<PAGE>   1
                                ESCROW AGREEMENT
                             (SUB-THRUST TEST WELL)

         WHEREAS, SEVEN SEAS PETROLEUM INC., a Cayman Islands exempted company
limited by shares (the "Debtor"), and CHESAPEAKE ENERGY CORPORATION, an Oklahoma
corporation, as collateral agent (the "Collateral Agent") have caused or will
cause certain funds to be deposited in escrow with SOUTHWEST BANK OF TEXAS N.A.,
a national banking corporation ("Escrow Agent"), on terms and conditions more
particularly described herein.

         NOW, THEREFORE, in consideration of the premises, the undersigned
hereby agree as follows:


                                    ARTICLE I
                              TERMS AND CONDITIONS

         1.1 ESTABLISHMENT OF FUND. The Debtor has caused or will cause to be
deposited with the Escrow Agent the sum of $15,000,000.00 (such sum, or the
balance thereof remaining from time to time being referred to herein as the
"Fund").


         1.2 TREATMENT OF FUND. The monies constituting the Fund shall be
deposited in a segregated, interest-bearing account pursuant to the terms of
this Escrow Agreement. Such account shall be styled Seven Seas Sub Thrust Well
Account No. 3228207, with federal tax identification no. 731468669.


         1.3 ESCROW PROCEDURE AND PAYMENT INSTRUCTION. The Fund, together with
all interest earned thereon, which interest shall become and remain a part of
the Fund, shall be held and disbursed in accordance with the terms of this
Escrow Agreement as follows:

         The Escrow Agent is hereby authorized and directed to deliver the
         Escrow Fund only: (i) to the Debtor upon receipt by the Escrow Agent of
         a funding request in the form attached hereto as Exhibit "A" executed
         by the Debtor and the Collateral Agent (an "Approved Funding Request");
         or (ii) to the Collateral Agent upon written direction of the
         Collateral Agent in the form attached hereto as Exhibit "B" that the
         Collateral Agent is entitled to the balance of the Fund in accordance
         with the Security Agreement between the Collateral Agent and the Debtor
         (the "Security Agreement"); or (iii) in accordance with the joint
         written instruction of the Debtor and the Collateral Agent.

         1.4 TERMINATION. This Escrow Agreement shall terminate upon the first
to occur of any of the following events:

                  A. The disbursement of the balance of the Fund in accordance
         with the provisions of Section 1.3 hereof.

                  B. The expiration of three (3) years from the date of this
         Escrow Agreement, in which case the remaining balance of the Fund shall
         be disbursed to the Collateral Agent unless the Collateral Agent
         otherwise instructs the Escrow Agent in writing.


<PAGE>   2


                                   ARTICLE II
                          PROVISIONS AS TO ESCROW AGENT

         2.1. LIMITATION OF ESCROW AGENT'S CAPACITY.

                  A. This Escrow Agreement expressly and exclusively sets forth
         the duties of Escrow Agent with respect to any and all matters
         pertinent hereto, and no implied duties or obligations shall be read
         into this Escrow Agreement against Escrow Agent. This Escrow Agreement
         constitutes the entire agreement between the Escrow Agent and the other
         parties hereto in connection with the subject matter of this escrow,
         and no other agreement entered into between the parties, or any of
         them, shall be considered as adopted or binding, in whole or in part,
         upon the Escrow Agent notwithstanding that any such other agreement may
         be deposited with Escrow Agent or the Escrow Agent may have knowledge
         thereof.

                  B. Escrow Agent acts hereunder as a depository only, and is
         not responsible or liable in any manner whatsoever for the sufficiency,
         correctness, genuineness or validity of the subject matter of this
         Escrow Agreement or any part thereof, or for the form of execution
         thereof, or for the identity or authority of any person executing or
         depositing such subject matter. Escrow Agent shall in no way be
         responsible for notifying, nor shall it be its duty to notify, any
         party hereto or any other party interested in this Escrow Agreement of
         any payment required or maturity occurring under this Escrow Agreement
         or under the terms of any instrument deposited herewith.

         2.2 AUTHORITY TO ACT.

                  A. Escrow Agent is hereby authorized and directed by the
         Debtor and the Collateral Agent to deliver the subject matter of this
         Escrow Agreement only in accordance with the provisions of Article I of
         this Escrow Agreement.

                  B. Escrow Agent shall be protected in acting upon any written
         notice, request, waiver, consent, certificate, receipt, authorization,
         power of attorney or other paper or document which Escrow Agent in good
         faith believes to be genuine and what it purports to be, including, but
         not limited to, items directing investment or non-investment of funds,
         items requesting or authorizing release, disbursement or retainage of
         the subject matter of this Escrow Agreement and items amending the
         terms of this Escrow Agreement.

                  C. Escrow Agent may consult with legal counsel in the event of
         any dispute or question as to the construction of any of the provisions
         hereof or its duties hereunder, and it shall incur no liability and
         shall be fully protected in acting in accordance with the advice of
         such counsel.

                  D. In the event of any disagreement between any of the parties
         to this Escrow Agreement, or between any of them and any other person,
         resulting in adverse claims or demands being made in connection with
         the matters covered by this Escrow Agreement, or in the event that
         Escrow Agent, in good faith, be in doubt as to what action it should
         take hereunder, Escrow Agent may, at its option, refuse to comply with
         any claims or demands on it, or refuse to take any other action
         hereunder, so long as such disagreement continues or such doubt exists,
         and in any such event, Escrow Agent shall not be or become liable in
         any way or to any person for its failure or refusal to act, and Escrow
         Agent shall be entitled to continue so to refrain from acting until (i)
         the rights of the Debtor and the Collateral Agent shall have been fully
         and finally adjudicated by a court of competent jurisdiction, or (ii)
         all differences shall have been adjudged and all doubt resolved by
         agreement among the Debtor and the Collateral Agent, and Escrow Agent
         shall have been notified thereof in writing signed by the Debtor and
         the Collateral Agent. Notwithstanding the foregoing, Escrow Agent may
         in its discretion obey the order, judgment, decree or levy of any
         court, whether with or without jurisdiction, or of any agency of the
         United States or any political subdivision thereof, or of any agency of
         the State of Texas or of any political subdivision thereof, and Escrow
         Agent is hereby authorized in its sole discretion, to comply with and
         obey any such orders, judgments, decrees or


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         levies. The rights of Escrow Agent under this sub-paragraph are
         cumulative of all other rights which it may have by law or otherwise.

                  E. In the event that any controversy should arise between the
         Debtor and the Collateral Agent with respect to this Escrow Agreement,
         or should the Escrow Agent resign and the parties fail to select
         another Escrow Agent to act in its stead, the Escrow Agent shall have
         the right to institute a bill of interpleader in any court of competent
         jurisdiction to determine the rights of the parties.

         2.3 COMPENSATION/INDEMNIFICATION.

                  A. Escrow Agent shall be entitled to reasonable compensation
         as well as reimbursement for its reasonable costs and expenses incurred
         in connection with the performance by it of service under this Escrow
         Agreement (including reasonable fees and expenses of Escrow Agent's
         counsel). The Debtor agrees that escrow fees in the amount of $4,000.00
         will be deducted from the Fund upon the commencement of the escrow and
         on each anniversary date thereafter.

                  B. The Debtor hereby agrees to indemnify and hold Escrow Agent
         harmless from all losses, costs, claims, demands, expenses, damages,
         and attorney's fees suffered or incurred by Escrow Agent as a result of
         anything which it may do or refrain from doing in connection with this
         Escrow Agreement or any litigation or cause of action arising from or
         in conjunction with this Escrow Agreement or involving the subject
         matter hereof or Escrow Funds or monies deposited hereunder or for any
         interest upon any such monies. This indemnity shall include, but not be
         limited to, all costs incurred in conjunction with any interpleader
         which the Escrow Agent may enter into regarding this Escrow Agreement.

         2.4 MISCELLANEOUS.

                  A. Escrow Agent shall make no disbursement, investment or
         other use of funds until and unless it has collected funds. Escrow
         Agent shall not be liable for collection items until the proceeds of
         the same in actual cash have been received or the Federal Reserve has
         given Escrow Agent credit for the funds.

                  B. Escrow Agent may resign at any time by giving written
         notice to the parties hereto, whereupon the parties hereto will
         immediately appoint a successor Escrow Agent. Until a successor Escrow
         Agent has been named and accepts its appointment or until another
         disposition of the subject matter of this Escrow Agreement has been
         agreed upon by the Debtor and the Collateral Agent, Escrow Agent shall
         be discharged of all of its duties hereunder save to keep the subject
         matter whole.

                  C. All representations, covenants, and indemnifications
         contained in this Article II shall survive the termination of this
         Escrow Agreement.

                                   ARTICLE III
                               GENERAL PROVISIONS

         3.2 DISCHARGE OF ESCROW AGENT. Upon the delivery of all of the subject
matter or monies pursuant to the terms of this Escrow Agreement, the duties of
Escrow Agent shall terminate and Escrow Agent shall be discharged from any
further obligation hereunder.

         3.3 ESCROW INSTRUCTIONS. Where directions or instructions from more
than one of the undersigned are required, such directions or instructions may be
given by separate instruments of similar tenor. Any of the undersigned may act
hereunder through an agent or attorney-in-fact, provided satisfactory written
evidence of authority is first furnished to any party relying on such authority.


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         3.4 NOTICE. Any payment, notice, request for consent, report, or any
other communication required or permitted in this Escrow Agreement shall be in
writing and shall be deemed to have been given when personally delivered to the
party hereunder specified or when placed in the United States mail, registered
or certified, with return receipt requested, postage prepaid and addressed as
follows:

         If to Escrow Agent:

                  Southwest Bank of Texas, N.A.
                  5 Post Oak Park, 440 Post Oak Parkway
                  P. O. Box 27459
                  Houston, Texas  77227-7459
                  Attn:  Jenifer Stepanik

         If to the Debtor:

                  Seven Seas Petroleum Inc.
                  5555 San Felipe, Suite 1700
                  Houston, Texas 77056
                  Attn: Larry A. Ray, President

         If to the Collateral Agent:

                  Chesapeake Energy Corporation
                  6100 North Western Avenue
                  Oklahoma City, Oklahoma 73118
                  Attn: Marcus C. Rowland, Executive Vice President

         Any party may unilaterally designate a different address by giving
notice of each such change in the manner specified above to each other party.

         3.5 GOVERNING LAW. This Escrow Agreement is being made in and is
intended to be construed according to the laws of the State of Texas. It shall
inure to and be binding upon the parties hereto and their respective successors,
heirs and assigns.

         3.6 CONSTRUCTION. Words used in the singular number may include the
plural and the plural may include the singular. The section headings appearing
in this instrument have been inserted for convenience only and shall be given no
substantive meaning or significance whatsoever in construing the terms and
conditions of this Escrow Agreement.

         3.7 AMENDMENT. The terms of this Escrow Agreement may be altered,
amended, modified or revoked only by an instrument in writing signed by the
Debtor, the Collateral Agent and Escrow Agent.

         EXECUTED as of the dates set forth below.


                                               SEVEN SEAS PETROLEUM INC.



Date: 7/23/01                                  By: /s/ LARRY A. RAY
      -----------------                            -----------------------------
                                                   Larry A. Ray, President


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                                               CHESAPEAKE ENERGY CORPORATION,
                                               Collateral Agent


Date: 7/23/01                                  By: /s/ TOM L. WARD
      -----------------                            -----------------------------
                                               Name:   Tom L. Ward
                                                    ----------------------------
                                               Title:  President
                                                     ---------------------------


         SOUTHWEST BANK OF TEXAS, N.A., Escrow Agent, hereby accepts its
appointment as Escrow Agent as described in the foregoing Escrow Agreement,
subject to the terms and conditions set forth therein.


                                               SOUTHWEST BANK OF TEXAS, N.A.



Date:                                          By: /s/ JENIFER STEPANIK
      -----------------                            -----------------------------
                                               Name:   Jenifer Stepanik
                                                    ----------------------------
                                               Title:  Senior Vice President
                                                     ---------------------------


                            ACKNOWLEDGMENT OF RECEIPT

         The undersigned hereby acknowledge receipt from and/or disbursement by
Southwest Bank, N.A., Escrow Agent under the foregoing Escrow Agreement, of the
subject matter of the Escrow Agreement as described in such Escrow Agreement;
the undersigned acknowledge a faithful and proper performance by said Escrow
Agent of its duties under said Escrow Agreement, and in consideration of such
disbursement hereby release and discharge said Escrow Agent from all further
responsibility or liability as Escrow Agent under said Escrow Agreement.

         Executed this ________ day of _____________ , 200__.


                                               ---------------------------------

                                               By:
                                                   -----------------------------
                                               Name:
                                                    ----------------------------


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                                    EXHIBIT A
                                       TO
                                ESCROW AGREEMENT


To:      Southwest Bank of Texas, N.A.
         Escrow Agent under Escrow Agreement dated July 23, 2001
            With Seven Seas Petroleum Inc. and Chesapeake Energy
            Corporation (the "Escrow Agreement")

                                 FUNDING REQUEST


                  Please transfer $____________ (the "Approved Funding Amount")
to Southwest Bank of Texas, N.A. deposit account number _____________ of Seven
Seas Petroleum Inc. The Approved Funding Amount will be used to pay those
certain costs and expenses in preparing, drilling, testing and completing the
Sub-Thrust Test Well (defined in the Note Purchase and Loan Agreement dated July
23, 2001 between Seven Seas Petroleum Inc. and Chesapeake Energy Corporation),
including vendor deposits required for work or services to be performed in
connection therewith, described below:


Description of Cost or Expense In Reasonable Detail              Amount
---------------------------------------------------              ------







                  EXECUTED this ____ day of ____________ , 200___.

         Seven Seas Petroleum Inc.             Chesapeake Energy Corporation



         By                                    By
            -------------------------------       ------------------------------
         Name                                  Name
             ------------------------------         ----------------------------
         Title                                 Title
               ----------------------------          ---------------------------


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                                    EXHIBIT B
                                       TO
                                ESCROW AGREEMENT


To:      Southwest Bank of Texas, N.A.
         Escrow Agent under Escrow Agreement dated July 23, 2001
            With Seven Seas Petroleum Inc. and Chesapeake Energy
            Corporation (the "Escrow Agreement")

                Direction by Collateral Agent for Balance of Fund


                  The Collateral Agent is entitled to the balance of the Fund in
accordance with the Security Agreement between the Collateral Agent and Debtor.
Please transfer the balance of the Fund to Chesapeake Energy Corporation, as
collateral agent for itself and U.S. Trust Company of Texas, N.A. as follows:

                  [Specify bank transfer instructions.]




                  EXECUTED this ____ day of ____________ , 200__ .


                                           Chesapeake Energy Corporation, Agent


                                           By
                                              ----------------------------------
                                           Name
                                                --------------------------------
                                           Title
                                                 -------------------------------