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                                                                    Exhibit 10.4

                          ABRAXAS PETROLEUM CORPORATION

                          REGISTRATION RIGHTS AGREEMENT

                                                                January 23, 2003

Jefferies & Company, Inc.
Two Houston Center
909 Fannin Street, Suite 3100
Houston, Texas 77010

Gentlemen:

     Abraxas Petroleum Corporation, a Nevada corporation ("ABRAXAS" or the
"ISSUER"), has agreed pursuant to the terms of its Offer to Exchange dated
December 9, 2002, as amended and supplemented by Supplement No. 1 to its Offer
to Exchange dated January 15, 2003 (the "EXCHANGE OFFER") to issue and sell up
to an aggregate of $118,250,000 principal amount of the Issuer's 11 1/2% Secured
Notes due 2007, Series A (the "NEW NOTES"), and up to an aggregate of 5,990,000
shares of Abraxas common stock, par value $0.01 per share ("COMMON STOCK"), in
exchange for Abraxas' 11 1/2% Senior Secured Notes due 2004, Series A, and 11
1/2% Senior Notes due 2004, Series D (collectively, "OLD NOTES") to all
tendering noteholders of Old Notes. The New Notes are unconditionally guaranteed
by each of the Issuer's current and future subsidiaries (collectively, the
"SUBSIDIARY GUARANTORS"), as more fully described in that certain Indenture
dated as of January 23, 2003 by and among Abraxas, the Subsidiary Guarantors and
U.S. Bank, N.A., as Trustee. Any reference to "Issuer" in this Registration
Rights Agreement (this "AGREEMENT") shall also include the Subsidiary Guarantors
and any other person who may become an issuer of Registrable Securities.
Jefferies & Company, Inc. ("JEFFERIES") which is acting as the dealer manager
for the Exchange Offer is entering into this Agreement on behalf of the Holders,
which are intended by the parties to be third-party beneficiaries of this
Agreement. In connection therewith, the Issuer agrees with Jefferies for the
benefit of the Holders as follows:

     1.   DEFINITIONS. As used in this Agreement, the following capitalized
defined terms shall have the following meanings:

     "ACT" means the Securities Act of 1933, as amended, and the rules and
regulations of the Commission promulgated thereunder.

     "ADDITIONAL NOTES" means any additional Secured Notes issued in lieu of
cash interest payments on any outstanding Secured Notes or issued as Liquidated
Damages pursuant to Section 7 hereof.

     "AFFILIATE" of any specified person means any other person which, directly
or indirectly, is in control of, is controlled by, or is under common control
with, such specified person. For purposes of this definition, control of a
person means the power, direct or indirect, to direct or cause the direction of
the management and policies of such person whether through ownership of

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voting securities, by contract or otherwise; and the terms "controlling" and
"controlled" have meanings correlative to the foregoing.

     "BUSINESS DAY" means any day except a Saturday, Sunday or other day in the
City of New York, or in the city of the corporate trust office of the Trustee
(as defined herein), on which banks are authorized to close.

     "CLOSING DATE" means January 23, 2003.

     "COMMISSION" means the Securities and Exchange Commission.

     "COMMON STOCK" refers to the Issuer's Common Stock, par value $0.01 per
share.

     "ENGAGEMENT LETTER" means the Engagement Letter between Abraxas and
Jefferies dated July 24, 2002, as amended on August 2, 2002.

     "EXCHANGE ACT" means the Securities Exchange Act of 1934, as amended, and
the rules and regulations of the Commission promulgated thereunder.

     "EXCHANGE OFFER REGISTRATION STATEMENT" means any Registration Statement
relating to the Series B Exchange Offer, including the related Prospectus.

     "HOLDER" or "HOLDERS" means any holder of Registrable Securities.

     "INDENTURE" means the Indenture, dated as of January 23, 2003, by and among
the Issuer, the Subsidiary Guarantors and U.S. Bank, N.A., as trustee (the
"TRUSTEE"), pursuant to which the Secured Notes are being issued, as the same
may be amended or supplemented from time to time in accordance with the terms
thereof.

     "LIQUIDATED DAMAGES" shall have the meaning set forth in Section 7 hereof.

     "MANAGING UNDERWRITERS" means the investment banker or investment bankers
and manager or managers that shall administer an underwritten offering.

     "NASD" means the National Association of Securities Dealers, Inc.

     "NEW NOTES" has the meaning set forth in the preamble to this Agreement.
References in this Agreement to New Notes shall be deemed to include any
Additional Notes (as defined herein) relating thereto, to the extent applicable.

     "PERSON" means an individual, partnership, limited liability company,
corporation, association, trust, joint venture or any other unincorporated
organization or entity.

     "PROSPECTUS" means each prospectus included in any Registration Statement
(including, without limitation, a Prospectus that discloses information
previously omitted from a prospectus filed as part of an effective registration
statement in reliance upon Rule 430A under the Act), as amended or supplemented
by any prospectus supplement, with respect to the terms of the

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offering of any portion of the Registrable Securities, covered by such
Registration Statement, and all amendments and supplements to the Prospectus,
including post effective amendments and all material incorporated by reference
or deemed to be incorporated by reference in such prospectus.

     "REGISTRABLE SECURITIES" means (a) the Secured Notes, Additional Notes and
shares of Common Stock issued to the Holders as described in the introductory
paragraph to this Agreement, and (b) any shares of Common Stock or other
securities issued or issuable in respect of or in exchange for any of such
Secured Notes, Additional Notes or shares of Common Stock (or other securities
issued or issuable in respect of or in exchange for any of the foregoing),
whether by result of a reclassification, recapitalization, merger, other
reorganization, distribution, stock split or stock dividend paid thereon or
otherwise.

     "REGISTRATION STATEMENT" means any registration statement of the Issuer
relating to (a) an offering of Series B Notes pursuant to a Series B Exchange
Offer or (b) the registration for resale of Transfer Restricted Notes and/or
other Registrable Securities held by Holders pursuant to the Shelf Registration
Statement, in each case, (i) which is filed pursuant to the provisions of this
Agreement and (ii) including the Prospectus included therein, all amendments and
supplements thereto (including post-effective amendments) and all exhibits and
material incorporated by reference therein.

     "SECURED NOTES" means the New Notes and/or the Series B Notes. References
in this Agreement to Secured Notes shall be deemed to include any Additional
Notes relating thereto, to the extent applicable.

     "SERIES B EXCHANGE OFFER" means the exchange offer contemplated by the
registration by the Issuer under the Act of the Series B Notes pursuant to the
Exchange Offer Registration Statement pursuant to which the Issuer shall offer
the Holders of all outstanding Transfer Restricted Notes the opportunity to
exchange all such outstanding Transfer Restricted Notes for Series B Notes in an
aggregate principal amount equal to the aggregate principal amount of the
Transfer Restricted Notes tendered in such exchange offer by such Holders.

     "SERIES B NOTES" means the Issuer's 11 1/2% Secured Notes due 2007, Series
B, to be issued pursuant to the Indenture (i) in the Series B Exchange Offer or
(ii) upon the request of any Holder of New Notes covered by a Shelf Registration
Statement, in exchange for such New Notes. References in this Agreement to
Series B Notes shall be deemed to include any Additional Notes relating thereto,
to the extent applicable.

     "SHELF REGISTRATION" means a registration effected pursuant to Section 3
hereof.

     "SHELF REGISTRATION STATEMENT" means a "shelf" registration statement of
the Issuer pursuant to the provisions of Section 3 hereof which covers some or
all of the Registrable Securities on an appropriate form under Rule 415 under
the Act, or any similar rule that may be adopted by the Commission, amendments
and supplements to such registration statement, including post-effective
amendments, in each case including the Prospectus contained therein, all
exhibits thereto and all material incorporated by reference or deemed to be
incorporated by reference therein.

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     "TIA" means the Trust Indenture Act of 1939 (15 U.S.C. Section
77aaa-77bbbb) as in effect on the date of the Indenture.

     "TRANSFER RESTRICTED NOTES" means each New Note, until the earliest to
occur of (a) the date on which such New Note is exchanged in the Series B
Exchange Offer for a Series B Note and such Series B Note is entitled to be
resold to the public by the Holder thereof without complying with the prospectus
delivery requirements of the Act, (b) the date on which such New Note has been
disposed of in accordance with a Shelf Registration Statement, or (c) the date
on which such New Note is distributed to the public without volume or manner of
sale restrictions pursuant to Rule 144 under the Act.

     "UNDERWRITER" means any underwriter of Registrable Securities in connection
with an underwritten offering thereof under a Registration Statement.

     "UNDERWRITTEN REGISTRATION" or "UNDERWRITTEN OFFERING" means a registration
in which Registrable Securities are sold to any Underwriter for reoffering to
the public pursuant to a Registration Statement.

     "WARRANTS" means the warrants to purchase an aggregate amount of 950,000
shares of the Issuer's Common Stock evidenced by the Common Stock Purchase
Warrant dated August 1, 2000 between Abraxas and Basil Street Company, Common
Stock Purchase Warrant dated September 1, 2000 between Abraxas and Jessup &
Lamont Holdings, Common Stock Purchase Warrant dated August 1, 2000 between
Abraxas and TNC, Inc., and Common Stock Purchase Warrant dated August 1, 2000
between Abraxas and Charles K. Butler.

     2.   EXCHANGE OFFER REGISTRATION.

     (a)  Unless the Series B Exchange Offer shall not be permitted by
applicable federal law (after the procedures set forth in Section 2(c)(i) below
have been complied with), the Issuer shall (i) cause to be filed with the
Commission, as promptly as practicable after the Closing Date and (subject to
the provisions of Section 2(c)(i)) no later than 15 days after the Closing Date,
the Exchange Offer Registration Statement, (ii) use its reasonable best efforts
to cause such Exchange Offer Registration Statement to become effective at the
earliest possible time, but in no event later than 105 days after the Closing
Date, (iii) in connection with the foregoing, (A) file all pre-effective
amendments to such Exchange Offer Registration Statement as may be necessary in
order to cause such Exchange Offer Registration Statement to become effective,
(B) file, if applicable, a post-effective amendment to such Exchange Offer
Registration Statement pursuant to Rule 430A under the Act and (C) cause all
necessary filings, if any, in connection with the registration and qualification
of the Series B Notes to be made under the "blue sky" laws of such jurisdictions
as are necessary to permit consummation of the Series B Exchange Offer;
PROVIDED, HOWEVER, that in no event shall the Issuer be obligated to qualify to
do business in any jurisdiction where it is not now so qualified, or take any
action which would subject it to general service of process or to taxation in
any jurisdiction where it is not now so subject, and (iv) upon the effectiveness
of such Exchange Offer Registration Statement, use its reasonable best efforts
to commence and consummate the Series B Exchange Offer. The Series B Exchange
Offer shall be on the appropriate form permitting registration of the Series B
Notes to be offered in exchange

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for the New Notes that are Transfer Restricted Notes. Each Holder that
participates in the Series B Exchange Offer will be required to represent that
any Series B Notes to be received by it will be acquired in the ordinary course
of its business, that at the time of the consummation of the Series B Exchange
Offer, such Holder will have no arrangement or understanding with any Person to
participate in the distribution of the Series B Notes in violation of the
provisions of the Securities Act, and that such Holder is not an affiliate of
the Issuer within the meaning of the Securities Act.

     (b)  The Issuer shall use its reasonable best efforts to cause the Series B
Exchange Offer Registration Statement to be effective continuously, and shall
keep the Series B Exchange Offer open, for a period of not less than the minimum
period required under applicable federal and state securities laws to consummate
the Series B Exchange Offer; PROVIDED, HOWEVER, that in no event shall such
period be less than 20 Business Days. The Issuer shall cause the Series B
Exchange Offer to comply with all applicable federal and state securities laws.
No securities other than the Series B Notes shall be included in the Exchange
Offer Registration Statement. The Issuer shall cause the Series B Exchange Offer
to be consummated within 30 Business Days after the Exchange Offer Registration
Statement has become effective, subject to any extension that may be legally
required as a result of an event referred to in Section 4(c)(2).

     (c)  In connection with the Series B Exchange Offer, the Issuer shall
comply with all applicable provisions of Section 4 hereof, shall use its
reasonable best efforts to effect such exchange and shall comply with all of the
following provisions:

          (i)     If, following the date hereof and prior to consummation of the
Series B Exchange Offer, there has been published a change in Commission policy
with respect to exchange offers such as the Series B Exchange Offer, such that
in the reasonable judgment of counsel to the Issuer there is a substantial
question as to whether the Series B Exchange Offer is permitted by applicable
federal law or Commission policy, the Issuer hereby agrees, upon the request of
any 10% Holder (as defined herein), to seek a no-action letter or other
favorable decision from the Commission allowing the Issuer to consummate a
Series B Exchange Offer for such New Notes. The Issuer hereby agrees to pursue
the issuance of such a decision to the Commission staff level but shall not be
required to take commercially unreasonable action to effect a change of
Commission policy. In connection with the foregoing, the Issuer hereby agrees,
however, but subject to the proviso set forth above, to take all such other
actions as are reasonably requested by the Commission or otherwise required in
connection with the issuance of such decision, including without limitation to
(A) participate in telephonic conferences with the Commission, (B) deliver to
the Commission staff an analysis prepared by counsel to the Issuer setting forth
the legal bases, if any, upon which such counsel has concluded that such a
Series B Exchange Offer should be permitted and (C) diligently pursue a
resolution (which need not be favorable) by the Commission staff of such
submission.

          (ii)    To the extent required by the Commission, prior to
effectiveness of the Exchange Offer Registration Statement, the Issuer shall
provide a supplemental letter to the Commission (A) stating that the Issuer is
registering the Series B Exchange Offer in reliance on the position of the
Commission enunciated in EXXON CAPITAL HOLDINGS CORPORATION (available May 13,
1988), MORGAN STANLEY AND CO., INC. (available June 5, 1991) and, if applicable,
any no-

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action letter obtained pursuant to clause (c)(i) immediately above, (B)
including a representation that the Issuer has not entered into any arrangement
or understanding with any Person to distribute the Series B Notes to be received
in the Series B Exchange Offer and that, to the best of the Issuer's information
and belief, each Holder participating in the Series B Exchange Offer is
acquiring the Series B Notes in its ordinary course of business and has no
arrangement or understanding with any Person to participate in the distribution
of the Series B Notes received in the Series B Exchange Offer and (C) any other
undertaking or representation required by the Commission as set forth in any
no-action letter obtained pursuant to clause (c)(i) immediately above.

     3.   SHELF REGISTRATION. References to "Registrable Securities" in this
Section 3 do not include Series B Notes or Additional Notes relating thereto:

     (a)  The Issuer shall as promptly as practicable after the Closing Date and
no later than 15 days after the Closing Date file a Shelf Registration Statement
relating to all Registrable Securities held by Holders with the Commission and
thereafter shall use its reasonable best efforts to cause such Registration
Statement relating to the offer and sale of the Registrable Securities by the
Holders to be declared effective by the Commission at the earliest possible
time, but in no event later than 105 days after the Closing Date, such offer and
sale of such Registrable Securities by the Holders being made from time to time
in accordance with the methods of distribution elected by such Holders and set
forth in such Registration Statement, including an Underwritten Offering. The
Issuer shall use its reasonable best efforts to keep each Shelf Registration
Statement discussed in this Section 3(a) continuously effective, supplemented
and amended as required by and subject to the provisions of Sections 2 and 3
hereof as applicable, and to the extent necessary to ensure that it is available
for sales of Registrable Securities by the Holders thereof entitled to the
benefit of this Section 3(a), and to ensure that it conforms with the
requirements of this Agreement, the Act and the policies, rules and regulations
of the Commission as announced from time to time, for the period specified in
Section 3(b) below. The Issuer shall not permit any securities other than the
Registrable Securities (and any shares issuable upon exercise of the Warrants)
to be included in any Shelf Registration Statement. In the event of an
Underwritten Offering, the managing underwriter or underwriters selected for
such offering shall be selected by such Holders, and reasonably acceptable to
the Issuer. Such Holders shall provide the Issuer with notice of the identity of
the managing underwriter or underwriters it or they have selected at a
reasonable time prior to the commencement of any such underwritten offering.

     (b)  The Issuer shall use its reasonable best efforts to keep each Shelf
Registration Statement continuously effective in order to permit the Prospectus
forming part thereof to be usable by Holders until the earlier of (i) the date
that is two years from the Closing Date plus any Suspension Period or Black Out
Period (as respectively defined hereafter), (ii) the date that all of the
Registrable Securities covered thereby have been sold pursuant to such
Registration Statement, (iii) the date that Jefferies on behalf of the Holders
receives an opinion of counsel to the Issuer addressed to Jefferies and the
Holders, which counsel shall be reasonably acceptable to Jefferies on behalf of
the Holders, that all of the Registrable Securities (other than those held by
Affiliates) covered thereby may be sold under the provisions of Rule 144 without
limitation as to volume or manner of sale (a copy of which opinion shall be
provided by the Issuer to any Holder

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upon request by such Holder), or (iv) the date that all Registrable Securities
covered thereby have been otherwise transferred to persons who may trade such
shares without restriction or limitation under the Act, and the Issuer has
delivered a new certificate or other evidence of ownership for such securities
not bearing a restrictive legend, (in any such case, such period being called
the "REGISTRATION PERIOD"). If a Registration Statement filed pursuant to
Section 3(a) ceases to be effective during the Registration Period, then, if the
effectiveness can be reinstated, the Issuer shall use all reasonable best
efforts to have such Registration Statement reinstated immediately, and if such
Registration Statement cannot be reinstated or is not reinstated immediately,
the Issuer shall use all reasonable best efforts to file promptly a substitute
registration statement and cause such substitute registration statement to
become effective as soon as practicable and continuously effective during the
balance of the Registration Period. Issuer may replace (or convert) any
Registration Statement on Form S-1 with a Registration Statement on Form S-3,
provided, that there is no interruption in the effectiveness of such Shelf
Registration Statement and such replacement is at Issuer's sole expense and the
Holders shall have no obligation as a result of such replacement or conversion.

     (c)  Each Holder of Registrable Securities agrees by its acquisition of
such Registrable Securities that, upon actual receipt of any written notice from
the Issuer of the occurrence of any event of the kind described in Section
4(c)(2) hereof, such Holder will forthwith discontinue disposition of such
Registrable Securities covered by such Registration Statement or Prospectus, as
the case may be (and will rescind any pending disposition, to the extent
practicable), until such Holder's receipt of the copies of the supplemented or
amended Prospectus contemplated by Section 4(i) hereof, or until it is advised
in writing (the "ADVICE") by the Issuer that the use of the applicable
Prospectus may be resumed, and has received copies of any amendments or
supplements thereto. In the event that the Issuer shall give any such notice,
the Issuer shall use all reasonable best efforts to ensure the filing and/or
effectiveness of the Registration Statement and/or use of the Prospectus may be
resumed as promptly as practicable, and the period during which the Registration
Statement and the Prospectus are required to remain continuously effective shall
be extended by the number of days during such period from and including the date
of the giving of such notice to and including the date (the "SUSPENSION PERIOD")
when each seller of Registrable Securities covered by such Registration
Statement shall have received (x) the copies of the supplemented or amended
Prospectus contemplated by Section 4(i) hereof or (y) the Advice; provided,
however, that such Suspension Period shall in no event exceed 45 consecutive
days and 90 days in any 12-month period.

     (d)  No Holder of Registrable Securities may include any Registrable
Securities in any Shelf Registration Statement pursuant to this Agreement or
enforce the provisions of Section 7 hereof unless and until such Holder
furnishes to the Issuer in writing, within 7 days after receipt of a written
request from the Issuer therefor, such information as the Issuer may reasonably
request for use in connection with any Shelf Registration Statement or
Prospectus or preliminary prospectus included therein as is legally required for
registration statements and prospectuses for similar securities. Each Holder of
Registrable Securities as to which any Shelf Registration Statement is being
effected agrees to furnish promptly to the Issuer all information required to be
disclosed in order to make information previously furnished to the Issuer by
such Holder not materially misleading.

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     4.   REGISTRATION PROCEDURES. As expeditiously as practicable, at the
Issuer's sole expense:

     (a)  The Issuer shall furnish to any Holder that furnishes information for
inclusion therein, prior to the filing thereof with the Commission but in any
event at least five Business Days prior to such filing so that such Holders have
a reasonable opportunity to review and comment, a copy of any Registration
Statement, and each amendment thereof and each amendment or supplement, if any,
to the Prospectus included therein. The Issuer shall consider all comments it
receives from such Holders in good faith. The Issuer shall not file any
Registration Statement to which any 10% Holder reasonably objects.

     (b)  The Issuer will ensure that (i) any Registration Statement and any
amendment thereto and any Prospectus forming part thereof and any amendment or
supplement thereto comply in all material respects with the Act and the rules
and regulations thereunder, (ii) any Registration Statement or any amendment
thereto does not, when it becomes effective, 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 and (iii) any Prospectus
forming part of any Registration Statement, and any amendment or supplement to
such Prospectus, do not include an untrue statement of a material fact or omit
to state a material fact necessary in order to make the statements, in the light
of the circumstances under which they were made, not misleading.

     (c)  For the sole purposes of a Registration Statement, as described in
Section 3 of this Agreement:

     (1)  The Issuer shall advise the trustee for the New Notes, the transfer
agent for the Common Stock and the 10% Holders and, if requested by any of them,
confirm such advice in writing:

          (i)     when a Registration Statement or any amendment thereto has
been filed with the Commission and when the Registration Statement or any
post-effective amendment thereto has become effective; and

          (ii)    of any request by the Commission for amendments or supplements
to the Registration Statement or the Prospectus included therein or for
additional information or if a prospectus is required to be delivered under the
Act.

     (2)  The Issuer shall advise the trustee for the New Notes, the transfer
agent for the Common Stock and the 10% Holders and, if requested by any of them,
confirm such advice in writing:

          (i)     of the issuance (or threat of issuance) by the Commission of
any stop order suspending the effectiveness of any Registration Statement or the
initiation of any proceedings for that purpose or that any Registration
Statement has otherwise ceased to be effective;

          (ii)    of the receipt by the Issuer of any notification with respect
to the suspension of the qualification or exemption from qualification of any of
the Registrable

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Securities included therein for sale in any jurisdiction or the initiation of
any proceeding for such purpose;

          (iii)   of the discovery or happening of any event that requires the
making of any changes in any Registration Statement or any Prospectus so that,
as of such date, the statements therein do not include an untrue statement of a
material fact or omit to state any material fact necessary to make the
statements therein, in the light of the circumstances under which they were
made, not misleading (which advice shall be accompanied by an instruction to
suspend the use of such Prospectus until the requisite changes have been made);
and

          (iv)    of the Issuer's reasonable determination that a post-effective
amendment to any Registration Statement would be appropriate.

Any notice provided by the Issuer pursuant to this section 4(c) shall be kept
confidential by any recipient unless disclosure thereof is made in connection
with a court or administrative proceeding or action required by law or such
information becomes available to the public generally or through a third party
without a known obligation of confidentiality.

     (d)  The Issuer will use its reasonable best efforts to prevent the
issuance of and to obtain the withdrawal of any order suspending the
effectiveness of any Shelf Registration Statement or suspending or preventing
the use of any related Prospectus or suspending the qualification (or exemption
from qualification) of any securities included in such Shelf Registration
Statement for sale in any jurisdiction at the earliest possible time and the
Issuer will use its reasonable best efforts to cause all Registrable Securities
covered by such Shelf Registration Statement to be registered with or approved
by such other federal or state governmental agencies or authorities as may be
necessary in the opinion of counsel to the Issuer to enable the seller or
sellers thereof to consummate the disposition of such Registrable Securities.

     (e)  The Issuer will promptly furnish to each Holder of Registrable
Securities, upon receipt of such Holder's written request, and any Underwriter
included within the coverage of any Shelf Registration Statement, without
charge, at least one copy of such Shelf Registration Statement and any
post-effective amendment thereto, including financial statements and schedules,
and, if the Holder or an Underwriter so requests in writing, all exhibits and
documents incorporated or deemed to be incorporated by reference therein.

     (f)  The Issuer will, during the Registration Period, deliver to each
Holder of Registrable Securities included within the coverage of any Shelf
Registration Statement, promptly upon receipt of such Holder's written request,
without charge, as many copies of the Prospectus (including each preliminary
Prospectus) included in such Shelf Registration Statement and any amendment or
supplement thereto and any document or exhibit incorporated or deemed
incorporated therein as such Holder may reasonably request in writing; and the
Issuer consents to the use of the Prospectus or any amendment or supplement
thereto and any document or exhibit incorporated or deemed incorporated therein
by each of the selling Holders of Registrable Securities and any Underwriter in
connection with the offering and sale of the Registrable Securities covered by
the Prospectus or any amendment or supplement thereto.

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     (g)  Prior to any offering of Registrable Securities pursuant to any Shelf
Registration Statement, the Issuer will register or qualify or cooperate with
the Holders of Registrable Securities included therein and their respective
counsel in connection with the registration or qualification (or exemption from
such registration or qualification) of such Registrable Securities for offer and
sale under the securities or blue sky laws of such jurisdictions as any such
Holders or any Underwriter reasonably requests in writing, and do any and all
other acts or things necessary or advisable to enable the offer and sale in such
jurisdictions of the Registrable Securities covered by such Shelf Registration
Statement and will keep such registration, qualification or exemption effective
during the Registration Period; PROVIDED, HOWEVER, that the Issuer will not be
required to qualify generally to do business in any jurisdiction where it is not
then so qualified or to take any action which would subject it to general
service of process or to taxation in any such jurisdiction where it is not then
so subject.

     (h)  The Issuer will cooperate with the Holders of Registrable Securities
to facilitate the timely preparation and delivery of certificates representing
Registrable Securities to be sold pursuant to any Shelf Registration Statement
free of any restrictive legends and in such denominations and registered in such
names as either the Holders or any Underwriter may request prior to sales of
Registrable Securities pursuant to such Registration Statement.

     (i)  Subject to the last sentence of this Section 4(i), upon the occurrence
of any event contemplated by paragraphs (c)(2)(iii) or (c)(2)(iv) above, the
Issuer will promptly prepare a post-effective amendment to any Shelf
Registration Statement or an amendment or supplement to the related Prospectus
or file any other required document so that the Prospectus, as supplemented or
amended, will not include an untrue statement of a material fact or omit to
state any material fact necessary to make the statements therein, in the light
of the circumstances under which they were made, not misleading. Notwithstanding
the foregoing, the Issuer shall not be required to amend or supplement a Shelf
Registration Statement, any related Prospectus or any document incorporated
therein by reference in the event that, and for a period (a "BLACK OUT PERIOD")
not to exceed, for so long as this Agreement is in effect, 45 days consecutively
and 90 days in any 12-month period if either (A) any action by the Issuer
pursuant to this Section 4(i) would violate applicable law or (B) (x) an event
occurs and is continuing as a result of which a Registration Statement, any
related Prospectus or any document incorporated therein by reference as then
amended or supplemented would, in the Issuer's good faith judgment, contain 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 (y) (1) the Issuer determines in good
faith that the disclosure of such event at such time would have a material
adverse effect on the business, operations or prospects of the Issuer or (2) the
disclosure otherwise relates to a material business transaction which has not
yet been publicly disclosed in any relevant jurisdiction.

     (j)  The Issuer shall, if reasonably requested, promptly incorporate in a
Prospectus supplement or post-effective amendment to a Shelf Registration
Statement, such information as the Managing Underwriters or any of the 10%
Holders reasonably agrees should be included therein and shall make all required
filings of such Prospectus supplement or post-effective amendment as soon as
notified of the matters to be incorporated in such Prospectus supplement or
post-effective amendment.

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     (k)  The Issuer shall cause all such Registrable Securities to be listed on
each securities exchange on which similar securities issued by the Issuer are
then listed, provide a transfer agent and registrar for all such Registrable
Securities not later than the effective date of a Registration Statement and
shall enter into such agreements (including underwriting agreements) and take
all other appropriate actions necessary or advisable in order to expedite or
facilitate the registration or the disposition of the Registrable Securities;
the Issuer shall also (i) make such representations, warranties to, and
covenants with the Underwriters and any 10% Holder upon request by such 10%
Holder, with respect to the businesses of the Issuer and its subsidiaries and
the Registration Statement, the Prospectus and documents incorporated by
reference therein, in each case, as are customarily made by issuers to
underwriters in underwritten offerings of securities similar to the Registrable
Securities to be sold in an underwritten offering, (ii) furnish to the
Underwriters and any 10% Holder upon request by such 10% Holder opinions of
counsel to the Issuer and updates thereof in form and substance reasonably
satisfactory to the Managing Underwriters and any such 10% Holders covering the
matters customarily covered in opinions delivered in underwritten offerings of
securities similar to the Registrable Securities, but in any event including (A)
an opinion that any Registration Statement filed by the Issuer is being filed on
the appropriate form for registration of the Registrable Securities and that
such Registration Statement has been declared effective by the Commission and
there is no applicable stop order or other legal reason impairing the use of the
prospectus therein as a result of the action or failure to act by the Issuer or
as a result of any action by a governmental authority, and any Holder may trade
the Registrable Securities relating thereto freely (subject to any prospectus
delivery requirements) and (B) negative assurances regarding the substance of
Rule 10b-5 of the Exchange Act (which opinion and negative assurances shall be
reissued upon and dated the date of any amendment or supplement or incorporation
by reference to any Registration Statement or conclusion of any Black Out Period
or Suspension Period), (iii) obtain and furnish to the Underwriters and any 10%
Holder upon written request by such Holder "cold comfort" letters and updates
thereof in form and substance reasonably satisfactory to the Managing
Underwriters and such 10% Holder, as the case may be, from the independent
public accountants of the Issuer (and, if necessary, any other independent
public accountants of any subsidiary of the Issuer or of any business acquired
by the Issuer for which financial statements and financial data are, or are
required to be, included in the Registration Statement), such letters to be in
customary form and covering matters of the type customarily covered in "cold
comfort" letters in connection with underwritten offerings of securities similar
to the Registrable Securities to be sold (which shall be reissued upon and dated
the date of any amendment or supplement or incorporation by reference to any
Registration Statement or conclusion of any Black Out Period or Suspension
Period), and (iv) cause the same to contain indemnification provisions and
procedures no less favorable than those set forth in Section 6 of this Agreement
(or such other provisions and procedures acceptable to the Holders and the
Managing Underwriters, if any, with respect to all parties to be indemnified
pursuant to Section 6 of this Agreement from Holders of Registrable Securities
to the Issuer). The above shall be done additionally at each closing under such
underwriting agreement, or as and to the extent required thereunder.

     (l)  The Issuer shall (i) make reasonably available for inspection by a
representative or representatives of the Holders of Registrable Securities to be
registered thereunder, any Underwriter participating in any disposition pursuant
to a Shelf Registration Statement, and any

                                     - 11 -
<Page>

attorney, accountant or other agent retained by the Holders or any such
Underwriter, during reasonable business hours all relevant financial and other
records, pertinent corporate documents and properties of the Issuer and its
subsidiaries and (ii) cause the Issuer's officers, directors and employees to
supply all relevant information reasonably requested by any such representatives
or any such Underwriter, attorney, accountant or agent in connection with any
such Shelf Registration Statement as is customary for similar due diligence
examinations; PROVIDED, HOWEVER, that any information that is designated by the
Issuer, in good faith, as confidential at the time of delivery of such
information shall be kept confidential by any such representatives or any such
Underwriter, attorney, accountant or agent, unless such disclosure is made in
connection with a court or administrative proceeding or action or required by
law or is necessary to avoid or correct a misstatement or omission of material
fact in any Registration Statement, or such information becomes available to the
public generally or through a third party without a known obligation of
confidentiality.

     (m)  The Issuer shall comply with all applicable rules and regulations of
the Commission and make generally available to the securityholders of Abraxas
earnings statements satisfying the provisions of Section 11(a) of the Act and
Rule 158 thereunder (or any similar rule promulgated under the Act) no later
than 45 days after the end of any 12-month period (or 90 days after the end of
any 12-month period if such period is a fiscal year) (A) commencing at the end
of any fiscal quarter in which Registrable Securities are sold to Underwriters
in a firm commitment or best efforts Underwritten Offering and (B) if not sold
to Underwriters in such an offering, then commencing on the first day of the
first fiscal quarter of Abraxas after the effective date of a Registration
Statement, which statements shall cover such 12-month periods.

     (n)  The Issuer shall cooperate with each seller of Registrable Securities
covered by any Registration Statement and each Underwriter, if any,
participating in the disposition of such Registrable Securities and their
respective counsel in connection with any filings required to be made with the
NASD.

     (o)  In connection with each Registration Statement filed with the
Commission, the Issuer shall cause the Indenture to be qualified under the TIA
not later than the effective date of such Registration Statement and, in
connection therewith, cooperate with the Trustee and the Holders to effect such
changes to the Indenture as may be required for such Indenture to be so
qualified in accordance with the terms of the TIA; and execute and use its
reasonable best efforts to cause the Trustee to execute, all documents that may
be required to effect such changes and all other forms and documents required to
be filed with the Commission to enable such Indenture to be so qualified in a
timely manner.

     5.   REGISTRATION EXPENSES. The Issuer will bear all expenses incident to
or incurred in connection with the preparation and filing of any Registration
Statement whether or not declared effective, and including, without limitation,
in connection with the performance of its obligations under Sections 2, 3 and 4
hereof, including, without limitation, all registration and filing fees and
expenses, fees and expenses of compliance with federal and state securities laws
or with blue sky laws as provided in Section 4(g), any NASD filing fees required
to be made in connection with an Underwritten Offering of Registrable
Securities, application and filing fees and expenses, word processing,
duplicating and printing expenses, telephone, fax, messenger and delivery

                                     - 12 -
<Page>

expenses, and fees and disbursements of counsel to the Issuer (including
expenses of legal opinions) and all independent accountants (including the
expenses of "cold comfort" letters and annual audits), underwriters (excluding
discounts and commissions), and fees and expenses of other Persons retained by
the Issuer, in each case, whether all, some or none of the Registrable
Securities are sold but excluding fees and expenses of counsel to any of the
Holders, fees and expenses of any accountants, engineers, consultants or any
other advisers to the Holders, any underwriting discount or commission and any
broker-dealer sales commission that the Holders may incur in disposing of their
Registrable Securities. The Issuer will, in any event, bear its internal
expenses (including, without limitation, all salaries and expenses of any of its
respective officers and employees performing legal or accounting duties).

     6.   INDEMNIFICATION AND CONTRIBUTION. (a) In connection with any
Registration Statement, the Issuer agrees to indemnify and hold harmless each
Holder of Registrable Securities covered thereby, the directors, officers,
managers, members, partners, employees, agents and affiliates of each such
Holder and each Person who controls any such Holder within the meaning of either
the Act or the Exchange Act against any and all losses, claims, damages and
liabilities, joint or several, to which they or any of them may become subject
under the Act, the Exchange Act or other Federal or state statutory law or
regulation or otherwise, at common law or otherwise, insofar as such losses,
claims, damages or liabilities (or actions or proceedings in respect thereof)
arise out of or are based upon any untrue statement or alleged untrue statement
of a material fact contained in the Registration Statement as originally filed
or in any amendment thereof, or in any preliminary Prospectus or the Prospectus,
or in any amendment thereof or supplement thereto, or arise out of or are based
upon the omission or alleged omission to state therein a material fact required
to be stated therein or necessary to make the statements therein not misleading,
and the Issuer upon demand by such indemnified party agrees to reimburse each
such indemnified party for any legal or other expenses reasonably incurred by it
in connection with investigating or defending any such loss, claim, damage,
liability or action or proceeding; PROVIDED, HOWEVER, that the Issuer will not
be liable in any case (i) to the extent that any such loss, claim, damage or
liability arises out of or is based upon any such untrue statement or alleged
untrue statement or omission or alleged omission made therein in reliance upon
and in conformity with written information furnished to the Issuer by such
Holder specifically for inclusion therein and (ii) to the extent that any such
loss, claim, damage or liability is caused by any untrue statement or alleged
untrue statement or omission or alleged omission made in the preliminary
Prospectus which is corrected in the Prospectus and a copy of the corrected
Prospectus was not sent or given to the person asserting any such loss, claim,
damage or liability who purchased Registrable Securities sold by the Holders at
or before the written confirmation of the sale to such person.

     The Issuer also agrees, to indemnify or contribute to Losses (as defined in
Section 6(d) below) of, as provided in Section 6(d), any Underwriters of
Registrable Securities registered under a Registration Statement, their officers
and directors and each person who controls such Underwriters on substantially
the same basis as that of the indemnification of the Holders provided in this
Section 6(a) and shall, if requested by any Holder, enter into an underwriting
agreement reflecting such agreement, as provided in Section 4(k) hereof.

                                     - 13 -
<Page>

     (b)  Each Holder of Registrable Securities covered by a Registration
Statement severally and not jointly agrees to indemnify and hold harmless (i)
the Issuer, (ii) each of its directors, (iii) each of its officers who signs
such Registration Statement and (iv) each person who controls the Issuer within
the meaning of either the Act or the Exchange Act to the same extent as the
foregoing indemnity from the Issuer to such Holder, but only with reference to
written information relating to such Holder furnished in writing to the Issuer
by such Holder specifically for inclusion in the documents referred to in the
foregoing indemnity. Notwithstanding anything to the contrary herein, the
foregoing obligations of any such Holder shall not exceed the amount of proceeds
received by such Holder for the sale of the relevant Registrable Securities
pursuant to the relevant Registration Statement.

     (c)  Promptly after receipt by any person in respect of which indemnity may
be sought pursuant to this Section 6 (such person, the "INDEMNIFIED PARTY"), of
notice of the commencement of any action or proceeding or governmental
investigation or proceeding, such indemnified party will, if a claim in respect
thereof is to be made under this Section 6, notify the party against whom such
indemnity may be sought (the "INDEMNIFYING PARTY") in writing of the
commencement thereof; but the failure to so notify the indemnifying party (i)
will not relieve it from liability under paragraph (a) or (b) above unless and
to the extent it did not otherwise learn of such action and such failure results
in the forfeiture by the indemnifying party of substantial rights and defenses
and (ii) will not, in any event, relieve the indemnifying party from any
obligations to any indemnified party other than the indemnification obligation
provided in paragraph (a) or (b) above. The indemnifying party shall be entitled
to appoint counsel of the indemnifying party's choice at the indemnifying
party's expense to represent the indemnified party in any action for which
indemnification is sought (in which case the indemnifying party shall not
thereafter be responsible for the fees and expenses of any separate counsel
retained by the indemnified party or parties except as set forth below);
PROVIDED, HOWEVER, that such counsel shall be satisfactory to the indemnified
party. Notwithstanding the indemnifying party's election to appoint counsel to
represent the indemnified party in an action, the indemnified party shall have
the right to employ separate counsel (including local counsel), and the
indemnifying party shall bear the reasonable fees, costs and expenses of such
separate counsel (and local counsel) only in the event that (i) the use of
counsel chosen by the indemnifying party to represent the indemnified party
would, in the opinion of counsel for the indemnified party, present such counsel
with a potential or actual conflict of interest, (ii) the actual or potential
defendants in, or targets of, any such action include both the indemnified party
and the indemnifying party and the indemnified party shall have reasonably
concluded that there may be legal defenses available to it and/or other
indemnified parties which are different from or additional to those available to
the indemnifying party, (iii) the indemnifying party shall not have employed
counsel satisfactory to the indemnified party to represent the indemnified party
within a reasonable time after notice of the institution of such action or (iv)
the indemnifying party shall authorize the indemnified party to employ separate
counsel at the expense of the indemnifying party. An indemnifying party will
not, without the prior written consent of the indemnified parties, settle or
compromise or consent to the entry of any judgment with respect to any pending
or threatened claim, action, suit or proceeding in respect of which
indemnification or contribution may be sought hereunder (whether or not the
indemnified parties are actual or potential parties to such claim or action)
unless such settlement, compromise or consent includes an unconditional release
of each

                                     - 14 -
<Page>

indemnified party from all liability arising out of such claim, action, suit or
proceeding and does not include any non-monetary terms of settlement relating to
the indemnified party. The indemnifying party shall not be liable for any
settlement of any proceeding effected without its written consent, which consent
shall not be unreasonably withheld or delayed but in the event of such consent,
or if there be a final judgment for the plaintiff, the indemnifying party shall
indemnify and hold harmless any such indemnified parties from and against any
loss, claim, damage or liability by reason of such settlement or judgment.

     (d)  In the event that the indemnity provided in paragraph (a) or (b) of
this Section 6 is unavailable to or insufficient to hold harmless an indemnified
party for any reason, then each applicable indemnifying party, in lieu of
indemnifying such indemnified party, shall have a joint and several obligation
to contribute to the aggregate losses, claims, damages and liabilities
(including legal or other expenses reasonably incurred in connection with
investigating or defending same) (collectively "LOSSES") to which such
indemnified party may be subject in such proportion as is appropriate to reflect
the relative benefits received by such indemnifying party, on the one hand, and
such indemnified party, on the other hand, from the Registration Statement which
resulted in such Losses. If the allocation provided by the immediately preceding
sentence is unavailable for any reason, the indemnifying party and the
indemnified party shall contribute in such proportion as is appropriate to
reflect not only such relative benefits but also the relative fault of such
indemnifying party, on the one hand, and such indemnified party, on the other
hand, in connection with the statements or omissions which resulted in such
Losses as well as any other relevant equitable considerations. When determining
such relative benefits, with respect to any Holder, the benefits shall be the
amount of proceeds received by such Holder for the relevant Registrable
Securities pursuant to the relevant Registration Statement and, with respect to
the Issuer, the benefits shall be the benefits to the Issuer of the transactions
contemplated by the Exchange Offer, including the restructuring described in the
Exchange Offer. Notwithstanding the provisions of this paragraph (d), no person
guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of
the Act) with respect to statements in a Registration Statement shall be
entitled to contribution from any person who was not guilty of such fraudulent
misrepresentation. For purposes of this Section 6, each person who controls a
Holder within the meaning of either the Act or the Exchange Act and each
director, officer, manager, member, affiliate, partner, employee and agent of
such Holder shall have the same rights to contribution as such Holder, and each
person who controls the Issuer within the meaning of either the Act or the
Exchange Act, each officer of the Issuer who shall have signed the Registration
Statement and each director of the Issuer shall have the same rights to
contribution as the Issuer, subject in each case to the applicable terms and
conditions of this paragraph (d).

     (e)  The provisions of this Section 6 will remain in full force and effect,
regardless of any termination of this Agreement or any underwriting agreement or
investigation made by or on behalf of any Holder or the Issuer or any other
indemnified party referred to in Section 6 hereof, and will survive the sale,
transfer and successive resales of the Registrable Securities.

     (f)  Any losses, claims, damages, liabilities or expenses for which an
indemnified party is entitled pursuant to Section 6 shall be paid by the
indemnifying party promptly upon request as such losses, claims, damages,
liabilities or expenses are incurred.

                                     - 15 -
<Page>

     7.   LIQUIDATED DAMAGES. The Issuer and Jefferies, on behalf of the
Holders, agree that the Holders will suffer damages if the Issuer fails to
fulfill its obligations under Section 2 or Section 3 hereof and that it would
not be feasible to ascertain the extent of such damages with precision.
Accordingly, the Issuer agrees that if (a) it fails to file any Registration
Statement as required by Section 2 or Section 3 of this Agreement on or before
the date specified for such filing, (b) any Registration Statement is not
declared effective by the Commission on or prior to 105 days after the Closing
Date, or (c) any Registration Statement is declared effective but thereafter
ceases to be effective or usable in connection with resales of the Registrable
Securities during the periods specified in Section 3 of this Agreement, other
than during a Black Out Period and except as a result of the occurrence of any
event of the kind described in Section 4(c)(2) hereof (each such event referred
to in clauses (a) through (c) above a "REGISTRATION DEFAULT"), then the interest
rate on either the New Notes or Series B Notes, as applicable, with respect to
the first 90 day period immediately following the occurrence of such
Registration Default will increase ("LIQUIDATED DAMAGES") by 3.5% per annum and
will increase by an additional 0.5% per annum with respect to each subsequent 30
day period until all Registration Defaults have been cured, up to a maximum per
annum interest rate on either the New Notes or Series B Notes, as applicable of
18% with respect to all Registration Defaults. All accrued Liquidated Damages
will be paid by the Issuer in the same manner and at the same time as payments
of interest on the Secured Notes. Following the cure of all Registration
Defaults, the accrual of Liquidated Damages will cease.

     8.   MISCELLANEOUS.

     (a)  AMENDMENTS AND WAIVERS. The provisions of this Agreement, including
the provisions of this sentence, may not be amended, qualified, modified or
supplemented, and waivers or consents to departures from the provisions hereof
(each, an "Amendment") may not be given, in each case without the prior written
consent of (i) the Issuer and (ii) the Holders of not less than a majority in
aggregate principal amount of the then outstanding Secured Notes; PROVIDED,
HOWEVER, that each Amendment shall require the prior written consent of any
Holder adversely effected by any such Amendment.

     (b)  NOTICES. All notices and other communications provided for or
permitted hereunder shall be made in writing by hand-delivery, first-class mail,
telecopier, or air courier guaranteeing overnight delivery:

          (1)     if to the Issuer:

                  c/o Abraxas Petroleum Corporation
                  500 North Loop 1604 East, Suite 100
                  San Antonio, TX 78232
                  Facsimile No.: (210) 490-8816
                  Attention: Chief Executive Officer

          (2)     if to Jefferies:

                  c/o Jefferies & Company, Inc.

                                     - 16 -
<Page>

                  Two Houston Center
                  909 Fannin Street, Suite 3100
                  Houston, TX 77010
                  Facsimile No.: (713) 308-4569
                  Attention: Todd Dittmann

          (3)     if to any Holder, to the address and facsimile number for such
Holder listed on the Issuer's books or otherwise supplied to the Issuer by such
Holder.

     All such notices and communications shall be deemed to have been duly given
when received.

     The Issuer or Jefferies by notice to the other may designate additional or
different addresses for subsequent notices or communications from the other.

     (c)  SUCCESSORS AND ASSIGNS. This Agreement shall inure to the benefit of
and be binding upon the successors and assigns of each of the parties,
including, without the need for an express assignment or any consent by the
Issuer thereto, subsequent Holders of Registrable Securities and their
transferees. The Issuer hereby agrees to extend the benefits of this Agreement
to any subsequent record holder of Registrable Securities and any other holder
of Registrable Securities if such holder holds such securities directly or
indirectly or has the right to acquire directly or indirectly such Registrable
Securities (upon conversion or exercise in connection with a transfer of
securities or otherwise, but disregarding any restrictions or limitations upon
the exercise of such right), whether or not such acquisition has actually been
effected (each such holder shall be deemed a "HOLDER" for purposes of this
Agreement) and any such holder may specifically enforce the provisions of this
Agreement as if an original party hereto. Except by operation of law, this
Agreement may not be assigned by the Issuer.

     (d)  RELEASE OF SUBSIDIARY GUARANTORS. If any Subsidiary Guarantor becomes
a party to this Agreement and is subsequently released from its obligations
under the Indenture in accordance with the terms thereof, then such Subsidiary
Guarantor shall be released from its obligations hereunder.

     (e)  COUNTERPARTS. This Agreement may be executed by facsimile and in any
number of counterparts and by the parties hereto in separate counterparts, each
of which when so executed shall be deemed to be an original and all of which
taken together shall constitute one and the same agreement.

     (f)  HEADINGS. The headings in this Agreement are for convenience of
reference only and shall not limit or otherwise affect the meaning hereof.

     (g)  GOVERNING LAW. THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE WITH THE INTERNAL LAWS OF THE STATE OF NEW YORK APPLICABLE TO
AGREEMENTS MADE AND TO BE PERFORMED IN SAID STATE WITHOUT REGARD TO PRINCIPLES
OF

                                     - 17 -
<Page>

CONFLICTS OF LAW. Each of the parties hereto also hereby irrevocably and
unconditionally consents to submit to the exclusive jurisdiction of the courts
of the State of New York located within the County of New York and of the United
States of America located in the Southern District of the State of New York for
any actions, suits or proceedings arising out of or relating to this Agreement
and the transactions contemplated hereby (and agrees not to commence any action,
suit or proceeding relating thereto except in such courts), irrevocably and
unconditionally waives any objection to the laying of venue of any action, suit
or proceeding arising out of this Agreement or the transactions contemplated
hereby in the courts of the State of New York or the United States of America
located in the State of New York, and hereby further irrevocably and
unconditionally waives and agrees not to plead or claim in any such court that
any such action, suit or proceeding brought in any such court has been brought
in an inconvenient forum.

     (h)  SEVERABILITY. In the event that any one of more of the provisions
contained herein, or the application thereof in any circumstances, is held
invalid, illegal or unenforceable in any respect for any reason, the validity,
legality and enforceability of any such provision in every other respect and of
the remaining provisions hereof shall not be in any way impaired or affected
thereby, it being intended that all of the rights and privileges of the parties
shall be enforceable to the fullest extent permitted by law.

     (i)  NO INCONSISTENT AGREEMENTS. The Issuer has not as of the date hereof
and shall not enter, after the date of this Agreement, into any agreement with
respect to any of their securities that is inconsistent with the rights granted
to the Holders in this Agreement or otherwise conflicts with the provisions
hereof. Except for the registration rights granted to the holders of the
Warrants, the Issuer has not entered and will not enter into any agreement with
respect to any of its securities that will grant to any person piggy-back rights
with respect to a Registration Statement.

     (j)  THIRD-PARTY BENEFICIARIES. Holders of Registrable Securities are
third-party beneficiaries of this Agreement, and this Agreement may be enforced
by such persons.

     (k)  SUBSIDIARY GUARANTOR A PARTY. Immediately upon a Person becoming a
Subsidiary of the Issuer after the Closing Date, the Issuer shall cause such
Person to become a party hereto as a Subsidiary Guarantor by executing and
delivering to Jefferies a counterpart hereof.

     (l)  RULE 144 AND RULE 144A. The Issuer shall take all actions reasonably
necessary to enable Holders of Registrable Securities to sell such securities
without registration under the Act within the limitation of the provisions of
(a) Rule 144 under the Act, as such Rule may be amended from time to time, (b)
Rule 144A under the Act, as such Rule may be amended from time to time, or (c)
any similar rules or regulations hereafter adopted by the Commission. Upon the
request of any 10% Holder of Registrable Securities, the Issuer will deliver to
such Holder a written statement as to whether it has complied with such
requirements. Any person or group who receives or beneficially owns 10% of the
total principal amount of New Notes on the Closing Date shall be a "10% HOLDER"
for purposes of this Agreement for so long as it owns such minimum percentage.

                                     - 18 -
<Page>

     (m)  NOMINEES FOR BENEFICIAL OWNERS. In the event that any Registrable
Securities are held by a nominee for the beneficial owner thereof, the
beneficial owner thereof may, at its election in writing delivered to the
Issuer, be treated as the Holder of such Registrable Securities for purposes of
any request or other action by any Holder or Holders of Registrable Securities
pursuant to this Agreement or any determination of any number or percentage of
shares of Registrable Securities held by any Holder or Holders of Registrable
Securities contemplated by this Agreement. If the beneficial owner of any
Registrable Securities so elects, the Issuer may require assurances reasonably
satisfactory to it of such owner's beneficial ownership of such Registrable
Securities.


                            [SIGNATURE PAGES FOLLOW]

                                     - 19 -
<Page>

     Please confirm that the foregoing correctly sets forth the agreement
between the Issuer and Jefferies.

                                           Very truly yours,

                                           ABRAXAS PETROLEUM CORPORATION


                                           /s/   Robert W. Carington, Jr.
                                                 ------------------------
                                                 Executive Vice President


                                           SANDIA OIL & GAS CORP.


                                           /s/   Robert W. Carington, Jr.
                                                 ------------------------
                                                 Vice President

                                           SANDIA OPERATING CORP.


                                           /s/   Robert W. Carington, Jr.
                                                 ------------------------
                                                 Vice President

                                           WAMSUTTER HOLDINGS, INC.


                                           /s/   Robert W. Carington, Jr.
                                                 ------------------------
                                                 Vice President

                                           WESTERN ASSOCIATED ENERGY
                                           CORPORATION


                                           /s/   Robert W. Carington, Jr.
                                                 ------------------------
                                                 Vice President

                                           GREY WOLF EXPLORATION INC.


                                           /s/   Robert W. Carington, Jr.
                                                 ------------------------
                                                 Vice President

                                           EASTSIDE COAL COMPANY, INC.


                                           /s/   Robert W. Carington, Jr.
                                                 ------------------------
                                                 Vice President


            [SIGNATURE PAGE OF ABRAXAS REGISTRATION RIGHTS AGREEMENT]

<Page>

                                           JEFFERIES & COMPANY, INC.


                                           /s/   Todd Dittmann
                                                 ------------------------
                                                 Senior Vice-President


            [SIGNATURE PAGE OF ABRAXAS REGISTRATION RIGHTS AGREEMENT]