset accountability; (C) access to assets is permitted only in accordance with management’s general or specific authorization; and (D) the recorded accountability for assets is compared with the existing assets at reasonable intervals and appropriate action is taken with respect to any differences. Except as disclosed in the General Disclosure Package and the Final Offering Circular, the Company is not aware of (i) any significant deficiencies or material weaknesses in the design or operation of internal controls or (ii) any fraud, whether or not material, that involves management or other employees who have a significant role in the Company’s internal controls over financial reporting which are likely to adversely affect the Company’s ability to record, process, summarize and report financial information. The Company’s auditors and the Audit Committee of the Board of Directors of the Company have been advised of: (1) all significant deficiencies and material weaknesses in the design or operation of internal controls over financial reporting which have adversely affected or are reasonably likely to adversely affect the Company’s ability to record, process, summarize and report financial information; and (2) any fraud, whether or not material, that involves management or other employees who have a significant role in the Company’s internal controls over financial reporting.

(w) Absence of Accounting Issues . A member of the Audit Committee has confirmed to the Chief Executive Officer, Chief Financial Officer or General Counsel that, except as set forth in the General Disclosure Package and the Final Offering Circular, the Audit Committee is not reviewing or investigating, and neither the Company’s independent auditors nor its internal

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auditors have recommended that the Audit Committee review or investigate, (A) adding to, deleting, changing the application of, or changing the Company’s disclosure with respect to, any of the Company’s material accounting policies; (B) any matter which could result in a restatement of the Company’s financial statements for any annual or interim period during the current or prior three fiscal years; or (C) any Internal Control Event.

(x) Litigation . Except as disclosed in the General Disclosure Package and the Final 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 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, would reasonably be expected to have a Material Adverse Effect; no such investigations, actions, suits or proceedings are threatened by any governmental or regulatory authority.

(y) Taxes. The Company and its subsidiaries have on a timely basis paid all Federal, state, local and foreign taxes and filed all tax returns required to be paid or filed through the date hereof (except in any case in which the failure to so file has not had and would not reasonably be expected to result in a Material Adverse Effect); and except as otherwise disclosed in the General Disclosure Package and the Final Offering Circular, 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 tax deficiency that is currently being contested in good faith or would not result in a Material Adverse Effect.

(z) Financial Statements . The financial statements (including the related notes thereto) of the Company and its consolidated subsidiaries included or incorporated by reference in the General Disclosure Package and the Final Offering Circular comply in all material respects with the applicable requirements of the Securities Act and the Exchange Act, as applicable, and present fairly 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 any supporting schedules included or incorporated by reference in the General Disclosure Package and the Final Offering Circular present fairly the information required to be stated therein; and the other financial information included or incorporated by reference in the General Disclosure Package and the Final Offering Circular has been derived from the accounting records of the Company and its consolidated subsidiaries and presents fairly the information shown thereby.

(aa) No Material Adverse Change . Since the date of the most recent financial statements of the Company included or incorporated by reference in the General Disclosure Package and the Final Offering Circular, (A) there has not been any material change in the capital stock (other than the issuance of shares of Common Stock upon exercise of stock options and warrants described as outstanding in, and the grant of options and awards under existing equity incentive plans described in, the General Disclosure Package and the Final Offering Circular), short-term debt or 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, shareholders’ equity, results of operations or prospects of the Company and its subsidiaries taken as a whole; (B) neither the Company nor any of its subsidiaries has entered into any transaction or agreement (whether or not in the ordinary course of business) 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 (C) neither the Company nor any of its subsidiaries has sustained any loss or interference with its business that is material to the Company and its subsidiaries taken as a whole and that is either 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 General Disclosure Package and the Final Offering Circular.

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(bb) Investment Company Act . The Company is not and, after giving effect to the offering and sale of the Offered Securities and the application of the proceeds thereof as described in the General Disclosure Package and the Final Offering Circular, 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, the “ Investment Company Act ”).

(cc) Regulations T, U, X. The application of the proceeds received by the Company from the issuance, sale and delivery of the Offered Securities as described in the General Disclosure Package and the Final Offering Circular will not violate Regulation T, U or X of the Board of Governors of the Federal Reserve System or any other regulation of such Board of Governors.

(dd) Ratings . No “nationally recognized statistical rating organization” as such term is defined for purposes of Rule 436(g)(2) (i) has imposed (or has informed the Company that it is considering imposing) any condition (financial or otherwise) on the Company’s retaining any rating assigned to the Company or any securities of the Company or (ii) has indicated to the Company that it is considering any of the actions described in Section 7(c)(ii) hereof.

(ee) Class of Securities Not Listed . No securities of the same class (within the meaning of Rule 144A(d)(3)) as the Offered Securities are listed on any national securities exchange registered under Section 6 of the Exchange Act or quoted in a U.S. automated inter-dealer quotation system.

(ff) No Registration . The offer and sale of the Offered Securities in the manner contemplated by this Agreement will be exempt from the registration requirements of the Securities Act by reason of Section 4(2) thereof, Regulation D thereunder and Regulation S thereunder.

(gg) No General Solicitation; No Directed Selling Efforts . Neither the Company, nor any of its affiliates, nor any person acting on its or their behalf (i) has, within the six-month period prior to the date hereof, offered or sold in the United States or to any U.S. person (as such terms are defined in Regulation S under the Securities Act) the Offered Securities or any security of the same class or series as the Offered Securities or (ii) has offered or will offer or sell the Offered Securities (A) in the United States by means of any form of general solicitation or general advertising within the meaning of Rule 502(c) or (B) with respect to any such securities sold in reliance on Rule 903 of Regulation S (“ Regulation S ”) under the Securities Act, by means of any directed selling efforts within the meaning of Rule 902(c) of Regulation S. The Company, its affiliates and any person acting on its or their behalf have complied and will comply with the offering restrictions requirement of Regulation S. The Company has not entered and will not enter into any contractual arrangement with respect to the distribution of the Offered Securities except for this Agreement.

(hh) Use of Proceeds . The proceeds to the Company from the offering of the Offered Securities will not be used to purchase or carry any security.

(ii) Reporting Status . The Company is subject to Section 13 or 15(d) of the Exchange Act.

(jj) Insurance. The Company and its subsidiaries have insurance covering their respective properties, operations, personnel and businesses, including business interruption insurance, which insurance is in amounts and insures against such losses and risks as are customary for the businesses in which they are engaged; all such policies insuring the Company

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and its subsidiaries are in full force and effect; and neither the Company nor any of its subsidiaries has received notice from any insurer or agent of such insurer that it will not be able to renew insurance coverage as and when such coverage expires or to obtain coverage acceptable to the Company at reasonable cost from similar insurers as may be necessary to continue its business.

(kk) Compliance with ERISA. The minimum funding standard under Section 302 of the Employee Retirement Income Security Act of 1974, as amended, and the regulations and published interpretations thereunder (“ ERISA ”), has been satisfied by each “pension plan” (as defined in Section 3(2) of ERISA) which has been established or maintained by the Company, and the trust forming part of each such plan which is intended to be qualified under Section 401 of the Internal Revenue Code of 1986, as amended (the “ Code ”), is so qualified; each of the Company and each of its subsidiaries has fulfilled its obligations, if any, under Section 515 of ERISA; neither the Company nor any of its subsidiaries maintains and is required to contribute to a “welfare plan” (as defined in Section 3(1) of ERISA) which provides retiree or other post-employment welfare benefits or insurance coverage (other than “continuation coverage” (as defined in Section 602 of ERISA)); each pension plan and welfare plan established or maintained by the Company and/or one of the subsidiaries is in compliance with the currently applicable provisions of ERISA, except where the failure to comply would not cause a Material Adverse Effect; no prohibited transaction, within the meaning of Section 406 of ERISA or Section 4975 of the Code, has occurred with respect to any pension plan or welfare plan (excluding transactions effected pursuant to statutory or administrative exemption) that could reasonably be expected to result in a material liability to the Company or its subsidiaries; and neither the Company nor any of its subsidiaries has incurred or could reasonably be expected to incur any withdrawal liability under Section 4201 of ERISA, any liability under Section 4062, 4063, or 4064 of ERISA, or any other liability under Title IV of ERISA.

(ll) Reserve Report Data . The oil and gas reserve estimates of the Company contained or incorporated by reference into the General Disclosure Package and the Final Offering Circular have been prepared by (A) Ryder Scott Company, L.P., (B) Collarini Associates and (C) DeGolyer & MacNaughton (collectively, the “ Engineers ”), and the Company has no reason to believe that such estimates do not fairly reflect the oil and gas reserves of the Company at the dates indicated. The information underlying the estimates of the reserves of the Company and its subsidiaries supplied by the Company to the Engineers, for the purposes of preparing the reserve reports of Company and its subsidiaries referenced in the General Disclosure Package and the Final Offering Circular (the “ Reserve Reports ”), was true and correct in all material respects on the date of each such Reserve Report; the estimates of future capital expenditures and other future exploration and development costs supplied to the Engineers were prepared in good faith and with a reasonable basis; the information provided to the Engineers was prepared in good faith and with a reasonable basis. Other than production of the reserves in the ordinary course of business and intervening product price fluctuations described in the General Disclosure Package and the Final Offering Circular, the Company is not aware of any facts or circumstances that would cause a Material Adverse Change in the reserves or the present value of future net cash flows therefrom as described in the General Disclosure Package and the Final Offering Circular. Each of the Engineers is an independent reserve engineer with respect to the Company and its subsidiaries.

(mm) Related Party Transactions . All business relationships or related-party transactions involving the Company or any of its subsidiaries or any of their respective directors, managers, executive officers, nominees for election as director, manager or executive officer, any security holder, member interest holder or partnership interest holder, each as applicable, who is known to the Company or any of its subsidiaries to own of record or beneficially more than five percent of any class of the Company’s or any of its subsidiaries’ voting securities or interests, as applicable, any member of the immediate family of the foregoing persons, or any other person, required to be disclosed pursuant to the requirements of Item 404 of Regulation S-K under the Securities Act, are accurately described in the General Disclosure Package and the Final Offering Circular, and all other related-party transactions required to be disclosed pursuant to the requirements of Item 404 of Regulation S-K under the Securities Act have been accurately described in the General Disclosure Package.

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(nn) Independent Accountants. PricewaterhouseCoopers LLP, who have certified certain financial statements of the Company and its subsidiaries, and Deloitte & Touche LLP, who have certified certain financial statements of the Company and its subsidiaries, are each 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.

(oo) Incorporated Documents. The documents incorporated by reference in the General Disclosure Package and the Final Offering Circular, when they were filed with the Commission, conformed in all material respects to the requirements of the Exchange Act, and none of such documents contained any untrue statement of a material fact or omitted to state a material fact necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading; and any further documents so filed and incorporated by reference in the General Disclosure Package and the Final Offering Circular, when such documents are filed with the Commission, will conform in all material respects to the requirements of the Exchange Act and will not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading.

(pp) 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 (A) used any corporate funds for any unlawful contribution, gift, entertainment or other unlawful expense relating to political activity; (B) made any direct or indirect unlawful payment to any foreign or domestic government official or employee from corporate funds; (C) violated or is in violation of any provision of the Foreign Corrupt Practices Act of 1977; or (D) made any bribe, rebate, payoff, influence payment, kickback or other unlawful payment.

(qq) Compliance with Money Laundering Laws . The operations of the Company