Exhibit 5.1


                               COX SMITH MATTHEWS
                                  INCORPORATED
                              112 EAST PECAN STREET
                                   SUITE 1800
                          SAN ANTONIO, TEXAS 78205-1521
                                 (210) 554-5500
                               FAX (210) 226-8395
                                www.coxsmith.com



Writer's Direct Number                                Writer's E-Mail Address
(210) 554-5255                                        srjacobs@coxsmith.com


                                December 3, 2004


Abraxas Petroleum Corporation
500 North Loop 1604 East, Suite 100
San Antonio, TX  78232



                         Re:  Registration   Statement  on  Form  S-4  filed  on
                              December 3, 2004 by Abraxas Petroleum Corporation


Ladies and Gentlemen:

     We have  acted  as  counsel  to  Abraxas  Petroleum  Corporation,  a Nevada
corporation (the "Company"), and its subsidiaries Eastside Coal Company, Inc., a
Colorado corporation,  Sandia Oil & Gas Corporation, a Texas corporation, Sandia
Operating  Corp.,  a Texas  corporation,  Wamsutter  Holdings,  Inc.,  a Wyoming
corporation  and Western  Associated  Energy  Corporation,  a Texas  corporation
(these  subsidiaries,  the  "Subsidiary  Guarantors"  and  the  Company  and the
Subsidiary  Guarantors  collectively the "Registrants"),  in connection with the
Registrants'  Registration  Statement on Form S-4 filed on December 3, 2004 (the
"Registration  Statement"),  under the  Securities  Act of 1933, as amended (the
"Securities  Act"),  relating to the Company's  offer to exchange (the "Exchange
Offer") up to $125,000,000  aggregate principal amount of the Company's Floating
Rate Senior Secured Notes due 2009, Series B (the "Exchange Notes"),  for a like
principal  amount of the Company's  issued and outstanding  Floating Rate Senior
Secured Notes due 2009, Series A (the "Old Notes").  The Indenture dated October
28, 2004 (the "Indenture"),  by and among the Company, the Subsidiary Guarantors
and U.S. Bank National Association, as trustee (the "Trustee"), provides for the
guarantee  of the  Exchange  Notes  by each of the  Subsidiary  Guarantors  (the
"Guarantees")  to  the  extent  set  forth  in the  Indenture.  The  Company  is
conducting the Exchange Offer to satisfy its obligations  under the Exchange and
Registration Rights Agreement,  dated October 28, 2004 (the "Registration Rights
Agreement"),  by and among the Company, the Subsidiary Guarantors and Guggenheim
Capital Markets, LLC.





December 3, 2004
Page2



     In our  examination,  we have  assumed  the legal  capacity  of all natural
persons,  the genuineness of all signatures,  the  authenticity of all documents
submitted  to us as  originals,  the  conformity  to original  documents  of all
documents submitted to us as facsimile,  electronic,  or photostatic copies, and
the  authenticity of the originals of such copies.  In making our examination of
documents  executed or to be executed,  we have assumed that the parties thereto
had the power, corporate or otherwise, to enter into and perform all obligations
thereunder and have also assumed the due  authorization by all requisite action,
corporate or otherwise,  by such parties, and the execution and delivery by such
parties of such documents and,  except to the extent  expressly set forth in our
opinion below,  the validity and binding  effect thereof on such parties.  As to
any  facts  material  to  the  opinions   expressed   herein  that  we  did  not
independently   establish  or  verify,   we  have  relied  upon  statements  and
representations of officers and other  representatives of the Company and others
and of public officials.

     We  have  examined  and  are  familiar  with   originals  or  copies,   the
authenticity  of which have been  established to our  satisfaction,  of all such
documents, corporate records, certificates of officers of the Company and public
officials,  and other  instruments  as we have deemed  necessary  to express the
opinions hereinafter set forth. In expressing our opinions herein, we express no
opinion as to compliance  with federal and state  securities  laws. The opinions
expressed  herein are  limited to the laws of the State of Texas and the federal
laws of the United States that are normally  applicable to  transactions  of the
type contemplated by the Exchange Offer (the "Applicable Law").

     The opinions set forth below are subject to the  following  qualifications,
further assumptions and limitations:

             (a) we do not express any opinion as to the effect on the  opinions
expressed  herein of (i) the compliance or noncompliance of any party to each of
the Exchange Notes, the Guarantees,  the Indenture and the  Registration  Rights
Agreement with any state, federal or other laws or regulations  applicable to it
or them or (ii) the legal or regulatory  status or the nature of the business of
any party; and

             (b) we do not express any opinion as to the  enforceability  of the
Indenture, the Exchange Notes and the Guarantees.

     Members of our firm are  admitted  to the  practice  of law in the state of
Texas and we do not express any opinion as to the laws of any other jurisdiction
other than the Applicable  Law to the extent  referred to  specifically  herein.
Insofar as the  opinions  expressed  herein  relate to matters  governed by laws





December 3, 2004
Page 3



other  than  the  Applicable  Law,  we have  assumed,  without  having  made any
independent investigation,  that such laws do not affect any of the opinions set
forth herein.  The opinions  expressed herein are based on laws in effect on the
date hereof, which laws are subject to change with possible retroactive effect.

     Based upon the  foregoing and subject to the  limitations,  qualifications,
exceptions and assumptions set forth herein, it is our opinion that:

     (1) the Indenture has been duly authorized,  validly executed and delivered
by the Company and the Subsidiary Guarantors;

     (2)  the  Exchange  Notes  to be  issued  and  sold  as  described  in  the
Registration  Statement have been duly and validly authorized by the Company for
such issuance and sale;

     (3) the Exchange Notes, when duly executed,  issued,  sold and delivered by
the Company,  authenticated  by the Trustee in accordance with the provisions of
the  Indenture  and  exchanged  for the Old Notes,  will be duly issued and will
constitute valid and binding  obligations of the Company enforceable against the
Company  in  accordance  with  their  terms,  except  to  the  extent  that  the
enforceability  of the Exchange Notes may be limited by bankruptcy,  insolvency,
moratorium,  reorganization,  fraudulent  conveyance  or other laws or decisions
relating to or affecting the enforcement of creditors'  rights  generally and by
general  principles  of equity  (regardless  of whether such  enforceability  is
considered in a proceeding in equity or at law);

     (4) each Guarantee has been duly and validly  authorized by such Subsidiary
Guarantor; and

     (5) each  Guarantee,  when  executed  in  accordance  with the terms of the
Indenture and upon due  execution,  authentication  and delivery of the Exchange
Notes in  accordance  with the Exchange  Offer and the  Indenture,  will be duly
issued and will  constitute a valid and binding  obligation  of such  Subsidiary
Guarantor  in  accordance  with  its  terms,  except  to  the  extent  that  the
enforceability  of such  Guarantee  may be  limited by  bankruptcy,  insolvency,
moratorium,  reorganization,  fraudulent  conveyance  or other laws or decisions
relating to or affecting the enforcement of creditors'  rights  generally and by
general  principles  of equity  (regardless  of whether such  enforceability  is
considered in a proceeding in equity or at law).




December 3, 2004
Page 4


     We hereby consent to the use of our name in the  Registration  Statement as
counsel who has  expressed an opinion upon certain  legal  matters in connection
with the  issue  and sale of the  Exchange  Notes  (including  specifically  the
reference contained under the caption "Legal Matters") and to the filing of this
opinion with the Securities and Exchange  Commission  (the  "Commission")  as an
exhibit to the Registration  Statement.  In giving this consent, we do not admit
that we are within the  category  of persons  whose  consent is  required  under
Section 7 of the  Securities  Act or the general  rules and  regulations  of the
Commission promulgated thereunder.

                         Yours very truly,

                         COX SMITH MATTHEWS INCORPORATED


                         By:  /s/ Steven R. Jacobs
                              -------------------------------------------------
                              Steven R. Jacobs
                              For the Firm