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                                REVOLVING NOTE                    Exhibit 10.63

$20,000,000.00                  Houston, Texas                 October 21, 1997

         On the dates hereinafter prescribed, for value received, HORIZON
EXPLORATION LIMITED, an English company (the "Borrower"), having a Registered
Office at Napier House, 14-16 Mount Ephraim Road, Tunbridge Wells, Kent TN1
1EE, promises to pay to the order of BANK ONE, TEXAS, N.A. (herein called
"Bank"), at its principal offices at 910 Travis, Houston, Harris County, Texas
77002, (i) the principal amount of TWENTY MILLION AND NO/100 DOLLARS
($20,000,000.00) or the principal amount advanced pursuant to the terms of the
Loan Agreement (defined herein) as of the date of maturity hereof, whether by
acceleration or otherwise, whichever may be the lesser, and (ii) interest on
the principal balance from time to time advanced and remaining unpaid from the
date of the advance until maturity at a rate of interest equal to lesser of (a)
the "Interest Rate" (as defined in the Loan Agreement), or (b) the Maximum Rate
(as hereinafter defined).  Any increase or decrease in interest rate resulting
from a change in the Maximum Rate shall be effective immediately when such
change becomes effective, without notice to Borrower, unless Applicable Law (as
defined below) requires that such increase or decrease not be effective until a
later time, in which event such increase or decrease shall be effective at the
earliest time permitted under the provisions of such law.

         Notwithstanding the foregoing, if during any period the Interest Rate
exceeds the Maximum Rate, the rate of interest in effect on this Note shall be
limited to the Maximum Rate during each such period, but at all times
thereafter the rate of interest in effect on this Note shall be the Maximum
Rate until the total amount of interest accrued on this Note equals the total
amount of interest which would have accrued hereon if the Floating Rate had at
all times been in effect.

         All payments on this Note shall be applied first to accrued interest
and the balance, if any, to principal.

         This Note is a revolving credit note and it is contemplated that by
reason of prepayments hereon there may be times when no indebtedness is owing
hereunder; but notwithstanding such occurrence, this Note shall remain valid
and in full force and effect as to each principal advance made hereunder
subsequent to each such occurrence.  Each principal advance and each payment
hereof made pursuant to this Note shall be reflected by Bank's records and the
aggregate unpaid amounts reflected by such records shall constitute rebuttably
presumptive evidence of the principal and unpaid, accrued interest remaining
outstanding on this Note.

         "Maximum Rate" means the Maximum Rate of non-usurious interest
permitted from day to day by applicable law, including as to Article 5069-1.04,
Vernon's Texas Revised Civil Statutes Annotated (and as the same may be
incorporated by reference in other Texas statutes), but otherwise without
limitation, that rate based upon the "indicated weekly rate ceiling."

         "Applicable Law" means that law in effect from time to time and
applicable to this Note which lawfully permits the charging and collection of
the highest permissible lawful, non-usurious rate of interest on this Note,
including laws of the State of Texas and laws of the United States of
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America.  It is intended that Article 1.04, Title 79, Revised Civil Statutes of
Texas, 1927, as amended (Article 5069-1.04, as amended, Vernon's Texas Civil
Statutes) shall be included in the laws of the State of Texas in determining
Applicable Law; and for the purpose of applying said Article 1.04 to this Note,
the interest ceiling applicable to this Note under said Article 1.04 shall be
the indicated weekly rate ceiling from time to time in effect.  Borrower and
Bank hereby agree that Chapter 15 of Subtitle 3, Title 79, Revised Civil
Statutes of Texas, 1925, as amended, shall not apply to this Note or the loan
transaction evidenced by, and referenced in, the Loan Agreement (hereinafter
defined) in any manner, including without limitation, to any account or
arrangement evidenced or created by, or provided for in, this Note.

         "Business Day" shall mean any day on which banks are open for general
banking business in the State of Texas, other than a Saturday, a Sunday, a
legal holiday or any other day on which banks in the State of Texas are
required or authorized by law or executive order to close.

         The principal sum of this Note, after giving credit for unadvanced
principal, if any, remaining at final maturity, shall be due and payable on or
before the Maturity Date, as prescribed in the Loan Agreement defined below;
interest to accrue upon the principal sum from time to time owing and unpaid
hereunder shall be due and payable in monthly installments, as it accrues, with
the first such monthly installment of interest hereon being due and payable on
the first day of November 1997, and with such subsequent installments of
interest being due and payable on the first day of each succeeding month
thereafter; provided, however, the final installment of interest hereunder
shall be due and payable not later than the maturity of the principal sum
hereof, howsoever such maturity may be brought about.

         When the first (1st) day of a calendar month falls upon a Saturday,
Sunday or legal holiday, the payment of interest and principal, if any, due
upon such date shall be due and payable upon the next succeeding Business Day.

         In no event shall the aggregate of the interest on this Note, plus any
other amounts paid in connection with the loan evidenced by this Note which
would under Applicable Law be deemed "interest," ever exceed the maximum amount
of interest which, under Applicable Law, could be lawfully charged on this
Note.  Bank and Borrower specifically intend and agree to limit contractually
the interest payable on this Note to not more than an amount determined at the
Maximum Rate.  Therefore, none of the terms of this Note or any other
instruments pertaining to or securing this Note shall ever be construed to
create a contract to pay interest at a rate in excess of the Maximum Rate, and
neither Borrower nor any other party liable herefor shall ever be liable for
interest in excess of that determined at the Maximum Rate, and the provisions
of this paragraph shall control over all provisions of this Note or of any
other instruments pertaining to or securing this Note.  If any amount of
interest taken or received by Bank shall be in excess of the maximum amount of
interest which, under Applicable Law, could lawfully have been collected on
this Note, then the excess shall be deemed to have been the result of a
mathematical error by the parties hereto and shall be refunded promptly to
Borrower.  All amounts paid or agreed to be paid in connection with the
indebtedness evidenced by this Note which would under Applicable Law be





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deemed "Interest" shall, to the extent permitted by Applicable Law, be
amortized, prorated, allocated and spread throughout the full term of this
Note.

         This Note is secured by all security agreements, collateral
assignments, mortgages and lien instruments executed by Borrower (or by any
other party) in favor of Bank, including those executed simultaneously
herewith, those executed heretofore and those hereafter executed, and including
specifically and without limitation the "Security Instruments" described and
defined in the Revolving Credit Agreement of even date between Borrower and
Bank (the "Credit Agreement").

         This Revolving Note is the Note issued pursuant to the Credit
Agreement. Reference is hereby made to the Credit Agreement for a statement of
the rights and obligations of the holder of this Note and the duties and
obligations of Borrower in relation thereto; but neither this reference to the
Credit Agreement nor any provisions thereof shall affect or impair the absolute
and unconditional obligation of Borrower to pay any outstanding and unpaid
principal of and interest on this Note when due, in accordance with the terms
of the Credit Agreement.  Each advance and each payment made pursuant to this
Note shall be reflected by notations made by Bank on its records and the
aggregate unpaid amounts reflected by the notations on the records of Bank
shall be deemed rebuttably presumptive evidence of the principal amount owing
under this Note.

         In the event of default in the payment when due of any of the
principal of or any interest on this Note, or in the event of default under the
terms of the Credit Agreement or any of the Security Instruments, or if any
event occurs or condition exists which authorizes the acceleration of the
maturity of this Note under any agreement made by Borrower, Bank (or other
holder of this Note) may, at its option, without presentment or demand or any
notice to Borrower or any other person liable herefor, declare the unpaid
principal balance of and accrued interest on this Note to be immediately due
and payable.

         If this Note is collected by suit or through the Probate or Bankruptcy
Court, or any judicial proceeding, or if this Note is not paid at maturity,
however such maturity may be brought about, and is placed in the hands of an
attorney for collection, then Borrower agrees to pay reasonable attorneys'
fees, not to exceed 10% of the full amount of principal and interest owing
hereon at the time this Note is placed in the hands of an attorney.

         Borrower and all sureties, endorsers and guarantors of this Note waive
demand, presentment for payment, notice of nonpayment, protest, notice of
protest, notice of intent to accelerate maturity, notice of acceleration of
maturity, and all other notices, filing of suit and diligence in collecting
this Note or enforcing any of the security herefor, and agree to any
substitution, exchange or release of any such security or the release of any
party primarily or secondarily liable hereon and further agrees that it will
not be necessary for Bank, in order to enforce payment of this Note by them, to
first institute suit or exhaust its remedies against any Borrower or others
liable herefor, or to enforce its rights against any security herefor, and
consent to any one or more extensions or postponements of time of payment of
this Note on any terms or





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any other indulgences with respect hereto, without notice thereof to any of
them.  Bank may transfer this Note, and the rights and privileges of Bank under
this Note shall inure to the benefit of Bank's representatives, successors or
assigns.


                 Executed this 21st day of October 1997.

                                             HORIZON EXPLORATION LIMITED


                                             By: /s/ RICHARD W. MCNAIRY
                                                -------------------------------
                                                     Richard w. McNairy
                                                     Agent and Attorney-in-Fact