POWER OF ATTORNEY
                         For Executing Forms 3, 4, and 5

The  undersigned  hereby  appoints each of Mark L. Lemond,  W. Kerry Jackson
and David A. Kapp,  signing  singly,  as true and lawful attorney-in-fact to:

         (1)      execute for and on behalf of the undersigned Forms 3, 4 and 5
                  and any amendments to previously filed forms in accordance
                  with Section 16(a) of the Securities Exchange Act of 1934 and
                  the rules thereunder.

         (2)      do and perform any and all acts for and on behalf of the
                  undersigned which may be necessary or desirable to complete
                  the execution of any such Form 3, 4 or 5 and the timely filing
                  of such form with the United States Securities and Exchange
                  Commission and any other authority; and

         (3)      take any other action of any type whatsoever in connection
                  with the foregoing which, in the opinion of such
                  attorney-in-fact, may be of benefit to, in the best interest
                  of, or legally required by, the undersigned, it being
                  understood that the documents executed by such
                  attorney-in-fact on behalf of the undersigned pursuant to this
                  Power of Attorney shall be in such form and shall contain such
                  terms and conditions as such attorney-in-fact may approve in
                  his discretion.

         The undersigned hereby grants to each such attorney-in-fact full power
and authority to do and perform all and every act and thing whatsoever
requisite, necessary and proper to be done in the exercise of any of the rights
and powers herein granted, as fully to all intents and purposes as such
attorney-in-fact might or could do if personally present, with full power of
substitution or revocation, hereby ratifying and confirming all that such
attorney-in-fact, or his substitute or substitutes, shall lawfully do or cause
to be done by virtue of this power of attorney and the rights and powers herein
granted. The undersigned acknowledges that the foregoing attorneys-in-fact, in
serving in such capacity at the request of the undersigned, are not assuming any
of the undersigned's responsibilities to comply with Section 16 of the
Securities Exchange Act of 1934.

         IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney
to be executed as of this 1st day of July, 2003.


                                    /s/ Kent Kleeberger
                                    Signature