LUCA TECHNOLOGIESINC. [ ] Shares Common Stock ($.001 par value per Share) UNDERWRITING AGREEMENT

Exhibit 1.1

DRAFT

LUCA TECHNOLOGIES INC.

[            ] Shares

Common Stock

($.001 par value per Share)

UNDERWRITING AGREEMENT

[            ], 2012

UNDERWRITING AGREEMENT

[            ], 2012

Citigroup Global Markets Inc.

Piper Jaffray & Co.

Raymond James & Associates, Inc.

as Managing Underwriters

Citigroup Global Markets Inc.

388 Greenwich Street

New York, New York 10013

and

Piper Jaffray & Co.

800 Nicollet Mall, Suite 800

Minneapolis, MN 55402

and

Raymond James & Associates, Inc.

880 Carillon Parkway

St. Petersburg, FL 33716

Ladies and Gentlemen:

Luca Technologies Inc., a Delaware corporation (the “Company”), proposes to issue and sell to the underwriters named in Schedule A annexed hereto (the “Underwriters”), for whom you are acting as representatives, an aggregate of [            ] shares (the “Firm Shares”) of common stock, $.001 par value per share (the “Common Stock”), of the Company. In addition, solely for the purpose of covering over-allotments, the Company proposes to grant to the Underwriters the option to purchase from the Company up to an additional [            ] shares of Common Stock (the “Additional Shares”). The Firm Shares and the Additional Shares are hereinafter collectively sometimes referred to as the “Shares.” The Shares are described in the Prospectus which is referred to below.

The Company has prepared and filed, in accordance with the provisions of the Securities Act of 1933, as amended, and the rules and regulations thereunder (collectively, the “Act”), with the Securities and Exchange Commission (the “Commission”) a registration statement on Form S-1 (File No. 333-175211) under the Act, including a prospectus, relating to the Shares.

Except where the context otherwise requires, “Registration Statement,” as used herein, means the registration statement, as amended at the time of such registration statement’s effectiveness for purposes of Section 11 of the Act, as such section applies to the respective Underwriters (the “Effective Time”), including (i) all documents filed as a part thereof, (ii) any information contained in a prospectus filed with the Commission pursuant to Rule 424(b) under the Act, to the extent such information is deemed, pursuant to Rule 430A under the Act, to be part of the registration statement at the Effective Time, and (iii) any registration statement filed to register the offer and sale of Shares pursuant to Rule 462(b) under the Act.

The Company has furnished to you, for use by the Underwriters and by dealers in connection with the offering of the Shares, copies of one or more preliminary prospectuses relating to the Shares. Except where the context otherwise requires, “Preliminary Prospectus” as used herein, means each such preliminary prospectus, in the form so furnished.

Except where the context otherwise requires, “Prospectus,” as used herein, means the prospectus, relating to the Shares, filed by the Company with the Commission pursuant to Rule 424(b) under the Act on or before the second business day after the date hereof (or such earlier time as may be required under the Act), or, if no such filing is required, the final prospectus included in the Registration Statement at the time it became effective under the Act, in each case in the form furnished by the Company to you for use by the Underwriters and by dealers in connection with the offering of the Shares.

“Permitted Free Writing Prospectuses,” as used herein, means the documents listed on Schedule B attached hereto and each “road show” (as defined in Rule 433 under the Act), if any, related to the offering of the Shares contemplated hereby that is a “written communication” (as defined in Rule 405 under the Act) (each such road show, an “Electronic Road Show”). The Underwriters have not offered or sold and will not offer or sell, without the Company’s consent, any Shares by means of any “free writing prospectus” (as defined in Rule 405 under the Act) that is required to be filed by the Underwriters or the Company with the Commission pursuant to Rule 433 under the Act, other than a Permitted Free Writing Prospectus.

“Disclosure Package,” as used herein, means any Preliminary Prospectus together with any combination of one or more of the Permitted Free Writing Prospectuses, if any.

As used in this Underwriting Agreement (“Agreement”), “business day” shall mean a day on which The NASDAQ Stock Market (the “NASDAQ”) is open for trading. The terms “herein,” “hereof,” “hereto,” “hereinafter” and similar terms, as used in this Agreement, shall in each case refer to this Agreement as a whole and not to any particular section, paragraph, sentence or other subdivision of this Agreement. The term “or,” as used herein, is not exclusive.

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The Company has prepared and filed, in accordance with Section 12 of the Securities Exchange Act of 1934, as amended, and the rules and regulations thereunder (collectively, the “Exchange Act”), a registration statement (as amended, the “Exchange Act Registration Statement”) on Form 8-A (File No. [            ]) under the Exchange Act to register, under Section 12(b) of the Exchange Act, the class of securities consisting of the Common Stock.

The Company and the Underwriters agree as follows:

1. Sale and Purchase. Upon the basis of the representations and warranties and subject to the terms and conditions herein set forth, the Company agrees to issue and sell to the respective Underwriters and each of the Underwriters, severally and not jointly, agrees to purchase from the Company the number of Firm Shares set forth opposite the name of such Underwriter in Schedule A attached hereto, subject to adjustment in accordance with Section 8 hereof, provided, however, that the Underwriters will purchase [    ] of the Firm Shares to be sold to certain existing stockholders of the Company at a price of $[    ] per share (which shall be equal to the price to the public), and the remaining [    ] Firm Shares will be purchased at a price of $[    ] per share, in each case on a pro rata basis based on the number of Firm Shares opposite their respective names in Schedule A attached hereto. The Company is advised by you that the Underwriters intend (i) to make a public offering of their respective portions of the Firm Shares as soon after the effective date of the Registration Statement as in your judgment is advisable and (ii) initially to offer the Firm Shares upon the terms set forth in the Prospectus. You may from time to time increase or decrease the public offering price after the initial public offering to such extent as you may determine.

In addition, the Company hereby grants to the several Underwriters the option (the “Over-Allotment Option”) to purchase, and upon the basis of the representations and warranties and subject to the terms and conditions herein set forth, the Underwriters shall have the right to purchase, severally and not jointly, from the Company, ratably in accordance with the number of Firm Shares to be purchased by each of them, all or a portion of the Additional Shares as may be necessary to cover over-allotments made in connection with the offering of the Firm Shares, at the same purchase price per Share to be paid by the Underwriters to the Company for the Firm Shares, less an amount per share equal to any dividends or distributions declared by the Company and payable on the Firm Shares but not payable on the Additional Shares. The Over-Allotment Option may be exercised by Citigroup Global Markets Inc. (“Citigroup”), Piper Jaffray & Co. and Raymond James & Associates, Inc. (together with Citigroup and Piper Jaffray & Co., the “Representatives”) on behalf of the several Underwriters at any time and from time to time on or before the thirtieth day following the date of the Prospectus, by written notice to the Company. Such notice shall set forth the aggregate number of Additional Shares as to which the Over-Allotment Option is being exercised and the date and time when the Additional Shares are to be delivered (any such date and time being herein referred to as an “additional time of purchase”); provided, however, that no additional time of purchase shall be earlier than the “time of purchase” (as defined below) nor earlier than the second business day after the date on which the Over-Allotment Option shall have been exercised nor later than the tenth business day after the date on which the Over-Allotment Option shall have been exercised. The number of Additional Shares to be sold to each Underwriter shall be the number which bears the same proportion to the aggregate number of Additional Shares being purchased as the number of Firm Shares set forth opposite the name of such Underwriter on Schedule A hereto bears to the total number of Firm Shares (subject, in each case, to such adjustment as the Representatives may determine to eliminate fractional shares), subject to adjustment in accordance with Section 8 hereof.

2. Payment and Delivery. Payment of the purchase price for the Firm Shares shall be made to the Company by Federal Funds wire transfer against delivery of the certificates for the Firm Shares to you through the facilities of The Depository Trust Company (“DTC”) for the respective accounts of the Underwriters. Such payment and delivery shall be made at 10:00 A.M., New York City time, on [    ], 2012 (unless another time shall be agreed to by you and the Company or unless

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postponed in accordance with the provisions of Section 8 hereof). The time at which such payment and delivery are to be made is hereinafter sometimes called the “time of purchase.” Electronic transfer of the Firm Shares shall be made to you at the time of purchase in such names and in such denominations as you shall specify.

Payment of the purchase price for the Additional Shares shall be made at the additional time of purchase in the same manner and at the same office and time of day as the payment for the Firm Shares. Electronic transfer of the Additional Shares shall be made to you at the additional time of purchase in such names and in such denominations as you shall specify.

Deliveries of the documents described in Section 6 hereof with respect to the purchase of the Shares shall be made at the offices of Davis Polk & Wardwell, 450 Lexington Avenue, New York, New York 10017, at 9:00 A.M., New York City time, on the date of the closing of the purchase of the Firm Shares or the Additional Shares, as the case may be.

3. Representations and Warranties of the Company. The Company represents and warrants to and agrees with each of the Underwriters that:

(a) the Registration Statement has heretofore become effective under the Act or, with respect to any registration statement to be filed to register the offer and sale of Shares pursuant to Rule 462(b) under the Act, will be filed with the Commission and become effective under the Act no later than 10:00 P.M., New York City time, on the date of determination of the public offering price for the Shares; no stop order of the Commission preventing or suspending the use of any Preliminary Prospectus or Permitted Free Writing Prospectus, or the effectiveness of the Registration Statement, has been issued, and no proceedings for such purpose have been instituted or, to the Company’s knowledge, are contemplated by the Commission; the Exchange Act Registration Statement has become effective as provided in Section 12 of the Exchange Act;

(b) the Registration Statement complied when it became effective, complies as of the date hereof and, as amended or supplemented, at the time of purchase, each additional time of purchase, if any, and at all times during which a prospectus is required by the Act to be delivered (whether physically or through compliance with Rule 172 under the Act or any similar rule) in connection with any sale of Shares, will comply, in all material respects, with the requirements of the Act; the Registration Statement did not, as of the Effective Time, contain an untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein not misleading; each Preliminary Prospectus complied, at the time it was filed with the Commission, and complies as of the date hereof, in all material respects with the requirements of the Act; at no time during the period that begins on the earlier of the date of such Preliminary Prospectus and the date such Preliminary Prospectus was filed with the Commission and ends at the time of purchase did or will any Preliminary Prospectus, as then amended or supplemented, include an untrue statement of a material fact or omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading, and at no time during such period did or will any Preliminary Prospectus, as then amended or supplemented, together with any combination of one or more of the then issued Permitted Free Writing Prospectuses, if any, include an untrue statement of a material fact or omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not

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misleading; the Prospectus will comply, as of its date, the date that it is filed with the Commission, the time of purchase, each additional time of purchase, if any, and at all times during which a prospectus is required by the Act to be delivered (whether physically or through compliance with Rule 172 under the Act or any similar rule) in connection with any sale of Shares, in all material respects, with the requirements of the Act (including, without limitation, Section 10(a) of the Act); at no time during the period that begins on the earlier of the date of the Prospectus and the date the Prospectus is filed with the Commission and ends at the later of the time of purchase, the latest additional time of purchase, if any, and the end of the period during which a prospectus is required by the Act to be delivered (whether physically or through compliance with Rule 172 under the Act or any similar rule) in connection with any sale of Shares did or will the Prospectus, as then amended or supplemented, include an untrue statement of a material fact or omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading; at no time during the period that begins on the date of such Permitted Free Writing Prospectus and ends at the time of purchase did or will any Permitted Free Writing Prospectus, together with the Disclosure Package including the then most recent Preliminary Prospectus, include an untrue statement of a material fact or omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading; provided, however, that the Company makes no representation or warranty in this Section 3(b) with respect to any statement contained in the Registration Statement, any Preliminary Prospectus, the Prospectus or any Permitted Free Writing Prospectus in reliance upon and in conformity with information concerning an Underwriter and furnished in writing by or on behalf of such Underwriter through you to the Company expressly for use in the Registration Statement, such Preliminary Prospectus, the Prospectus or such Permitted Free Writing Prospectus, it being understood and agreed that the only such information furnished by any Underwriter consists of the information described as such in Section 10 hereof;

(c) prior to the execution of this Agreement, the Company has not, directly or indirectly, offered or sold any Shares by means of any “prospectus” (within the meaning of the Act) or used any “prospectus” (within the meaning of the Act) in connection with the offer or sale of the Shares, in each case other than the Preliminary Prospectuses and the Permitted Free Writing Prospectuses, if any; the Company has not, directly or indirectly, prepared, used or referred to any Permitted Free Writing Prospectus except in compliance with Rules 164 and 433 under the Act; assuming that such Permitted Free Writing Prospectus is accompanied or preceded by the most recent Preliminary Prospectus that contains a price range or the Prospectus, as the case may be, and that such Permitted Free Writing Prospectus is so sent or given after the Registration Statement was filed with the Commission (and after such Permitted Free Writing Prospectus was, if required pursuant to Rule 433(d) under the Act, filed with the Commission), the sending or giving, by any Underwriter, of any Permitted Free Writing Prospectus will satisfy the provisions of Rule 164 and Rule 433 (without reliance on subsections (b), (c) and (d) of Rule 164); the Preliminary Prospectus dated [            ], 2012 is a prospectus that, other than by reason of Rule 433 or Rule 431 under the Act, satisfies the requirements of Section 10 of the Act, including a price range where required by rule; neither the Company nor the Underwriters are disqualified, by reason of subsection (f) or (g) of Rule 164 under the Act, from using, in connection with the offer and sale of the Shares, “free writing prospectuses” (as defined in Rule 405 under the Act) pursuant to Rules 164 and 433 under the Act; the Company is not an “ineligible issuer” (as defined in Rule 405 under the Act) as of the eligibility

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determination date for purposes of Rules 164 and 433 under the Act with respect to the offering of the Shares contemplated by the Registration Statement, without taking into account any determination by the Commission pursuant to Rule 405 under the Act that it is not necessary under the circumstances that the Company be considered an “ineligible issuer”; the parties hereto agree and understand that the content of any and all “road shows” (as defined in Rule 433 under the Act) related to the offering of the Shares contemplated hereby is solely the property of the Company; the Company has caused there to be made available at least one version of a “bona fide electronic road show” (as defined in Rule 433 under the Act) in a manner that, pursuant to Rule 433(d)(8)(ii) under the Act, causes the Company not to be required, pursuant to Rule 433(d) under the Act, to file, with the Commission, any Electronic Road Show;

(d) as of the date of this Agreement, the Company has an authorized and outstanding capitalization as set forth in the sections of the Registration Statement, the Preliminary Prospectuses and the Prospectus entitled “Capitalization” and “Description of capital stock” (and any similar sections or information, if any, contained in any Permitted Free Writing Prospectus), and, as of the time of purchase and any additional time of purchase, as the case may be, the Company shall have an authorized and outstanding capitalization as set forth in the sections of the Registration Statement, the Preliminary Prospectuses and the Prospectus entitled “Capitalization” and “Description of capital stock” (and any similar sections or information, if any, contained in any Permitted Free Writing Prospectus) (subject, in each case, to the issuance of shares of Common Stock upon conversion of outstanding shares of preferred stock and exercise of stock options and warrants disclosed as outstanding in the Registration Statement (excluding the exhibits thereto), each Preliminary Prospectus and the Prospectus and the grant of options under existing equity incentive plans described in the Registration Statement (excluding the exhibits thereto), each Preliminary Prospectus and the Prospectus); all of the issued and outstanding shares of capital stock, including the Common Stock, of the Company have been duly authorized and validly issued and are fully paid and non-assessable, have been issued in compliance with all applicable securities laws and were not issued in violation of any preemptive right, resale right, right of first refusal or similar right; prior to the time of purchase, all outstanding shares of preferred stock of the Company shall convert into, and all outstanding warrants of the Company shall be exercised for, shares of Common Stock in the manner described in the Registration Statement (excluding the exhibits thereto), each Preliminary Prospectus and the Prospectus; and the Third Amended and Restated Certificate of Incorporation of the Company and the Third Amended and Restated Bylaws of the Company, each in the form filed as an exhibit to the Registration Statement, have been heretofore duly authorized and approved in accordance with the Delaware General Corporation Law and shall become effective and in full force and effect at or before the time of purchase; the Shares are duly listed, and admitted and authorized for trading, subject to official notice of issuance and evidence of satisfactory distribution, on the NASDAQ;

(e) the Company has been duly incorporated and is validly existing as a corporation in good standing under the General Corporation Law of the State of Delaware, with full corporate power and authority to own, lease and operate its properties and conduct

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its business as described in the Registration Statement, the Preliminary Prospectuses, the Prospectus and the Permitted Free Writing Prospectuses, if any, to execute and deliver this Agreement and to issue, sell and deliver the Shares as contemplated herein;

(f) the Company is duly qualified to do business as a foreign corporation and is in good standing in each jurisdiction where the ownership or leasing of its properties or the conduct of its business requires such qualification, except where the failure to be so qualified and in good standing would not, individually or in the aggregate, (i) have a material adverse effect on the business, properties, financial condition, results of operations or prospects of the Company and the Subsidiaries (as defined below) taken as a whole, whether or not arising from transactions in the ordinary course of business or (ii) prevent or materially interfere with consummation of the transactions contemplated hereby or (iii) prevent the shares of Common Stock from being accepted for listing on the NASDAQ (the occurrence of any such effect or any such prevention or interference or any such result described in the foregoing clauses (i), (ii) and (iii) being herein referred to as a “Material Adverse Effect”);

(g) the Company has no subsidiaries (as defined under the Act) other than Patriot Energy Resources LLC and Patriot Energy Gathering LLC (collectively, the “Subsidiaries”); the Company owns all of the issued and outstanding capital stock of each of the Subsidiaries; other than the capital stock of the Subsidiaries, the Company does not own, directly or indirectly, any shares of stock or any other equity interests or long-term debt securities of any corporation, firm, partnership, joint venture, association or other entity; complete and correct copies of the charters and the bylaws (or similar organizational document) of the Company and each Subsidiary and all amendments thereto have been delivered to you, and except as set forth in the exhibits to the Registration Statement, no changes therein will be made on or after the date hereof through and including the time of purchase or, if later, any additional time of purchase; each Subsidiary has been duly incorporated or formed and is validly existing as a corporation or limited liability company in good standing under the laws of the jurisdiction of its incorporation or formation, with full corporate or other power and authority to own, lease and operate its properties and to conduct its business as described in the Registration Statement, the Preliminary Prospectuses, the Prospectus and the Permitted Free Writing Prospectuses, if any; each Subsidiary is duly qualified to do business as a foreign limited liability company and is in good standing in each jurisdiction where the ownership or leasing of its properties or the conduct of its business requires such qualification, except where the failure to be so qualified and in good standing would not, individually or in the aggregate, have a Material Adverse Effect; all of the outstanding equity interests of each of the Subsidiaries have been duly authorized and validly issued, have been issued in compliance with all applicable securities laws, were not issued in violation of any preemptive right, resale right, right of first refusal or similar right and are owned by the Company subject to no security interest, other encumbrance or adverse claims; and no options, warrants or other rights to purchase, agreements or other obligations to issue or other rights to convert any obligation into shares of capital stock or ownership interests in the Subsidiaries are outstanding;

(h) the Shares have been duly and validly authorized and, when issued and delivered against payment therefor as provided herein, will be duly and validly issued, fully paid and non-assessable and free of statutory and contractual preemptive rights, resale rights, rights of first refusal and similar rights; the Shares, when issued and delivered against

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payment therefor as provided herein, will be free of any restriction upon the voting or transfer thereof pursuant to the General Corporation Law of the State of Delaware or the Company’s charter or bylaws or any agreement or other instrument to which the Company is a party;

(i) the capital stock of the Company, including the Shares, conforms in all material respects to each description thereof, if any, contained in the Registration Statement, the Preliminary Prospectuses, the Prospectus and the Permitted Free Writing Prospectuses, if any; and the certificates for the Shares are in due and proper form;

(j) this Agreement has been duly authorized, executed and delivered by the Company;

(k) neither the Company nor any of the Subsidiaries is in breach or violation of or in default under (nor has any event occurred which, with notice, lapse of time or both, would result in any breach or violation of, constitute a default under or give the holder of any indebtedness (or a person acting on such holder’s behalf) the right to require the repurchase, redemption or repayment of all or a part of such indebtedness under) (i) its respective charter or bylaws (or other organizational document), or (ii) any indenture, mortgage, deed of trust, bank loan or credit agreement or other evidence of indebtedness, or any license, lease, contract or other agreement or instrument to which it is a party or by which it or any of its properties may be bound or affected, or (iii) any federal, state, local or foreign law, regulation or rule applicable to the Company or any of the Subsidiaries or any of their respective properties, or (iv) any rule or regulation of any self-regulatory organization or other non-governmental regulatory authority (including, without limitation, the rules and regulations of the NASDAQ) having jurisdiction over the Company or any of the Subsidiaries or any of their respective properties, or (v) any decree, judgment or order applicable to it or any of its properties, except, in the cases of clauses (ii), (iii), (iv) and (v), such breaches, violations, defaults, or rights that would not, individually or in the aggregate, have a Material Adverse Effect;

(l) the execution, delivery and performance of this Agreement by the Company, the issuance and sale of the Shares and the consummation by the Company of the transactions contemplated hereby will not conflict with, result in any breach or violation of or constitute a default under (nor constitute any event which, with notice, lapse of time or both, would result in any breach or violation of, constitute a default under or give the holder of any indebtedness (or a person acting on such holder’s behalf) the right to require the repurchase, redemption or repayment of all or a part of such indebtedness under) (or result in the creation or imposition of a lien, charge or encumbrance on any property or assets of the Company or any Subsidiary pursuant to) (i) the charter or bylaws (or other organizational document) of the Company or any of the Subsidiaries, or (ii) any indenture, mortgage, deed of trust, bank loan or credit agreement or other evidence of indebtedness, or any license, lease, contract or other agreement or instrument to which the Company or any of the Subsidiaries is a party or by which any of them or any of their respective properties may be bound or affected, or (iii) any federal, state, local or foreign law, regulation or rule applicable to the Company or any of the Subsidiaries or any of their respective properties, or (iv) any rule or regulation of any self-regulatory organization or other non-governmental regulatory authority (including, without limitation, the rules and regulations of the NASDAQ) having jurisdiction over the Company or any of the Subsidiaries or any of their

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respective properties, or (v) any decree, judgment or order applicable to the Company or any of the Subsidiaries or any of their respective properties; except, in the cases of clauses (ii), (iii), (iv) and (v) such breaches, violations, defaults, or rights that would not, individually or in the aggregate, have a Material Adverse Effect;

(m) no approval, authorization, consent or order of or filing with any federal, state, local or foreign governmental or regulatory commission, board, body, authority or agency, or of or with any self-regulatory organization or other non-governmental regulatory authority (including, without limitation, the NASDAQ), or approval of the stockholders of the Company, is required to be obtained or made by the Company in connection with the issuance and sale of the Shares or the consummation by the Company of the transactions contemplated hereby, other than (i) registration of the Shares under the Act, which has been effected (or, with respect to any registration statement to be filed hereunder pursuant to Rule 462(b) under the Act, will be effected in accordance herewith), (ii) the filing of the Third Amended and Restated Certificate of Incorporation, which will be effected at or prior to the time of purchase, (iii) any necessary qualification under the securities or blue sky laws of the various jurisdictions in which the Shares are being offered by the Underwriters, (iv) under the Conduct Rules of the Financial Industry Regulatory Authority, Inc. (“FINRA”) or (v) such as have been obtained or made;

(n) except as described in the Registration Statement (excluding the exhibits thereto), each Preliminary Prospectus and the Prospectus, (i) no person has the right, contractual or otherwise, to cause the Company to issue or sell to it any shares of Common Stock or shares of any other capital stock or other equity interests of the Company, (ii) no person has any preemptive rights, resale rights, rights of first refusal or other rights to purchase from the Company any shares of Common Stock or shares of any other capital stock of or other equity interests in the Company, (iii) no person has the right to act as an underwriter or as a financial advisor to the Company in connection with the offer and sale of the Shares, and (iv) no person has the right, contractual or otherwise, to cause the Company to register under the Act any shares of Common Stock or shares of any other capital stock of or other equity interests in the Company, or to include any such shares or interests in the Registration Statement or the offering contemplated thereby;

(o) except as described in the Registration Statement (excluding the exhibits thereto), each Preliminary Prospectus and the Prospectus, (i) each of the Company and the Subsidiaries has all necessary licenses, authorizations, consents and approvals and has made all necessary filings required under any applicable law, regulation or rule, and has obtained all necessary licenses, authorizations, consents and approvals from other persons, in order to conduct their respective businesses as is presently conducted, except where the failure to have such licenses, authorizations, consents and approvals and make such filings would not, individually or in the aggregate, have a Material Adverse Effect; and (ii) neither the Company nor any of the Subsidiaries is in violation of, or in default under, or has received notice of any proceedings relating to revocation or modification of, any such license, authorization, consent or approval or any federal, state, local or foreign law, regulation or rule or any decree, order or judgment applicable to the Company or any of the Subsidiaries, except where such violation, default, revocation or modification would not, individually or in the aggregate, have a Material Adverse Effect;

(p) except as described in the Registration Statement (excluding the exhibits thereto), each Preliminary Prospectus and the Prospectus, there are no actions, suits, claims,

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investigations or proceedings pending or, to the Company’s knowledge, threatened or contemplated to which the Company or any of the Subsidiaries or, to the best of the Company’s knowledge, any of their respective directors or officers is or would be a party or of which any of their respective properties is or would be subject at law or in equity, before or by any federal, state, local or foreign governmental or regulatory commission, board, body, authority or agency, or before or by any self-regulatory organization or other non-governmental regulatory authority (including, without limitation, the NASDAQ) applicable to it, except any such action, suit, claim, investigation or proceeding which, if resolved adversely to the Company or any Subsidiary, would not, individually or in the aggregate, have a Material Adverse Effect;

(q) Ernst & Young LLP, whose report on certain of the consolidated financial statements of the Company and the Subsidiaries is included in the Registration Statement, the Preliminary Prospectus and the Prospectus, are independent registered public accountants as required by the Act and by the rules of the Public Company Accounting Oversight Board;

(r) Ehrhardt Keefe Steiner & Hottman PC are independent registered public accountants as required by the Act and by the rules of the Public Company Accounting Oversight Board;

(s) the financial statements included in the Registration Statement, the Preliminary Prospectuses, the Prospectus and the Permitted Free Writing Prospectuses, if any, together with the related notes and schedules, present fairly, in all material respects, the consolidated financial position of the Company and the Subsidiaries as of the dates indicated and the consolidated results of operations, cash flows and changes in stockholders’ equity of the Company and the Subsidiaries for the periods specified and have been prepared in compliance, in all material respects, with the requirements of the Act and the Exchange Act and in conformity with US generally accepted accounting principles applied on a consistent basis during the periods involved; all pro forma financial statements or data included in the Registration Statement, the Preliminary Prospectuses, the Prospectus and the Permitted Free Writing Prospectuses, if any, comply, in all material respects, with the requirements of the Act and the Exchange Act, and the assumptions used in the preparation of such pro forma financial statements and data are reasonable, the pro forma adjustments used therein are appropriate to give effect to the transactions or circumstances described therein and the pro forma adjustments have been properly applied to the historical amounts in the compilation of those statements and data; the other financial and statistical data contained in the Registration Statement, the Preliminary Prospectuses, the Prospectus and the Permitted Free Writing Prospectuses, if any, are accurately and fairly presented and prepared on a basis consistent with the financial statements and books and records of the Company; there are no financial statements (historical or pro forma) that are required to be included in the Registration Statement, any Preliminary Prospectus or the Prospectus that are not included as required; the Company and the Subsidiaries do not have any material liabilities or obligations, direct or contingent (including any off-balance sheet obligations), not described in the Registration Statement (excluding the exhibits thereto), each Preliminary Prospectus and the Prospectus; and all disclosures contained in the Registration Statement, the Preliminary Prospectuses, the Prospectus and the Permitted Free Writing Prospectuses, if

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any, regarding “non-GAAP financial measures” (as such term is defined by the rules and regulations of the Commission), if any, comply with Regulation G of the Exchange Act and Item 10 of Regulation S-K under the Act, to the extent applicable;

(t) except as disclosed in the Registration Statement (excluding the exhibits thereto), each Preliminary Prospectus and the Prospectus, each stock option granted under any equity incentive plan of the Company or any Subsidiary (each, a “Stock Plan”) was granted with a per share exercise price no less than the fair market value per share of Common Stock on the grant date of such option, and no such grant involved any “back-dating,” “forward-dating” or similar practice with respect to the effective date of such grant; except as would not, individually or in the aggregate, have a Material Adverse Effect, each such option (i) was granted in compliance with applicable law and with the applicable Stock Plan(s), (ii) was duly approved by the board of directors (or a duly authorized committee thereof) of the Company or such Subsidiary, as applicable, and (iii) has been properly accounted for in the Company’s financial statements in accordance with U.S. generally accepted accounting principles;

(u) subsequent to the respective dates as of which information is given in the Registration Statement, the Preliminary Prospectuses, the Prospectus and the Permitted Free Writing Prospectuses, if any, except as disclosed therein, in each case excluding any amendments or supplements to the foregoing made after the execution of this Agreement, there has not been (i) any material adverse change, or any development involving a prospective material adverse change, in the business, properties, management, financial condition or results of operations of the Company and the Subsidiaries taken as a whole, (ii) any transaction which is material to the Company and the Subsidiaries taken as a whole, (iii) any obligation or liability, direct or contingent (including any off-balance sheet obligations), incurred by the Company or any Subsidiary, which is material to the Company and the Subsidiaries taken as a whole, (iv) any change in the capital stock or material change in outstanding indebtedness of the Company or any Subsidiaries or (v) any dividend or distribution of any kind declared, paid or made on the capital stock of the Company or any Subsidiary;

(v) the Company has obtained for the benefit of the Underwriters the agreement (a “Lock-Up Agreement”), in the form set forth as Exhibit A hereto, of (i) each of its directors and “officers” (within the meaning of Rule 16a-1(f) under the Exchange Act) and (ii) each security holder (and each “group,” within the meaning of Rule 13d-5(b)(1) under the Exchange Act, of security holders) of the Company holding in the aggregate at least 5% of the outstanding shares of Common Stock (treating, for purposes of this Section 3(v), each holder of any security convertible into or exercisable or exchangeable for shares of Common Stock or any warrant or other right to acquire shares of Common Stock or any such security as a holder of the shares of Common Stock underlying such security, warrant or right (but not treating any such underlying shares as “outstanding” for purposes of determining whether the shares attributable to such security holder or group constitute at least 5% of the outstanding shares of Common Stock));

(w) neither the Company nor any Subsidiary is, and at no time during which a prospectus is required by the Act to be delivered (whether physically or through compliance with Rule 172 under the Act or any similar rule) in connection with any sale of Shares will

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either of them be, and, after giving effect to the offering and sale of the Shares and the application of the proceeds thereof, neither of them will be, an “investment company” or an entity “controlled” by an “investment company,” as such terms are defined in the Investment Company Act of 1940, as amended (the “Investment Company Act”);

(x) the Company and each of the Subsidiaries have good title to all property (real and personal) described in the Registration Statement, the Preliminary Prospectuses, the Prospectus and the Permitted Free Writing Prospectuses, if any, as being owned by any of them, except as disclosed in the Registration Statement (excluding the exhibits thereto), each Preliminary Prospectus and the Prospectus or as would not materially and adversely affect the value of such property in the aggregate and would not materially interfere with the use made or proposed to be made of such property by the Company or the Subsidiaries, free and clear of all liens, claims, security interests or other encumbrances; all the property described in the Registration Statement, the Preliminary Prospectuses, the Prospectus and the Permitted Free Writing Prospectuses, if any, as being held under lease by the Company or a Subsidiary is held thereby under valid and subsisting leases enforceable by the Company or a Subsidiary, as applicable;

(y) the Company and the Subsidiaries own, or have obtained valid and enforceable licenses for, or other rights to use, the inventions, patent applications, patents, trademarks (both registered and unregistered), tradenames, service names, copyrights, trade secrets and other proprietary information described in the Registration Statement, the Preliminary Prospectuses, the Prospectus and the Permitted Free Writing Prospectuses, if any, as being owned or licensed by them or which are necessary for the conduct of their respective businesses as currently conducted as described in the Registration Statement, the Preliminary Prospectuses, the Prospectus and the Permitted Free Writing Prospectuses, if any, or for the commercialization of processes, products or services described in the Registration Statement, the Preliminary Prospectuses, the Prospectus and the Permitted Free Writing Prospectuses, if any, except where the failure to own, license or have such rights would not, individually or in the aggregate, have a Material Adverse Effect (collectively, “Intellectual Property”); (i) there are no third parties who have or, to the Company’s knowledge, will be able to establish rights to any Intellectual Property owned by the Company or any of its Subsidiaries (the “Company Intellectual Property”); (ii) to the Company’s knowledge, there is no infringement by third parties of any Company Intellectual Property; (iii) there is no pending or, to the Company’s knowledge, threatened action, suit, proceeding or claim by others challenging the Company’s rights in or to any Intellectual Property, and the Company is unaware of any facts which could form a reasonable basis for any such action, suit, proceeding or claim; (iv) there is no pending or, to the Company’s knowledge, threatened action, suit, proceeding or claim by others challenging the validity, enforceability or scope of any Company Intellectual Property, and the Company is unaware of any facts which could form a reasonable basis for any such action, suit, proceeding or claim; (v) there is no pending or, to the Company’s knowledge, threatened action, suit, proceeding or claim by others that the Company or any Subsidiary infringes or otherwise violates, or would, upon the commercialization of any product or service described in the Registration Statement, the Preliminary Prospectuses, the Prospectus and the Permitted Free Writing Prospectuses, if any, as under development, infringe or violate, any patent, trademark, tradename, service name, copyright, trade secret or other proprietary rights of others, and the Company is unaware of any facts which could form a reasonable basis for any such action, suit, proceeding or claim; (vi) the Company and

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the Subsidiaries have complied with the terms of each agreement pursuant to which Intellectual Property has been licensed to the Company or any Subsidiary, and all such agreements are in full force and effect; (vii) there is no patent or, to the Company’s knowledge, patent application that contains claims that interfere with the issued or pending claims of any of the Company Intellectual Property or that challenges the validity, enforceability or scope of any of the Company Intellectual Property; and (viii) there is no prior art that may render any patent application within the Company Intellectual Property unpatentable that has not been disclosed to the U.S. Patent and Trademark Office;

(z) neither the Company nor any of the Subsidiaries is engaged in any unfair labor practice; except for matters which would not, individually or in the aggregate, have a Material Adverse Effect, (i) there is (A) no unfair labor practice complaint pending or, to the Company’s knowledge, threatened against the Company or any of the Subsidiaries before the National Labor Relations Board, and no grievance or arbitration proceeding arising out of or under collective bargaining agreements is pending or, to the Company’s knowledge, threatened, (B) no strike, labor dispute, slowdown or stoppage pending or, to the Company’s knowledge, threatened against the Company or any of the Subsidiaries and (C) no union representation dispute currently existing concerning the employees of the Company or any of the Subsidiaries, (ii) to the Company’s knowledge, no union organizing activities are currently taking place concerning the employees of the Company or any of the Subsidiaries and (iii) there has been no violation of any federal, state, local or foreign law relating to discrimination in the hiring, promotion or pay of employees, any applicable wage or hour laws or any provision of the Employee Retirement Income Security Act of 1974, as amended, or the rules and regulations promulgated thereunder concerning the employees of the Company or any of the Subsidiaries;

(aa) except as disclosed in the Registration Statement (excluding the exhibits thereto), the Preliminary Prospectus and the Prospectus, the Company and the Subsidiaries and their respective properties, assets and operations are in compliance with, and the Company and each of the Subsidiaries hold all permits, authorizations and approvals required under, Environmental Laws (as defined below), except to the extent that failure to so comply or to hold such permits, authorizations or approvals would not, individually or in the aggregate, have a Material Adverse Effect; except as disclosed in the Registration Statement (excluding the exhibits thereto), the Preliminary Prospectus and the Prospectus, there are no past, present or, to the Company’s knowledge, reasonably anticipated future events, conditions, circumstances, activities, practices, actions, omissions or plans that would reasonably be expected to give rise to any material costs or liabilities to the Company or any Subsidiary under, or to interfere with or prevent compliance in all material respects by the Company or any Subsidiary with, Environmental Laws; except as would not, individually or in the aggregate, have a Material Adverse Effect, neither the Company nor any of the Subsidiaries (i) to the Company’s knowledge, is the subject of any investigation, (ii) has received any written notice or claim, (iii) is a party to any pending or, to the Company’s knowledge, threatened action, suit or proceeding, (iv) to the Company’s knowledge, is affected by any pending or threatened action, suit or proceeding, (v) is bound by any judgment, decree or order regarding any Environmental Law or (vi) has entered into any agreement, in each case relating to any alleged violation of any Environmental Law or any actual or alleged release or threatened release or cleanup at any location of any Hazardous Materials (as defined below) (as used herein, “Environmental Law” means any federal, state, local or foreign law, statute, ordinance, rule, regulation, order, decree,

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judgment, injunction, permit, license, authorization or other binding requirement, or common law, relating to health, safety or the protection, cleanup or restoration of the environment or natural resources, including those relating to the distribution, processing, generation, treatment, storage, disposal, transportation, other handling or release or threatened release of Hazardous Materials, and “Hazardous Materials” means any material (including, without limitation, pollutants, contaminants, hazardous or toxic substances or wastes) that is regulated by or may give rise to liability under any Environmental Law); neither the Company nor any Subsidiary has been named as a “potentially responsible party” under the Comprehensive Environmental Response, Compensation, and Liability Act of 1980, as amended;

(bb) in the ordinary course of their business, the Company and each of the Subsidiaries conduct periodic reviews of the effect of the Environmental Laws on their respective businesses, operations and properties, in the course of which they identify and evaluate associated costs and liabilities (including, without limitation, any capital or operating expenditures required for cleanup, closure of properties or compliance with the Environmental Laws or any permit, license or approval, any related constraints on operating activities and any potential liabilities to third parties); on the basis of such reviews, the Company has reasonably concluded that such associated costs and liabilities would not, singly or in the aggregate, have a Material Adverse Effect;

(cc) except as would not, individually or in the aggregate, have a Material Adverse Effect, all tax returns required to be filed by the Company or any of the Subsidiaries have been timely filed, and all taxes and other assessments of a similar nature (whether imposed directly or through withholding) including any interest, additions to tax or penalties applicable thereto due or claimed to be due from such entities have been timely paid, other than those being contested in good faith and for which adequate reserves have been provided;

(dd) there are no stamp or other issuance or transfer taxes or duties or other similar fees or charges required to be paid in connection with the execution and delivery of this Agreement or the issuance or sale of the Shares;

(ee) the Company and each of the Subsidiaries maintain insurance covering their respective properties, operations, personnel and businesses as the Company reasonably deems adequate; such insurance insures against such losses and risks to an extent which is adequate in accordance with customary industry practice to protect the Company and the Subsidiaries and their respective businesses; all such insurance is fully in force on the date hereof; neither the Company nor any Subsidiary has reason to believe that it will not be able to renew any such insurance as and when such insurance expires;

(ff) neither the Company nor any Subsidiary has sent or received any written communication regarding termination of, or intent not to renew, any of the contracts or agreements referred to or described in any Preliminary Prospectus, the Prospectus or any Permitted Free Writing Prospectus, or referred to or described in, or filed as an exhibit to, the Registration Statement, and no such termination or non-renewal has been threatened by the Company or any Subsidiary or, to the Company’s knowledge, any other party to any such contract or agreement;

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

(hh) the Company has established and maintains and evaluates “disclosure controls and procedures” (as such term is defined in Rules 13a-15 and 15d-15 under the Exchange Act) and “internal control over financial reporting” (as such term is defined in Rules 13a-15 and 15d-15 under the Exchange Act); such disclosure controls and procedures are designed to ensure that material information relating to the Company, including its consolidated subsidiaries, is made known to the Company’s Chief Executive Officer and its Chief Financial Officer by others within those entities, and such disclosure controls and procedures are effective to perform the functions for which they were established; the Company’s independent registered public accountants have been advised of: (i) all significant deficiencies, if any, in the design or operation of internal controls which could adversely affect the Company’s ability to record, process, summarize and report financial data; and (ii) all fraud, if any, whether or not material, that involves management or other employees who have a role in the Company’s internal controls; all material weaknesses, if any, in internal controls have been identified to the Company’s independent registered public accountants; all “significant deficiencies” and “material weaknesses”, if any, (as such terms are defined in Rule 1-02(a)(4) of Regulation S-X under the Act) of the Company have been disclosed in the Registration Statement (excluding the exhibits thereto), each Preliminary Prospectus and the Prospectus; since the date of the most recent evaluation of such disclosure controls and procedures and internal controls, there have been no significant changes in internal controls or in other factors that could significantly affect internal controls, including any corrective actions with regard to significant deficiencies and material weaknesses; and the Company has taken all necessary actions to ensure that, upon and at all times after the filing of the Registration Statement, the Company and the Subsidiaries and their respective officers and directors, in their capacities as such, will be in compliance in all material respects with the applicable provisions of the Sarbanes-Oxley Act of 2002 and the rules and regulations promulgated thereunder;

(ii) each “forward-looking statement” (within the meaning of Section 27A of the Act or Section 21E of the Exchange Act) contained in the Registration Statement, the Preliminary Prospectuses, the Prospectus and the Permitted Free Writing Prospectuses, if any, has been made or reaffirmed with a reasonable basis and in good faith;

(jj) all statistical or market-related data included in the Registration Statement, the Preliminary Prospectuses, the Prospectus and the Permitted Free Writing Prospectuses, if any, are based on or derived from sources that the Company reasonably believes to be reliable and accurate, and the Company has obtained the written consent to the use of such data from such sources to the extent required;

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(kk) neither the Company nor any of the Subsidiaries nor, to the knowledge of the Company, any director, officer, agent, employee or affiliate of the Company or any of the Subsidiaries, is aware of or has taken any action, directly or indirectly, that would result in a violation by such persons of the Foreign Corrupt Practices Act of 1977, as amended, and the rules and regulations thereunder; and the Company, the Subsidiaries and, to the knowledge of the Company, its affiliates have instituted and maintain policies and procedures designed to ensure continued compliance therewith;

(ll) the operations of the Company and the 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 applicable to the Company or the Subsidiaries, the rules and regulations thereunder and any related or similar rules, regulations or guidelines applicable to the Company or the Subsidiaries, 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 or non-governmental authority involving the Company or any of the Subsidiaries with respect to the Money Laundering Laws is pending or, to the Company’s knowledge, threatened;

(mm) neither the Company nor any of the Subsidiaries nor, to the knowledge of the Company, any director, officer, agent, employee or affiliate of the Company or any of the Subsidiaries is currently subject to any U.S. sanctions administered by the Office of Foreign Assets Control of the U.S. Treasury Department (“OFAC”); and the Company will not directly or indirectly use the proceeds of the offering of the Shares contemplated hereby, 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;

(nn) no Subsidiary is currently prohibited, directly or indirectly, 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 property or assets to the Company or any other Subsidiary of the Company, except as described in the Registration Statement (excluding the exhibits thereto), each Preliminary Prospectus and the Prospectus;

(oo) other than pursuant to the warrant to purchase 13,992 shares of the Company’s Series B Preferred Stock issued on April 30, 2008 to Silicon Valley Bank, as amended on June 28, 2011 and December 29, 2011, the issuance and sale of the Shares as contemplated hereby will not cause any holder of any shares of capital stock, securities convertible into or exchangeable or exercisable for capital stock or options, warrants or other rights to purchase capital stock or any other securities of the Company to have any right to acquire any shares of preferred stock of the Company;

(pp) except pursuant to this Agreement, neither the Company nor any of the Subsidiaries has incurred any liability for any finder’s or broker’s fee or agent’s commission in connection with the execution and delivery of this Agreement or the consummation of the transactions contemplated hereby or by the Registration Statement;

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(qq) neither the Company nor any of the Subsidiaries nor any of their respective directors, officers, affiliates or controlling persons has taken, directly or indirectly, any action designed, or which has constituted or might reasonably be expected to cause or result in the stabilization or manipulation of the price of any security of the Company to facilitate the sale or resale of the Shares;

(rr) to the Company’s knowledge, there are no affiliations or associations between (i) any member of FINRA and (ii) the Company or any of the Company’s officers, directors or 5% or greater security holders or any beneficial owner of the Company’s unregistered equity securities that were acquired at any time on or after the 180th day immediately preceding the date the Registration Statement was initially filed with the Commission, except as disclosed in the Registration Statement (excluding the exhibits thereto), the Preliminary Prospectuses and the Prospectus;

(ss) each of the Amended and Restated Stockholder Agreement, dated December 1, 2008, between the Company and each investor listed on Schedule A thereto and each of the other Stockholders (as defined in the Stockholder Agreement) who has executed a signature page thereto (the “Stockholder Agreement”), and the Amended and Restated Rights Agreement, dated December 1, 2008, between the Company and each investor listed on Schedule A thereto and each of the other Common Investors (as defined in the Stockholder Rights Agreement) who has executed a signature page thereto (the “Stockholder Rights Agreement”), has been duly authorized, executed and delivered by the Company and constitutes a valid and legally binding agreement of the Company enforceable against the Company in accordance with its terms, except as enforceability may be limited by applicable bankruptcy, insolvency or similar laws affecting creditors’ rights generally or by equitable principles relating to enforceability;

(tt) the Company has given notice (in accordance with Section 6.5 of the Stockholder Rights Agreement and Section 11.6 of the Stockholder Agreement) to the Stockholders (as defined in the Stockholder Rights Agreement and Stockholder Agreement) that the date specified by the Company and the Managing Underwriter as the date on which the Market Stand-Off Period (as defined in the Stockholder Rights Agreement and Stockholder Agreement) will end shall be 180 days following the date of the Prospectus;

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(uu) The information underlying the estimates of the natural gas reserves of the Company and its Subsidiaries as described in the Registration Statement, each Preliminary Prospectus, the Prospectus and each Permitted Free Writing Prospectus, is complete and accurate in all material respects; other than production of the Company’s reserves in the ordinary course of business and intervening product price fluctuations described in the Registration Statement, each Preliminary Prospectus, the Prospectus and each Permitted Free Writing Prospectus, the Company is not aware of any facts or circumstances that, taken together, would have a Material Adverse Effect on such reserves or the present value of future net cash flows therefrom as described in the Registration Statement, each Preliminary Prospectus, the Prospectus and each Permitted Free Writing Prospectus. Estimates of such reserves and present values comply in all material respects with the applicable requirements of Regulation S-X and Industry Guide 2 under the Act; and

(vv) Ryder Scott Company, L.P., the petroleum engineers who have consented to being named as having audited certain reserve data included in the Registration Statement, each Preliminary Prospectus, the Prospectus and each Permitted Free Writing Prospectus, are independent petroleum engineers with respect to the Company and its Subsidiaries. The information underlying the estimates of natural gas reserves of the Company and its Subsidiaries, which the Company prepared and supplied to Ryder Scott Company, L.P. for the purpose of preparing the report referred to in the Registration Statement, each Preliminary Prospectus, the Prospectus and each Permitted Free Writing Prospectus was true and correct in all material respects on the dates such estimates were made and such information was supplied and was prepared in accordance with customary industry practices.

In addition, any certificate signed by any officer of the Company and delivered to any Underwriter or counsel for the Underwriters in connection with the offering of the Shares shall be deemed to be a representation and warranty by the Company, as to matters covered thereby, to each Underwriter.

4. Certain Covenants of the Company. The Company hereby agrees:

(a) to furnish such information as may be required and otherwise to cooperate in qualifying the Shares for offering and sale under the securities or blue sky laws of such states or other jurisdictions as you may designate and to maintain such qualifications in effect so long as you may request for the distribution of the Shares; provided, however, that the Company shall not be required to qualify as a foreign corporation, to subject itself to taxation in any foreign jurisdiction or to consent to the service of process under the laws of any such jurisdiction (except service of process with respect to the offering and sale of the Shares); and to promptly advise you of the receipt by the Company of any notification with respect to the suspension of the qualification of the Shares for offer or sale in any jurisdiction or the initiation or threatening of any proceeding for such purpose;

(b) to make available to the Underwriters in New York City, as soon as

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practicable after this Agreement becomes effective, and thereafter from time to time to furnish to the Underwriters, as many copies of the Prospectus (or of the Prospectus as amended or supplemented if the Company shall have made any amendments or supplements thereto after the effective date of the Registration Statement) as the Underwriters may reasonably request for the purposes contemplated by the Act; in case any Underwriter is required to deliver (whether physically or through compliance with Rule 172 under the Act or any similar rule), in connection with the sale of the Shares, a prospectus after the nine-month period referred to in Section 10(a)(3) of the Act, the Company will prepare, at its expense, promptly upon request such amendment or amendments to the Registration Statement and the Prospectus as may be necessary to permit compliance with the requirements of Section 10(a)(3) of the Act;

(c) if, at the time this Agreement is executed and delivered, it is necessary for a post-effective amendment to the Registration Statement, or a Registration Statement under Rule 462(b) under the Act, to be filed with the Commission and become effective before the Shares may be sold, the Company will use its best efforts to cause such post-effective amendment or such Registration Statement to be filed and become effective, and will pay any applicable fees in accordance with the Act, as soon as possible; and the Company will advise you promptly and, if requested by you, will confirm such advice in writing, (i) when such post-effective amendment or such Registration Statement has become effective, and (ii) if Rule 430A under the Act is used, when the Prospectus is filed with the Commission pursuant to Rule 424(b) under the Act (which the Company agrees to file in a timely manner in accordance with such Rules);

(d) to advise you promptly, confirming such advice in writing, of any request by the Commission for amendments or supplements to the Registration Statement or the Exchange Act Registration Statement, any Preliminary Prospectus, the Prospectus or any Permitted Free Writing Prospectus or for additional information with respect thereto, or of notice of institution of proceedings for, or the entry of a stop order, suspending the effectiveness of the Registration Statement and, if the Commission should enter a stop order suspending the effectiveness of the Registration Statement, to use its best efforts to obtain the lifting or removal of such order as soon as possible; to advise you promptly of any proposal to amend or supplement the Registration Statement or the Exchange Act Registration Statement, any Preliminary Prospectus or the Prospectus, and to provide you and Underwriters’ counsel copies of any such documents for review and comment a reasonable amount of time prior to any proposed filing and to file no such amendment or supplement to which you shall reasonably object in writing;

(e) subject to Section 4(d) hereof, to timely file all reports and documents and any preliminary or definitive proxy or information statement required to be filed by the Company with the Commission in order to comply with the Exchange Act for so long as a prospectus is required by the Act to be delivered (whether physically or through compliance with Rule 172 under the Act or any similar rule) in connection with any sale of Shares; and to provide you with a copy of such reports and statements and other documents to be filed by the Company pursuant to Section 13, 14 or 15(d) of the Exchange Act during such period a reasonable amount of time prior to any proposed filing, and, except as reasonably determined by Company counsel to be required by law, to file no such report, statement or document to which you shall have reasonably objected in writing; and to promptly notify you of such filing;

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(f) to advise the Underwriters promptly of the happening of any event known to the Company within the period during which a prospectus is required by the Act to be delivered (whether physically or through compliance with Rule 172 under the Act or any similar rule) in connection with any sale of Shares, which event would require the making of any change in the Prospectus then being used so that the Prospectus would not include an untrue statement of a material fact or omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances under which they are made, not misleading, and to advise the Underwriters promptly if, during such period, it shall become necessary to amend or supplement the Prospectus to cause the Prospectus to comply with the requirements of the Act, and, in each case, during such time, subject to Section 4(d) hereof, to prepare and furnish, at the Company’s expense, to the Underwriters promptly such amendments or supplements to such Prospectus as may be necessary to reflect any such change or to effect such compliance;

(g) to make generally available to its security holders, and if not available on the Commission’s Electronic Data Gathering, Analysis, and Retrieval system (“EDGAR”), to deliver to you, an earnings statement of the Company (which will satisfy the provisions of Section 11(a) of the Act) covering a period of twelve months beginning after the effective date of the Registration Statement (as defined in Rule 158(c) under the Act) as soon as is reasonably practicable after the termination of such twelve-month period but in any case not later than [__];

(h) to furnish to you four copies of the Registration Statement (one copy for each Managing Underwriter and one copy for Underwriters’ counsel), as initially filed with the Commission, and of all amendments thereto (including all exhibits thereto) and sufficient copies of the foregoing (other than exhibits) for distribution of a copy to each of the other Underwriters;

(i) to furnish to you as early as practicable prior to the time of purchase and any additional time of purchase, as the case may be, but not later than two business days prior thereto, a copy of the latest available unaudited interim and monthly consolidated financial statements, if any, of the Company and the Subsidiaries which have been read by Ernst & Young LLP, as stated in their letter to be furnished pursuant to Section 6(e) hereof;

(j) to apply the net proceeds in the manner set forth under “Use of proceeds” in the Prospectus and to file such reports with the Commission with respect to the sale of the Shares and the application of the proceeds therefrom as may be required by Rule 463 under the Act;

(k) to pay all costs, expenses, fees and taxes in connection with (i) the preparation and filing of the Registration Statement, each Preliminary Prospectus, the Prospectus, each Permitted Free Writing Prospectus and any amendments or supplements thereto, and the printing and furnishing of copies of each thereof to the Underwriters and to dealers (including costs of mailing and shipment), (ii) the registration, issue, sale and delivery of the Shares including any stock or transfer taxes and stamp or similar duties payable upon the sale, issuance or delivery of the Shares to the Underwriters, (iii) the producing, word processing and/or printing of this Agreement, any Agreement Among Underwriters, any dealer agreements, any Powers of Attorney and any closing documents

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(including compilations thereof) and the reproduction and/or printing and furnishing of copies of each thereof to the Underwriters and (except closing documents) to dealers (including costs of mailing and shipment), (iv) the qualification of the Shares for offering and sale under state or foreign laws and the determination of their eligibility for investment under state or foreign law (including the reasonable legal fees and filing fees and other disbursements of counsel for the Underwriters incurred in connection with such qualifications and determinations) and the printing and furnishing of copies of any blue sky surveys or legal investment surveys to the Underwriters and to dealers, (v) any listing of the Shares on any securities exchange or qualification of the Shares for quotation on the NASDAQ and any registration thereof under the Exchange Act, (vi) any filing for review of the public offering of the Shares by FINRA, including the reasonable legal fees and filing fees and other disbursements of counsel to the Underwriters relating to FINRA matters, (vii) the fees and disbursements of any transfer agent or registrar for the Shares, (viii) the fees and expenses of the Company’s accountants and the fees and expenses of counsel (including local and special counsel) for the Company, (ix) the costs and expenses of the Company relating to presentations or meetings undertaken in connection with the marketing of the offering and sale of the Shares to prospective investors and the Underwriters’ sales forces, including, without limitation, expenses associated with the production of road show slides and graphics, fees and expenses of any consultants engaged in connection with the road show presentations, travel, lodging and other expenses incurred by the officers of the Company and any such consultants (provided, however, that the costs of any aircraft chartered for the road show shall be borne 50% by the Underwriters), (x) the costs and expenses of qualifying the Shares for inclusion in the book-entry settlement system of the DTC, (xi) the preparation and filing of the Exchange Act Registration Statement, including any amendments thereto and (xii) the performance of the Company’s other obligations hereunder;

(l) to comply with Rule 433(d) under the Act (without reliance on Rule 164(b) under the Act) and with Rule 433(g) under the Act;

(m) beginning on the date hereof and ending on, and including, the date that is 180 days after the date of the Prospectus (the “Lock-Up Period”), without the prior written consent of Citigroup, not to (i) issue, sell, offer to sell, contract or agree to sell, hypothecate, pledge, grant any option to purchase or otherwise dispose of or agree to dispose of, directly or indirectly, or establish or increase a put equivalent position or liquidate or decrease a call equivalent position within the meaning of Section 16 of the Exchange Act and the rules and regulations of the Commission promulgated thereunder, with respect to, any Common Stock or any other securities of the Company that are substantially similar to Common Stock, or any securities convertible into or exchangeable or exercisable for, or any warrants or other rights to purchase, the foregoing, (ii) file or cause to become effective a registration statement under the Act relating to the offer and sale of any Common Stock or any other securities of the Company that are substantially similar to Common Stock, or any securities convertible into or exchangeable or exercisable for, or any warrants or other rights to purchase, the foregoing, (iii) enter into any swap or other arrangement that transfers to another, in whole or in part, any of the economic consequences of ownership of Common Stock or any other securities of the Company that are substantially similar to Common Stock, or any securities convertible into or exchangeable or exercisable for, or any warrants

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or other rights to purchase, the foregoing, whether any such transaction is to be settled by delivery of Common Stock or such other securities, in cash or otherwise or (iv) publicly announce an intention to effect any transaction specified in clause (i), (ii) or (iii), except, in each case, for (A) the registration of the offer and sale of the Shares as contemplated by this Agreement, (B) issuances of Common Stock upon the exercise of options or warrants disclosed as outstanding in the Registration Statement (excluding the exhibits thereto), each Preliminary Prospectus and the Prospectus, (C) the issuance to employees, directors or consultants of restricted stock grants or stock options not exercisable during the Lock-Up Period pursuant to equity incentive plans described in the Registration Statement (excluding the exhibits thereto), each Preliminary Prospectus and the Prospectus, (D) the filing of registration statements on Form S-8 relating to shares of Common Stock which may be issued pursuant to existing equity incentive plans and (E) the issuance and sale by the Company of shares of Common Stock in connection with any acquisitions or strategic investments (including joint ventures, strategic alliances or partnerships) as long as (i) the number of shares issued does not exceed 10% of the number of shares of Common Stock outstanding immediately after the issuance and sale of the Shares (after giving effect to the conversion of all shares of convertible preferred stock outstanding as of the date of such issuance and sale), and (ii) each of the recipients of any such shares execute a Lock-Up Agreement for the remainder of the Lock-Up Period; provided, however, that if (a) during the period that begins on the date that is fifteen (15) calendar days plus three (3) business days before the last day of the Lock-Up Period and ends on the last day of the Lock-Up Period, the Company issues an earnings release or material news or a material event relating to the Company occurs; or (b) prior to the expiration of the Lock-Up Period, the Company announces that it will release earnings results during the sixteen (16) day period beginning on the last day of the Lock-Up Period, then the restrictions imposed by this Section 4(m) shall continue to apply until the expiration of the date that is fifteen (15) calendar days plus three (3) business days after the date on which the issuance of the earnings release or the material news or material event occurs; if Citigroup, in its sole discretion, agrees to release or waive the restrictions set forth in a Lock-Up Agreement for an officer or director of the Company and provides the Company with notice of the impending release or waiver at least three Business Days before the effective date of the release or waiver, the Company agrees to announce the impending release or waiver by a press release substantially in the form of Exhibit A-1 hereto through a major news service at least two Business Days before the effective date of the release or waiver.

(n) to provide notice to each 5% or greater security holder who has executed a Lock-Up Agreement if (a) during the period that begins on the date that is fifteen (15) calendar days plus three (3) business days before the last day of the Lock-Up Period and ends on the last day of the Lock-Up Period, the Company issues an earnings release or material news or a material event relating to the Company occurs; or (b) prior to the expiration of the Lock-Up Period, the Company announces that it will release earnings results during the sixteen (16) day period beginning on the last day of the Lock-Up Period; any failure by the Company to provide such notice will not excuse a breach of the Lock-Up Agreements;

(o) prior to the time of purchase or any additional time of purchase, as the case may be, except as may be required by law, to issue no press release or other communication directly or indirectly and hold no press conferences with respect to the Company or any

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Subsidiary, the financial condition, results of operations, business, properties, assets, or liabilities of the Company or any Subsidiary, or the offering of the Shares, without your prior consent (such consent not to be unreasonably withheld);

(p) not, at any time at or after the execution of this Agreement, to, directly or indirectly, offer or sell any Shares by means of any “prospectus” (within the meaning of the Act), or use any “prospectus” (within the meaning of the Act) in connection with the offer or sale of the Shares, in each case other than the Prospectus;

(q) not to, and to cause the Subsidiaries not to, take, directly or indirectly, any action designed, or which will constitute, or has constituted, or might reasonably be expected to cause or result in the stabilization or manipulation of the price of any security of the Company to facilitate the sale or resale of the Shares;

(r) to use its best efforts to cause the Common Stock, including the Shares, to be listed on the NASDAQ and to maintain such listing;

(s) to maintain a transfer agent and, if necessary under the jurisdiction of incorporation of the Company, a registrar for the Common Stock;

(t) to provide to the transfer agent a list of all stockholders of the Company that are subject to the Stockholder Agreement and/or the Stockholder Rights Agreement;

(u) not to, during the Lock-Up Period, amend Section 9.1 of, or the definition of “Market Stand-Off Period” in, the Stockholder Agreement or waive any of, or release any person from, the restrictions thereunder without the prior written consent of Citigroup; and

(v) not to, during the Lock-Up Period, amend Section 2.11 of, or the definition of “Market Stand-Off Period” in, the Stockholder Rights Agreement or waive any of, or release any person from, the restrictions thereunder without the prior written consent of Citigroup.

5. Reimbursement of the Underwriters’ Expenses. If, after the execution and delivery of this Agreement, the sale to the Underwriters of the Shares at the time of purchase or any additional time of purchase is not consummated because (i) of any refusal, inability or failure on the part of the Company to perform any agreement herein or to comply with any provision hereof, (ii) since the time of execution of this Agreement or the earlier respective dates as of which information is given in the Registration Statement, the Preliminary Prospectuses, the Prospectus and the Permitted Free Writing Prospectuses, if any, there has been any change or any development involving a prospective change

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in the business, properties, management, financial condition or results of operations of the Company and the Subsidiaries taken as a whole, the effect of which change or development is, in the sole judgment of the Representatives, so material and adverse as to make it impractical or inadvisable to proceed with the public offering or the delivery of the Shares on the terms and in the manner contemplated in the Registration Statement, the Preliminary Prospectuses, the Prospectus and the Permitted Free Writing Prospectuses, if any, (iii) since the time of execution of this Agreement, there shall have occurred a suspension or material limitation in trading in the Company’s securities on the NASDAQ or (iv) there shall have occurred any downgrading, or any notice or announcement shall have been given or made of: (A) any intended or potential downgrading, (B) any watch, review or possible change that does not indicate an affirmation or improvement in the rating accorded any securities of or guaranteed by the Company or any Subsidiary by any “nationally recognized statistical rating organization,” as such term is defined in Section 3(a)(62) of the Exchange Act, the Company shall, in addition to paying the amounts described in Section 4(k) hereof, reimburse the Underwriters for all of their reasonably incurred out-of-pocket expenses, including the reasonable fees and disbursements of their counsel.

6. Conditions of the Underwriters’ Obligations. The several obligations of the Underwriters hereunder are subject to the accuracy of the representations and warranties on the part of the Company on the date hereof, at the time of purchase and, if applicable, at the additional time of purchase, the performance by the Company of its obligations hereunder and to the following additional conditions precedent:

(a) The Company shall furnish to you at the time of purchase and, if applicable, at the additional time of purchase, an opinion of Porter Hedges LLP, counsel for the Company, addressed to the Underwriters, and dated the time of purchase or the additional time of purchase, as the case may be, with executed copies for each Underwriter, and in form and substance satisfactory to the Representatives, in the form set forth in Exhibit B hereto.

(b) The Company shall furnish to you at the time of purchase and, if applicable, at the additional time of purchase, an opinion of Kilpatrick Townsend & Stockton LLP, special counsel for the Company with respect to patents and proprietary rights, addressed to the Underwriters, and dated the time of purchase or the additional time of purchase, as the case may be, with executed copies for each Underwriter, and in form and substance satisfactory to the Representatives, in the form set forth in Exhibit C hereto.

(c) The Company shall furnish to you at the time of purchase and, if applicable, at the additional time of purchase, an opinion of Holland & Hart LLP, special counsel for the Company with respect to regulatory matters, addressed to the Underwriters, and dated the time of purchase or the additional time of purchase, as the case may be, with executed copies for each Underwriter, and in form and substance satisfactory to the Representatives, in the form set forth in Exhibit D hereto.

(d) The Company shall furnish to you at the time of purchase and, if applicable, at the additional time of purchase, an opinion of Matt Micheli, Senior Corporate Counsel of the Company, addressed to the Underwriters, and dated the time of purchase or the additional time of purchase, as the case may be, with executed copies for each Underwriter, and in form and substance satisfactory to the Representatives, in the form set forth in Exhibit E hereto.

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(e) You shall have received from Ernst & Young LLP letters dated, respectively, the date of this Agreement, the date of the Prospectus, the time of purchase and, if applicable, the additional time of purchase, and addressed to the Underwriters (with executed copies for each Underwriter) in the forms satisfactory to the Representatives, which letters shall cover certain financial disclosures contained in the Registration Statement, the Preliminary Prospectus, the Prospectus and the Permitted Free Writing Prospectuses, if any.

(f) You shall have received from Ehrhardt Keefe Steiner & Hottman PC letters dated, respectively, the date of this Agreement, the date of the Prospectus, the time of purchase and, if applicable, the additional time of purchase, and addressed to the Underwriters (with executed copies for each Underwriter) in the forms satisfactory to the Representatives, which letters shall cover certain financial disclosures contained in the Registration Statement, the Preliminary Prospectus, the Prospectus and the Permitted Free Writing Prospectuses, if any.

(g) You shall have received from Ryder Scott Company, L.P. letters dated, respectively, the date of this Agreement, the date of the Prospectus, the time of purchase and, if applicable, the additional time of purchase, and addressed to the Underwriters (with executed copies for each Underwriter) in the forms satisfactory to the Representatives, which letters shall cover certain proved reserves, future production and discounted future net income disclosures contained in the Registration Statement, the Preliminary Prospectus, the Prospectus and the Permitted Free Writing Prospectuses, if any.

(h) You shall have received at the time of purchase and, if applicable, at the additional time of purchase, the favorable opinion of Davis Polk & Wardwell LLP, counsel for the Underwriters, dated the time of purchase or the additional time of purchase, as the case may be, in form and substance reasonably satisfactory to the Representatives.

(i) No Prospectus or amendment or supplement to the Registration Statement or the Prospectus shall have been filed to which you shall have objected in writing.

(j) The Registration Statement, the Exchange Act Registration Statement and any registration statement required to be filed, prior to the sale of the Shares, under the Act pursuant to Rule 462(b) shall have been filed and shall have become effective under the Act or the Exchange Act, as the case may be. If Rule 430A under the Act is used, the Prospectus shall have been filed with the Commission pursuant to Rule 424(b) under the Act at or before 5:30 P.M., New York City time, on the second full business day after the date of this Agreement (or such earlier time as may be required under the Act).

(k) Prior to and at the time of purchase, and, if applicable, the additional time of purchase, (i) no stop order with respect to the effectiveness of the Registration Statement shall have been issued under the Act or proceedings initiated under Section 8(d) or 8(e) of the Act; (ii) the Registration Statement and all amendments thereto shall not contain an untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein not misleading; (iii) none of the

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Preliminary Prospectuses or the Prospectus, and no amendment or supplement thereto, shall include an untrue statement of a material fact or omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances under which they are made, not misleading; (iv) no Disclosure Package, and no amendment or supplement thereto, shall include an untrue statement of a material fact or omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances under which they are made, not misleading; and (v) none of the Permitted Free Writing Prospectuses, together with the Disclosure Package including the then most recent Preliminary Prospectus, if any, shall include an untrue statement of a material fact or omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances under which they are made, not misleading.

(l) The Company will, at the time of purchase and, if applicable, at the additional time of purchase, deliver to you a certificate of its Chief Executive Officer and its Chief Financial Officer, dated the time of purchase or the additional time of purchase, as the case may be, in the form attached as Exhibit F hereto.

(m) You shall have received each of the signed Lock-Up Agreements referred to in Section 3(v) hereof, and each such Lock-Up Agreement shall be in full force and effect at the time of purchase and the additional time of purchase, as the case may be.

(n) The Shares shall have been approved for listing on the NASDAQ, subject only to notice of issuance and evidence of satisfactory distribution at or prior to the time of purchase or the additional time of purchase, as the case may be.

(o) FINRA shall not have raised any objection with respect to the fairness or reasonableness of the underwriting, or other arrangements of the transactions, contemplated hereby.

7. Effective Date of Agreement; Termination. This Agreement shall become effective when the parties hereto have executed and delivered this Agreement.

The obligations of the several Underwriters hereunder shall be subject to termination in the absolute discretion of the Representatives, if (1) since the time of execution of this Agreement or the earlier respective dates as of which information is given in the Registration Statement, the Preliminary Prospectuses, the Prospectus and the Permitted Free Writing Prospectuses, if any, there has been any change or any development involving a prospective change in the business, properties, management, financial condition or results of operations of the Company and the Subsidiaries taken as a whole, the effect of which change or development is, in the sole judgment of the Representatives, so material and adverse as to make it impractical or inadvisable to proceed with the public offering or the delivery of the Shares on the terms and in the manner contemplated in the Registration Statement, the Preliminary Prospectuses, the Prospectus and the Permitted Free Writing Prospectuses, if any, or (2) since the time of execution of this Agreement, there shall have occurred: (A) a suspension or material limitation in trading in securities generally on the NYSE, the NYSE Amex or the NASDAQ; (B) a suspension or material limitation in trading in the Company’s securities on the NASDAQ; (C) a general moratorium on commercial banking activities declared by either federal or New York State authorities or a material disruption in commercial banking or securities settlement or clearance services in the United States; (D) an outbreak or escalation of hostilities or acts of terrorism involving the United States or a declaration by the United States of a

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national emergency or war; or (E) any other calamity or crisis or any change in financial, political or economic conditions in the United States or elsewhere, if the effect of any such event specified in clause (D) or (E), in the sole judgment of the Representatives, makes it impractical or inadvisable to proceed with the public offering or the delivery of the Shares on the terms and in the manner contemplated in the Registration Statement, the Preliminary Prospectuses, the Prospectus and the Permitted Free Writing Prospectuses, if any, or (3) since the time of execution of this Agreement, there shall have occurred any downgrading, or any notice or announcement shall have been given or made of: (A) any intended or potential downgrading or (B) any watch, review or possible change that does not indicate an affirmation or improvement in the rating accorded any securities of or guaranteed by the Company or any Subsidiary by any “nationally recognized statistical rating organization,” as such term is defined in Section 3(a)(62) of the Exchange Act.

If the Representatives elect to terminate this Agreement as provided in this Section 7, the Company and each other Underwriter shall be notified promptly in writing.

If the sale to the Underwriters of the Shares, as contemplated by this Agreement, is not carried out by the Underwriters for any reason permitted under this Agreement, or if such sale is not carried out because the Company shall be unable to comply with any of the terms of this Agreement, the Company shall not be under any obligation or liability under this Agreement (except to the extent provided in Sections 4(k), 5 and 9 hereof), and the Underwriters shall be under no obligation or liability to the Company under this Agreement (except to the extent provided in Section 9 hereof) or to one another hereunder.

8. Increase in Underwriters’ Commitments. Subject to Sections 6 and 7 hereof, if any Underwriter shall default in its obligation to take up and pay for the Firm Shares to be purchased by it hereunder (otherwise than for a failure of a condition set forth in Section 6 hereof or a reason sufficient to justify the termination of this Agreement under the provisions of Section 7 hereof) and if the number of Firm Shares which all Underwriters so defaulting shall have agreed but failed to take up and pay for does not exceed 10% of the total number of Firm Shares, the non-defaulting Underwriters (including the Underwriters, if any, substituted in the manner set forth below) shall take up and pay for (in addition to the aggregate number of Firm Shares they are obligated to purchase pursuant to Section 1 hereof) the number of Firm Shares agreed to be purchased by all such defaulting Underwriters, as hereinafter provided. Such Shares shall be taken up and paid for by such non-defaulting Underwriters in such amount or amounts as you may designate with the consent of each Underwriter so designated or, in the event no such designation is made, such Shares shall be taken up and paid for by all non-defaulting Underwriters pro rata in proportion to the aggregate number of Firm Shares set forth opposite the names of such non-defaulting Underwriters in Schedule A.

Without relieving any defaulting Underwriter from its obligations hereunder, the Company agrees with the non-defaulting Underwriters that it will not sell any Firm Shares hereunder unless all of the Firm Shares are purchased by the Underwriters (or by substituted Underwriters selected by you with the approval of the Company or selected by the Company with your approval).

If a new Underwriter or Underwriters are substituted by the Underwriters or by the Company for a defaulting Underwriter or Underwriters in accordance with the foregoing provision, the Company or you shall have the right to postpone the time of purchase for a period not exceeding five business days in order that any necessary changes in the Registration Statement and the Prospectus and other documents may be effected.

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The term “Underwriter” as used in this Agreement shall refer to and include any Underwriter substituted under this Section 8 with like effect as if such substituted Underwriter had originally been named in Schedule A hereto.

If the aggregate number of Firm Shares which the defaulting Underwriter or Underwriters agreed to purchase exceeds 10% of the total number of Firm Shares which all Underwriters agreed to purchase hereunder, and if neither the non-defaulting Underwriters nor the Company shall make arrangements within the five business day period stated above for the purchase of all the Firm Shares which the defaulting Underwriter or Underwriters agreed to purchase hereunder, this Agreement shall terminate without further act or deed and without any liability on the part of the Company to any Underwriter and without any liability on the part of any non-defaulting Underwriter to the Company. Nothing in this paragraph, and no action taken hereunder, shall relieve any defaulting Underwriter from liability in respect of any default of such Underwriter under this Agreement.

9. Indemnity and Contribution.

(a) The Company agrees to indemnify, defend and hold harmless each Underwriter, its agents, partners, directors, officers and members, any person who controls any Underwriter within the meaning of Section 15 of the Act or Section 20 of the Exchange Act, and any “affiliate” (within the meaning of Rule 405 under the Act) of such Underwriter, and the successors and assigns of all of the foregoing persons, from and against any loss, damage, expense, liability or claim (including the reasonable cost of investigation) which, jointly or severally, any such Underwriter or any such person may incur under the Act, the Exchange Act, the common law or otherwise, insofar as such loss, damage, expense, liability or claim arises out of or is based upon (i) any untrue statement or alleged untrue statement of a material fact contained in the Registration Statement (or in the Registration Statement as amended by any post-effective amendment thereof by the Company) or arises out of or is based upon any omission or alleged omission to state a material fact required to be stated therein or necessary to make the statements therein not misleading, except insofar as any such loss, damage, expense, liability or claim arises out of or is based upon any untrue statement or alleged untrue statement of a material fact contained in, and in conformity with information concerning such Underwriter furnished in writing by or on behalf of such Underwriter through you to the Company expressly for use in, the Registration Statement or arises out of or is based upon any omission or alleged omission to state a material fact in the Registration Statement in connection with such information, which material fact was not contained in such information and which material fact was required to be stated in such Registration Statement or was necessary to make such information not misleading or (ii) any untrue statement or alleged untrue statement of a material fact included in any Prospectus (the term Prospectus for the purpose of this Section 9 being deemed to include any Preliminary Prospectus, the Prospectus and any amendments or supplements to the foregoing), in any “issuer free writing prospectus” (as defined in Rule 433 under the Act), in any “issuer information” (as defined in Rule 433 under the Act) of the Company or in any Prospectus together with any combination of one or more of the issuer free writing prospectuses, if any, or arises out of or is based upon any omission or alleged omission 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, except, with respect to such Prospectus or issuer free writing prospectus, insofar as any such loss, damage, expense,

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liability or claim arises out of or is based upon any untrue statement or alleged untrue statement of a material fact contained in, and in conformity with information concerning such Underwriter furnished in writing by or on behalf of such Underwriter through you to the Company expressly for use in, such Prospectus or issuer free writing prospectus or arises out of or is based upon any omission or alleged omission to state a material fact in such Prospectus or issuer free writing prospectus in connection with such information, which material fact was not contained in such information and which material fact was necessary in order to make the statements in such information, in the light of the circumstances under which they were made, not misleading.

(b) Each Underwriter severally agrees to indemnify, defend and hold harmless the Company, its directors and officers, and any person who controls the Company within the meaning of Section 15 of the Act or Section 20 of the Exchange Act, and the successors and assigns of all of the foregoing persons, from and against any loss, damage, expense, liability or claim (including the reasonable cost of investigation) which, jointly or severally, the Company or any such person may incur under the Act, the Exchange Act, the common law or otherwise, insofar as such loss, damage, expense, liability or claim arises out of or is based upon (i) any untrue statement or alleged untrue statement of a material fact contained in, and

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in conformity with information concerning such Underwriter furnished in writing by or on behalf of such Underwriter through you to the Company expressly for use in, the Registration Statement (or in the Registration Statement as amended by any post-effective amendment thereof by the Company), or arises out of or is based upon any omission or alleged omission to state a material fact in such Registration Statement in connection with such information, which material fact was not contained in such information and which material fact was required to be stated in such Registration Statement or was necessary to make such information not misleading or (ii) any untrue statement or alleged untrue statement of a material fact contained in, and in conformity with information concerning such Underwriter furnished in writing by or on behalf of such Underwriter through you to the Company expressly for use in, a Prospectus or a Permitted Free Writing Prospectus, or arises out of or is based upon any omission or alleged omission to state a material fact in such Prospectus or Permitted Free Writing Prospectus in connection with such information, which material fact was not contained in such information and which material fact was necessary in order to make the statements in such information, in the light of the circumstances under which they were made, not misleading.

(c) If any action, suit or proceeding (each, a “Proceeding”) is brought against a person (an “indemnified party”) in respect of which indemnity may be sought against the Company or an Underwriter (as applicable, the “indemnifying party”) pursuant to subsection (a) or (b), respectively, of this Section 9, such indemnified party shall promptly notify such indemnifying party in writing of the institution of such Proceeding and such indemnifying party shall assume the defense of such Proceeding, including the employment of counsel reasonably satisfactory to such indemnified party and payment of all fees and expenses related to the defense of such Proceeding; provided, however, that the omission to so notify such indemnifying party shall not relieve such indemnifying party from any liability which such indemnifying party may have to any indemnified party or otherwise. The indemnified party or parties shall have the right to employ its or their own counsel in any such case, but the fees and expenses of such counsel shall be at the expense of such indemnified party or parties unless the employment of such counsel shall have been authorized in writing by the indemnifying party in connection with the defense of such Proceeding or the indemnifying party shall not have, within a reasonable period of time in light of the circumstances, employed counsel to defend such Proceeding or such indemnified party or parties shall have reasonably concluded that there may be defenses available to it or them which are different from, additional to or in conflict with those available to such indemnifying party (in which case such indemnifying party shall not have the right to direct the defense of such Proceeding on behalf of the indemnified party or parties), in any of which events such fees and expenses shall be borne by such indemnifying party and paid as incurred (it being understood, however, that, except as provided in the second paragraph of Section 9(a), such indemnifying party shall not be liable for the expenses of more than one separate counsel (in addition to any local counsel) in any one Proceeding or series of related Proceedings in the same jurisdiction representing the indemnified parties who are parties to such Proceeding). The indemnifying party shall not be liable for any settlement of any Proceeding effected without its written consent, but, if settled with its written consent, such indemnifying party agrees to indemnify and hold harmless the indemnified party or parties from and against any loss or liability by reason of such settlement. Notwithstanding the foregoing sentence, if at any time an indemnified party shall have requested an indemnifying party to reimburse the indemnified party for fees and expenses of counsel as contemplated by the second sentence

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of this Section 9(c), then the indemnifying party agrees that it shall be liable for any settlement of any Proceeding effected without its written consent if (i) such settlement is entered into more than 60 business days after receipt by such indemnifying party of the aforesaid request for reimbursement of fees and expenses of counsel in accordance with this Agreement, (ii) such indemnifying party shall not have fully reimbursed the indemnified party in accordance with such request prior to the date of such settlement and (iii) such indemnified party shall have given the indemnifying party at least 30 days’ prior notice of its intention to settle. No indemnifying party shall, without the prior written consent of the indemnified party, effect any settlement of any pending or threatened Proceeding in respect of which any indemnified party is or could have been a party and indemnity could have been sought hereunder by such indemnified party, unless such settlement includes an unconditional release of such indemnified party from all liability on claims that are the subject matter of such Proceeding and does not include an admission of fault or culpability or a failure to act by or on behalf of such indemnified party.

(d) If the indemnification provided for in this Section 9 is unavailable to an indemnified party under subsections (a) and (b) of this Section 9 or insufficient to hold an indemnified party harmless in respect of any losses, damages, expenses, liabilities or claims referred to therein, then each applicable indemnifying party shall contribute to the amount paid or payable by such indemnified party as a result of such losses, damages, expenses, liabilities or claims (i) in such proportion as is appropriate to reflect the relative benefits received by the Company on the one hand and the Underwriters on the other hand from the offering of the Shares or (ii) if the allocation provided by clause (i) above is not permitted by applicable law, in such proportion as is appropriate to reflect not only the relative benefits referred to in clause (i) above but also the relative fault of the Company on the one hand and of the Underwriters on the other in connection with the statements or omissions which resulted in such losses, damages, expenses, liabilities or claims, as well as any other relevant equitable considerations. The relative benefits received by the Company on the one hand and the Underwriters on the other shall be deemed to be in the same respective proportions as the total proceeds from the offering (net of underwriting discounts and commissions but before deducting expenses) received by the Company, and the total underwriting discounts and commissions received by the Underwriters, bear to the aggregate public offering price of the Shares. The relative fault of the Company on the one hand and of the Underwriters on the other shall be determined by reference to, among other things, whether the untrue statement or alleged untrue statement of a material fact or omission or alleged omission relates to information supplied by the Company or by the Underwriters and the parties’ relative intent, knowledge, access to information and opportunity to correct or prevent such statement or omission. The amount paid or payable by a party as a result of the losses, damages, expenses, liabilities and claims referred to in this subsection shall be deemed to include any legal or other fees or expenses reasonably incurred by such party in connection with investigating, preparing to defend or defending any Proceeding.

(e) The Company and the Underwriters agree that it would not be just and equitable if contribution pursuant to this Section 9 were determined by pro rata allocation (even if the Underwriters were treated as one entity for such purpose) or by any other method of allocation that does not take account of the equitable considerations referred to in subsection (d) above. Notwithstanding the provisions of this Section 9, no Underwriter shall be required to contribute any amount in excess of the amount by which the total price at which the Shares underwritten by such Underwriter and distributed to the public were offered

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to the public exceeds the amount of any damage which such Underwriter has otherwise been required to pay by reason of such untrue statement or alleged untrue statement or omission or alleged omission. No person guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of the Act) shall be entitled to contribution from any person who was not guilty of such fraudulent misrepresentation. The Underwriters’ obligations to contribute pursuant to this Section 9 are several in proportion to their respective underwriting commitments and not joint.

(f) The indemnity and contribution agreements contained in this Section 9 and the covenants, warranties and representations of the Company contained in this Agreement shall remain in full force and effect regardless of any investigation made by or on behalf of any Underwriter, its partners, agents, directors, officers or members or any person (including each partner, officer, director or member of such person) who controls any Underwriter within the meaning of Section 15 of the Act or Section 20 of the Exchange Act, or by or on behalf of the Company, its directors or officers or any person who controls the Company within the meaning of Section 15 of the Act or Section 20 of the Exchange Act, and shall survive any termination of this Agreement or the issuance and delivery of the Shares. The Company and each Underwriter agree promptly to notify each other of the commencement of any Proceeding against it and, in the case of the Company, against any of the Company’s officers or directors in connection with the issuance and sale of the Shares, or in connection with the Registration Statement, any Preliminary Prospectus, the Prospectus or any Permitted Free Writing Prospectus.

10. Information Furnished by the Underwriters. The statements set forth in the paragraph that is two paragraphs immediately preceding the subheading “Underwriting—Over-Allotment Option,” the first paragraph immediately under the subheading “Underwriting—Commissions and Discounts” and the paragraphs under the subheadings “Underwriting—Price-Stabilization, Short Positions,” constitute the only information furnished by or on behalf of the Underwriters, as such information is referred to in Sections 3 and 9 hereof.

11. Notices. Except as otherwise herein provided, all statements, requests, notices and agreements shall be in writing or by telegram or facsimile and, if to the Underwriters, shall be sufficient in all respects if delivered or sent to Citigroup Global Markets Inc., 388 Greenwich Street, New York, New York, 10013, Attention: General Counsel; Piper Jaffray & Co., 800 Nicollet Mall, Suite 800, Minneapolis, MN 55402, Attention Equity Capital Markets (facsimile: (612)  ###-###-####) and Attention: Legal Department (facsimile (612)  ###-###-####) and Raymond James & Associates, Inc., 880 Carillon Parkway, St. Petersburg, FL 33716, Attention: General Counsel; and if to the Company, shall be sufficient in all respects if delivered or sent to the Company at the offices of the Company at 500 Corporate Circle, Suite C, Golden, CO 80401 (facsimile: 303 ###-###-####), Attention: Brian Cree, Chief Financial Officer.

12. Governing Law; Construction. This Agreement and any claim, counterclaim or dispute of any kind or nature whatsoever arising out of or in any way relating to this Agreement (“Claim”), directly or indirectly, shall be governed by, and construed in accordance with, the laws of the State of New York. The section headings in this Agreement have been inserted as a matter of convenience of reference and are not a part of this Agreement.

13. Submission to Jurisdiction. Except as set forth below, no Claim may be commenced, prosecuted or continued in any court other than the courts of the State of New York located in the City and County of New York or in the United States District Court for the Southern District of New

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York, which courts shall have jurisdiction over the adjudication of such matters, and the Company consents to the jurisdiction of such courts and personal service with respect thereto. The Company hereby consents to personal jurisdiction, service and venue in any court in which any Claim arising out of or in any way relating to this Agreement is brought by any third party against any Underwriter or any indemnified party. Each Underwriter and the Company (on its behalf and, to the extent permitted by applicable law, on behalf of its stockholders and affiliates) waive all right to trial by jury in any action, proceeding or counterclaim (whether based upon contract, tort or otherwise) in any way arising out of or relating to this Agreement. The Company agrees that a final judgment in any such action, proceeding or counterclaim brought in any such court shall be conclusive and binding upon the Company and may be enforced in any other courts to the jurisdiction of which the Company is or may be subject, by suit upon such judgment.

14. Parties at Interest. The Agreement herein set forth has been and is made solely for the benefit of the Underwriters and the Company and to the extent provided in Section 9 hereof the controlling persons, partners, agents, directors, officers, members and affiliates referred to in such Section, and their respective successors, assigns, heirs, personal representatives and executors and administrators. No other person, partnership, association or corporation (including a purchaser, as such purchaser, from any of the Underwriters) shall acquire or have any right under or by virtue of this Agreement.

15. No Fiduciary Relationship. The Company hereby acknowledges that the Underwriters are acting solely as underwriters in connection with the purchase and sale of the Company’s securities. The Company further acknowledges that the Underwriters are acting pursuant to a contractual relationship created solely by this Agreement entered into on an arm’s length basis, and in no event do the parties intend that the Underwriters act or be responsible as a fiduciary to the Company, its management, stockholders or creditors or any other person in connection with any activity that the Underwriters may undertake or have undertaken in furtherance of the purchase and sale of the Company’s securities, either before or after the date hereof. The Underwriters hereby expressly disclaim any fiduciary or similar obligations to the Company, either in connection with the transactions contemplated by this Agreement or any matters leading up to such transactions, and the Company hereby confirms its understanding and agreement to that effect. The Company and the Underwriters agree that they are each responsible for making their own independent judgments with respect to any such transactions and that any opinions or views expressed by the Underwriters to the Company regarding such transactions, including, but not limited to, any opinions or views with respect to the price or market for the Company’s securities, do not constitute advice or recommendations to the Company. The Company and the Underwriters agree that the Underwriters are acting as principal and not the agent or fiduciary of the Company and no Underwriter has assumed, and none of them will assume, any advisory responsibility in favor of the Company with respect to the transactions contemplated hereby or the process leading thereto (irrespective of whether any Underwriter has advised or is currently advising the Company on other matters). The Company hereby waives and releases, to the fullest extent permitted by law, any claims that the Company may have against the Underwriters with respect to any breach or alleged breach of any fiduciary, advisory or similar duty to the Company in connection with the transactions contemplated by this Agreement or any matters leading up to such transactions.

16. Counterparts. This Agreement may be signed by the parties in one or more counterparts which together shall constitute one and the same agreement among the parties.

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17. Successors and Assigns. This Agreement shall be binding upon the Underwriters and the Company and their successors and assigns and any successor or assign of any substantial portion of the Company’s and any of the Underwriters’ respective businesses and/or assets.

[The Remainder of This Page Intentionally Left Blank; Signature Page Follows]

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If the foregoing correctly sets forth the understanding between the Company and the several Underwriters, please so indicate in the space provided below for that purpose, whereupon this Agreement and your acceptance shall constitute a binding agreement between the Company and the Underwriters, severally.

SCHEDULE A

SCHEDULE B

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