<PAGE>

                                                                    EXHIBIT 10.2

                        FIRST AMENDMENT TO LOAN AGREEMENT

         THIS FIRST AMENDMENT TO LOAN AGREEMENT (this "Amendment") is made and
entered into as of this ___ day of August, 2002 by and between Harken Energy
Corporation, a Delaware corporation (the "Borrower"), and Lyford Investments
Enterprises Ltd., a British Virgin Islands corporation (the "Lender") and amends
that certain Loan Agreement by and between Borrower and Lender dated July 15,
2002 (the "Loan Agreement").

                                    RECITALS

         WHEREAS, pursuant to the terms and subject to the conditions of the
Loan Agreement, the Lender loaned to the Borrower a total of $3,000,000 (the
"Existing Term Loan");

         WHEREAS, the Borrower has requested to borrow and, pursuant to the
terms and subject to the conditions hereof and in connection herewith, the
Lender has agreed to loan an additional $2,000,000 to the Borrower under the
same terms and conditions as the Existing Term Loan;

         WHEREAS, in furtherance of the foregoing and to evidence the agreements
of the parties hereto in relation thereto the parties hereto desire to amend the
Loan Agreement as hereinafter provided;

         NOW, THEREFORE, in consideration of the premises herein contained and
other good and valuable consideration, the receipt and sufficiency of which are
hereby acknowledged, the Borrower and the Lender, intending to be legally bound,
agree as follows:

             1. DEFINED TERMS. Capitalized terms used in this Amendment are
defined in the Loan Agreement, as amended hereby, unless otherwise stated.

             2. AMENDMENT OF LOAN AGREEMENT. Effective as of the respective date
herein indicated, the Loan Agreement is hereby amended as follows:

                (a) Amendment to Definition of Note in Section 1. The definition
         of the term "Note" as set forth in Section 1 of the Loan Agreement is
         amended and restated as follows:

                ""Note" means, either separately or together depending on the
             context, the following: (i) that certain Promissory Note dated July
             15, 2002 executed by the Borrower and payable to the Lender in the
             form of Exhibit A hereto (the "Existing Note"), and (ii) a
             Promissory Note to be issued by Borrower concurrent with the
             execution of the Amendment, in the principal amount of $2,000,000
             substantially in the form of Exhibit A to the Amendment (the
             "Additional Note")."

<PAGE>

                    (b) Amendment of Section 2. Section 2 of the Loan Agreement
               is hereby amended and restated as follows:

                    "2. LOAN TERMS.

                        (a) Term Loan. Subject to the terms and conditions
                    hereof, the Lender will lend the amount of Three Million
                    Dollars ($3,000,000.00) as of July 15, 2002 (the "Existing
                    Term Loan") and an additional Two Million Dollars
                    ($2,000,000) as of the date of the Amendment (the
                    "Additional Term Loan"). As used herein, "Term Loan" shall
                    mean, either separately or together depending on the
                    context, the Existing Term Loan and the Additional Term
                    Loan. The Existing Term Loan and the Additional Term Loan
                    shall each be evidenced by, and payable in accordance with
                    the terms of the appropriate Note. The proceeds of the Term
                    Loan shall be used by Borrower for general corporate
                    purposes, including working capital needs or to refinance or
                    pay long-term or short-term debt obligations.

                        (b) Interest. Except as otherwise provided in this
                    Agreement or in the Note, the unpaid principal amount of the
                    Term Loan outstanding from time to time shall bear interest
                    from the date of the issuance of the Note in respect of such
                    Term Loan until fully paid at the Interest Rate. All
                    interest shall be computed on the basis of a year of 360
                    days and the actual number of days elapsed (including the
                    first day but excluding the last day)."

                    3.  RATIFICATIONS, REPRESENTATIONS AND WARRANTIES.

                        (a) Ratifications. The terms and provisions set forth in
               this Amendment shall modify and supersede all inconsistent terms
               and provisions set forth in the Loan Agreement, and, except as
               expressly modified and superseded by this Amendment, the terms
               and provisions of the Loan Agreement are ratified and confirmed
               and shall continue in full force and effect. The Borrower and the
               Lender agree that the Loan Agreement, as amended hereby, shall
               continue to be legal, valid, binding and enforceable in
               accordance with its respective terms.

                        (b) Representations and Warranties. The parties each
               hereby represent and warrant that (a) the execution, delivery and
               performance of this Amendment and any and all other documents
               executed and/or delivered in connection herewith have been
               authorized by all requisite corporate action on the part of
               Borrower or Lender as the case may be and will not violate their
               respective certificates of incorporation or bylaws; (b) the
               representations and warranties contained in the Loan Agreement,
               as amended hereby, are true and correct on and as of the date
               hereof and on and as of the date of execution hereof as though
               made on and as of each such date; (c) no Event of Default under
               the Loan Agreement, as amended hereby, has occurred and is
               continuing, and (d) the parties are in full compliance with all
               covenants and agreements contained in the Loan Agreement, as
               amended hereby.

                                      -2-





<PAGE>

          4. COVENANT. As further consideration for Lender's agreement to enter
into this Amendment, Borrower covenants that, in addition to the GED Warrant
issued under the original terms of the Agreement, it shall deliver to Lender, on
or before 30 days after the date of this Amendment, a non-transferable
non-registered stock purchase warrant (the "Additional GED Warrant") for the
purchase of up to 2.8 million shares of GED ordinary shares exercisable by
Lender at any time on or before 90 days after the Maturity Date of the
Additional Note. The Additional GED Warrant shall have an exercise price of 50
pence per share of GED stock. If an Event of Default occurs on or before the
expiration date of the Additional GED Warrant, then such warrant shall continue
to be exercisable for a period extending three years after the original
expiration date for such warrant."

          5. MISCELLANEOUS PROVISIONS.

             (a) Reference to Loan Agreement. Each of the Loan Agreement and the
     other documents executed in connection therewith, and any and all other
     documents or instruments now or hereafter executed and delivered pursuant
     to the terms hereof or pursuant to the terms of the Loan Agreement, as
     amended hereby, are hereby amended so that any reference in the Loan
     Agreement shall mean a reference to the Loan Agreement, as amended hereby.

             (b) Transfer; Successors and Assigns. The terms and conditions of
     this Amendment shall inure to the benefit of and be binding upon the
     respective successors and assigns of the parties. Notwithstanding the
     foregoing, Lender may not assign, pledge, or otherwise transfer its
     obligations or rights under this Amendment without the prior written
     consent of Borrower.

             (c) Amendments and Waivers. Any term of this Amendment may be
     amended only with the written consent of the Lender and the Borrower. Any
     amendment or waiver effected in accordance with this Section 5(c) shall be
     binding upon the Lender, the Borrower and each transferee of the Amendment.
     Any waiver by the Lender or the Borrower of a breach of any provision of
     this Amendment shall not operate as or be construed to be a waiver of any
     other breach of such provision or of any breach of any other provision of
     this Amendment. The failure of the Lender or the Borrower to insist upon
     strict adherence to any term of this Amendment on one or more occasions
     shall not be considered a waiver or deprive that party of the right
     thereafter to insist upon strict adherence to that term or any other term
     of this Amendment.

             (d) Notices. All notices, consents, waivers and other
     communications under this Agreement must be in writing and will be deemed
     to have been duly given when (a) delivered by hand (with written
     confirmation of receipt), (b) sent by facsimile (with written confirmation
     of receipt), or (c) when received by the addressee, if sent by U.S. mail or
     a nationally recognized overnight delivery service, in each case to the

                                      -3-

<PAGE>


          appropriate addresses and facsimile numbers set forth below (or to
          such other addresses and facsimile numbers as a party may designate by
          notice to the other party):

          To Lender:

                  Lyford Investments Enterprises Ltd.
                  c/o Quadrant Management Inc.
                  720 Fifth Ave., 9/th/ Floor
                  New York, NY 10019
                  Attn: Alan Quasha

                  Facsimile No.: (212) 231-3939

          To Borrower:

                  Harken Energy Corporation
                  580 WestLake Park Boulevard, Suite 600
                  Houston, Texas 77079
                  Attention: A. Wayne Hennecke, Secretary
                  Facsimile No.: (281) 504-4104

                  with a required copy to:

                  James W. Ryan
                  Porter & Hedges, L.L.P.
                  700 Louisiana, 35/th/ Floor
                  Houston, Texas 77002-2764
                  Facsimile No.: (713) 226-0290

                      (e) Governing Law. Unless otherwise specified therein,
          this Amendment shall be governed by and construed in accordance with
          the laws of the State of New York and the United States of America.
          Each party hereby irrevocably agrees that any legal proceeding arising
          out of or in connection with this Amendment shall be brought in the
          district courts of Harris County, Texas, or in the United States
          District Court for the Southern District of Texas, Houston Division.

                      (f) Counterparts. This Amendment may be executed in
          several identical counterparts, and by the parties hereto on separate
          counterparts, and each counterpart, when so executed and delivered,
          shall constitute an original instrument, and all such separate
          counterparts shall constitute but one and the same instrument.

                      (g) Captions. The headings and captions appearing in this
          Amendment have been included solely for convenience and shall not be
          considered in construing the Amendment.

                                      -4-





<PAGE>

                   (h) Entire Agreement. This Amendment, the Loan Agreement, the
          Existing Note and the Additional Note together with any other document
          executed in connection herewith or therewith, embody the entire
          agreement between the Borrower and the Lender and supersede all prior
          proposals, agreements and understandings relating to the subject
          matter hereof and thereof.

                   (i) Invalidity. If any provision of this Amendment is
          invalid, illegal or unenforceable, the balance of this Amendment shall
          remain in effect, and if any provision is inapplicable to any person
          or circumstance, it shall nevertheless remain applicable to all other
          persons and circumstances. In such an event, the parties will in good
          faith attempt to effect the business agreement represented by such
          invalidated term to the fullest extent permitted by law.

                  [Remainder of page left blank intentionally]

                                      -5-

<PAGE>

         IN WITNESS WHEREOF, the parties hereto have executed this Agreement as
of the date set forth above.

                                    BORROWER:

                                    HARKEN ENERGY CORPORATION


                                    By: /s/ Bruce N. Huff
                                       ----------------------------------------
                                       Bruce N. Huff
                                       President and Chief Operating Officer

                                    LENDER:

                                    LYFORD INVESTMENTS ENTERPRISES LTD.

                                    By: /s/ Alan Quasha
                                       -------------------------------------
                                        Alan Quasha
                                        Title:__________________________

                                      -6-

<PAGE>

                                    EXHIBIT A

                           ADDITIONAL PROMISSORY NOTE

<PAGE>

THIS NOTE HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED,
AND HAS BEEN ACQUIRED FOR INVESTMENT AND NOT WITH A VIEW TO, OR IN CONNECTION
WITH, THE SALE OR DISTRIBUTION THEREOF. NO SUCH SALE OR DISTRIBUTION MAY BE
EFFECTED WITHOUT AN EFFECTIVE REGISTRATION STATEMENT RELATED THERETO OR AN
exemption from registration available so that SUCH REGISTRATION IS NOT REQUIRED
UNDER THE SECURITIES ACT OF 1933, AS AMENDED.

$2,000,000                                                      August __, 2002

                                 PROMISSORY NOTE

   FOR VALUE RECEIVED, Harken Energy Corporation, a Delaware corporation (the
"Maker"), promises to pay to the order of Lyford Investments Enterprises Ltd., a
British Virgin Islands company (the "Holder"), the principal amount of Two
Million Dollars ($2,000,000) together with interest thereon calculated from the
date hereof in accordance with the provisions of this Note. Terms not defined
herein, shall have the meaning given them in the Loan Agreement among the Maker
and the Holder dated as of July 15, 2002 as amended in the First Amendent to
Loan Agreement dated as of even date herewith and as further amended hereafter
(the "Loan Agreement").

1. LOAN AGREEMENT. This Note (the "Note") is issued under the terms of the Loan
Agreement. The Holder is entitled to the benefits and subject to certain
obligations under the Loan Agreement and may enforce the agreements of the Maker
contained therein and exercise the remedies provided for thereby. The benefits
and rights of the Holder are subject to certain conditions and restrictions also
set forth in the Loan Agreement, which conditions and restrictions may be
enforced against the Holder.

2. MATURITY. Except as otherwise provided in this Agreement or the Loan
Agreement, all accrued but unpaid interest and outstanding principal under this
Note shall be due and payable on August ___, 2005 (the "Maturity Date").
Notwithstanding the foregoing, Holder may declare the entire unpaid principal
sum of this Note, together with accrued and unpaid interest thereon, immediately
due and payable in advance of the Maturity Date upon the occurrence of a
Non-Payment Default under the terms of the Loan Agreement. Prepayments may be
made on this Note at any time, and without penalty. In accordance with the Loan
Agreement, Maker may also be required to prepay this Note in certain
circumstances as described therein.

3. INTEREST.

     (a) Rate. Except as otherwise provided in this Note or in the Loan
Agreement, the unpaid principal amount of the Note outstanding from time to time
shall bear interest from the date hereof until fully paid at the Interest Rate
(as defined in the Loan Agreement). All interest shall be computed and paid in
accordance with the Loan Agreement.

     (b) Payments. All accrued interest on the Note shall be due and payable on
a quarterly basis in arrears beginning with an initial payment of accrued
interest on December 15,







<PAGE>

2002 and continuing thereafter on March 15, June 15, September 15 and December
15 of each year until the Maturity Date.

4. DEFAULT. In the event of a Payment Default or Non-Payment Default (as defined
in the Loan Agreement, this Note shall be subject to the remedies and conditions
set forth in the Loan Agreement.

5. ABSENCE OF SECURITY. Repayment of this Note is not secured by any of the
assets or properties of the Maker, by any liens or encumbrances on any assets or
property of Maker, or in any other manner. Holder expressly agrees and
represents that nothing in this Note or in the Loan Agreement shall create or
constitute any security interest, pledge or lien upon any of the securities of
GED held by Maker.

6. MISCELLANEOUS.

     (a) Transfer; Successors and Assigns. The terms and conditions of this Note
shall inure to the benefit of and be binding upon the respective successors and
assigns of the parties. Notwithstanding the foregoing, Holder may not assign,
pledge, or otherwise transfer this Note without the prior written consent of
Maker.

     (b) Amendments and Waivers. Any term of this Note may be amended only with
the written consent of the Holder and the Maker. Any amendment or waiver
effected in accordance with this Section 5(c) shall be binding upon the Holder,
the Maker and each transferee of the Agreement. Any waiver by the Holder or the
Maker of a breach of any provision of this Note shall not operate as or be
construed to be a waiver of any other breach of such provision or of any breach
of any other provision of this Note. The failure of the Holder or the Maker to
insist upon strict adherence to any term of this Note on one or more occasions
shall not be considered a waiver or deprive that party of the right thereafter
to insist upon strict adherence to that term or any other term of this Note.

     (c) Notices. All notices, consents, waivers and other communications under
this Note must be in writing and will be deemed to have been duly given when (a)
delivered by hand (with written confirmation of receipt), (b) sent by facsimile
(with written confirmation of receipt), or (c) when received by the addressee,
if sent by U.S. mail or a nationally recognized overnight delivery service, in
each case to the appropriate addresses and facsimile numbers set forth below (or
to such other addresses and facsimile numbers as a party may designate by notice
to the other party):

   To Holder:

        Lyford Investments Enterprises Ltd.
        c/o Quadrant Management Inc.
        720 Fifth Ave., 9/th/ Floor
        New York, NY 10019
        Attn: Alan Quasha
        Facsimile No.: (212) 231-3939



<PAGE>

   To Maker:

       Harken Energy Corporation
       580 WestLake Park Boulevard, Suite 600
       Houston, Texas 77079
       Attention: A. Wayne Hennecke, Secretary
       Facsimile No.: (281) 504-4110

        with a required copy to:

       James W. Ryan
       Porter & Hedges, L.L.P.
       700 Louisiana, 35/th/ Floor
       Houston, Texas 77002-2764
       Facsimile No.: (713) 226-0290

       (d) Governing Law. Unless otherwise specified therein, this Note shall be
governed by and construed in accordance with the laws of the State of New York
and the United States of America. Each party hereby irrevocably agrees that any
legal proceeding arising out of or in connection with this Note shall be brought
in the district courts of Harris County, Texas, or in the United States District
Court for the Southern District of Texas, Houston Division.

       (e) Counterparts. This Note may be executed in several identical
counterparts, and by the parties hereto on separate counterparts, and each
counterpart, when so executed and delivered, shall constitute an original
instrument, and all such separate counterparts shall constitute but one and the
same instrument.

       (f) Captions. The headings and captions appearing in this Note have been
included solely for convenience and shall not be considered in construing the
Note.

       (g) Entire Agreement. This Note, together with the Loan Agreement and
any other document executed in connection with the Loan Agreement, embody the
entire agreement between the Holder and the Maker and supersede all prior
proposals, agreements and understandings relating to the subject matter hereof
and thereof.

       (h) Invalidity. If any provision of this Note is invalid, illegal or
unenforceable, the balance of this Note shall remain in effect, and if any
provision is inapplicable to any person or circumstance, it shall nevertheless
remain applicable to all other persons and circumstances. In such an event, the
parties will in good faith attempt to effect the business agreement represented
by such invalidated term to the fullest extent permitted by law.

<PAGE>

         IN WITNESS WHEREOF, the parties hereto have executed this Note as of
the date set forth above.

                                    MAKER:

                                    HARKEN ENERGY CORPORATION


                                    By:__________________________________
                                       Bruce N. Huff
                                       President and Chief Operating Officer


                                    HOLDER:

                                    LYFORD INVESTMENTS ENTERPRISES LTD.


                                    By:__________________________________
                                       Alan Quasha
                                       Title:__________________________