AMENDMENT NO. 4
(Amended and Restated Credit Agreement)

This Amendment No. 4 ("Agreement") dated as of June 30, 2009 ("Effective Date")
is among Abraxas Energy Partners, L.P., a Delaware limited partnership
("Borrower"), the lenders party to the Credit Agreement described below from
time to time as Lenders, and Société Générale, as Administrative Agent (in such
capacity, the "Administrative Agent") and as Issuing Lender (in such capacity,
the "Issuing Lender").

RECITALS

A. The Borrower, the Lenders, the Issuing Lender and the Administrative Agent
are parties to the Amended and Restated Credit Agreement dated as of January 31,
2008, as amended by that certain Amendment No. 1 dated as of January 16, 2009,
that certain Amendment No. 2 dated as of April 30, 2009, and that certain
Amendment No. 3 dated as of May 7, 2009 (as so amended and as the same may be
further amended, restated, supplemented or otherwise modified from time to time,
the "Credit Agreement"; each capitalized term defined in the Credit Agreement
and used herein without definition shall have the meaning assigned to such term
in the Credit Agreement, unless expressly provided to the contrary).

B. Contemporaneously herewith, the Borrower, the Subordinated Agent and the
Subordinated Lenders (each as defined in the Credit Agreement) propose to make
certain amendments to the Subordinated Credit Agreement (as defined in the
Credit Agreement) pursuant to that certain Amendment No. 4 dated as of June 30,
2009 (the "Subordinated Credit Agreement Amendment") among the Borrower, the
Subordinated Agent and the Subordinated Lenders.

C. The Borrower has proposed that it merge with and into Abraxas Petroleum
Corporation ("APC") (the "Merger"), pursuant to a definitive merger agreement
(the "Merger Agreement") between the Borrower and APC.

D. The Borrower has requested that the Lenders (a) consent to the Subordinated
Credit Agreement Amendment and (b) make certain amendments to the Credit
Agreement as provided herein.

THEREFORE, the Borrower, the Lenders, the Issuing Lender and the Administrative
Agent hereby agree as follows:

ARTICLE I.
 
DEFINITIONS
 
Section 1.1 Terms Defined Above.  As used in this Agreement, each of the terms
defined in the opening paragraph and the Recitals above shall have the meanings
assigned to such terms therein.
 
Section 1.2 Other Definitional Provisions. The words "hereby", "herein",
"hereinafter", "hereof", "hereto" and "hereunder" when used in this Agreement
shall refer to this Agreement as a whole and not to any particular Article,
Section, subsection or provision of this
 

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Section 1.3 Agreement.  Article, Section, subsection and Exhibit references
herein are to such Articles, Sections, subsections and Exhibits of this
Agreement unless otherwise specified. All titles or headings to Articles,
Sections, subsections or other divisions of this Agreement or the exhibits
hereto, if any, are only for the convenience of the parties and shall not be
construed to have any effect or meaning with respect to the other content of
such Articles, Sections, subsections, other divisions or exhibits, such other
content being controlling as the agreement among the parties hereto.  Whenever
the context requires, reference herein made to the single number shall be
understood to include the plural; and likewise, the plural shall be understood
to include the singular.  Words denoting gender shall be construed to include
the masculine, feminine and neuter, when such construction is appropriate; and
specific enumeration shall not exclude the general but shall be construed as
cumulative.  Definitions of terms defined in the singular or plural shall be
equally applicable to the plural or singular, as the case may be, unless
otherwise indicated.
 
ARTICLE II.
 
CONSENT
 
Section 2.1 Consent; Acknowledgment; Agreement.  Subject to the terms of this
Agreement, the Administrative Agent and the Lenders hereby consent to the
execution and delivery of the Subordinated Credit Agreement Amendment and the
terms and conditions thereof.  The consent by the Lenders and by the
Administrative Agent described in this Section 2.01 is referred to herein as the
"Consent."  The Consent is contingent upon the satisfaction of the conditions
precedent described in Article VI below.  Such Consent is strictly limited to
the extent described herein.  Nothing contained herein shall be construed to be
a consent to or a permanent waiver of the Sections covered by the Consent
provided for herein or any other terms, provisions, covenants, warranties or
agreements contained in the Credit Agreement or any other Loan Document.  The
Lenders reserve the right to exercise any rights and remedies available to them
in connection with any other present or future defaults with respect to any
provision of the Credit Agreement or any other Loan Document.  The description
herein of the Consent is based upon the information provided to the Lenders on
or prior to the date hereof, and, to the extent that material information is
incorrect or omitted with respect to any activity, event or circumstance that
could result in a Default or Event of Default, such Consent shall not be deemed
to apply to such activity, event or circumstance.  The failure of the Lenders to
give notice to the Borrower of any such Defaults or Events of Default is not
intended to be nor shall be a waiver thereof.  The Borrower hereby agrees and
acknowledges that the Lenders require and will require strict performance by the
Borrower of all of its obligations, agreements and covenants contained in the
Credit Agreement and the other Loan Documents pursuant to the terms thereof, and
no inaction or action regarding any Default or Event of Default is intended to
be or shall be a waiver thereof.
 
ARTICLE III.
 
AMENDMENTS
 
Section 3.1 Section 1.01 of the Credit Agreement is hereby amended as follows:
 
(a) The following new term is added in alphabetical order:
 
"Amendment No. 4 Effective Date" means June 30, 2009.
 

 
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(b) The defined term "May 14, 2009 Payment Amount" is deleted in its entirety.
 
Section 3.2 Section 2.02(a) of the Credit Agreement is hereby amended to read in
its entirety as follows:
 
(a)           Borrowing Base.  The Borrowing Base in effect as of the Amendment
No. 4 Effective Date has been set by the Administrative Agent and the Lenders
and acknowledged by the Borrower as $128,075,515.37.  The Borrowing Base shall
be determined in accordance with the standards set forth in Section 2.02(d) and
is subject to periodic redetermination or reduction pursuant to Sections
2.02(b), 2.02(c) and 6.04(b).
 
Section 3.3 Section 2.02(e) of the Credit Agreement is hereby deleted in its
entirety.
 
Section 3.4 Section 2.06 of the Credit Agreement is hereby amended to read in
its entirety as follows:
 
Section 2.06.  Repayment of Advances.  The Borrower shall repay to the
Administrative Agent for the ratable benefit of the Lenders the outstanding
principal amount of each Advance, together with any accrued interest thereon, in
installments in the aggregate amounts and on the dates indicated as follows or
on such earlier date pursuant to Section 7.02 or Section 7.03:
 
Date
Amount
Maturity Date
all remaining principal, interest, fees and other amounts owing in respect of
the Advances

Section 3.5 Article V of the Credit Agreement is hereby amended to add the
following new Section 5.15 to the end thereof:
 
Section 5.15  Preliminary Proxy Statement.  On or prior to July 10, 2009, APC
shall file a preliminary proxy statement pursuant to the Securities Exchange Act
of 1934, as amended, which preliminary proxy statement shall be in form and
substance satisfactory to the Administrative Agent in its sole reasonable
discretion.
 
Section 3.6 Section 6.05(b) of the Credit Agreement is hereby amended to add the
following new subsection (iv) to the end thereof:
 
(iv)           with respect to any such cash distribution, (a) the Borrower
shall deposit cash in an amount equal to such cash distribution into an account
established with a Lender (the "Designated Escrow Account"), (b) the
Administrative Agent shall have a first priority, perfected security interest in
the Designated Escrow Account on terms and subject to documentation satisfactory
to the Administrative Agent in its sole discretion, (c) funds in an amount equal
to any such cash distribution shall be held in the Designated Escrow Account
until the Subordinated Loan Termination Date, (d) the Borrower shall not pay
such cash distribution to any of the equity holders of the Borrower until the
Subordinated
 

 
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Loan Termination Date has occurred, and (e) the Borrower hereby agrees and
acknowledges that during the existence of any Event of Default, the
Administrative Agent may apply any funds held in the Designated Escrow Account
to the Obligations in any order determined by the Administrative Agent; and
 
Section 3.7 Section 7.01(c)(i) of the Credit Agreement is hereby amended to read
in its entirety as follows:
 
(i) perform or observe any covenant contained in Section 5.02(a), Section
5.06(e), Section 5.12, Section 5.13, Section 5.15, or Article VI of this
Agreement or
 
Section 3.8 Section 7.01 of the Credit Agreement is hereby amended to delete
subsection (q) thereof.
 
ARTICLE IV.
 
AGREEMENT
 
Section 4.1 Consent Fee.  In connection with this Agreement, the Borrower agrees
to pay to the Administrative Agent for the account of the Lenders having
Commitments a consent fee in an aggregate amount equal to $2,400,000 (the
"Consent Fee"), to be distributed among such Lenders in accordance with their
respective Pro Rata Shares.  The Consent Fee shall be due and payable on the
Effective Date.
 
ARTICLE V.
 
REPRESENTATIONS AND WARRANTIES
 
Section 5.1 Representations and Warranties.  The Borrower represents and
warrants that: (a) its representations and warranties contained in Article IV of
the Credit Agreement and its representations and warranties contained in the
Security Instruments, the Guaranties, and each of the other Loan Documents to
which it is a party are true and correct in all material respects on and as of
the Effective Date, as though made on and as of such date, except those
representations and warranties that speak of a certain date, which
representations and warranties were true and correct as of such date; (b) no
Default has occurred and is continuing; (c) the execution, delivery and
performance of this Agreement are within the corporate power and authority
of  the Borrower and have been duly authorized by appropriate corporate action
and proceedings; (d) this Agreement constitutes the legal, valid, and binding
obligation of the Borrower enforceable in accordance with its terms, except as
limited by applicable bankruptcy, insolvency, reorganization, moratorium, or
similar laws affecting the rights of creditors generally and general principles
of equity; (e) there are no governmental or other third party consents, licenses
and approvals required in connection with the execution, delivery, performance,
validity and enforceability of this Agreement; and (f) the Liens under the
Security Instruments are valid and subsisting and secure the Borrower's
obligations under the Loan Documents.
 
ARTICLE VI.
 
CONDITIONS
 
This Agreement shall become effective and enforceable against the parties hereto
upon the occurrence of the following conditions precedent:

 
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Section 6.1 Documentation.  The Administrative Agent shall have received
multiple original counterparts, as requested by the Administrative Agent, of
this Agreement duly and validly executed and delivered by duly authorized
officers of the Borrower, the Administrative Agent, the Issuing Lender and the
Required Lenders.
 
Section 6.2 Subordinated Credit Agreement Amendment.  The Administrative Agent
shall have received true and correct copies of the fully executed Subordinated
Credit Agreement Amendment and such agreement shall have become effective.
 
Section 6.3 Merger Agreement.  The Administrative Agent shall have received true
and correct copies of the fully executed Merger Agreement, and such agreement
shall be enforceable against the Borrower and APC in accordance with its terms,
except as such enforceability may be limited by any applicable bankruptcy,
insolvency, reorganization, moratorium, or similar law affecting creditors'
rights generally and by general principles of equity.
 
Section 6.4 No Default.  No Default shall have occurred and be continuing as of
the Effective Date.
 
Section 6.5 Representations.  The representations and warranties in this
Agreement shall be true and correct in all material respects.
 
Section 6.6 Fees and Expenses.  The Borrower shall have paid all fees and
expenses of the Administrative Agent's outside legal counsel and other
consultants pursuant to all invoices presented for payment on or prior to the
Effective Date.
 
ARTICLE VII.
 
MISCELLANEOUS
 
Section 7.1 Effect on Loan Documents; Acknowledgments.
 
(a) The Borrower acknowledges that on the date hereof all Obligations are
payable without defense, offset, counterclaim or recoupment.
 
(b) The Administrative Agent, the Issuing Lender, and the Lenders hereby
expressly reserve all of their rights, remedies, and claims under the Loan
Documents.  Nothing in this Agreement shall constitute a waiver or
relinquishment of (i) any Default or Event of Default under any of the Loan
Documents, (ii) any of the agreements, terms or conditions contained in any of
the Loan Documents, (iii) any rights or remedies of the Administrative Agent,
the Issuing Lender or any Lender with respect to the Loan Documents, or (iv) the
rights of the Administrative Agent, any Issuing Lender or any Lender to collect
the full amounts owing to them under the Loan Documents.
 
(c) Each of the Borrower, the Administrative Agent, the Issuing Lender, and the
Lenders does hereby adopt, ratify, and confirm the Credit Agreement, and
acknowledges and agrees that the Credit Agreement and all other Loan Documents
are and remain in full force and effect, and the Borrower acknowledges and
agrees that its liabilities under the Credit Agreement and the other Loan
Documents are not impaired in any respect by this Agreement or the consent and
amendment granted hereunder.
 

 
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            (d) This Agreement is a Loan Document for the purposes of the
provisions of the other Loan Documents.  Without limiting the foregoing, any
breach of representations, warranties, and covenants under this Agreement shall
be a Default or Event of Default, as applicable, under the Credit Agreement.
 
Section 7.2 Counterparts.  This Agreement may be signed in any number of
counterparts, each of which shall be an original and all of which, taken
together, constitute a single instrument.  This Agreement may be executed by
facsimile signature and all such signatures shall be effective as originals.
 
Section 7.3 Successors and Assigns.  This Agreement shall be binding upon and
inure to the benefit of the Lenders, the Borrower, the Administrative Agent, the
Issuing Lender and their respective successors and assigns permitted pursuant to
the Credit Agreement.
 
Section 7.4 Invalidity.  In the event that any one or more of the provisions
contained in this Agreement shall for any reason be held invalid, illegal or
unenforceable in any respect, such invalidity, illegality or unenforceability
shall not affect any other provision of this Agreement.
 
Section 7.5 Governing Law.  This Agreement shall be deemed to be a contract made
under and shall be governed by and construed in accordance with the laws of the
State of New York.
 
Section 7.6 RELEASE.  THE BORROWER ACKNOWLEDGES THAT ON THE DATE HEREOF ALL
OBLIGATIONS ARE PAYABLE WITHOUT DEFENSE, OFFSET, COUNTERCLAIM OR RECOUPMENT.  IN
ADDITION, EACH OF THE BORROWER AND ITS SUBSIDIARIES (FOR THEMSELVES AND THEIR
RESPECTIVE SUCCESSORS, AGENTS, ASSIGNS, TRANSFEREES, OFFICERS, DIRECTORS,
EMPLOYEES, SHAREHOLDERS, ATTORNEYS AND AGENTS) HEREBY RELEASES ANY AND ALL
CLAIMS, CAUSES OF ACTION OR OTHER DISPUTES IT MAY HAVE AGAINST THE
ADMINISTRATIVE AGENT, THE ISSUING LENDER, ANY OF THE LENDERS, LEGAL COUNSEL TO
THE ADMINISTRATIVE AGENT, THE ISSUING LENDER OR ANY OF THE LENDERS, CONSULTANTS
HIRED BY ANY OF THE FOREGOING, OR ANY OF THEIR RESPECTIVE AFFILIATES,
SUBSIDIARIES, SHAREHOLDERS, AGENTS, DIRECTORS, OFFICERS, EMPLOYEES,
REPRESENTATIVES, SUCCESSORS OR ASSIGNS OF ANY KIND OR NATURE ARISING OUT OF,
RELATED TO, OR IN ANY WAY CONNECTED WITH, THE CREDIT AGREEMENT OR THE LOAN
DOCUMENTS, IN EACH CASE WHICH MAY HAVE ARISEN ON OR BEFORE THE DATE OF THIS
AGREEMENT.  EACH OF THE BORROWER AND ITS SUBSIDIARIES HEREBY ACKNOWLEDGES THAT
IT HAS READ THIS AGREEMENT AND HAS CONFERRED WITH ITS COUNSEL AND ADVISORS
REGARDING ITS CONTENT, INCLUDING THIS SECTION 7.6, AND IS FREELY AND VOLUNTARILY
ENTERING INTO THIS AGREEMENT, AND HEREBY AGREES TO WAIVE ANY CLAIM THAT THE
TERMS OF THIS AGREEMENT (INCLUDING, WITHOUT LIMITATION, THE RELEASES CONTAINED
HEREIN) ARE INVALID OR OTHERWISE UNENFORCEABLE.
 

 
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Section 7.7 Entire Agreement. THIS AGREEMENT, THE CREDIT AGREEMENT, THE NOTES,
AND THE OTHER LOAN DOCUMENTS CONSTITUTE THE ENTIRE UNDERSTANDING AMONG THE
PARTIES HERETO WITH RESPECT TO THE SUBJECT MATTER HEREOF AND SUPERSEDE ANY PRIOR
AGREEMENTS, WRITTEN OR ORAL, WITH RESPECT THERETO.
 
THERE ARE NO UNWRITTEN ORAL AGREEMENTS AMONG THE PARTIES.
 
[Signature Pages Follow]

 
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