AMENDMENT NO. 2 TO EXCHANGE AND REGISTRATION RIGHTS AGREEMENT

THIS AMENDMENT NO. 2 TO EXCHANGE AND REGISTRATION RIGHTS AGREEMENT (this “ Amendment ”) is made and entered into as of May 1, 2009, by and among ABRAXAS PETROLEUM CORPORATION, a Nevada corporation (“ Parent ”), ABRAXAS ENERGY PARTNERS, L.P., a Delaware limited partnership (the “ Partnership ”), and the Purchasers listed on the signature pages attached hereto (individually, a “ Purchaser ” and collectively “ Purchasers ”).

WHEREAS , on May 25, 2007, the Partnership, Parent and the Purchasers entered into that certain Exchange and Registration Rights Agreement dated as of May 25, 2007 (the “ Original Agreement ”), pursuant to which the Partnership agreed to provide certain rights for the benefit of the Purchasers ;

WHEREAS , the Partnership, Parent and the Purchasers amended the Original Agreement pursuant to the terms of that certain Amendment No. 1 to Exchange and Registration Rights Agreement dated as of October 6, 2008 (“ Amendment No. 1 ”); and

WHEREAS , the Partnership, Parent and the Purchasers have agreed to further amend the Original Agreement and Amendment No. 1 as set forth in this Amendment;

NOW THEREFORE , in consideration of the mutual covenants and agreements set forth herein and for good and valuable consideration, the receipt and sufficiency of which is hereby acknowledged by each party hereto, the parties hereby agree as follows:

Section 1.                       Capitalized Terms .  Capitalized terms used in this Amendment shall have the meaning set forth in the Original Agreement as amended by Amendment No. 1 except as otherwise defined in this Amendment.

Section 2.                       Amendment of Original Agreement .  Pursuant to Section 11.7 of the Original Agreement, the Original Agreement is hereby amended as follows:

(a)             Section 1 of the Original Agreement is hereby amended as follows:

(1)           The definition of “AMEX” is hereby deleted in its entirety.

(2)           The definition of “IPO” is hereby amended to read, in its entirety, as follows:

“ IPO ” means the initial public offering of Common Units by the Partnership under the Securities Act that results in the Common

Units being listed for trading on the New York Stock Exchange, Nasdaq or NYSE AMEX or any affiliate of the New York Stock Exchange, Nasdaq or NYSE AMEX.

(3)           The definition of “Partnership Agreement” is hereby amended to read, in its entirety, as follows:

“ Partnership Agreement ” means that certain Second Amended and Restated Agreement of Limited Partnership of the Partnership, dated as of September 19, 2007.

(4)           The definition of “Stockholder Approval” is hereby amended to read, in its entirety, as follows:

“ Stockholder Approval ” means the approval by the holders of the requisite number of shares of Common Stock to the issuance of shares of Common Stock pursuant to the terms of this Agreement at a duly called meeting of the Stockholders in accordance with the rules of Nasdaq or such other securities exchange on which the Common Stock is then quoted or traded and all other Laws.

(5)           The following definitions are hereby added to Section 1 and shall read in their entirety as follows:

A.           “ Election Date ” shall have the meaning set forth in Section 3.3.

B.            “ Nasdaq ” means the Nasdaq Stock Market.

C.           “ NYSE AMEX ” means the NYSE AMEX, LLC.

(b)           Section 3.1 of the Original Agreement is hereby amended to read, in its entirety, as follows:

3.            Mechanics of Exchange .

3.1           Subject to the terms of this Section 3, if the IPO has not been consummated on or before 5:00 p.m. on June 30, 2009 (the “ Trigger Date ”), then beginning on the Business Day immediately following the Trigger Date (the “ Initial Exchange Date ”) and ending at the close of business on the Termination Date, each of the Purchasers shall have the right to exchange each of the Purchased Common Units into the Applicable Number of Exchange Shares.

(c)           Section 3.3 of the Original Agreement is hereby amended to read, in its entirety, as follows:

Beginning on the Business Day immediately following the date that Purchasers owning twenty percent (20%) of the Purchased Common Units have delivered written notice to the Partnership and Parent that they have elected to exchange Purchased Common Units for Common Stock (the “ Election Date ”), Parent shall take all action necessary to convene a meeting of its stockholders (the “ Parent Stockholders ”) to consider and vote upon the issuance of the aggregate number of shares of Common Stock issuable upon exchange of the Purchased Common Units for shares of Common Stock pursuant to this Agreement in excess of the Initial Exchange Shares as soon as practicable, but in any event not later than 60 days after the Election Date (the “ Stockholders’ Meeting ”).  Except as provided in this Section 3.3, the board of directors of Parent shall, in connection with such meeting, recommend approval of the issuance of shares of Common Stock in excess of the Initial Exchange Shares and take all other lawful action to solicit the approval of the issuance of shares of Common Stock in excess of the Initial Exchange Shares by the Parent Stockholders; provided, however, that the board of directors of Parent shall not be required to recommend such approval if it advised by counsel that such recommendation would violate its fiduciary duties to Parent’s stockholders under applicable Law.

(d)           Section 3.5 of the Original Agreement is hereby amended to read, in its entirety, as follows:

Notwithstanding anything to the contrary set forth in this Agreement, prior to the receipt of Stockholder Approval, in no even