<PAGE>


                                                                   Exhibit 10.11

                             VOTING AGREEMENT (PXP)

     VOTING AGREEMENT (this "Agreement") dated as of February 2, 2003, by and
among Plains Exploration & Production Company, a Delaware corporation ("PXP"),
3TEC Energy Corporation, a Delaware corporation ("3TEC"), EnCap Energy
Acquisition III-B, Inc., EnCap Energy Capital Fund III, L.P., BOCP Energy
Partners, L.P., and ECIC Corporation, (together with EnCap Energy Acquisition
III-B, Inc., EnCap Energy Capital Fund III, L.P. and BOCP Energy Partners, L.P.,
the "EnCap Entities"), Floyd C. Wilson ("Wilson"), Stephen W. Herod ("Herod"),
and R. A. Walker (with the EnCap Entities, Wilson, and Herod, each a
"Stockholder" and collectively, the "Stockholders").

     WHEREAS, each Stockholder desires that PXP, PXP Gulf Coast, Inc., a
Delaware corporation and wholly-owned subsidiary of PXP ("Merger Sub"), and
3TEC, enter into an Agreement and Plan of Merger dated the date hereof (the
"Merger Agreement"; undefined capitalized terms herein are defined in the Merger
Agreement) providing for the merger of 3TEC with and into Merger Sub (the
"Merger") upon the terms and subject to the conditions set forth in the Merger
Agreement;

     WHEREAS, each Stockholder is executing this Agreement as an inducement to
PXP to enter into and execute the Merger Agreement; and

     WHEREAS, concurrently with the execution and delivery of this Agreement,
3TEC is entering into a voting agreement with certain PXP Stockholders (the "PXP
Stockholders") under which such parties have, among other things, agreed to
support the Merger upon the terms and conditions set forth therein.

     NOW, THEREFORE, in consideration of the execution and delivery by PXP of
the Merger Agreement and the mutual covenants, conditions and agreements
contained herein and therein, the parties agree as follows:

     1. Representations and Warranties.

     (a) Each Stockholder severally represents and warrants to PXP as follows:

          (i) Such Stockholder is the record and beneficial owner of that number
     of shares of capital stock of 3TEC set forth opposite such Stockholder's
     name on Schedule A (together with any other shares of other capital stock
     of 3TEC acquired after the date hereof including through the exercise of
     any stock options, warrants or similar instruments) being collectively
     referred to herein as the "Subject Shares") and the other securities
     exercisable or exchangeable for such capital stock listed on Schedule A
     (the "Other Securities" and, together with the Subject Shares, the "Covered
     Securities"). The Subject Shares constitute the only shares, with respect
     to which such Stockholder is the record or beneficial owner, of capital
     stock of 3TEC or options, warrants or other rights (whether or not
     contingent) to acquire such shares of capital stock of 3TEC that are or may
     be entitled to vote on the Merger or the Merger Agreement at any meeting of
     3TEC's Stockholders called to vote upon the Merger or the Merger Agreement.
     Such


<PAGE>





     Stockholder has the sole right to vote and Transfer (as defined herein) the
     Covered Securities set forth opposite its name on Schedule A, and none of
     such Covered Securities is subject to any voting trust or other agreement,
     arrangement or restriction with respect to the voting or the Transfer of
     the Subject Shares, except (A) as provided by this Agreement (it being
     understood that any pledge of the Pledged Shares (as defined below) shall
     not be a breach of this representation) and (B) those arising under
     applicable securities laws. Such Stockholder has all requisite power and
     authority, and, if such Stockholder is a natural person, the legal
     capacity, to enter into this Agreement and to perform its obligations
     hereunder. To the extent that such Stockholder is an entity and not an
     individual, such Stockholder is duly organized, validly existing and in
     good standing under the laws of its jurisdiction of organization. The
     execution and delivery of this Agreement by such Stockholder and the
     performance by such Stockholder of its obligations hereunder have been duly
     authorized by all necessary action on the part of such Stockholder. This
     Agreement has been duly executed and delivered by, and constitutes a valid
     and binding agreement of, such Stockholder, enforceable against such
     Stockholder in accordance with its terms, except as enforcement may be
     limited by the Enforceability Exceptions.

          (ii) Neither the execution and delivery of this Agreement nor the
     performance by such Stockholder of its obligations hereunder will result in
     a violation of, or a default under, or conflict with, (A) if such
     Stockholder is an entity, any provision of its certificate of
     incorporation, bylaws, partnership agreement, limited liability company
     agreement or similar organizational documents, (B) any contract, trust,
     commitment, agreement, understanding, arrangement or restriction of any
     kind (other than as may relate to the Pledged Shares but subject to the
     proviso set forth in (iv) below) to which such Stockholder is a party or
     bound or to which the Covered Securities are subject, except, in the case
     of clause (B), as would not prevent, delay or otherwise materially impair
     such Stockholder's ability to perform its obligations hereunder. Execution,
     delivery and performance of this Agreement by such Stockholder will not
     violate, or require any consent, approval or notice under, any provision of
     any judgment, order, decree, statute, law, rule or regulation applicable to
     such Stockholder or the Covered Securities, except (x) for any reports
     under Sections 13(d) and 16 of the Exchange Act as may be required in
     connection with this Agreement and the transactions contemplated hereby or
     (y) as would not reasonably be expected to prevent, delay or otherwise
     materially impair such Stockholder's ability to perform its obligations
     hereunder.

          (iii) If the Stockholder is married and the Covered Securities of the
     Stockholder constitute community property or spousal approval is otherwise
     required for this Agreement to be legal, valid and binding, then, to the
     extent so required, this Agreement has been duly authorized, executed and
     delivered by, and constitutes a valid and binding agreement of, the
     Stockholder's spouse, enforceable against such spouse in accordance with
     its terms, subject to the Enforceability Exceptions.

          (iv) The Covered Securities and the certificates representing such
     Covered Securities are held by such Stockholder, or by a nominee or
     custodian for the benefit of such Stockholder, free and clear of all liens,
     claims, security interests, proxies, voting trusts or agreements,
     understandings or arrangements or any other encumbrances


                                       2

<PAGE>


     whatsoever, except for (A) any such encumbrances arising hereunder, or (B)
     any such encumbrances arising pursuant to the pledge of any Covered
     Securities by such Stockholder to a financial institution or a brokerage
     firm (the "Pledged Shares"); provided, however, that such Stockholder
     represents that any such arrangement regarding such Pledged Shares shall
     not prevent, delay or otherwise materially impair such Stockholder's
     ability to execute and deliver this Agreement or perform its obligations
     hereunder and such Stockholder shall use his reasonable efforts to obtain
     an acknowledgment by the pledgee of the terms of this Agreement and such
     pledgee's agreement to vote the Pledged Shares (if and to the extent the
     voting power of the Pledged Shares is being or to be exercised by pledgee)
     in accordance with Section 2.

          (v) No broker, investment banker, financial advisor or other person is
     entitled to any broker's, finder's, financial advisor's or other similar
     fee or commission based upon arrangements made by or on behalf of such
     Stockholder in connection with its entering into this Agreement.

          (vi) Such Stockholder understands and acknowledges that PXP is
     entering into the Merger Agreement in reliance upon such Stockholder's
     execution and delivery of this Agreement.

     (b) PXP represents and warrants to each Stockholder and 3TEC that the
execution and delivery of this Agreement by PXP and the consummation by PXP of
the transactions contemplated hereby have been duly authorized by all necessary
action on the part of PXP.

     (c) 3TEC represents and warrants to each Stockholder and PXP that the
execution and delivery of this Agreement by 3TEC and the consummation by 3TEC of
the transactions contemplated hereby have been duly authorized by all necessary
action on the part of 3TEC.

     2. Voting Agreements. During the Term (as defined below) of this Agreement,
at any meeting of stockholders of 3TEC or at any adjournment thereof or in any
other circumstances upon which a vote, consent or other approval (including by
written consent) is sought, each Stockholder shall, including by executing a
written consent solicitation if requested by PXP, vote (or cause to be voted)
the Subject Shares: (a) in favor of the Merger, the adoption by 3TEC of the
Merger Agreement and the approval of the terms thereof and each of the other
Transactions and (b) against any transaction, agreement, matter or 3TEC
Acquisition Proposal that would impede, interfere with, delay, postpone or
attempt to discourage the Merger and the Merger Agreement.

     3. Irrevocable Proxy. Each Stockholder hereby appoints PXP as its proxy to
vote all of such Stockholder's Subject Shares at any meeting of stockholders of
3TEC (including any adjournments and postponements thereof) on the matters
described in Section 2, and to execute and deliver any written consents to
fulfill such Stockholder's obligations under this Agreement. This proxy is
coupled with an interest and is irrevocable until the end of the Term.


                                       3

<PAGE>


     4. Revocation of Other Proxies. To the extent inconsistent with the other
provisions of this Agreement or the Merger Agreement, each Stockholder hereby
revokes any and all previous proxies with respect to such Stockholder's Subject
Shares.

     5. Other Covenants. Each Stockholder severally agrees with, and covenants
to, PXP during the Term of this Agreement as follows:

     (a) Such Stockholder shall not after the date hereof (i) sell, transfer,
pledge, assign or otherwise dispose of (including by gift) (collectively,
"Transfer"), or consent to any Transfer of, any Covered Securities or any
interest therein, except pursuant to the Merger, (ii) enter into any contract,
option or other agreement with respect to any Transfer of any or all of the
Covered Securities or any interest therein, (iii) grant any proxy,
power-of-attorney or other authorization in or with respect to the Subject
Shares or (iv) deposit the Subject Shares into a voting trust or enter into a
voting agreement or voting arrangement with respect to the Subject Shares;
provided, that any such Stockholder may Transfer any of the Covered Securities
to an affiliate of such Stockholder (provided such affiliates evidences in a
writing reasonably satisfactory to the other parties hereto such affiliate's
agreement to the terms hereof) or any other Stockholder who is on the date
hereof or hereafter becomes a party to this Agreement; provided, further, that
the restrictions in this Section 5 shall not be deemed violated by any Transfer
of Covered Securities pursuant to a cashless exercise of stock options or
warrants; and provided, further, that a pledge of Pledged Shares made in
accordance with Section 1(a)(iv) shall not be deemed to be a violation of the
restrictions in this Section 5.

     (b) Such Stockholder hereby waives any rights of appraisal, or rights to
dissent from the Merger, that such Stockholder may have.

     (c) Such Stockholder shall not take any action prohibited by Section 7.2 of
the Merger Agreement.

     6. Additional Covenants. During the Term of this Agreement no Stockholder
shall (a) exercise any of the Other Securities other than as contemplated by
Section 3.3 of the Merger Agreement or (b) convert any shares of Series D
Preferred Stock, par value $.02, of 3TEC.

     7. Certain Events. This Agreement and the obligations hereunder shall
attach to each Stockholder's Covered Securities and shall be binding upon any
Person to which legal or beneficial ownership of such Shares shall pass, whether
by operation of law or otherwise, including such Stockholder's heirs, guardians,
administrators or successors. In the event of any stock split, stock dividend,
merger, reorganization, recapitalization or other change in the capital
structure of 3TEC affecting the Covered Securities or the acquisition of
additional shares of Covered Securities or other voting securities of 3TEC by
any Stockholder, the number of Covered Securities listed on Schedule A beside
the name of such Stockholder shall be adjusted appropriately and this Agreement
and the obligations hereunder shall attach to any additional Covered Securities
or other voting securities of 3TEC issued to or acquired by such Stockholder.

     8. Stop Transfer. 3TEC shall not register the transfer of any certificate
representing any Covered Securities, unless such transfer is made to PXP or
otherwise in compliance with this Agreement.


                                       4

<PAGE>


     9. Stockholder Capacity. No person executing this Agreement (or an
affiliate thereof) who is or becomes during the Term a director of 3TEC makes
any agreement or understanding herein in his or her capacity as such director.
Each Stockholder signs solely in his or her capacity as the record and
beneficial owner of, or the trustee of a trust whose beneficiaries are the
beneficial owners of, such Stockholder's Covered Securities.

     10. Further Assurances. Each Stockholder shall, upon request of PXP,
execute and deliver any additional documents and take such further actions as
may reasonably be deemed by PXP to be necessary or desirable to carry out the
provisions hereof.

     11. Termination. This Agreement, and all rights and obligations of the
parties hereunder, shall terminate upon (and shall only be effective from the
date hereof until) the first to occur of (i) the Effective Time of the Merger,
or (ii) the date upon which the Merger Agreement is terminated in accordance
with its terms (such period from the date hereof until such termination is
referred to herein as the "Term"); provided, however, that (x) Section 12 shall
survive any termination of this Agreement and (y) termination of this Agreement
pursuant to clause (ii) above shall not relieve any party hereto from liability
for any willful and knowing breach hereof prior to such termination.

     12. Miscellaneous.

     (a) All notices, requests, claims, demands and other communications under
this Agreement shall be in writing and shall be deemed given if delivered
personally or sent by overnight courier (providing proof of delivery) to the
parties at the following addresses (or at such other address for a party as
shall be specified by like notice): (i) if to PXP or 3TEC, to the appropriate
address set forth in Section 11.1 of the Merger Agreement; and (ii) if to a
Stockholder, to the appropriate address set forth on Schedule A.

     (b) Each Party submits to the jurisdiction of any state or federal court
sitting in the State of Delaware in any dispute or action arising out of or
relating to this Agreement and agrees that all claims in respect of such dispute
or action may be heard and determined in any such court. Each Party also agrees
not to bring any dispute or action arising out of or relating to this Agreement
in any other court. Each Party agrees that a final judgment in any dispute or
action so brought will be conclusive and may be enforced by action on the
judgment or in any other manner provided at law (common, statutory or other) or
in equity. Each Party waives any defense of inconvenient forum to the
maintenance of any dispute or action so brought and waives any bond, surety, or
other security that might be required of any other Party with respect thereto.

     (c) Each Party appoints RLF Service Corp., One Rodney Square, Wilmington,
Delaware 19801 as their agent to receive on their behalf service of copies of
the summons and complaint and any other process that might be served in an
dispute or action (the "Process Agent"). Any Party may make service on any other
Party by sending or delivering a copy of the process (i) to the Party to be
served at the address and in the manner provided for the giving of notices in
Section 12(a) or (ii) to the Party to be served in care of the Process Agent at
the address and in the manner provided for the giving of notices in Section
12(a).


                                       5

<PAGE>


     (d) The headings contained in this Agreement are for reference purposes
only and shall not affect in any way the meaning or interpretation of this
Agreement.

     (e) This Agreement may be executed in two or more counterparts, all of
which shall be considered one and the same agreement and shall become effective
as to any Stockholder when one or more counterparts have been signed by each of
PXP, 3TEC and such Stockholder and delivered to PXP, 3TEC and such Stockholder.

     (f) This Agreement (including the documents and instruments referred to
herein) constitutes the entire agreement, and supersedes all prior agreements
and understandings, both written and oral, among the parties with respect to the
subject matter hereof, and this Agreement is not intended to confer upon any
other person (other than PXP) any rights or remedies hereunder.

     (g) This Agreement shall be governed by, and construed in accordance with,
the laws of the State of Delaware, regardless of the laws that might otherwise
govern under applicable principles of conflicts of laws thereof.

     (h) Neither this Agreement nor any of the rights, interests or obligations
under this Agreement shall be assigned, in whole or in part, by operation of law
or otherwise, by any of the parties without the prior written consent of the
other parties, except by laws of descent or as expressly provided by Section
5(a). Any assignment in violation of the foregoing shall be void.

     (i) As between any Stockholder and PXP, each of such parties agrees that
irreparable damage to the other, non-breaching party would occur and that such
non-breaching party would not have any adequate remedy at law in the event that
any of the provisions of this Agreement were not performed in accordance with
their specific terms or were otherwise breached. It is accordingly agreed that
the non-breaching party shall be entitled to an injunction or injunctions to
prevent breaches by the other party of this Agreement and to enforce
specifically the terms and provisions of this Agreement, this being in addition
to any other remedy to which it may be entitled at law or in equity.

     (j) If any term, provision, covenant or restriction herein, or the
application thereof to any circumstance, shall, to any extent, be held by a
court of competent jurisdiction to be invalid, void or unenforceable, the
remainder of the terms, provisions, covenants and restrictions herein and the
application thereof to any other circumstances shall remain in full force and
effect, shall not in any way be affected, impaired or invalidated, and shall be
enforced to the fullest extent permitted by law.

     (k) No amendment, modification or waiver in respect of this Agreement shall
be effective against any party unless it shall be in writing and signed by such
party.

                            [SIGNATURE PAGE FOLLOWS]


                                       6

<PAGE>


     IN WITNESS WHEREOF, PXP, 3TEC, and the Stockholders party hereto have
caused this Agreement to be duly executed and delivered as of the date first
written above.

                                     PLAINS EXPLORATION AND PRODUCTION COMPANY


                                     By:
                                        ----------------------------------------
                                     Name: James C. Flores
                                     Title: Chief Executive Officer

                                     3TEC ENERGY CORPORATION

                                     By:
                                        ----------------------------------------
                                     Name: Floyd C. Wilson
                                     Title: Chief Executive Officer


                                     STOCKHOLDERS:


                                     -------------------------------------------
                                     FLOYD C. WILSON


                                     -------------------------------------------
                                     STEPHEN W. HEROD


                                     -------------------------------------------
                                     R. A. WALKER


                                     ENCAP ENERGY CAPITAL FUND III, L.P.

                                     By:  ENCAP INVESTMENTS L.L.C.,
                                          General Partner

                                     By:
                                        ----------------------------------------
                                     Name:
                                           -------------------------------------
                                     Title: Managing Director


                                       7

<PAGE>



                                     ENCAP ENERGY ACQUISITION III-B, INC.

                                     By:
                                        ----------------------------------------
                                     Name:
                                           -------------------------------------
                                     Title: Vice President


                                     BOCP ENERGY PARTNERS, L.P.

                                     By:  ENCAP INVESTMENTS L.L.C.,  Manager

                                     By:
                                        ----------------------------------------
                                     Name:
                                           -------------------------------------
                                     Title: Managing Director


                                     ECIC CORPORATION

                                     By:
                                        ----------------------------------------
                                     Name:
                                           -------------------------------------
                                     Title: Vice President


                                     ENCAP INVESTMENTS L.L.C.


                                     By:
                                        ----------------------------------------
                                     Name:
                                           -------------------------------------
                                     Title: Managing Director



                                       8

<PAGE>



                                   SCHEDULE A

<TABLE>
<CAPTION>
                                                                                                  Other Securities
                                                                                                 *= $3.00 Warrants,
                                           Common Stock                                         **=$30.00 Warrants,
   Stockholder Name and Address      (# includes Res. Shares)    Series D Preferred Stock        += Vested Options
   ----------------------------      ------------------------    ------------------------      -----------------------
<S>                                           <C>                        <C>                          <C>
EnCap Energy Acquisition                      957,587                    145,850                      281,642*
III-B, Inc.                                                                                            60,458**
1100 Louisiana
Suite 3150
Houston, Texas 77002
Attn: Managing Director

EnCap Energy Capital Fund III,              1,266,144                    192,846                      372,393*
L.P.                                                                                                   79,939**
1100 Louisiana                                                                                        110,000+
Suite 3150
Houston, Texas 77002
Attn: Managing Director

BOCP Energy Partners, L.P.                    309,809                     47,187                      91,120*
1100 Louisiana                                                                                        19,560**
Suite 3150
Houston, Texas 77002
Attn: Managing Director

ECIC Corporation                              447,095                     68,097                     131,498*
1100 Louisiana                                                                                        28,227**
Suite 3150
Houston, Texas 77002
Attn: Managing Director

Floyd C. Wilson                               572,610/1/                     -0-                     290,014*
848 Kuhlman Rd.                                37,500#                                               633,335+
Houston, Texas 77024

Stephen W. Herod                               47,686                        -0-                     194,167+
1110 Briar Ridge                                5,000#
Houston, Texas 77057

R. A. Walker                                    2,000                        -0-                     725,001+
21 North Wynden #4                             25,000#
Houston, Texas 77056

TOTAL                                       3,602,931                    453,980                   1,166,667*
                                               62,500#                                               188,184**
                                                                                                   1,662,503+
</TABLE>
--------
/1/  Includes 5,000 shares held by Wilvest Limited Partnership, of which Mr.
     Wilson is a general partner.

                                       9