<PAGE>   1





                                  July 23, 2001





                            SEVEN SEAS PETROLEUM INC
                                 (as Mortgagor)


                          CHESAPEAKE ENERGY CORPORATION
                                 (as Mortgagee)




                      ------------------------------------
                           LEGAL MORTGAGE OVER SHARES






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THIS DEED OF MORTGAGE ("Deed of Mortgage") is made as of July 23, 2001

BETWEEN

(1)      SEVEN SEAS PETROLEUM INC., a Cayman Islands exempted company limited by
         shares, the registered office of which is at Walker House, Mary Street,
         George Town, Grand Cayman, Cayman Islands (the "Mortgagor"); and

(2)      CHESAPEAKE ENERGY CORPORATION, an Oklahoma corporation, whose principal
         place of business is at 6100 North Western Avenue, Oklahoma City,
         Oklahoma, 73118 (the "Mortgagee") as Collateral Agent under the
         Collateral Sharing Agreement (as hereinafter defined) for itself and
         United States Trust Company of New York, ("Trustee") under that certain
         Indenture dated July 23, 2001 (the "Indenture"), pursuant to which the
         Trustee is trustee for the holders of the Mortgagor's 12% Senior
         Secured Series A Notes (the "Series A Notes") and the Mortgagor's 12%
         Senior Secured Series B Notes (the "Series B Notes").

WHEREAS

(A)      Pursuant to a Note Purchase and Loan Agreement dated as of July 9, 2001
         (the "Note Purchase and Loan Agreement") the Mortgagee agreed to
         advance to the Mortgagor the sum of Twenty-two Million Five Hundred
         Thousand United States Dollars (US$22,500,000.00), evidenced by a 12%
         Senior Secured Note due 2004 in the principal amount of TWENTY-TWO
         MILLION FIVE HUNDRED THOUSAND DOLLARS ($22,500,000.00) (the "CEC Note")
         subject to the terms and conditions stated in: (a) the Note Purchase
         and Loan Agreement; (b) the CEC Note; (c) the detachable Warrants to
         purchase twelve million six hundred twelve thousand one hundred forty
         (12,612,140) shares of the Mortgagor's ordinary shares (the
         "Warrants"); (d) the Shareholder's Rights Agreement dated July 23, 2001
         between the Mortgagor and the Mortgagee (the "Shareholder's
         Agreement"); (e) the Registration Rights Agreement dated July 23, 2001
         between the Mortgagor and the Mortgagee (the "Registration Agreement");
         (f) the Security Agreement dated July 23, 2001 between the Mortgagor
         and the Mortgagee as Collateral Agent for itself and the Trustee (the
         "Security Agreement"); (g) certain other Deeds of Mortgage Over Shares
         of the subsidiaries of the Mortgagor other than the Companies (as
         hereinafter defined) dated July 23, 2001 (the "Other Deeds of
         Mortgage"); (h) the Collateral Sharing and Agency Agreement dated as of
         July 23, 2001 between the Mortgagee and the Trustee pursuant to which
         the Mortgagee agrees to act as collateral agent for itself and the
         Trustee (the "Collateral Sharing Agreement"); and (i) any and all other
         documents and instruments executed and delivered in connection with the
         Note Purchase and Loan Agreement, the Indenture and any of the other
         documents executed in connection with the Note Purchase and Loan
         Agreement or the Indenture.

Upon satisfaction of certain conditions set forth in the Note Purchase and
         Loan Agreement, the CEC Note, the Warrants, and the other Related
         Agreements, the CEC Note issued under the Note Purchase and Loan
         Agreement may be exchanged by the Mortgagee in part for ordinary shares
         of the Mortgagor.



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The Note Purchase and Loan Agreement was executed on the agreement that the
         Mortgagor shall enter into this mortgage over shares in the capital of
         Seven Seas Petroleum Australia Inc., a company organized under the laws
         of British Colombia and Seven Seas Petroleum Turkey Inc., a company
         organized under the laws of British Colombia.

The Mortgagor has agreed to secure the Secured Amounts (as defined below)
         by entering into this Deed of Mortgage, as well as the other Financing
         Documents (as defined below).

IT IS AGREED as follows

1.       INTERPRETATION

         1.1      Except where the context otherwise requires, words and
                  expressions defined in the Note Purchase and Loan Agreement or
                  the recitals above shall have the same meaning where used
                  herein and the further words and expressions set out below
                  shall have the following meanings;

                  ACTIVE SUBSIDIARIES means Seven Seas Petroleum USA Inc., a
                  Delaware corporation, Seven Seas Petroleum Colombia Inc., a
                  Cayman Islands company, Petrolinson SA, a Panamanian
                  corporation, and GHK Company Colombia, an Oklahoma
                  corporation.

                  COLLATERAL AGENT means the Mortgagee as collateral agent under
                  the certain Collateral Sharing Agreement;

                  COMPANIES means the companies specified in Schedule 1;

                  ENFORCEMENT NOTICE means an enforcement notice served by the
                  Mortgagee on the Mortgagor pursuant to the terms of this Deed
                  of Mortgage;

                  FINANCING DOCUMENTS means the Note Purchase and Loan
                  Agreement, the Indenture, the CEC Note, the Series A Notes,
                  the Series B Notes, the Security Agreement, the Other Deeds of
                  Mortgage, this Deed of Mortgage, the Related Agreements, the
                  Collateral Sharing Agreement and any and all other documents
                  and instruments executed and delivered in connection with the
                  Note Purchase and Loan Agreement or the Indenture.

                  INACTIVE SUBSIDIARIES means Seven Seas Petroleum Holdings
                  Inc., a Cayman Islands company, Seven Seas Petroleum Turkey
                  Inc., a British Colombia corporation, Seven Seas Resources
                  Australia Inc., a British Colombia corporation, Seven Seas
                  Petroleum Australia Inc., a Cayman Islands company, Seven Seas
                  Petroleum PNG Inc., a Cayman Islands company, Seven Seas
                  Petroleum Argentina, a Cayman Islands company, Seven Seas
                  Mediterranean Inc., a Cayman Islands company, Seven Seas
                  Petroleum Turkey Inc., a Cayman Islands company, and Guaduas
                  Pipeline Company, a Cayman Islands company.



<PAGE>   4


                  INDENTURE means the Indenture for the Series A Notes and the
                  Series B Notes as referred to in paragraph (2) above.

                  MORTGAGED PROPERTY means the Original Securities and all and
                  any other shares, securities, rights, moneys and property for
                  the time being mortgaged or charged to the Mortgagee pursuant
                  to Clause 2;

                  NOTE PURCHASE AND LOAN AGREEMENT means the facility referred
                  to in recital A;

                  ORIGINAL SECURITIES means the securities listed in Schedule 1
                  which are all registered in the name of the Mortgagor and
                  following execution of this Deed of Mortgage will be
                  transferred into the name of the Mortgagee or its nominee as
                  Collateral Agent;

                  OTHER DEEDS OF MORTGAGE means each Legal Mortgage Over Shares
                  between Mortgagor and Mortgagee delivered concurrently
                  herewith or hereafter delivered;

                  RELATED AGREEMENTS means the Warrants, the warrants granted to
                  the holders of the Series A Notes, the Shareholder's
                  Agreement, the Registration Agreement and any other documents
                  or instruments executed in connection with any of the
                  foregoing;

                  SECURED AMOUNTS means all and any amounts of any kind now or
                  in the future, actual or contingent, due and payable by the
                  Mortgagor to the Mortgagee under the CEC Note or to the
                  Trustee for the benefit of the holders of the Series A Notes
                  or the Series B Notes or under or in connection with this Deed
                  of Mortgage or the other Financing Documents and references to
                  the Secured Amounts include references to any part of them;
                  and

                  SECURITY INTEREST means any mortgage, charge, pledge, lien,
                  encumbrance, right of set off or any security interest,
                  howsoever created or arising.

         1.2      In this Deed of Mortgage:

                  (a)      references to the Mortgagor or the Mortgagee include
                           references to any person for the time being deriving
                           title under each of them respectively;

                  (b)      references to this Deed of Mortgage and the Financing
                           Documents are references to the same as from time to
                           time varied, supplemented or amended in any manner or
                           respect whatsoever;

                  (c)      references to the Original Securities or to the
                           Mortgaged Property include references to any property
                           included in such term;

                  (d)      "mortgage" includes a transfer or assignment by way
                           of mortgage;

                  (e)      Unless the context otherwise indicates, words
                           importing the singular shall include the plural and
                           vice versa, and the use of the neuter, masculine, or


<PAGE>   5

                           feminine gender is for convenience only and shall be
                           deemed to mean and include the neuter, masculine or
                           feminine gender; and

                  (f)      Clause headings are for ease of reference only.

2.       COVENANT TO PAY SECURED AMOUNTS AND CHARGE

         2.1      The Mortgagor covenants with the Mortgagee for the benefit of
                  the Mortgagee and the Trustee that it shall, whether or not
                  the Mortgagor shall have received an Enforcement Notice in
                  accordance with this Deed of Mortgage or notice of demand in
                  respect of the Secured Amounts, pay and discharge any moneys
                  and liabilities in respect of the Secured Amounts whatsoever
                  which are now or at any time hereafter may be due, owing or
                  payable by the Mortgagor in any currency, actually or
                  contingently, solely and/or jointly and/or severally with
                  another or others, as principal or surety on any account
                  whatsoever pursuant to this Deed of Mortgage or the other
                  Financing Documents or as a consequence of any breach,
                  non-performance, disclaimer or repudiation by the Mortgagor of
                  any of its obligations, covenants, representations or
                  warranties under this Deed of Mortgage, the other Financing
                  Documents or otherwise.

         2.2      The Mortgagor hereby transfers absolutely by way of mortgage
                  to the Mortgagee as a continuing security for the payment and
                  discharge of the Secured Amounts, all its rights, title,
                  interest and benefit, present and future in, to and under:

                  (a)      the Original Securities; and

                  (b)      all other securities and all rights, monies
                           (including, without limitation, dividends) and
                           property whatsoever which may from time to time at
                           any time be derived from, accrued on or be offered in
                           respect of the Original Shares whether by way of
                           redemption, exchange, conversion, rights, bonus,
                           capital reorganisation or otherwise howsoever.

3.       CONTINUING AND PRIMARY SECURITY

         3.1      This Deed of Mortgage shall be a continuing security, and
                  shall be in addition to and shall not affect any continuing
                  liens or other Security Interests to which the Mortgagee is or
                  will be otherwise entitled over the Mortgaged Property, which
                  liens and other Security Interests shall remain in force
                  independently of this Deed of Mortgage.

         3.2      The Original Securities and other Mortgaged Property are
                  hereby mortgaged to the Mortgagee as primary and not as
                  collateral security.

         3.3      The Mortgagor's liability hereunder shall not be discharged or
                  impaired by:

                  (a)      the existence or validity of any other security taken
                           by the Mortgagee in relation to the Financing
                           Documents or any enforcement of or failure to enforce
                           or the release of any such security;



<PAGE>   6

                  (b)      any amendment to or variation of the Financing
                           Documents or any security relating to the Financing
                           Documents or any assignment thereof or hereof;

                  (c)      any release of or granting of time or any other
                           indulgence to the Mortgagor or any third party;

                  (d)      any invalidity, irregularity, unenforceability,
                           imperfection or avoidance of or any defect in any
                           security granted by, or any obligations of, the
                           Mortgagor or any other person hereunder or under the
                           Financing Documents or any amendment to or variation
                           thereof or of any other document or security
                           comprised therein;

                  (e)      the insolvency, liquidation, bankruptcy or
                           dissolution (or proceedings analogous thereto) of the
                           Mortgagor, the Companies or any other person or the
                           appointment of a receiver or administrative receiver
                           or administrator (whether by administration order or
                           otherwise) or trustee or similar officer of any of
                           the assets of the Mortgagor, the Companies or any
                           other person or the occurrence of any circumstances
                           whatsoever affecting the Mortgagor, or any other
                           person's liability to discharge its obligations under
                           the Financing Documents;

                  (f)      any release, renewal, exchange or realisation of any
                           security or obligation provided under or by virtue of
                           this Deed of Mortgage or the other Financing
                           Documents or the provision of any further security to
                           the Mortgagee at any other time; or

                  (g)      any other act, event, neglect or omission which would
                           or might but for this clause operate to impair or
                           discharge the Mortgagor's liability hereunder.

         3.4      Any release, compromise or discharge of the obligations of the
                  Mortgagor shall be deemed to be made subject to the condition
                  that it will be void if any payment or security which the
                  Mortgagee may receive or have received is set aside or proves
                  invalid for whatever reason.

         3.5      Rights may be exercised and demands may be made under this
                  Deed of Mortgage from time to time, and the liabilities and
                  obligations of the Mortgagor and the rights and security or
                  other consideration contained in this Deed of Mortgage may be
                  exercised and enforced, irrespective of

                  (a)      whether any demands, steps or proceedings are being
                           or have been taken against the Mortgagor or any third
                           party; or

                  (b)      whether or in what order any security to which the
                           Mortgagee may be entitled in respect of the Secured
                           Amounts is enforced.




<PAGE>   7

4.       WARRANTIES AND UNDERTAKING

         4.1      The Mortgagor represents and warrants to the Mortgagee and
                  undertakes that:

                  (a)      it is the absolute legal and beneficial owner of all
                           of the Original Securities free of all Security
                           Interests, encumbrances, trusts, equities, proxies
                           and claims whatsoever (save under this Deed of
                           Mortgage or the other Financing Documents) and that
                           all of the Original Securities are fully paid up and
                           are non-assessable;

                  (b)      except as limited by the Financing Documents,
                           Mortgagor has the full legal and unlimited right to
                           vote the Original Securities in its sole discretion;

                  (c)      the Original Securities of each of the Companies
                           constitute 100% of the issued and outstanding equity
                           capital of each of the Companies and are all
                           currently registered in the name of the Mortgagor
                           (subject to the registration of the Original
                           Securities in the name of the Mortgagee as Collateral
                           Agent concurrently with the execution and delivery of
                           this Deed of Mortgage);

                  (d)      each of the Mortgagor and the Companies are duly
                           incorporated and in good standing under the
                           respective laws of the jurisdiction in which each of
                           them is incorporated and the Mortgagor has and will
                           at all times have the necessary power to enter into
                           and perform its obligations under this Deed of
                           Mortgage and has duly authorized the execution and
                           delivery of this Deed of Mortgage;

                  (e)      neither this Deed of Mortgage or the transfer of the
                           Original Securities to the Mortgagee is subject to
                           any stamp or other tax under the laws of the Cayman
                           Islands or British Colombia, and this Deed of
                           Mortgage is capable of being enforced without being
                           subject to any stamp or other tax under the laws of
                           the Cayman Islands or British Colombia;

                  (f)      the Companies have no contractual or other business
                           relationship with any Inactive Subsidiary;

                  (g)      No Inactive Subsidiary has any operations, assets or
                           liabilities, direct, indirect or contingent;

                  (h)      the Mortgagor holds no rights or Security Interests
                           with respect to present or future revenues and
                           assets, tangible or intangible, relating to the
                           exploration, development, production, transportation
                           and sale of petroleum in and from the Republic of
                           Colombia, directly, by assignment, or otherwise,
                           except as a shareholder of companies whose shares are
                           pledged to Mortgagee pursuant to the Financing
                           Documents;



<PAGE>   8

                  (i)      this Deed of Mortgage constitutes its legal, valid,
                           binding and enforceable obligation and is a first
                           priority security interest over the Mortgaged Shares
                           effective in accordance with its terms;

                  (j)      the execution, delivery, observance and performance
                           by the Mortgagor of this Deed of Mortgage will not
                           require the Mortgagor to obtain any licenses,
                           consents or approvals and will not result in any
                           violation to the best of the Mortgagor's knowledge,
                           of any law, statute, ordinance, rule or regulation
                           applicable to it or any other agreements;

                  (k)      the Companies are not a party or otherwise bound to
                           any employment, management or other agreement, the
                           effect of which would be to limit the ability of the
                           Mortgagee to manage the Companies upon an event of
                           Default under the Financing Documents or give rise to
                           any payment or penalty to terminate any such
                           arrangement;

                  (l)      it has obtained all the necessary authorizations and
                           consents to enable it to enter into this Mortgage and
                           the necessary authorizations and consents will remain
                           in full force and effect at all times during the
                           existence of the security constituted by this Deed of
                           Mortgage;

                  (m)      the execution, delivery, observance and performance
                           by the Mortgagor of the Deed of Mortgage will not
                           constitute an event of default or trigger any
                           enforcement under any Security Interest in the
                           Mortgagor's assets nor will it result in the creation
                           of any Security Interest over or in respect of the
                           present or future assets of the Companies;

                  (n)      the Mortgagor has fully disclosed in writing to the
                           Mortgagee all facts relating to the Mortgagor and the
                           Companies which the Mortgagor knows or should
                           reasonably know and which are material for disclosure
                           to the Mortgagee in the context of the Financing
                           Documents; and

                  (o)      no agreement to which the Mortgagor or the Companies
                           are a party, or law, decree or regulation to which
                           either is subject requires the consent of any such
                           person to the execution, delivery or performance of
                           this Deed of Mortgage and the other Financing
                           Documents and each obligation and covenant contained
                           herein and therein.

         4.2      The Mortgagor undertakes that, for so long as any Secured
                  Amounts remain outstanding:

                  (a)      the Mortgagor shall pay to the Mortgagee, upon
                           demand, the amount of all reasonable expenses which
                           the Mortgagee may incur in, about or with a view to
                           perfecting or enforcing this security or otherwise in
                           connection with this security;

                  (b)      the Mortgagor shall promptly pay (and shall indemnify
                           the Mortgagee on demand against) all calls,
                           installments and other payments which may be




<PAGE>   9

                           made or become due in respect of the Mortgaged
                           Property and so that, in the event of default by the
                           Mortgagor, the Mortgagee may do so on behalf of the
                           Mortgagor and clause 4.2(a) shall apply accordingly;

                  (c)      to the extent any Mortgaged Property is at any time
                           not vested in the Mortgagee or its nominee as
                           Collateral Agent the Mortgagor shall forthwith and
                           from time to time deposit with the Mortgagee all
                           certificates and other documents of title relating to
                           the Mortgaged Property and signed share transfer
                           forms;

                  (d)      the Mortgagor will maintain the Companies in good
                           standing under the laws of their respective
                           jurisdictions and will not do anything that would
                           cause the completion of transactions or enforcement
                           actions contemplated hereunder to incur any stamp or
                           other tax under the laws of the Cayman Islands or
                           British Colombia;

                  (e)      the Mortgagor will not permit the Company to enter
                           into or become bound by any employment, management or
                           other agreement, the effect of which would be to
                           limit the ability of the Mortgagee to manage the
                           Company upon an event of Default under the Financing
                           Documents or give rise to any payment or penalty to
                           terminate any such arrangement;

                  (f)      the Mortgagor will not permit any Inactive Subsidiary
                           to conduct operations or own any asset or incur any
                           liability, direct, indirect or contingent;

                  (g)      Mortgagor will not permit the Company to engage in
                           any transaction, contractual or otherwise, with any
                           affiliate of Mortgagor except with Mortgagor and
                           Active Subsidiaries and as may otherwise be permitted
                           by the Financing Documents; provided however, that in
                           no event shall the Company engage in any transaction,
                           contractual or otherwise, with an Inactive
                           Subsidiary;

                  (h)      the Mortgagor shall deliver to the Mortgagee undated
                           letters of resignation executed by all persons now or
                           hereafter serving as Directors of the Companies from
                           time to time, which letters the Mortgagee shall be
                           entitled to date and cause to be given immediate
                           effect as of the date of an Enforcement Notice;

                  (i)      the Mortgagor shall forthwith sign, seal, deliver and
                           complete all transfers, renunciations, proxies
                           (including irrevocable proxies if the Mortgagee so
                           requests) mandates, assignments, deeds and documents
                           and do all acts and things which the Mortgagee may,
                           in its absolute discretion, at any time and from time
                           to time specify for enabling or assisting the
                           Mortgagee:

(i) to perfect or improve its title to and security over the Mortgaged Property
including, without limitation, obtaining such approvals or consents to the
rights and








<PAGE>   10

remedies granted to the Mortgagee herein as the Mortgagee requests in the
Mortgagee's sole discretion;

(ii) to vest the Mortgaged Property (including without limitation the
registration thereof in the applicable share registry) in the Mortgagee or its
nominee or nominees as Collateral Agent as of the date of execution of this Deed
of Mortgage;

(iii) to exercise (or enable its nominee or nominees to exercise) any rights or
powers attaching to the Mortgaged Property;

(iv) after the service of an Enforcement Notice to sell or dispose of the
Mortgaged Property; or

(v) otherwise to enforce any of the rights of the Mortgagee under or in
connection with this Deed of Mortgage;

                  (j)      the Mortgagor shall not (without the written consent
                           of the Mortgagee):

(i) create or permit to exist over all or part of the Mortgaged Property (or any
interest therein) any Security Interest (other than created or expressly
permitted to be created under this Deed of Mortgage or under other Financing
Documents) whether ranking prior to, pari passu with or behind the security
contained in this Deed of Mortgage;

(ii) sell, transfer or otherwise dispose of the Mortgaged Property or any
interest therein or attempt or agree to so dispose;

(iii) permit any person other than the Mortgagee or its nominee to be registered
as or become the holder of the Mortgaged Property as Collateral Agent; or

(iv) vote in favour of a resolution or amend, modify or change the certificate
of incorporation, memorandum or articles of incorporation of either of the
Companies or authorize the issuance by any of the Companies of any shares or any
other equity security.

(v) except as otherwise permitted by the Financing Documents permit the
Companies to transfer, assign, dispose of or encumber any rights or interests of
the Companies, direct or indirect, with respect to petroleum exploration,
development, production, transportation, sale or other disposition or with
respect to any association or other contract under which the Companies have such
rights or interests;

(vi) permit the Companies to grant any Security Interest in, or otherwise
encumber, any of its assets, tangible or intangible, except as may be expressly
permitted by the Financing Documents;

(vii) permit the Companies to make any distribution or payment to or for the
benefit of Mortgagor, whether directly or otherwise, if the effect of that
distribution or payment is to render the Companies insolvent or unable to pay
its obligations as they mature; or




<PAGE>   11

(viii) take any other action that would have as its effect a breach of a
Financing Document.

                  (k)      to the extent received by the Mortgagor, it shall
                           forward to the Mortgagee all notices, reports,
                           accounts and other documents relating to the
                           Mortgaged Property or which are sent to the holders
                           of any of the Mortgaged Property as soon as they are
                           received;

                  (l)      no further shares or equity securities of any kind in
                           the Companies (or any options or other rights with
                           respect thereto) will be issued and the authorized
                           shares shall at no time exceed the issued shares;

                  (m)      at any time after the service of an Enforcement
                           Notice, it shall exercise all voting and other rights
                           and powers which may at any time be exercisable by
                           the holder of the Mortgaged Property as the Mortgagee
                           may in its absolute discretion direct, it being
                           understood that the Mortgagee has reserved the right
                           to exercise all such voting rights directly for any
                           proper purpose, including without limitation the
                           immediate removal of Directors of the Companies and
                           their replacement;

                  (n)      the Mortgagor shall not take or accept any Security
                           Interest from the Companies or, in relation to the
                           Secured Amounts, from any third party, without first
                           obtaining the Mortgagee's written consent or permit
                           any Security Interest to be granted by the Companies
                           to any third party, except as may be expressly
                           permitted by the Financing Documents;

                  (o)      the Mortgagor shall not prove in a liquidation or
                           winding up of the Companies in competition with the
                           Mortgagee for any amount whatsoever owing to the
                           Mortgagee by the Mortgagor on any account whatsoever;
                           and

                  (p)      the Mortgagor shall not claim payment whether
                           directly or by set-off, lien, counterclaim or
                           otherwise of any amount which may be or has become
                           due to the Mortgagor by the Companies.

5.       POWER OF ATTORNEY

         5.1      The Mortgagor hereby irrevocably and by way of security for
                  the payment by it of the Secured Amounts and the performance
                  of its obligations under this Deed of Mortgage appoints the
                  Mortgagee as its true and lawful attorney (with full power to
                  appoint substitutes and to subdelegate) on behalf of the
                  Mortgagor and in the Mortgagor's own name or otherwise, at any
                  time and from time to time, to sign, seal, deliver and
                  complete all transfers, renunciations, proxies, mandates,
                  assignments, deeds and documents and do all acts and things
                  which the Mortgagee may, in its sole and absolute discretion,
                  consider to be necessary or advisable to perfect or improve
                  its security over the Mortgaged Property or to give proper
                  effect to the intent and purposes of this Deed of Mortgage or,
                  after delivery of an Enforcement Notice to enable or assist in
                  any way in the exercise








<PAGE>   12

                  of any power of sale of the Mortgaged Property (whether
                  arising under this Deed of Mortgage or implied by statute or
                  otherwise).

6.       ENFORCEMENT

         6.1      The Mortgagee may at any time after the occurrence of an event
                  of Default (as defined in the Note Purchase and Loan
                  Agreement) which has not been timely cured but including,
                  without limitation, the breach of any representation, warranty
                  or covenant contained in this Deed of Mortgage and the other
                  Financing Documents) serve an Enforcement Notice on the
                  Mortgagor. Unless and until the Mortgagee shall have served an
                  Enforcement Notice, but not thereafter:

                  (a)      Mortgagee agrees to the fullest extent permitted by
                           applicable law that the Mortgagor has the right to
                           receive payments distributed in respect of the
                           Original Securities and all other securities which
                           may from time to time at any time be derived from the
                           Original Securities; and

                  (b)      Appoints Mortgagor as Mortgagee's agent and proxy to
                           vote all of the securities described in clause (a)
                           above and exercise all rights and privileges
                           attributable to such securities as permitted under
                           applicable law. Prior to default, if the Mortgagee
                           shall receive any dividend or money described in
                           clause (a) above, the Mortgagee shall receive the
                           same as agent for Mortgagor and upon receipt shall
                           promptly pay or remit the same, without reduction, to
                           Mortgagor. At the request of Mortgagor, Mortgagee
                           shall give such reasonable assurances, confirmations
                           and advice to any third party as may be necessary for
                           Mortgagor to enjoy the full benefit of the rights and
                           privileges described in clauses (a) and (b) above

         6.2      If the Mortgagee shall serve an Enforcement Notice, the
                  Mortgagee shall, without prejudice to any other right or
                  remedy available hereunder or under applicable law, forthwith
                  become entitled:

                  (a)      solely and exclusively to exercise all voting rights
                           attaching to the Mortgaged Property or any thereof
                           and shall exercise such rights in such manner as the
                           Mortgagee may in its absolute discretion determine;
                           and/or

                  (b)      solely and exclusively to exercise any and all other
                           rights and/or powers and/or discretions of the
                           Mortgagor in, to and under the Mortgaged Property
                           pursuant to the constitutional documents of the
                           Company; and/or

                  (c)      to receive and retain all dividends and other
                           distributions made on or in respect of the Mortgaged
                           Property or any thereof and any such dividends and
                           other distributions received by the Mortgagor after
                           such time shall be held in trust by the Mortgagor for
                           the Mortgagee and be paid or transferred to the
                           Mortgagee on demand; and/or



<PAGE>   13

                  (d)      without notice to, or further consent or concurrence
                           by, the Mortgagor to sell the Mortgaged Property or
                           any part thereof by such method, at such place and
                           upon such terms as the Mortgagee may in its absolute
                           discretion determine, with power to postpone any such
                           sale and in any such case the Mortgagee may exercise
                           any and all rights attaching to the Mortgaged
                           Property as the Mortgagee in its discretion may
                           determine and without being answerable for any loss
                           occasioned by such sale or resulting from
                           postponement thereof or the exercise of such rights;
                           upon any sale of the Mortgaged Property or any part
                           thereof the purchaser thereof shall not be bound to
                           see or enquire whether the power of sale of the
                           Mortgagee has arisen in the manner herein provided
                           and the sale shall be deemed to be within the power
                           of the Mortgagee and the receipt of the Mortgagee for
                           the purchase money shall effectively discharge the
                           purchaser of the Mortgaged Property, or any part
                           thereof, who shall not be concerned or be in any way
                           answerable therefor; and/or

                  (e)      to appoint a receiver in respect of the Mortgaged
                           Property and the provisions of Clause 7 shall apply
                           thereto.

         6.3      The Mortgagee shall not be liable for any loss or damage
                  occasioned by any sale or disposal of the Mortgaged Property
                  (or interest therein) or arising out of the exercise of or
                  failure to exercise any of its powers under this Deed of
                  Mortgage or for any neglect or default to pay any instalment
                  or accept any offer or notify the Mortgagor of any such matter
                  or for any other loss of any nature whatsoever in connection
                  with the Mortgaged Property.

7.       MORTGAGEE'S RIGHTS AS TO MORTGAGED PROPERTY

         If the Mortgagee shall serve an Enforcement Notice, the Mortgagee
         shall, without prejudice to any other right or remedy available
         hereunder or under applicable law, forthwith become entitled:

         7.1      solely and exclusively to exercise all voting rights attaching
                  to the Mortgaged Property or any thereof and shall exercise
                  such rights in such manner as the Mortgagee may in its
                  absolute discretion determine; and/or

         7.2      solely and exclusively to exercise all other rights and/or
                  powers and/or discretions of the Mortgagor in, to and under
                  the Mortgaged Property pursuant to the memorandum and articles
                  of association of the Company; and/or

         7.3      to receive and retain all dividends and other distributions
                  made on or in respect of the Mortgaged Property or any thereof
                  and any such dividends and other distributions received by the
                  Mortgagor after such time shall be held in trust by the
                  Mortgagor for the Mortgagee and be paid or transferred to the
                  Mortgagee on demand to be applied towards the discharge of the
                  Secured Obligations; and/or

         7.4      without notice to, or further consent or concurrence by, the
                  Mortgagor to sell or otherwise dispose of the Mortgaged
                  Property or any part thereof by such method,








<PAGE>   14

                  at such place and upon such terms as the Mortgagee may in its
                  absolute discretion determine, with power to postpone any such
                  sale and in any such case the Mortgagee may exercise any and
                  all rights attaching to the Mortgaged Property as the
                  Mortgagee in its absolute discretion may determine and without
                  being answerable for any loss occasioned by such sale or
                  resulting from postponement thereof or the exercise of such
                  rights; and/or

         7.5      to date and deliver the documents delivered to it pursuant to
                  this Mortgage as it considers appropriate and to take all
                  steps not already taken to register the Mortgaged Property in
                  the name of the Mortgagee or its nominee or nominees as
                  Collateral Agent and to assume control as registered owner of
                  the Mortgaged Property.

8.       OTHER SECURITY

         8.1      This security is in addition to and shall not affect or be
                  merged in any bills, notes, guarantees, indemnities,
                  undertakings, Security Interests, or other security whatsoever
                  which the Mortgagee may hold now or hereafter in connection
                  with the Financing Documents or the obligations of any other
                  person liable for any of the Secured Amounts.

9.       FURTHER PROVISIONS

         9.1      (a)      This security is in addition to, and shall
                           neither be merged in, nor in any way exclude or
                           prejudice, any other Security Interest or right of
                           recourse or other right whatsoever which the
                           Mortgagee may now or at any time hereafter hold or
                           have (or would apart from this security hold or have)
                           as regards the Mortgagor or any other, person in
                           respect of the Secured Amounts.

                  (b)      The powers which this Deed of Mortgage confer on the
                           Mortgagee are cumulative, without prejudice to its
                           powers under the general law, and may be exercised as
                           often as the Mortgagee thinks appropriate; the
                           Mortgagee may, in connection with the exercise of its
                           powers, join or concur with any person in any
                           transaction, scheme or arrangement whatsoever; and
                           the Mortgagor acknowledges that the respective powers
                           of the Mortgagee shall in no circumstances whatsoever
                           be suspended, waived or otherwise prejudiced by
                           anything other than an express waiver or variation in
                           writing.

                  (c)      The rights of the Mortgagee in relation to the
                           Mortgaged Property and the recovery of the Secured
                           Amounts (whether arising under this Deed of Mortgage,
                           the other Financing Documents or under the general
                           law) shall not be capable of being waived or varied
                           otherwise than by an express waiver or variation in
                           writing; and in particular any failure to exercise or
                           any delay in exercising any of such rights shall not
                           operate as a waiver or variation of that or any other
                           such right; any defective or partial exercise





<PAGE>   15

                           of any such right shall not preclude any other or
                           further exercise of that or any other such right; and
                           no act or course of conduct or negotiation on its
                           part or on its behalf shall in any way preclude it
                           from exercising any such right or constitute a
                           suspension or any variation of any such right.

                  (d)      If any of the provisions of this Deed of Mortgage
                           becomes invalid, illegal or unenforceable in any
                           respect under any law, the validity, legality and
                           enforceability of the remaining provisions shall not
                           in any way be affected or impaired.

                  (e)      In any proceedings relating to this Deed of Mortgage
                           a statement as to any amount due to the Mortgagee or
                           the Trustee under the Financing Documents which is
                           certified as being correct by an officer or agent of
                           the Mortgagee shall, save in the case of manifest
                           error, be conclusive evidence that such amount is in
                           fact due and payable.

         9.2      Assignment

                  9.2.1    This Deed of Mortgage shall be binding upon and inure
                           to the benefit of each party hereto and its
                           successors in title and permitted assigns.

                  9.2.2    The Mortgagor shall not be entitled to assign or
                           transfer any of its rights, benefits or obligations
                           hereunder without the prior written consent of the
                           Mortgagee.

                  9.2.3    The Mortgagee may assign or transfer all or any part
                           of its rights, benefits or obligations under this
                           Deed of Mortgage to any other person which is its
                           successor under the Financing Documents. Where the
                           Mortgagee assigns or transfers its obligations or any
                           part thereof, the Mortgagor shall execute such
                           documents as the Mortgagee may specify to release the
                           Mortgagee to the extent of the assignment or transfer
                           or with a view to perfecting such assignment or
                           transfer, or where necessary, shall execute further
                           security documentation in favour of the assignee or
                           transferee in like form to this Deed of Mortgage.

         9.3      Release of Security

                  Upon final and unconditional repayment of the Secured Amounts
                  in full and provided that no event of Default has occurred,
                  the Mortgagee shall promptly assign the Mortgaged Property to
                  the Mortgagor free of all Security Interests, encumbrances,
                  trusts, equities and claims whatsoever imposed by the
                  Mortgagee and the Mortgagee shall forthwith sign, seal,
                  deliver and complete all transfers, renunciations, proxies,
                  mandates, assignments, deeds and documents and do all acts and
                  things which the Mortgagor may reasonably specify to vest all
                  of the Mortgaged Property in the name of the Mortgagor or its
                  nominee.

         9.4      This Deed of Mortgage is governed by, and shall be construed
                  in accordance with, the laws of the Cayman Islands.




<PAGE>   16

         9.5      (a)      The parties agree that the courts of the Cayman
                           Islands are to have exclusive jurisdiction to settle
                           any disputes which may arise in connection with the
                           legal relationships established by this Deed of
                           Mortgage (including, without limitation, claims for
                           set-off or counterclaim) or otherwise arising in
                           connection with this Deed of Mortgage.

                  (b)      The parties irrevocably waive any objections on the
                           grounds of venue of forum non conveniens or any
                           similar grounds.

                  The parties irrevocably consent to service of process by mail
                  or in any other manner permitted by the relevant law.

10.      NOTICES, ENGLISH LANGUAGE

                  (a)      Each notice or other communication to be given or
                           made hereunder shall be in the English language and
                           shall, unless otherwise stated be made in writing as
                           provided below.

                  Any notice or other communication or document to be made or
                  delivered by one person to another pursuant to this Deed of
                  Mortgage shall (unless that other person has by fifteen days'
                  written notice to the other specified another address and/or
                  fax or telex number) be made or delivered to that other person
                  at the following address, fax or telex number:

                           The Mortgagor:

                           SEVEN SEAS PETROLEUM INC.
                           5555 San Felipe, Suite 1700
                           Houston, Texas 77056
                           Attention: Larry A. Ray
                           Fax No. (713) 621-9770


                           The Mortgagee:

                           CHESAPEAKE ENERGY CORPORATION
                           6100 North Western Avenue
                           Oklahoma City, Oklahoma 73118
                           Attention: M. Rowland
                           Fax No. (405) 879-9580


                  and shall be deemed to have been made or delivered when such
                  communication or document has been dispatched and the
                  appropriate answer back received (in the case of any
                  communication made by telex) or sent by fax to the fax number
                  of the party set out herein and when receipt is confirmed by
                  facsimile or telephone (in the case of any communication by
                  fax) or (in the case of any communication







<PAGE>   17

                  made by letter) when left at that address or, as the case may
                  be, three days after being deposited in the post first class
                  postage prepaid in an envelope addressed to it at that
                  address; Provided that any communication or document to be
                  made or delivered to the Mortgagee shall be effective only
                  when received by the Mortgagee.

11.      COUNTERPARTS

This Deed of Mortgage may be executed in any number of counterparts and all such
counterparts taken together shall be deemed to constitute one and the same
instrument.

IN WITNESS WHEREOF this Deed of Mortgage has been executed and delivered as a
Deed the day and year first above written.

EXECUTED AS A DEED by                       )
the duly authorised representative          )
of SEVEN SEAS PETROLEUM INC.,               )/s/ LARRY A. RAY
in the presence of:                         )

EXECUTED AS A DEED by                       )
the duly authorised representative          )
of CHESAPEAKE ENERGY CORPORATION            )/s/ TOM L. WARD
as Collateral Agent                         )
in the presence of:                         )

<PAGE>   18







                                   SCHEDULE 1
                               ORIGINAL SECURITIES


<Table>
<Caption>
                                    Amount or number of
         Company                    Original Securities       Description of Original Securities
         -------                    -------------------       ----------------------------------

<S>                                 <C>                       <C>
Seven Seas Petroleum Turkey Inc.,           1                         Shares no par value
a company organized under
the laws of British Colombia

Seven Seas Resources Australia Inc.         1                         Shares no par value
a company organized under
the laws of British Colombia
</Table>



<PAGE>   19
THIS DEED OF MORTGAGE ("Deed of Mortgage") is made as of July 23, 2001

BETWEEN

(1)      SEVEN SEAS PETROLEUM INC., a Cayman Islands exempted company limited by
         shares, the registered office of which is at Walker House, Mary Street,
         George Town, Grand Cayman, Cayman Islands (the "Mortgagor"); and

(2)      CHESAPEAKE ENERGY CORPORATION, an Oklahoma corporation, whose principal
         place of business is at 6100 North Western Avenue, Oklahoma City,
         Oklahoma, 73118 (the "Mortgagee") as Collateral Agent under the
         Collateral Sharing Agreement (as hereinafter defined) for itself and
         United States Trust Company of New York, ("Trustee") under that certain
         Indenture dated July 23, 2001 (the "Indenture"), pursuant to which the
         Trustee is trustee for the holders of the Mortgagor's 12% Senior
         Secured Series A Notes (the "Series A Notes") and the Mortgagor's 12%
         Senior Secured Series B Notes (the "Series B Notes").

WHEREAS

(A)      Pursuant to a Note Purchase and Loan Agreement dated as of July 9, 2001
         (the "Note Purchase and Loan Agreement") the Mortgagee agreed to
         advance to the Mortgagor the sum of Twenty-two Million Five Hundred
         Thousand United States Dollars (US$22,500,000.00), evidenced by a 12%
         Senior Secured Note due 2004 in the principal amount of TWENTY-TWO
         MILLION FIVE HUNDRED THOUSAND DOLLARS ($22,500,000.00) (the "CEC Note")
         subject to the terms and conditions stated in: (a) the Note Purchase
         and Loan Agreement; (b) the CEC Note; (c) the detachable Warrants to
         purchase twelve million six hundred twelve thousand one hundred forty
         (12,612,140) shares of the Mortgagor's ordinary shares (the
         "Warrants"); (d) the Shareholder's Rights Agreement dated July 23, 2001
         between the Mortgagor and the Mortgagee (the "Shareholder's
         Agreement"); (e) the Registration Rights Agreement dated July 23, 2001
         between the Mortgagor and the Mortgagee (the "Registration Agreement");
         (f) the Security Agreement dated July 23, 2001 between the Mortgagor
         and the Mortgagee as Collateral Agent for itself and the Trustee (the
         "Security Agreement"); (g) certain other Deeds of Mortgage Over Shares
         of the subsidiaries of the Mortgagor other than the Companies (as
         hereinafter defined) dated July 23, 2001 (the "Other Deeds of
         Mortgage"); (h) the Collateral Sharing and Agency Agreement dated as of
         July 23, 2001 between the Mortgagee and the Trustee pursuant to which
         the Mortgagee agrees to act as collateral agent for itself and the
         Trustee (the "Collateral Sharing Agreement"); and (i) any and all other
         documents and instruments executed and delivered in connection with the
         Note Purchase and Loan Agreement, the Indenture and any of the other
         documents executed in connection with the Note Purchase and Loan
         Agreement or the Indenture.

Upon satisfaction of certain conditions set forth in the Note Purchase and
         Loan Agreement, the CEC Note, the Warrants, and the other Related
         Agreements, the CEC Note issued under the Note Purchase and Loan
         Agreement may be exchanged by the Mortgagee in part for ordinary shares
         of the Mortgagor.




<PAGE>   20

The Note Purchase and Loan Agreement was executed on the agreement that the
         Mortgagor shall enter into this mortgage over shares in the capital of
         the Companies (as hereinafter defined).

The Mortgagor has agreed to secure the Secured Amounts (as defined below)
         by entering into this Deed of Mortgage, as well as the other Financing
         Documents (as defined below).

IT IS AGREED as follows

1.       INTERPRETATION

         1.1      Except where the context otherwise requires, words and
                  expressions defined in the Note Purchase and Loan Agreement or
                  the recitals above shall have the same meaning where used
                  herein and the further words and expressions set out below
                  shall have the following meanings;

                  ACTIVE SUBSIDIARIES means Seven Seas Petroleum USA Inc., a
                  Delaware corporation, Seven Seas Petroleum Colombia Inc., a
                  Cayman Islands company, Petrolinson SA, a Panamanian
                  corporation, and GHK Company Colombia, an Oklahoma
                  corporation.

                  COLLATERAL AGENT means the Mortgagee as collateral agent under
                  the certain Collateral Sharing Agreement;

                  COMPANIES means the companies specified in Schedule 1;

                  ENFORCEMENT NOTICE means an enforcement notice served by the
                  Mortgagee on the Mortgagor pursuant to the terms of this Deed
                  of Mortgage;

                  FINANCING DOCUMENTS means the Note Purchase and Loan
                  Agreement, the Indenture, the CEC Note, the Series A Notes,
                  the Series B Notes, the Security Agreement, the Other Deeds of
                  Mortgage, this Deed of Mortgage, the Related Agreements, the
                  Collateral Sharing Agreement and any and all other documents
                  and instruments executed and delivered in connection with the
                  Note Purchase and Loan Agreement or the Indenture.

                  INACTIVE SUBSIDIARIES means Seven Seas Petroleum Holdings
                  Inc., a Cayman Islands company, Seven Seas Petroleum Turkey
                  Inc., a British Colombia corporation, Seven Seas Resources
                  Australia Inc., a British Colombia corporation, Seven Seas
                  Petroleum Australia Inc., a Cayman Islands company, Seven Seas
                  Petroleum PNG Inc., a Cayman Islands company, Seven Seas
                  Petroleum Argentina, a Cayman Islands company, Seven Seas
                  Mediterranean Inc., a Cayman Islands company, Seven Seas
                  Petroleum Turkey Inc., a Cayman Islands company, and Guaduas
                  Pipeline Company, a Cayman Islands company.




<PAGE>   21


                  INDENTURE means the Indenture for the Series A Notes and the
                  Series B Notes as referred to in paragraph (2) above.

                  MORTGAGED PROPERTY means the Original Securities and all and
                  any other shares, securities, rights, moneys and property for
                  the time being mortgaged or charged to the Mortgagee pursuant
                  to Clause 2;

                  NOTE PURCHASE AND LOAN AGREEMENT means the facility referred
                  to in recital A;

                  ORIGINAL SECURITIES means the securities listed in Schedule 1
                  which are all registered in the name of the Mortgagor and
                  following execution of this Deed of Mortgage will be
                  transferred into the name of the Mortgagee or its nominee as
                  Collateral Agent;

                  OTHER DEEDS OF MORTGAGE means each Legal Mortgage Over Shares
                  between Mortgagor and Mortgagee delivered concurrently
                  herewith or hereafter delivered;

                  RELATED AGREEMENTS means the Warrants, the warrants granted to
                  the holders of the Series A Notes, the Shareholder's
                  Agreement, the Registration Agreement and any other documents
                  or instruments executed in connection with any of the
                  foregoing;

                  SECURED AMOUNTS means all and any amounts of any kind now or
                  in the future, actual or contingent, due and payable by the
                  Mortgagor to the Mortgagee under the CEC Note or to the
                  Trustee for the benefit of the holders of the Series A Notes
                  or the Series B Notes or under or in connection with this Deed
                  of Mortgage or the other Financing Documents and references to
                  the Secured Amounts include references to any part of them;
                  and

                  SECURITY INTEREST means any mortgage, charge, pledge, lien,
                  encumbrance, right of set off or any security interest,
                  howsoever created or arising.

         1.2      In this Deed of Mortgage:

                  (a)      references to the Mortgagor or the Mortgagee include
                           references to any person for the time being deriving
                           title under each of them respectively;

                  (b)      references to this Deed of Mortgage and the Financing
                           Documents are references to the same as from time to
                           time varied, supplemented or amended in any manner or
                           respect whatsoever;

                  (c)      references to the Original Securities or to the
                           Mortgaged Property include references to any property
                           included in such term;

                  (d)      "mortgage" includes a transfer or assignment by way
                           of mortgage;

                  (e)      Unless the context otherwise indicates, words
                           importing the singular shall include the plural and
                           vice versa, and the use of the neuter, masculine, or



<PAGE>   22

                           feminine gender is for convenience only and shall be
                           deemed to mean and include the neuter, masculine or
                           feminine gender; and

                  (f)      Clause headings are for ease of reference only.

2.       COVENANT TO PAY SECURED AMOUNTS AND CHARGE

         2.1      The Mortgagor covenants with the Mortgagee for the benefit of
                  the Mortgagee and the Trustee that it shall, whether or not
                  the Mortgagor shall have received an Enforcement Notice in
                  accordance with this Deed of Mortgage or notice of demand in
                  respect of the Secured Amounts, pay and discharge any moneys
                  and liabilities in respect of the Secured Amounts whatsoever
                  which are now or at any time hereafter may be due, owing or
                  payable by the Mortgagor in any currency, actually or
                  contingently, solely and/or jointly and/or severally with
                  another or others, as principal or surety on any account
                  whatsoever pursuant to this Deed of Mortgage or the other
                  Financing Documents or as a consequence of any breach,
                  non-performance, disclaimer or repudiation by the Mortgagor of
                  any of its obligations, covenants, representations or
                  warranties under this Deed of Mortgage, the other Financing
                  Documents or otherwise.

         2.2      The Mortgagor hereby transfers absolutely by way of mortgage
                  to the Mortgagee as a continuing security for the payment and
                  discharge of the Secured Amounts, all its rights, title,
                  interest and benefit, present and future in, to and under:

                  (a)      the Original Securities; and

                  (b)      all other securities and all rights, monies
                           (including, without limitation, dividends) and
                           property whatsoever which may from time to time at
                           any time be derived from, accrued on or be offered in
                           respect of the Original Shares whether by way of
                           redemption, exchange, conversion, rights, bonus,
                           capital reorganisation or otherwise howsoever.

3.       CONTINUING AND PRIMARY SECURITY

         3.1      This Deed of Mortgage shall be a continuing security, and
                  shall be in addition to and shall not affect any continuing
                  liens or other Security Interests to which the Mortgagee is or
                  will be otherwise entitled over the Mortgaged Property, which
                  liens and other Security Interests shall remain in force
                  independently of this Deed of Mortgage.

         3.2      The Original Securities and other Mortgaged Property are
                  hereby mortgaged to the Mortgagee as primary and not as
                  collateral security.

         3.3      The Mortgagor's liability hereunder shall not be discharged or
                  impaired by:

                  (a)      the existence or validity of any other security taken
                           by the Mortgagee in relation to the Financing
                           Documents or any enforcement of or failure to enforce
                           or the release of any such security;




<PAGE>   23

                  (b)      any amendment to or variation of the Financing
                           Documents or any security relating to the Financing
                           Documents or any assignment thereof or hereof;

                  (c)      any release of or granting of time or any other
                           indulgence to the Mortgagor or any third party;

                  (d)      any invalidity, irregularity, unenforceability,
                           imperfection or avoidance of or any defect in any
                           security granted by, or any obligations of, the
                           Mortgagor or any other person hereunder or under the
                           Financing Documents or any amendment to or variation
                           thereof or of any other document or security
                           comprised therein;

                  (e)      the insolvency, liquidation, bankruptcy or
                           dissolution (or proceedings analogous thereto) of the
                           Mortgagor, the Companies or any other person or the
                           appointment of a receiver or administrative receiver
                           or administrator (whether by administration order or
                           otherwise) or trustee or similar officer of any of
                           the assets of the Mortgagor, the Companies or any
                           other person or the occurrence of any circumstances
                           whatsoever affecting the Mortgagor, or any other
                           person's liability to discharge its obligations under
                           the Financing Documents;

                  (f)      any release, renewal, exchange or realisation of any
                           security or obligation provided under or by virtue of
                           this Deed of Mortgage or the other Financing
                           Documents or the provision of any further security to
                           the Mortgagee at any other time; or

                  (g)      any other act, event, neglect or omission which would
                           or might but for this clause operate to impair or
                           discharge the Mortgagor's liability hereunder.

         3.4      Any release, compromise or discharge of the obligations of the
                  Mortgagor shall be deemed to be made subject to the condition
                  that it will be void if any payment or security which the
                  Mortgagee may receive or have received is set aside or proves
                  invalid for whatever reason.

         3.5      Rights may be exercised and demands may be made under this
                  Deed of Mortgage from time to time, and the liabilities and
                  obligations of the Mortgagor and the rights and security or
                  other consideration contained in this Deed of Mortgage may be
                  exercised and enforced, irrespective of

                  (a)      whether any demands, steps or proceedings are being
                           or have been taken against the Mortgagor or any third
                           party; or

                  (b)      whether or in what order any security to which the
                           Mortgagee may be entitled in respect of the Secured
                           Amounts is enforced.




<PAGE>   24

4.       WARRANTIES AND UNDERTAKING

         4.1      The Mortgagor represents and warrants to the Mortgagee and
                  undertakes that:

                  (a)      it is the absolute legal and beneficial owner of all
                           of the Original Securities free of all Security
                           Interests, encumbrances, trusts, equities, proxies
                           and claims whatsoever (save under this Deed of
                           Mortgage or the other Financing Documents) and that
                           all of the Original Securities are fully paid up and
                           are non-assessable;

                  (b)      except as limited by the Financing Documents,
                           Mortgagor has the full legal and unlimited right to
                           vote the Original Securities in its sole discretion;

                  (c)      the Original Securities of each of the Companies
                           constitute 100% of the issued and outstanding equity
                           capital of each of the Companies and are all
                           currently registered in the name of the Mortgagor
                           (subject to the registration of the Original
                           Securities in the name of the Mortgagee as Collateral
                           Agent concurrently with the execution and delivery of
                           this Deed of Mortgage);

                  (d)      each of the Mortgagor and the Companies are duly
                           incorporated and in good standing under the
                           respective laws of the jurisdiction in which each of
                           them is incorporated and the Mortgagor has and will
                           at all times have the necessary power to enter into
                           and perform its obligations under this Deed of
                           Mortgage and has duly authorized the execution and
                           delivery of this Deed of Mortgage;

                  (e)      the Companies are each exempted companies under the
                           laws of the Cayman Islands and neither this Deed of
                           Mortgage or the transfer of the Original Securities
                           to the Mortgagee is subject to any stamp or other tax
                           under the laws of the Cayman Islands, as the case may
                           be, and this Deed of Mortgage is capable of being
                           enforced without being subject to any stamp or other
                           tax under the laws of the Cayman Islands;

                  (f)      the Companies have no contractual or other business
                           relationship with any Inactive Subsidiary;

                  (g)      No Inactive Subsidiary has any operations, assets or
                           liabilities, direct, indirect or contingent;

                  (h)      the Mortgagor holds no rights or Security Interests
                           with respect to present or future revenues and
                           assets, tangible or intangible, relating to the
                           exploration, development, production, transportation
                           and sale of petroleum in and from the Republic of
                           Colombia, directly, by assignment, or otherwise,
                           except as a shareholder of companies whose shares are
                           pledged to Mortgagee pursuant to the Financing
                           Documents;



<PAGE>   25

                  (i)      this Deed of Mortgage constitutes its legal, valid,
                           binding and enforceable obligation and is a first
                           priority security interest over the Mortgaged Shares
                           effective in accordance with its terms;

                  (j)      the execution, delivery, observance and performance
                           by the Mortgagor of this Deed of Mortgage will not
                           require the Mortgagor to obtain any licenses,
                           consents or approvals and will not result in any
                           violation to the best of the Mortgagor's knowledge,
                           of any law, statute, ordinance, rule or regulation
                           applicable to it or any other agreements;

                  (k)      the Companies are not a party or otherwise bound to
                           any employment, management or other agreement, the
                           effect of which would be to limit the ability of the
                           Mortgagee to manage the Companies upon an event of
                           Default under the Financing Documents or give rise to
                           any payment or penalty to terminate any such
                           arrangement;

                  (l)      it has obtained all the necessary authorizations and
                           consents to enable it to enter into this Mortgage and
                           the necessary authorizations and consents will remain
                           in full force and effect at all times during the
                           existence of the security constituted by this Deed of
                           Mortgage;

                  (m)      the execution, delivery, observance and performance
                           by the Mortgagor of the Deed of Mortgage will not
                           constitute an event of default or trigger any
                           enforcement under any Security Interest in the
                           Mortgagor's assets nor will it result in the creation
                           of any Security Interest over or in respect of the
                           present or future assets of the Companies;

                  (n)      the Mortgagor has fully disclosed in writing to the
                           Mortgagee all facts relating to the Mortgagor and the
                           Companies which the Mortgagor knows or should
                           reasonably know and which are material for disclosure
                           to the Mortgagee in the context of the Financing
                           Documents; and

                  (o)      no agreement to which the Mortgagor or the Companies
                           are a party, or law, decree or regulation to which
                           either is subject requires the consent of any such
                           person to the execution, delivery or performance of
                           this Deed of Mortgage and the other Financing
                           Documents and each obligation and covenant contained
                           herein and therein.

         4.2      The Mortgagor undertakes that, for so long as any Secured
                  Amounts remain outstanding:

                  (a)      the Mortgagor shall pay to the Mortgagee, upon
                           demand, the amount of all reasonable expenses which
                           the Mortgagee may incur in, about or with a view to
                           perfecting or enforcing this security or otherwise in
                           connection with this security;

                  (b)      the Mortgagor shall promptly pay (and shall indemnify
                           the Mortgagee on demand against) all calls,
                           installments and other payments which may be




<PAGE>   26

                           made or become due in respect of the Mortgaged
                           Property and so that, in the event of default by the
                           Mortgagor, the Mortgagee may do so on behalf of the
                           Mortgagor and clause 4.2(a) shall apply accordingly;

                  (c)      to the extent any Mortgaged Property is at any time
                           not vested in the Mortgagee or its nominee as
                           Collateral Agent the Mortgagor shall forthwith and
                           from time to time deposit with the Mortgagee all
                           certificates and other documents of title relating to
                           the Mortgaged Property and signed share transfer
                           forms;

                  (d)      the Mortgagor will maintain the Companies as exempted
                           companies under the laws of the Cayman Islands so
                           that the transactions or enforcement actions
                           contemplated hereunder will be capable of being
                           completed without incurrence of any stamp or other
                           tax under the laws of the Cayman Islands;

                  (e)      the Mortgagor will not permit the Company to enter
                           into or become bound by any employment, management or
                           other agreement, the effect of which would be to
                           limit the ability of the Mortgagee to manage the
                           Company upon an event of Default under the Financing
                           Documents or give rise to any payment or penalty to
                           terminate any such arrangement;

                  (f)      the Mortgagor will not permit any Inactive Subsidiary
                           to conduct operations or own any asset or incur any
                           liability, direct, indirect or contingent;

                  (g)      Mortgagor will not permit the Company to engage in
                           any transaction, contractual or otherwise, with any
                           affiliate of Mortgagor except with Mortgagor and
                           Active Subsidiaries and as may otherwise be permitted
                           by the Financing Documents; provided however, that in
                           no event shall the Company engage in any transaction,
                           contractual or otherwise, with an Inactive
                           Subsidiary;

                  (h)      the Mortgagor shall deliver to the Mortgagee undated
                           letters of resignation executed by all persons now or
                           hereafter serving as Directors of the Companies from
                           time to time, which letters the Mortgagee shall be
                           entitled to date and cause to be given immediate
                           effect as of the date of an Enforcement Notice;

                  (i)      the Mortgagor shall forthwith sign, seal, deliver and
                           complete all transfers, renunciations, proxies
                           (including irrevocable proxies if the Mortgagee so
                           requests) mandates, assignments, deeds and documents
                           and do all acts and things which the Mortgagee may,
                           in its absolute discretion, at any time and from time
                           to time specify for enabling or assisting the
                           Mortgagee:

(i) to perfect or improve its title to and security over the Mortgaged Property
including, without limitation, obtaining such approvals or consents to the
rights and




<PAGE>   27

remedies granted to the Mortgagee herein as the Mortgagee requests in the
Mortgagee's sole discretion;

(ii) to vest the Mortgaged Property (including without limitation the
registration thereof in the applicable share registry) in the Mortgagee or its
nominee or nominees as Collateral Agent as of the date of execution of this Deed
of Mortgage;

(iii) to exercise (or enable its nominee or nominees to exercise) any rights or
powers attaching to the Mortgaged Property;

(iv) after the service of an Enforcement Notice to sell or dispose of the
Mortgaged Property; or

(v) otherwise to enforce any of the rights of the Mortgagee under or in
connection with this Deed of Mortgage;

                  (j)      the Mortgagor shall not (without the written consent
                           of the Mortgagee):

(i) create or permit to exist over all or part of the Mortgaged Property (or any
interest therein) any Security Interest (other than created or expressly
permitted to be created under this Deed of Mortgage or under other Financing
Documents) whether ranking prior to, pari passu with or behind the security
contained in this Deed of Mortgage;

(ii) sell, transfer or otherwise dispose of the Mortgaged Property or any
interest therein or attempt or agree to so dispose;

(iii) permit any person other than the Mortgagee or its nominee to be registered
as or become the holder of the Mortgaged Property as Collateral Agent; or

(iv) vote in favour of a resolution or amend, modify or change the memorandum
and articles of association of the Companies or authorize the issuance by any of
the Companies of any shares or any other equity security.

(v) except as otherwise permitted by the Financing Documents permit the
Companies to transfer, assign, dispose of or encumber any rights or interests of
the Companies, direct or indirect, with respect to petroleum exploration,
development, production, transportation, sale or other disposition or with
respect to any association or other contract under which the Companies have such
rights or interests;

(vi) permit the Companies to grant any Security Interest in, or otherwise
encumber, any of its assets, tangible or intangible, except as may be expressly
permitted by the Financing Documents;

(vii) permit the Companies to make any distribution or payment to or for the
benefit of Mortgagor, whether directly or otherwise, if the effect of that
distribution or payment is to render the Companies insolvent or unable to pay
its obligations as they mature; or




<PAGE>   28

(viii) take any other action that would have as its effect a breach of a
Financing Document.

                  (k)      to the extent received by the Mortgagor, it shall
                           forward to the Mortgagee all notices, reports,
                           accounts and other documents relating to the
                           Mortgaged Property or which are sent to the holders
                           of any of the Mortgaged Property as soon as they are
                           received;

                  (l)      no further shares or equity securities of any kind in
                           the Companies (or any options or other rights with
                           respect thereto) will be issued and the authorized
                           shares shall at no time exceed the issued shares;

                  (m)      at any time after the service of an Enforcement
                           Notice, it shall exercise all voting and other rights
                           and powers which may at any time be exercisable by
                           the holder of the Mortgaged Property as the Mortgagee
                           may in its absolute discretion direct, it being
                           understood that the Mortgagee has reserved the right
                           to exercise all such voting rights directly for any
                           proper purpose, including without limitation the
                           immediate removal of Directors of the Companies and
                           their replacement;

                  (n)      the Mortgagor shall not take or accept any Security
                           Interest from the Companies or, in relation to the
                           Secured Amounts, from any third party, without first
                           obtaining the Mortgagee's written consent or permit
                           any Security Interest to be granted by the Companies
                           to any third party, except as may be expressly
                           permitted by the Financing Documents;

                  (o)      the Mortgagor shall not prove in a liquidation or
                           winding up of the Companies in competition with the
                           Mortgagee for any amount whatsoever owing to the
                           Mortgagee by the Mortgagor on any account whatsoever;
                           and

                  (p)      the Mortgagor shall not claim payment whether
                           directly or by set-off, lien, counterclaim or
                           otherwise of any amount which may be or has become
                           due to the Mortgagor by the Companies.

5.       POWER OF ATTORNEY

         5.1      The Mortgagor hereby irrevocably and by way of security for
                  the payment by it of the Secured Amounts and the performance
                  of its obligations under this Deed of Mortgage appoints the
                  Mortgagee as its true and lawful attorney (with full power to
                  appoint substitutes and to subdelegate) on behalf of the
                  Mortgagor and in the Mortgagor's own name or otherwise, at any
                  time and from time to time, to sign, seal, deliver and
                  complete all transfers, renunciations, proxies, mandates,
                  assignments, deeds and documents and do all acts and things
                  which the Mortgagee may, in its sole and absolute discretion,
                  consider to be necessary or advisable to perfect or improve
                  its security over the Mortgaged Property or to give proper
                  effect to the intent and purposes of this Deed of Mortgage or,
                  after delivery of an Enforcement Notice to enable or assist in
                  any way in the exercise





<PAGE>   29

                  of any power of sale of the Mortgaged Property (whether
                  arising under this Deed of Mortgage or implied by statute or
                  otherwise).

6.       ENFORCEMENT

         6.1      The Mortgagee may at any time after the occurrence of an event
                  of Default (as defined in the Note Purchase and Loan
                  Agreement) which has not been timely cured but including,
                  without limitation, the breach of any representation, warranty
                  or covenant contained in this Deed of Mortgage and the other
                  Financing Documents) serve an Enforcement Notice on the
                  Mortgagor. Unless and until the Mortgagee shall have served an
                  Enforcement Notice, but not thereafter:

                  (a)      Mortgagee agrees to the fullest extent permitted by
                           applicable law that the Mortgagor has the right to
                           receive payments distributed in respect of the
                           Original Securities and all other securities which
                           may from time to time at any time be derived from the
                           Original Securities; and

                  (b)      Appoints Mortgagor as Mortgagee's agent and proxy to
                           vote all of the securities described in clause (a)
                           above and exercise all rights and privileges
                           attributable to such securities as permitted under
                           applicable law. Prior to default, if the Mortgagee
                           shall receive any dividend or money described in
                           clause (a) above, the Mortgagee shall receive the
                           same as agent for Mortgagor and upon receipt shall
                           promptly pay or remit the same, without reduction, to
                           Mortgagor. At the request of Mortgagor, Mortgagee
                           shall give such reasonable assurances, confirmations
                           and advice to any third party as may be necessary for
                           Mortgagor to enjoy the full benefit of the rights and
                           privileges described in clauses (a) and (b) above

         6.2      If the Mortgagee shall serve an Enforcement Notice, the
                  Mortgagee shall, without prejudice to any other right or
                  remedy available hereunder or under applicable law, forthwith
                  become entitled:

                  (a)      solely and exclusively to exercise all voting rights
                           attaching to the Mortgaged Property or any thereof
                           and shall exercise such rights in such manner as the
                           Mortgagee may in its absolute discretion determine;
                           and/or

                  (b)      solely and exclusively to exercise any and all other
                           rights and/or powers and/or discretions of the
                           Mortgagor in, to and under the Mortgaged Property
                           pursuant to the constitutional documents of the
                           Company; and/or

                  (c)      to receive and retain all dividends and other
                           distributions made on or in respect of the Mortgaged
                           Property or any thereof and any such dividends and
                           other distributions received by the Mortgagor after
                           such time shall be held in trust by the Mortgagor for
                           the Mortgagee and be paid or transferred to the
                           Mortgagee on demand; and/or



<PAGE>   30

                  (d)      without notice to, or further consent or concurrence
                           by, the Mortgagor to sell the Mortgaged Property or
                           any part thereof by such method, at such place and
                           upon such terms as the Mortgagee may in its absolute
                           discretion determine, with power to postpone any such
                           sale and in any such case the Mortgagee may exercise
                           any and all rights attaching to the Mortgaged
                           Property as the Mortgagee in its discretion may
                           determine and without being answerable for any loss
                           occasioned by such sale or resulting from
                           postponement thereof or the exercise of such rights;
                           upon any sale of the Mortgaged Property or any part
                           thereof the purchaser thereof shall not be bound to
                           see or enquire whether the power of sale of the
                           Mortgagee has arisen in the manner herein provided
                           and the sale shall be deemed to be within the power
                           of the Mortgagee and the receipt of the Mortgagee for
                           the purchase money shall effectively discharge the
                           purchaser of the Mortgaged Property, or any part
                           thereof, who shall not be concerned or be in any way
                           answerable therefor; and/or

                  (e)      to appoint a receiver in respect of the Mortgaged
                           Property and the provisions of Clause 7 shall apply
                           thereto.

         6.3      The Mortgagee shall not be liable for any loss or damage
                  occasioned by any sale or disposal of the Mortgaged Property
                  (or interest therein) or arising out of the exercise of or
                  failure to exercise any of its powers under this Deed of
                  Mortgage or for any neglect or default to pay any instalment
                  or accept any offer or notify the Mortgagor of any such matter
                  or for any other loss of any nature whatsoever in connection
                  with the Mortgaged Property.

7.       MORTGAGEE'S RIGHTS AS TO MORTGAGED PROPERTY

         If the Mortgagee shall serve an Enforcement Notice, the Mortgagee
         shall, without prejudice to any other right or remedy available
         hereunder or under applicable law, forthwith become entitled:

         7.1      solely and exclusively to exercise all voting rights attaching
                  to the Mortgaged Property or any thereof and shall exercise
                  such rights in such manner as the Mortgagee may in its
                  absolute discretion determine; and/or

         7.2      solely and exclusively to exercise all other rights and/or
                  powers and/or discretions of the Mortgagor in, to and under
                  the Mortgaged Property pursuant to the memorandum and articles
                  of association of the Company; and/or

         7.3      to receive and retain all dividends and other distributions
                  made on or in respect of the Mortgaged Property or any thereof
                  and any such dividends and other distributions received by the
                  Mortgagor after such time shall be held in trust by the
                  Mortgagor for the Mortgagee and be paid or transferred to the
                  Mortgagee on demand to be applied towards the discharge of the
                  Secured Obligations; and/or

         7.4      without notice to, or further consent or concurrence by, the
                  Mortgagor to sell or otherwise dispose of the Mortgaged
                  Property or any part thereof by such method,







<PAGE>   31

                  at such place and upon such terms as the Mortgagee may in its
                  absolute discretion determine, with power to postpone any such
                  sale and in any such case the Mortgagee may exercise any and
                  all rights attaching to the Mortgaged Property as the
                  Mortgagee in its absolute discretion may determine and without
                  being answerable for any loss occasioned by such sale or
                  resulting from postponement thereof or the exercise of such
                  rights; and/or

         7.5      to date and deliver the documents delivered to it pursuant to
                  this Mortgage as it considers appropriate and to take all
                  steps not already taken to register the Mortgaged Property in
                  the name of the Mortgagee or its nominee or nominees as
                  Collateral Agent and to assume control as registered owner of
                  the Mortgaged Property.

8.       OTHER SECURITY

         8.1      This security is in addition to and shall not affect or be
                  merged in any bills, notes, guarantees, indemnities,
                  undertakings, Security Interests, or other security whatsoever
                  which the Mortgagee may hold now or hereafter in connection
                  with the Financing Documents or the obligations of any other
                  person liable for any of the Secured Amounts.

9.       FURTHER PROVISIONS

         9.1      (a)      This security is in addition to, and shall
                           neither be merged in, nor in any way exclude or
                           prejudice, any other Security Interest or right of
                           recourse or other right whatsoever which the
                           Mortgagee may now or at any time hereafter hold or
                           have (or would apart from this security hold or have)
                           as regards the Mortgagor or any other, person in
                           respect of the Secured Amounts.

                  (b)      The powers which this Deed of Mortgage confer on the
                           Mortgagee are cumulative, without prejudice to its
                           powers under the general law, and may be exercised as
                           often as the Mortgagee thinks appropriate; the
                           Mortgagee may, in connection with the exercise of its
                           powers, join or concur with any person in any
                           transaction, scheme or arrangement whatsoever; and
                           the Mortgagor acknowledges that the respective powers
                           of the Mortgagee shall in no circumstances whatsoever
                           be suspended, waived or otherwise prejudiced by
                           anything other than an express waiver or variation in
                           writing.

                  (c)      The rights of the Mortgagee in relation to the
                           Mortgaged Property and the recovery of the Secured
                           Amounts (whether arising under this Deed of Mortgage,
                           the other Financing Documents or under the general
                           law) shall not be capable of being waived or varied
                           otherwise than by an express waiver or variation in
                           writing; and in particular any failure to exercise or
                           any delay in exercising any of such rights shall not
                           operate as a waiver or variation of that or any other
                           such right; any defective or partial exercise




<PAGE>   32

                           of any such right shall not preclude any other or
                           further exercise of that or any other such right; and
                           no act or course of conduct or negotiation on its
                           part or on its behalf shall in any way preclude it
                           from exercising any such right or constitute a
                           suspension or any variation of any such right.

                  (d)      If any of the provisions of this Deed of Mortgage
                           becomes invalid, illegal or unenforceable in any
                           respect under any law, the validity, legality and
                           enforceability of the remaining provisions shall not
                           in any way be affected or impaired.

                  (e)      In any proceedings relating to this Deed of Mortgage
                           a statement as to any amount due to the Mortgagee or
                           the Trustee under the Financing Documents which is
                           certified as being correct by an officer or agent of
                           the Mortgagee shall, save in the case of manifest
                           error, be conclusive evidence that such amount is in
                           fact due and payable.

         9.2      Assignment

                  9.2.1    This Deed of Mortgage shall be binding upon and inure
                           to the benefit of each party hereto and its
                           successors in title and permitted assigns.

                  9.2.2    The Mortgagor shall not be entitled to assign or
                           transfer any of its rights, benefits or obligations
                           hereunder without the prior written consent of the
                           Mortgagee.

                  9.2.3    The Mortgagee may assign or transfer all or any part
                           of its rights, benefits or obligations under this
                           Deed of Mortgage to any other person which is its
                           successor under the Financing Documents. Where the
                           Mortgagee assigns or transfers its obligations or any
                           part thereof, the Mortgagor shall execute such
                           documents as the Mortgagee may specify to release the
                           Mortgagee to the extent of the assignment or transfer
                           or with a view to perfecting such assignment or
                           transfer, or where necessary, shall execute further
                           security documentation in favour of the assignee or
                           transferee in like form to this Deed of Mortgage.

         9.3      Release of Security

                  Upon final and unconditional repayment of the Secured Amounts
                  in full and provided that no event of Default has occurred,
                  the Mortgagee shall promptly assign the Mortgaged Property to
                  the Mortgagor free of all Security Interests, encumbrances,
                  trusts, equities and claims whatsoever imposed by the
                  Mortgagee and the Mortgagee shall forthwith sign, seal,
                  deliver and complete all transfers, renunciations, proxies,
                  mandates, assignments, deeds and documents and do all acts and
                  things which the Mortgagor may reasonably specify to vest all
                  of the Mortgaged Property in the name of the Mortgagor or its
                  nominee.

         9.4      This Deed of Mortgage is governed by, and shall be construed
                  in accordance with, the laws of the Cayman Islands.



<PAGE>   33

         9.5      (a)      The parties agree that the courts of the Cayman
                           Islands are to have exclusive jurisdiction to settle
                           any disputes which may arise in connection with the
                           legal relationships established by this Deed of
                           Mortgage (including, without limitation, claims for
                           set-off or counterclaim) or otherwise arising in
                           connection with this Deed of Mortgage.

                  (b)      The parties irrevocably waive any objections on the
                           grounds of venue of forum non conveniens or any
                           similar grounds.

                  The parties irrevocably consent to service of process by mail
                  or in any other manner permitted by the relevant law.

10.      NOTICES, ENGLISH LANGUAGE

                  (a)      Each notice or other communication to be given or
                           made hereunder shall be in the English language and
                           shall, unless otherwise stated be made in writing as
                           provided below.

                  Any notice or other communication or document to be made or
                  delivered by one person to another pursuant to this Deed of
                  Mortgage shall (unless that other person has by fifteen days'
                  written notice to the other specified another address and/or
                  fax or telex number) be made or delivered to that other person
                  at the following address, fax or telex number:

                           The Mortgagor:

                           SEVEN SEAS PETROLEUM INC.
                           5555 San Felipe, Suite 1700
                           Houston, Texas 77056
                           Attention: Larry A. Ray
                           Fax No. (713) 621-9770


                           The Mortgagee:

                           CHESAPEAKE ENERGY CORPORATION
                           6100 North Western Avenue
                           Oklahoma City, Oklahoma 73118
                           Attention: M. Rowland
                           Fax No. (405) 879-9580


                  and shall be deemed to have been made or delivered when such
                  communication or document has been dispatched and the
                  appropriate answer back received (in the case of any
                  communication made by telex) or sent by fax to the fax number
                  of the party set out herein and when receipt is confirmed by
                  facsimile or telephone (in the case of any communication by
                  fax) or (in the case of any communication






<PAGE>   34

                  made by letter) when left at that address or, as the case may
                  be, three days after being deposited in the post first class
                  postage prepaid in an envelope addressed to it at that
                  address; Provided that any communication or document to be
                  made or delivered to the Mortgagee shall be effective only
                  when received by the Mortgagee.

11.      COUNTERPARTS

This Deed of Mortgage may be executed in any number of counterparts and all such
counterparts taken together shall be deemed to constitute one and the same
instrument.

IN WITNESS WHEREOF this Deed of Mortgage has been executed and delivered as a
Deed the day and year first above written.

EXECUTED AS A DEED by                       )
the duly authorised representative          )/s/ LARRY A. RAY
of SEVEN SEAS PETROLEUM INC.,               )
in the presence of:                         )

EXECUTED AS A DEED by                       )
the duly authorised representative          )
of CHESAPEAKE ENERGY CORPORATION            )/s/ TOM L. WARD
as Collateral Agent                         )
in the presence of:                         )

<PAGE>   35



                                   SCHEDULE 1
                               ORIGINAL SECURITIES

<Table>
<Caption>
                                             Amount or number of
                  Company                    Original Securities              Description of Original Securities
                  -------                    -------------------              ----------------------------------

<S>                                          <C>                              <C>
Seven Seas Petroleum Holdings Inc., with              1                       Shares of US$1.00 each
its registered office at Caribbean           -------------------
Management Ltd. of P.O. Box 1044, 3rd
Floor, West Wind Building, George Town,
Grand Cayman

Seven Seas Petroleum Australia Inc., with             1                       Shares of US$1.00 each
its registered office at Caribbean           -------------------
Management Ltd. of P.O. Box 1044, 3rd
Floor, West Wind Building, George Town,
Grand Cayman

Seven Seas Petroleum PNG Inc., with its               1                       Shares of US$1.00 each
registered office at Caribbean Management    -------------------
Ltd. of P.O. Box 1044, 3rd Floor, West
Wind Building, George Town, Grand Cayman


Seven Seas Petroleum Argentina Inc., with             1                       Shares of US$1.00 each
its registered office at Caribbean           -------------------
Management Ltd. of P.O. Box 1044, 3rd
Floor, West Wind Building, George Town,
Grand Cayman

Guadas Pipeline Company, with its                     1                       Shares of US$1.00 each
registered office at International           -------------------
Corporation Services Ltd., One Regis
Place, Fort and Mary Streets, P.O. Box 472

Seven Seas Petroleum Turkey Inc., with its            1                       Shares of US$1.00 each
registered office at Caribbean Management    -------------------
Ltd. of P.O. Box 1044, 3rd Floor, West
Wind Building, George Town, Grand Cayman
</Table>



<PAGE>   36

<Table>
<S>                                          <C>                              <C>
Seven Seas Petroleum Mediterranean Inc.,              1                       Shares of US$1.00 each
with its registered office at Caribbean      -------------------
Management Ltd. of P.O. Box 1044, 3rd
Floor, West Wind Building, George Town,
Grand Cayman
</Table>





<PAGE>   37





                                  July 23, 2001





                            SEVEN SEAS PETROLEUM INC
                                 (as Mortgagor)


                          CHESAPEAKE ENERGY CORPORATION
                                 (as Mortgagee)




                    ---------------------------------------
                           LEGAL MORTGAGE OVER SHARES






<PAGE>   38


THIS DEED OF MORTGAGE ("Deed of Mortgage") is made as of July 23, 2001

BETWEEN

(1)      SEVEN SEAS PETROLEUM INC., a Cayman Islands exempted company limited by
         shares, the registered office of which is at Walker House, Mary Street,
         George Town, Grand Cayman, Cayman Islands (the "Mortgagor"); and

(2)      CHESAPEAKE ENERGY CORPORATION, an Oklahoma corporation, whose principal
         place of business is at 6100 North Western Avenue, Oklahoma City,
         Oklahoma, 73118 (the "Mortgagee") as Collateral Agent under the
         Collateral Sharing Agreement (as hereinafter defined) for itself and
         United States Trust Company of New York, ("Trustee") under that certain
         Indenture dated July 23, 2001 (the "Indenture"), pursuant to which the
         Trustee is trustee for the holders of the Mortgagor's 12% Senior
         Secured Series A Notes (the "Series A Notes") and the Mortgagor's 12%
         Senior Secured Series B Notes (the "Series B Notes").

WHEREAS

(A)      Pursuant to a Note Purchase and Loan Agreement dated as of July 9, 2001
         (the "Note Purchase and Loan Agreement") the Mortgagee agreed to
         advance to the Mortgagor the sum of Twenty-two Million Five Hundred
         Thousand United States Dollars (US$22,500,000.00), evidenced by a 12%
         Senior Secured Note due 2004 in the principal amount of TWENTY-TWO
         MILLION FIVE HUNDRED THOUSAND DOLLARS ($22,500,000.00) (the "CEC Note")
         subject to the terms and conditions stated in: (a) the Note Purchase
         and Loan Agreement; (b) the CEC Note; (c) the detachable Warrants to
         purchase twelve million six hundred twelve thousand one hundred forty
         (12,612,140) shares of the Mortgagor's ordinary shares (the
         "Warrants"); (d) the Shareholder's Rights Agreement dated July 23, 2001
         between the Mortgagor and the Mortgagee (the "Shareholder's
         Agreement"); (e) the Registration Rights Agreement dated July 23, 2001
         between the Mortgagor and the Mortgagee (the "Registration Agreement");
         (f) the Security Agreement dated July 23, 2001 between the Mortgagor
         and the Mortgagee as Collateral Agent for itself and the Trustee (the
         "Security Agreement"); (g) certain other Deeds of Mortgage Over Shares
         of the subsidiaries of the Mortgagor other than the Company (as
         hereinafter defined) dated July 23, 2001 (the "Other Deeds of
         Mortgage"); (h) the Collateral Sharing and Agency Agreement dated as of
         July 23, 2001 between the Mortgagee and the Trustee pursuant to which
         the Mortgagee agrees to act as collateral agent for itself and the
         Trustee (the "Collateral Sharing Agreement"); and (i) any and all other
         documents and instruments executed and delivered in connection with the
         Note Purchase and Loan Agreement, the Indenture and any of the other
         documents executed in connection with the Note Purchase and Loan
         Agreement or the Indenture.

Upon satisfaction of certain conditions set forth in the Note Purchase and
         Loan Agreement, the CEC Note, the Warrants, and the other Related
         Agreements, the CEC Note issued under the Note Purchase and Loan
         Agreement may be exchanged by the Mortgagee in part for ordinary shares
         of the Mortgagor.



<PAGE>   39

The Note Purchase and Loan Agreement was executed on the agreement that the
         Mortgagor shall enter into this mortgage over shares in the capital of
         the Company, a Cayman Islands company, the registered office of which
         is at Caribbean Management Ltd., of P.O. Box 1044, 3rd Floor, West Wind
         Building, George Town, Grand Cayman, Cayman Islands.

The Mortgagor has agreed to secure the Secured Amounts (as defined below)
         by entering into this Deed of Mortgage, as well as the other Financing
         Documents (as defined below).

IT IS AGREED as follows

1.       INTERPRETATION

         1.1      Except where the context otherwise requires, words and
                  expressions defined in the Note Purchase and Loan Agreement or
                  the recitals above shall have the same meaning where used
                  herein and the further words and expressions set out below
                  shall have the following meanings;

                  ACTIVE SUBSIDIARIES means Seven Seas Petroleum USA Inc., a
                  Delaware corporation, Seven Seas Petroleum Colombia Inc., a
                  Cayman Islands company, Petrolinson SA, a Panamanian
                  corporation, and GHK Company Colombia, an Oklahoma
                  corporation.

                  COLLATERAL AGENT means the Mortgagee as collateral agent under
                  the certain Collateral Sharing Agreement;

                  COMPANY means the company specified in Schedule 1;

                  ENFORCEMENT NOTICE means an enforcement notice served by the
                  Mortgagee on the Mortgagor pursuant to the terms of this Deed
                  of Mortgage;

                  FINANCING DOCUMENTS means the Note Purchase and Loan
                  Agreement, the Indenture, the CEC Note, the Series A Notes,
                  the Series B Notes, the Security Agreement, the Other Deeds of
                  Mortgage, this Deed of Mortgage, the Related Agreements, the
                  Collateral Sharing Agreement and any and all other documents
                  and instruments executed and delivered in connection with the
                  Note Purchase and Loan Agreement or the Indenture.

                  INACTIVE SUBSIDIARIES means Seven Seas Petroleum Holdings
                  Inc., a Cayman Islands company, Seven Seas Petroleum Turkey
                  Inc., a British Colombia corporation, Seven Seas Resources
                  Australia Inc., a British Colombia corporation, Seven Seas
                  Petroleum Australia Inc., a Cayman Islands company, Seven Seas
                  Petroleum PNG Inc., a Cayman Islands company, Seven Seas
                  Petroleum Argentina, a Cayman Islands company, Seven Seas
                  Mediterranean Inc., a Cayman Islands company, Seven Seas
                  Petroleum Turkey Inc., a Cayman Islands company, and Guaduas
                  Pipeline Company, a Cayman Islands company.






                                       2
<PAGE>   40

                  INDENTURE means the Indenture for the Series A Notes and the
                  Series B Notes as referred to in paragraph (2) above.

                  MORTGAGED PROPERTY means the Original Securities and all and
                  any other shares, securities, rights, moneys and property for
                  the time being mortgaged or charged to the Mortgagee pursuant
                  to Clause 2;

                  NOTE PURCHASE AND LOAN AGREEMENT means the facility referred
                  to in recital A;

                  ORIGINAL SECURITIES means the securities listed in Schedule 1
                  which are all registered in the name of the Mortgagor and
                  following execution of this Deed of Mortgage will be
                  transferred into the name of the Mortgagee or its nominee as
                  Collateral Agent;

                  OTHER DEEDS OF MORTGAGE means each Legal Mortgage Over Shares
                  between Mortgagor and Mortgagee delivered concurrently
                  herewith or hereafter delivered;

                  RELATED AGREEMENTS means the Warrants, the warrants granted to
                  the holders of the Series A Notes, the Shareholder's
                  Agreement, the Registration Agreement and any other documents
                  or instruments executed in connection with any of the
                  foregoing;

                  SECURED AMOUNTS means all and any amounts of any kind now or
                  in the future, actual or contingent, due and payable by the
                  Mortgagor to the Mortgagee under the CEC Note or to the
                  Trustee for the benefit of the holders of the Series A Notes
                  or the Series B Notes or under or in connection with this Deed
                  of Mortgage or the other Financing Documents and references to
                  the Secured Amounts include references to any part of them;
                  and

                  SECURITY INTEREST means any mortgage, charge, pledge, lien,
                  encumbrance, right of set off or any security interest,
                  howsoever created or arising.

         1.2      In this Deed of Mortgage:

                  (a)      references to the Mortgagor or the Mortgagee include
                           references to any person for the time being deriving
                           title under each of them respectively;

                  (b)      references to this Deed of Mortgage and the Financing
                           Documents are references to the same as from time to
                           time varied, supplemented or amended in any manner or
                           respect whatsoever;

                  (c)      references to the Original Securities or to the
                           Mortgaged Property include references to any property
                           included in such term;

                  (d)      "mortgage" includes a transfer or assignment by way
                           of mortgage;

                  (e)      Unless the context otherwise indicates, words
                           importing the singular shall include the plural and
                           vice versa, and the use of the neuter, masculine, or




                                       3
<PAGE>   41

                           feminine gender is for convenience only and shall be
                           deemed to mean and include the neuter, masculine or
                           feminine gender; and

                  (f)      Clause headings are for ease of reference only.

2.       COVENANT TO PAY SECURED AMOUNTS AND CHARGE

         2.1      The Mortgagor covenants with the Mortgagee for the benefit of
                  the Mortgagee and the Trustee that it shall, whether or not
                  the Mortgagor shall have received an Enforcement Notice in
                  accordance with this Deed of Mortgage or notice of demand in
                  respect of the Secured Amounts, pay and discharge any moneys
                  and liabilities in respect of the Secured Amounts whatsoever
                  which are now or at any time hereafter may be due, owing or
                  payable by the Mortgagor in any currency, actually or
                  contingently, solely and/or jointly and/or severally with
                  another or others, as principal or surety on any account
                  whatsoever pursuant to this Deed of Mortgage or the other
                  Financing Documents or as a consequence of any breach,
                  non-performance, disclaimer or repudiation by the Mortgagor of
                  any of its obligations, covenants, representations or
                  warranties under this Deed of Mortgage, the other Financing
                  Documents or otherwise.

         2.2      The Mortgagor hereby transfers absolutely by way of mortgage
                  to the Mortgagee as a continuing security for the payment and
                  discharge of the Secured Amounts, all its rights, title,
                  interest and benefit, present and future in, to and under:

                  (a)      the Original Securities; and

                  (b)      all other securities and all rights, monies
                           (including, without limitation, dividends) and
                           property whatsoever which may from time to time at
                           any time be derived from, accrued on or be offered in
                           respect of the Original Shares whether by way of
                           redemption, exchange, conversion, rights, bonus,
                           capital reorganisation or otherwise howsoever.

3.       CONTINUING AND PRIMARY SECURITY

         3.1      This Deed of Mortgage shall be a continuing security, and
                  shall be in addition to and shall not affect any continuing
                  liens or other Security Interests to which the Mortgagee is or
                  will be otherwise entitled over the Mortgaged Property, which
                  liens and other Security Interests shall remain in force
                  independently of this Deed of Mortgage.

         3.2      The Original Securities and other Mortgaged Property are
                  hereby mortgaged to the Mortgagee as primary and not as
                  collateral security.

         3.3      The Mortgagor's liability hereunder shall not be discharged or
                  impaired by:

                  (a)      the existence or validity of any other security taken
                           by the Mortgagee in relation to the Financing
                           Documents or any enforcement of or failure to enforce
                           or the release of any such security;




                                       4
<PAGE>   42

                  (b)      any amendment to or variation of the Financing
                           Documents or any security relating to the Financing
                           Documents or any assignment thereof or hereof;

                  (c)      any release of or granting of time or any other
                           indulgence to the Mortgagor or any third party;

                  (d)      any invalidity, irregularity, unenforceability,
                           imperfection or avoidance of or any defect in any
                           security granted by, or any obligations of, the
                           Mortgagor or any other person hereunder or under the
                           Financing Documents or any amendment to or variation
                           thereof or of any other document or security
                           comprised therein;

                  (e)      the insolvency, liquidation, bankruptcy or
                           dissolution (or proceedings analogous thereto) of the
                           Mortgagor, the Company or any other person or the
                           appointment of a receiver or administrative receiver
                           or administrator (whether by administration order or
                           otherwise) or trustee or similar officer of any of
                           the assets of the Mortgagor, the Company or any other
                           person or the occurrence of any circumstances
                           whatsoever affecting the Mortgagor, or any other
                           person's liability to discharge its obligations under
                           the Financing Documents;

                  (f)      any release, renewal, exchange or realisation of any
                           security or obligation provided under or by virtue of
                           this Deed of Mortgage or the other Financing
                           Documents or the provision of any further security to
                           the Mortgagee at any other time; or

                  (g)      any other act, event, neglect or omission which would
                           or might but for this clause operate to impair or
                           discharge the Mortgagor's liability hereunder.

         3.4      Any release, compromise or discharge of the obligations of the
                  Mortgagor shall be deemed to be made subject to the condition
                  that it will be void if any payment or security which the
                  Mortgagee may receive or have received is set aside or proves
                  invalid for whatever reason.

         3.5      Rights may be exercised and demands may be made under this
                  Deed of Mortgage from time to time, and the liabilities and
                  obligations of the Mortgagor and the rights and security or
                  other consideration contained in this Deed of Mortgage may be
                  exercised and enforced, irrespective of

                  (a)      whether any demands, steps or proceedings are being
                           or have been taken against the Mortgagor or any third
                           party; or

                  (b)      whether or in what order any security to which the
                           Mortgagee may be entitled in respect of the Secured
                           Amounts is enforced.




                                       5
<PAGE>   43

4.       WARRANTIES AND UNDERTAKING

         4.1      The Mortgagor represents and warrants to the Mortgagee and
                  undertakes that:

                  (a)      it is the absolute legal and beneficial owner of all
                           of the Original Securities free of all Security
                           Interests, encumbrances, trusts, equities, proxies
                           and claims whatsoever (save under this Deed of
                           Mortgage or the other Financing Documents) and that
                           all of the Original Securities are fully paid up and
                           are non-assessable;

                  (b)      except as limited by the Financing Documents,
                           Mortgagor has the full legal and unlimited right to
                           vote the Original Securities in its sole discretion;

                  (c)      the Original Securities constitute 100% of the issued
                           and outstanding equity capital of the Company and are
                           all currently registered in the name of the Mortgagor
                           (subject to the registration of the Original
                           Securities in the name of the Mortgagee as Collateral
                           Agent concurrently with the execution and delivery of
                           this Deed of Mortgage);

                  (d)      the Mortgagor and the Company are duly incorporated
                           and in good standing under the respective laws of the
                           jurisdiction in which each of them is incorporated
                           and the Mortgagor has and will at all times have the
                           necessary power to enter into and perform its
                           obligations under this Deed of Mortgage and has duly
                           authorized the execution and delivery of this Deed of
                           Mortgage;

                  (e)      the Company is an exempted company under the laws of
                           the Cayman Islands and neither this Deed of Mortgage
                           or the transfer of the Original Securities to the
                           Mortgagee is subject to any stamp or other tax under
                           the laws of the Cayman Islands and this Deed of
                           Mortgage is capable of being enforced without being
                           subject to any stamp or other tax under the laws of
                           the Cayman Islands;

                  (f)      pursuant to amendments to the articles of association
                           within 45 days after the date of this Agreement, the
                           Company will not be permitted to issue any equity
                           capital other than the Original Securities;

                  (g)      the Company has no contractual or other business
                           relationship with any Inactive Subsidiary;

                  (h)      No Inactive Subsidiary has any operations, assets or
                           liabilities, direct, indirect or contingent;

                  (i)      the Mortgagor holds no rights or Security Interests
                           with respect to present or future revenues and
                           assets, tangible or intangible, relating to the
                           exploration, development, production, transportation
                           and sale of petroleum in and from the Republic of
                           Colombia, directly, by assignment, or






                                       6
<PAGE>   44

                           otherwise, except as a shareholder of companies whose
                           shares are pledged to Mortgagee pursuant to the
                           Financing Documents;

                  (j)      this Deed of Mortgage constitutes its legal, valid,
                           binding and enforceable obligation and is a first
                           priority security interest over the Mortgaged Shares
                           effective in accordance with its terms;

                  (k)      the execution, delivery, observance and performance
                           by the Mortgagor of this Deed of Mortgage will not
                           require the Mortgagor to obtain any licenses,
                           consents or approvals and will not result in any
                           violation to the best of the Mortgagor's knowledge,
                           of any law, statute, ordinance, rule or regulation
                           applicable to it or any other agreements;

                  (l)      the Company is not a party or otherwise bound to any
                           employment, management or other agreement, the effect
                           of which would be to limit the ability of the
                           Mortgagee to manage the Company upon an event of
                           Default under the Financing Documents or give rise to
                           any payment or penalty to terminate any such
                           arrangement;

                  (m)      it has obtained all the necessary authorizations and
                           consents to enable it to enter into this Mortgage and
                           the necessary authorizations and consents will remain
                           in full force and effect at all times during the
                           existence of the security constituted by this Deed of
                           Mortgage;

                  (n)      the execution, delivery, observance and performance
                           by the Mortgagor of the Deed of Mortgage will not
                           constitute an event of default or trigger any
                           enforcement under any Security Interest in the
                           Mortgagor's assets nor will it result in the creation
                           of any Security Interest over or in respect of the
                           present or future assets of the Company;

                  (o)      the Mortgagor has fully disclosed in writing to the
                           Mortgagee all facts relating to the Mortgagor and the
                           Company which the Mortgagor knows or should
                           reasonably know and which are material for disclosure
                           to the Mortgagee in the context of the Financing
                           Documents; and

                  (p)      no agreement to which the Mortgagor or the Company or
                           its Colombian branch is a party, or law, decree or
                           regulation to which either is subject, including
                           without limitation any agreement with Empresa
                           Colombiana de Petroleos or imposition by the Ministro
                           de Minas y Energia de Colombia or any other
                           instrumentality of the Republic of Colombia requires
                           the consent of any such person to the execution,
                           delivery or performance of this Deed of Mortgage and
                           the other Financing Documents and each obligation and
                           covenant contained herein and therein.

         4.2      The Mortgagor undertakes that, for so long as any Secured
                  Amounts remain outstanding:




                                       7
<PAGE>   45

                  (a)      the Mortgagor shall pay to the Mortgagee, upon
                           demand, the amount of all reasonable expenses which
                           the Mortgagee may incur in, about or with a view to
                           perfecting or enforcing this security or otherwise in
                           connection with this security;

                  (b)      the Mortgagor shall promptly pay (and shall indemnify
                           the Mortgagee on demand against) all calls,
                           installments and other payments which may be made or
                           become due in respect of the Mortgaged Property and
                           so that, in the event of default by the Mortgagor,
                           the Mortgagee may do so on behalf of the Mortgagor
                           and clause 4.2(a) shall apply accordingly;

                  (c)      to the extent any Mortgaged Property is at any time
                           not vested in the Mortgagee or its nominee as
                           Collateral Agent the Mortgagor shall forthwith and
                           from time to time deposit with the Mortgagee all
                           certificates and other documents of title relating to
                           the Mortgaged Property and signed share transfer
                           forms;

                  (d)      the Mortgagor will maintain the Company as an
                           exempted company under the laws of the Cayman Islands
                           so that the transactions or enforcement actions
                           contemplated hereunder will be capable of being
                           completed without incurrence of any stamp or other
                           tax under the laws of the Cayman Islands;

                  (e)      the Mortgagor will not permit the Company to enter
                           into or become bound by any employment, management or
                           other agreement, the effect of which would be to
                           limit the ability of the Mortgagee to manage the
                           Company upon an event of Default under the Financing
                           Documents or give rise to any payment or penalty to
                           terminate any such arrangement;

                  (f)      the Mortgagor will not permit any Inactive Subsidiary
                           to conduct operations or own any asset or incur any
                           liability, direct, indirect or contingent;

                  (g)      Mortgagor will not permit the Company to engage in
                           any transaction, contractual or otherwise, with any
                           affiliate of Mortgagor except with Mortgagor and
                           Active Subsidiaries and as may otherwise be permitted
                           by the Financing Documents; provided however, that in
                           no event shall the Company engage in any transaction,
                           contractual or otherwise, with an Inactive
                           Subsidiary;

                  (h)      the Mortgagor shall deliver to the Mortgagee undated
                           letters of resignation executed by all persons now or
                           hereafter serving as Directors of the Company from
                           time to time, which letters the Mortgagee shall be
                           entitled to date and cause to be given immediate
                           effect as of the date of an Enforcement Notice;

                  (i)      the Mortgagor shall forthwith sign, seal, deliver and
                           complete all transfers, renunciations, proxies
                           (including irrevocable proxies if the Mortgagee so



                                       8
<PAGE>   46

                           requests) mandates, assignments, deeds and documents
                           and do all acts and things which the Mortgagee may,
                           in its absolute discretion, at any time and from time
                           to time specify for enabling or assisting the
                           Mortgagee:

(i) to perfect or improve its title to and security over the Mortgaged Property
including, without limitation, obtaining such approvals or consents to the
rights and remedies granted to the Mortgagee herein as the Mortgagee requests in
the Mortgagee's sole discretion;

(ii) to vest the Mortgaged Property (including without limitation the
registration thereof in the applicable share registry) in the Mortgagee or its
nominee or nominees as Collateral Agent as of the date of execution of this Deed
of Mortgage;

(iii) to exercise (or enable its nominee or nominees to exercise) any rights or
powers attaching to the Mortgaged Property;

(iv) after the service of an Enforcement Notice to sell or dispose of the
Mortgaged Property; or

(v) otherwise to enforce any of the rights of the Mortgagee under or in
connection with this Deed of Mortgage;

                  (j)      the Mortgagor shall not (without the written consent
                           of the Mortgagee):

(i) create or permit to exist over all or part of the Mortgaged Property (or any
interest therein) any Security Interest (other than created or expressly
permitted to be created under this Deed of Mortgage or under other Financing
Documents) whether ranking prior to, pari passu with or behind the security
contained in this Deed of Mortgage;

(ii) sell, transfer or otherwise dispose of the Mortgaged Property or any
interest therein or attempt or agree to so dispose;

(iii) permit any person other than the Mortgagee or its nominee to be registered
as or become the holder of the Mortgaged Property as Collateral Agent; or

(iv) vote in favour of a resolution or amend, modify or change the memorandum
and articles of association of the Company or authorize the issuance by the
Company of any shares or any other equity security.

(v) except as otherwise permitted by the Financing Documents permit the Company
to transfer, assign, dispose of or encumber any rights or interests of the
Company, direct or indirect, with respect to petroleum exploration, development,
production, transportation, sale or other disposition or with respect to any
association or other contract under which the Company has such rights or
interests;

(vi) permit the Company to grant any Security Interest in, or otherwise
encumber, any of its assets, tangible or intangible, except as may be expressly
permitted by the Financing Documents;




                                       9
<PAGE>   47

(vii) permit the Company to make any distribution or payment to or for the
benefit of Mortgagor, whether directly or otherwise, if the effect of that
distribution or payment is to render the Company insolvent or unable to pay its
obligations as they mature; or

(viii) take any other action that would have as its effect a breach of a
Financing Document.

                  (k)      to the extent received by the Mortgagor, it shall
                           forward to the Mortgagee all notices, reports,
                           accounts and other documents relating to the
                           Mortgaged Property or which are sent to the holders
                           of any of the Mortgaged Property as soon as they are
                           received;

                  (l)      no further shares or equity securities of any kind in
                           the Company (or any options or other rights with
                           respect thereto) will be issued and the authorized
                           shares shall at no time exceed the issued shares;

                  (m)      at any time after the service of an Enforcement
                           Notice, it shall exercise all voting and other rights
                           and powers which may at any time be exercisable by
                           the holder of the Mortgaged Property as the Mortgagee
                           may in its absolute discretion direct, it being
                           understood that the Mortgagee has reserved the right
                           to exercise all such voting rights directly for any
                           proper purpose, including without limitation the
                           immediate removal of Directors of the Company and
                           their replacement;

                  (n)      the Mortgagor shall not take or accept any Security
                           Interest from the Company or, in relation to the
                           Secured Amounts, from any third party, without first
                           obtaining the Mortgagee's written consent or permit
                           any Security Interest to be granted by the Company to
                           any third party, except as may be expressly permitted
                           by the Financing Documents;

                  (o)      the Mortgagor shall not prove in a liquidation or
                           winding up of the Company in competition with the
                           Mortgagee for any amount whatsoever owing to the
                           Mortgagee by the Mortgagor on any account whatsoever;
                           and

                  (p)      the Mortgagor shall not claim payment whether
                           directly or by set-off, lien, counterclaim or
                           otherwise of any amount which may be or has become
                           due to the Mortgagor by the Company.

5.       POWER OF ATTORNEY

         5.1      The Mortgagor hereby irrevocably and by way of security for
                  the payment by it of the Secured Amounts and the performance
                  of its obligations under this Deed of Mortgage appoints the
                  Mortgagee as its true and lawful attorney (with full power to
                  appoint substitutes and to subdelegate) on behalf of the
                  Mortgagor and in the Mortgagor's own name or otherwise, at any
                  time and from time to time, to sign, seal, deliver and
                  complete all transfers, renunciations, proxies, mandates,
                  assignments, deeds and documents and do all acts and things
                  which the Mortgagee may, in its sole and absolute discretion,
                  consider to be necessary or





                                       10
<PAGE>   48

                  advisable to perfect or improve its security over the
                  Mortgaged Property or to give proper effect to the intent and
                  purposes of this Deed of Mortgage or, after delivery of an
                  Enforcement Notice to enable or assist in any way in the
                  exercise of any power of sale of the Mortgaged Property
                  (whether arising under this Deed of Mortgage or implied by
                  statute or otherwise).

6.       ENFORCEMENT

         6.1      The Mortgagee may at any time after the occurrence of an event
                  of Default (as defined in the Note Purchase and Loan
                  Agreement) which has not been timely cured but including,
                  without limitation, the breach of any representation, warranty
                  or covenant contained in this Deed of Mortgage and the other
                  Financing Documents) serve an Enforcement Notice on the
                  Mortgagor. Unless and until the Mortgagee shall have served an
                  Enforcement Notice, but not thereafter:

                  (a)      Mortgagee agrees to the fullest extent permitted by
                           applicable law that the Mortgagor has the right to
                           receive payments distributed in respect of the
                           Original Securities and all other securities which
                           may from time to time at any time be derived from the
                           Original Securities; and

                  (b)      Appoints Mortgagor as Mortgagee's agent and proxy to
                           vote all of the securities described in clause (a)
                           above and exercise all rights and privileges
                           attributable to such securities as permitted under
                           applicable law. Prior to default, if the Mortgagee
                           shall receive any dividend or money described in
                           clause (a) above, the Mortgagee shall receive the
                           same as agent for Mortgagor and upon receipt shall
                           promptly pay or remit the same, without reduction, to
                           Mortgagor. At the request of Mortgagor, Mortgagee
                           shall give such reasonable assurances, confirmations
                           and advice to any third party as may be necessary for
                           Mortgagor to enjoy the full benefit of the rights and
                           privileges described in clauses (a) and (b) above

         6.2      If the Mortgagee shall serve an Enforcement Notice, the
                  Mortgagee shall, without prejudice to any other right or
                  remedy available hereunder or under applicable law, forthwith
                  become entitled:

                  (a)      solely and exclusively to exercise all voting rights
                           attaching to the Mortgaged Property or any thereof
                           and shall exercise such rights in such manner as the
                           Mortgagee may in its absolute discretion determine;
                           and/or

                  (b)      solely and exclusively to exercise any and all other
                           rights and/or powers and/or discretions of the
                           Mortgagor in, to and under the Mortgaged Property
                           pursuant to the constitutional documents of the
                           Company; and/or

                  (c)      to receive and retain all dividends and other
                           distributions made on or in respect of the Mortgaged
                           Property or any thereof and any such dividends and
                           other distributions received by the Mortgagor after
                           such time shall be






                                       11
<PAGE>   49

                           held in trust by the Mortgagor for the Mortgagee and
                           be paid or transferred to the Mortgagee on demand;
                           and/or

                  (d)      without notice to, or further consent or concurrence
                           by, the Mortgagor to sell the Mortgaged Property or
                           any part thereof by such method, at such place and
                           upon such terms as the Mortgagee may in its absolute
                           discretion determine, with power to postpone any such
                           sale and in any such case the Mortgagee may exercise
                           any and all rights attaching to the Mortgaged
                           Property as the Mortgagee in its discretion may
                           determine and without being answerable for any loss
                           occasioned by such sale or resulting from
                           postponement thereof or the exercise of such rights;
                           upon any sale of the Mortgaged Property or any part
                           thereof the purchaser thereof shall not be bound to
                           see or enquire whether the power of sale of the
                           Mortgagee has arisen in the manner herein provided
                           and the sale shall be deemed to be within the power
                           of the Mortgagee and the receipt of the Mortgagee for
                           the purchase money shall effectively discharge the
                           purchaser of the Mortgaged Property, or any part
                           thereof, who shall not be concerned or be in any way
                           answerable therefor; and/or

                  (e)      to appoint a receiver in respect of the Mortgaged
                           Property and the provisions of Clause 7 shall apply
                           thereto.

         6.3      The Mortgagee shall not be liable for any loss or damage
                  occasioned by any sale or disposal of the Mortgaged Property
                  (or interest therein) or arising out of the exercise of or
                  failure to exercise any of its powers under this Deed of
                  Mortgage or for any neglect or default to pay any instalment
                  or accept any offer or notify the Mortgagor of any such matter
                  or for any other loss of any nature whatsoever in connection
                  with the Mortgaged Property.

7.       MORTGAGEE'S RIGHTS AS TO MORTGAGED PROPERTY

         If the Mortgagee shall serve an Enforcement Notice, the Mortgagee
         shall, without prejudice to any other right or remedy available
         hereunder or under applicable law, forthwith become entitled:

         7.1      solely and exclusively to exercise all voting rights attaching
                  to the Mortgaged Property or any thereof and shall exercise
                  such rights in such manner as the Mortgagee may in its
                  absolute discretion determine; and/or

         7.2      solely and exclusively to exercise all other rights and/or
                  powers and/or discretions of the Mortgagor in, to and under
                  the Mortgaged Property pursuant to the memorandum and articles
                  of association of the Company; and/or

         7.3      to receive and retain all dividends and other distributions
                  made on or in respect of the Mortgaged Property or any thereof
                  and any such dividends and other distributions received by the
                  Mortgagor after such time shall be held in trust by the
                  Mortgagor for the Mortgagee and be paid or transferred to the
                  Mortgagee on demand to be applied towards the discharge of the
                  Secured Obligations; and/or






                                       12
<PAGE>   50

         7.4      without notice to, or further consent or concurrence by, the
                  Mortgagor to sell or otherwise dispose of the Mortgaged
                  Property or any part thereof by such method, at such place and
                  upon such terms as the Mortgagee may in its absolute
                  discretion determine, with power to postpone any such sale and
                  in any such case the Mortgagee may exercise any and all rights
                  attaching to the Mortgaged Property as the Mortgagee in its
                  absolute discretion may determine and without being answerable
                  for any loss occasioned by such sale or resulting from
                  postponement thereof or the exercise of such rights; and/or

         7.5      to date and deliver the documents delivered to it pursuant to
                  this Mortgage as it considers appropriate and to take all
                  steps not already taken to register the Mortgaged Property in
                  the name of the Mortgagee or its nominee or nominees as
                  Collateral Agent and to assume control as registered owner of
                  the Mortgaged Property.

8.       OTHER SECURITY

         8.1      This security is in addition to and shall not affect or be
                  merged in any bills, notes, guarantees, indemnities,
                  undertakings, Security Interests, or other security whatsoever
                  which the Mortgagee may hold now or hereafter in connection
                  with the Financing Documents or the obligations of any other
                  person liable for any of the Secured Amounts.

9.       FURTHER PROVISIONS

         9.1      (a)      This security is in addition to, and shall
                           neither be merged in, nor in any way exclude or
                           prejudice, any other Security Interest or right of
                           recourse or other right whatsoever which the
                           Mortgagee may now or at any time hereafter hold or
                           have (or would apart from this security hold or have)
                           as regards the Mortgagor or any other, person in
                           respect of the Secured Amounts.

                  (b)      The powers which this Deed of Mortgage confer on the
                           Mortgagee are cumulative, without prejudice to its
                           powers under the general law, and may be exercised as
                           often as the Mortgagee thinks appropriate; the
                           Mortgagee may, in connection with the exercise of its
                           powers, join or concur with any person in any
                           transaction, scheme or arrangement whatsoever; and
                           the Mortgagor acknowledges that the respective powers
                           of the Mortgagee shall in no circumstances whatsoever
                           be suspended, waived or otherwise prejudiced by
                           anything other than an express waiver or variation in
                           writing.

                  (c)      The rights of the Mortgagee in relation to the
                           Mortgaged Property and the recovery of the Secured
                           Amounts (whether arising under this Deed of Mortgage,
                           the other Financing Documents or under the general
                           law) shall not be capable of being waived or varied
                           otherwise than by an express waiver or variation in
                           writing; and in particular any failure to exercise or




                                       13
<PAGE>   51

                           any delay in exercising any of such rights shall not
                           operate as a waiver or variation of that or any other
                           such right; any defective or partial exercise of any
                           such right shall not preclude any other or further
                           exercise of that or any other such right; and no act
                           or course of conduct or negotiation on its part or on
                           its behalf shall in any way preclude it from
                           exercising any such right or constitute a suspension
                           or any variation of any such right.

                  (d)      If any of the provisions of this Deed of Mortgage
                           becomes invalid, illegal or unenforceable in any
                           respect under any law, the validity, legality and
                           enforceability of the remaining provisions shall not
                           in any way be affected or impaired.

                  (e)      In any proceedings relating to this Deed of Mortgage
                           a statement as to any amount due to the Mortgagee or
                           the Trustee under the Financing Documents which is
                           certified as being correct by an officer or agent of
                           the Mortgagee shall, save in the case of manifest
                           error, be conclusive evidence that such amount is in
                           fact due and payable.

         9.2      Assignment

                  9.2.1    This Deed of Mortgage shall be binding upon and inure
                           to the benefit of each party hereto and its
                           successors in title and permitted assigns.

                  9.2.2    The Mortgagor shall not be entitled to assign or
                           transfer any of its rights, benefits or obligations
                           hereunder without the prior written consent of the
                           Mortgagee.

                  9.2.3    The Mortgagee may assign or transfer all or any part
                           of its rights, benefits or obligations under this
                           Deed of Mortgage to any other person which is its
                           successor under the Financing Documents. Where the
                           Mortgagee assigns or transfers its obligations or any
                           part thereof, the Mortgagor shall execute such
                           documents as the Mortgagee may specify to release the
                           Mortgagee to the extent of the assignment or transfer
                           or with a view to perfecting such assignment or
                           transfer, or where necessary, shall execute further
                           security documentation in favour of the assignee or
                           transferee in like form to this Deed of Mortgage.

         9.3      Release of Security

                  Upon final and unconditional repayment of the Secured Amounts
                  in full and provided that no event of Default has occurred,
                  the Mortgagee shall promptly assign the Mortgaged Property to
                  the Mortgagor free of all Security Interests, encumbrances,
                  trusts, equities and claims whatsoever imposed by the
                  Mortgagee and the Mortgagee shall forthwith sign, seal,
                  deliver and complete all transfers, renunciations, proxies,
                  mandates, assignments, deeds and documents and do all acts and
                  things which the Mortgagor may reasonably specify to vest all
                  of the Mortgaged Property in the name of the Mortgagor or its
                  nominee.






                                       14
<PAGE>   52

         9.4      This Deed of Mortgage is governed by, and shall be construed
                  in accordance with, the laws of the Cayman Islands.

         9.5      (a)      The parties agree that the courts of the Cayman
                           Islands are to have exclusive jurisdiction to settle
                           any disputes which may arise in connection with the
                           legal relationships established by this Deed of
                           Mortgage (including, without limitation, claims for
                           set-off or counterclaim) or otherwise arising in
                           connection with this Deed of Mortgage.

                  (b)      The parties irrevocably waive any objections on the
                           grounds of venue of forum non conveniens or any
                           similar grounds.

                  The parties irrevocably consent to service of process by mail
                  or in any other manner permitted by the relevant law.

10.      NOTICES, ENGLISH LANGUAGE

                  (a)      Each notice or other communication to be given or
                           made hereunder shall be in the English language and
                           shall, unless otherwise stated be made in writing as
                           provided below.

                  Any notice or other communication or document to be made or
                  delivered by one person to another pursuant to this Deed of
                  Mortgage shall (unless that other person has by fifteen days'
                  written notice to the other specified another address and/or
                  fax or telex number) be made or delivered to that other person
                  at the following address, fax or telex number:

                           The Mortgagor:

                           SEVEN SEAS PETROLEUM INC.
                           5555 San Felipe, Suite 1700
                           Houston, Texas 77056
                           Attention: Larry A. Ray
                           Fax No. (713) 621-9770


                           The Mortgagee:

                           CHESAPEAKE ENERGY CORPORATION
                           6100 North Western Avenue
                           Oklahoma City, Oklahoma 73118
                           Attention: M. Rowland
                           Fax No. (405) 879-9580


                  and shall be deemed to have been made or delivered when such
                  communication or document has been dispatched and the
                  appropriate answer back received (in the






                                       15
<PAGE>   53

                  case of any communication made by telex) or sent by fax to the
                  fax number of the party set out herein and when receipt is
                  confirmed by facsimile or telephone (in the case of any
                  communication by fax) or (in the case of any communication
                  made by letter) when left at that address or, as the case may
                  be, three days after being deposited in the post first class
                  postage prepaid in an envelope addressed to it at that
                  address; Provided that any communication or document to be
                  made or delivered to the Mortgagee shall be effective only
                  when received by the Mortgagee.

11.      COUNTERPARTS

This Deed of Mortgage may be executed in any number of counterparts and all such
counterparts taken together shall be deemed to constitute one and the same
instrument.

IN WITNESS WHEREOF this Deed of Mortgage has been executed and delivered as a
Deed the day and year first above written.

EXECUTED AS A DEED by                       )
the duly authorised representative          )/s/ LARRY A. RAY
of SEVEN SEAS PETROLEUM INC.,               )
in the presence of:                         )

EXECUTED AS A DEED by                       )
the duly authorised representative          )
of CHESAPEAKE ENERGY CORPORATION            )/s/ TOM L. WARD
as Collateral Agent                         )
in the presence of:                         )



                                       16
<PAGE>   54




                                   SCHEDULE 1

                               ORIGINAL SECURITIES


Company: Seven Seas Petroleum Colombia Inc., a Cayman Islands company with its
registered office at: Caribbean Management Ltd., P.O. Box 1044, 3rd Floor, West
Wind Building, George Town, Grand Cayman, Cayman Islands.




<Table>
<Caption>
Amount or number of
Original Securities                                  Description of Original Securities
-------------------                                  ----------------------------------

<S>                                                  <C>
1                                                    Shares of US$1.00 par value
</Table>


<PAGE>   55



                                  July 23, 2001





                            SEVEN SEAS PETROLEUM INC
                                 (as Mortgagor)


                          CHESAPEAKE ENERGY CORPORATION
                                 (as Mortgagee)




                 -----------------------------------------------
                           LEGAL MORTGAGE OVER SHARES






<PAGE>   56





THIS DEED OF MORTGAGE ("Deed of Mortgage") is made as of July 23, 2001

BETWEEN

(1)      SEVEN SEAS PETROLEUM INC., a Cayman Islands exempted company limited by
         shares, the registered office of which is at Walker House, Mary Street,
         George Town, Grand Cayman, Cayman Islands (the "Mortgagor"); and

(2)      CHESAPEAKE ENERGY CORPORATION, an Oklahoma corporation, whose principal
         place of business is at 6100 North Western Avenue, Oklahoma City,
         Oklahoma, 73118 (the "Mortgagee") as Collateral Agent under the
         Collateral Sharing Agreement (as hereinafter defined) for itself and
         United States Trust Company of New York, ("Trustee") under that certain
         Indenture dated July 23, 2001 (the "Indenture"), pursuant to which the
         Trustee is trustee for the holders of the Mortgagor's 12% Senior
         Secured Series A Notes (the "Series A Notes") and the Mortgagor's 12%
         Senior Secured Series B Notes (the "Series B Notes").

WHEREAS

(A)      Pursuant to a Note Purchase and Loan Agreement dated as of July 9, 2001
         (the "Note Purchase and Loan Agreement") the Mortgagee agreed to
         advance to the Mortgagor the sum of Twenty-two Million Five Hundred
         Thousand United States Dollars (US$22,500,000.00), evidenced by a 12%
         Senior Secured Note due 2004 in the principal amount of TWENTY-TWO
         MILLION FIVE HUNDRED THOUSAND DOLLARS ($22,500,000.00) (the "CEC Note")
         subject to the terms and conditions stated in: (a) the Note Purchase
         and Loan Agreement; (b) the CEC Note; (c) the detachable Warrants to
         purchase twelve million six hundred twelve thousand one hundred forty
         (12,612,140) shares of the Mortgagor's ordinary shares (the
         "Warrants"); (d) the Shareholder's Rights Agreement dated July 23, 2001
         between the Mortgagor and the Mortgagee (the "Shareholder's
         Agreement"); (e) the Registration Rights Agreement dated July 23, 2001
         between the Mortgagor and the Mortgagee (the "Registration Agreement");
         (f) the Security Agreement dated July 23, 2001 between the Mortgagor
         and the Mortgagee as Collateral Agent for itself and the Trustee (the
         "Security Agreement"); (g) certain other Deeds of Mortgage Over Shares
         of the subsidiaries of the Mortgagor other than the Companies (as
         hereinafter defined) dated July 23, 2001 (the "Other Deeds of
         Mortgage"); (h) the Collateral Sharing and Agency Agreement dated as of
         July 23, 2001 between the Mortgagee and the Trustee pursuant to which
         the Mortgagee agrees to act as collateral agent for itself and the
         Trustee (the "Collateral Sharing Agreement"); and (i) any and all other
         documents and instruments executed and delivered in connection with the
         Note Purchase and Loan Agreement, the Indenture and any of the other
         documents executed in connection with the Note Purchase and Loan
         Agreement or the Indenture.

Upon satisfaction of certain conditions set forth in the Note Purchase and Loan
     Agreement, the CEC Note, the Warrants, and the other Related Agreements,
     the CEC Note issued under the Note Purchase and Loan Agreement may be
     exchanged by the Mortgagee in part for ordinary shares of the Mortgagor.


<PAGE>   57


The Note Purchase and Loan Agreement was executed on the agreement that the
     Mortgagor shall enter into this mortgage over shares in the capital of GHK
     Company Colombia, an Oklahoma corporation and Seven Seas Petroleum USA
     Inc., a Delaware corporation.

The Mortgagor has agreed to secure the Secured Amounts (as defined below) by
     entering into this Deed of Mortgage, as well as the other Financing
     Documents (as defined below).

IT IS AGREED as follows

1.       INTERPRETATION

         1.1      Except where the context otherwise requires, words and
                  expressions defined in the Note Purchase and Loan Agreement or
                  the recitals above shall have the same meaning where used
                  herein and the further words and expressions set out below
                  shall have the following meanings;

                  ACTIVE SUBSIDIARIES means Seven Seas Petroleum USA Inc., a
                  Delaware corporation, Seven Seas Petroleum Colombia Inc., a
                  Cayman Islands company, Petrolinson SA, a Panamanian
                  corporation, and GHK Company Colombia, an Oklahoma
                  corporation.

                  COLLATERAL AGENT means the Mortgagee as collateral agent under
                  the certain Collateral Sharing Agreement;

                  COMPANIES means the companies specified in Schedule 1;

                  ENFORCEMENT NOTICE means an enforcement notice served by the
                  Mortgagee on the Mortgagor pursuant to the terms of this Deed
                  of Mortgage;

                  FINANCING DOCUMENTS means the Note Purchase and Loan
                  Agreement, the Indenture, the CEC Note, the Series A Notes,
                  the Series B Notes, the Security Agreement, the Other Deeds of
                  Mortgage, this Deed of Mortgage, the Related Agreements, the
                  Collateral Sharing Agreement and any and all other documents
                  and instruments executed and delivered in connection with the
                  Note Purchase and Loan Agreement or the Indenture.

                  INACTIVE SUBSIDIARIES means Seven Seas Petroleum Holdings
                  Inc., a Cayman Islands company, Seven Seas Petroleum Turkey
                  Inc., a British Colombia corporation, Seven Seas Resources
                  Australia Inc., a British Colombia corporation, Seven Seas
                  Petroleum Australia Inc., a Cayman Islands company, Seven Seas
                  Petroleum PNG Inc., a Cayman Islands company, Seven Seas
                  Petroleum Argentina, a Cayman Islands company, Seven Seas
                  Mediterranean Inc., a Cayman Islands company, Seven Seas
                  Petroleum Turkey Inc., a Cayman Islands company, and Guaduas
                  Pipeline Company, a Cayman Islands company.


<PAGE>   58


                  INDENTURE means the Indenture for the Series A Notes and the
                  Series B Notes as referred to in paragraph (2) above.

                  MORTGAGED PROPERTY means the Original Securities and all and
                  any other shares, securities, rights, moneys and property for
                  the time being mortgaged or charged to the Mortgagee pursuant
                  to Clause 2;

                  NOTE PURCHASE AND LOAN AGREEMENT means the facility referred
                  to in recital A;

                  ORIGINAL SECURITIES means the securities listed in Schedule 1
                  which are all registered in the name of the Mortgagor and
                  following execution of this Deed of Mortgage will be
                  transferred into the name of the Mortgagee or its nominee as
                  Collateral Agent;

                  OTHER DEEDS OF MORTGAGE means each Legal Mortgage Over Shares
                  between Mortgagor and Mortgagee delivered concurrently
                  herewith or hereafter delivered;

                  RELATED AGREEMENTS means the Warrants, the warrants granted to
                  the holders of the Series A Notes, the Shareholder's
                  Agreement, the Registration Agreement and any other documents
                  or instruments executed in connection with any of the
                  foregoing;

                  SECURED AMOUNTS means all and any amounts of any kind now or
                  in the future, actual or contingent, due and payable by the
                  Mortgagor to the Mortgagee under the CEC Note or to the
                  Trustee for the benefit of the holders of the Series A Notes
                  or the Series B Notes or under or in connection with this Deed
                  of Mortgage or the other Financing Documents and references to
                  the Secured Amounts include references to any part of them;
                  and

                  SECURITY INTEREST means any mortgage, charge, pledge, lien,
                  encumbrance, right of set off or any security interest,
                  howsoever created or arising.

         1.2      In this Deed of Mortgage:

                  (a)      references to the Mortgagor or the Mortgagee include
                           references to any person for the time being deriving
                           title under each of them respectively;

                  (b)      references to this Deed of Mortgage and the Financing
                           Documents are references to the same as from time to
                           time varied, supplemented or amended in any manner or
                           respect whatsoever;

                  (c)      references to the Original Securities or to the
                           Mortgaged Property include references to any property
                           included in such term;

                  (d)      "mortgage" includes a transfer or assignment by way
                           of mortgage;

                  (e)      Unless the context otherwise indicates, words
                           importing the singular shall include the plural and
                           vice versa, and the use of the neuter, masculine, or


<PAGE>   59


                           feminine gender is for convenience only and shall be
                           deemed to mean and include the neuter, masculine or
                           feminine gender; and

                  (f)      Clause headings are for ease of reference only.

2.       COVENANT TO PAY SECURED AMOUNTS AND CHARGE

         2.1      The Mortgagor covenants with the Mortgagee for the benefit of
                  the Mortgagee and the Trustee that it shall, whether or not
                  the Mortgagor shall have received an Enforcement Notice in
                  accordance with this Deed of Mortgage or notice of demand in
                  respect of the Secured Amounts, pay and discharge any moneys
                  and liabilities in respect of the Secured Amounts whatsoever
                  which are now or at any time hereafter may be due, owing or
                  payable by the Mortgagor in any currency, actually or
                  contingently, solely and/or jointly and/or severally with
                  another or others, as principal or surety on any account
                  whatsoever pursuant to this Deed of Mortgage or the other
                  Financing Documents or as a consequence of any breach,
                  non-performance, disclaimer or repudiation by the Mortgagor of
                  any of its obligations, covenants, representations or
                  warranties under this Deed of Mortgage, the other Financing
                  Documents or otherwise.

         2.2      The Mortgagor hereby transfers absolutely by way of mortgage
                  to the Mortgagee as a continuing security for the payment and
                  discharge of the Secured Amounts, all its rights, title,
                  interest and benefit, present and future in, to and under:

                  (a)      the Original Securities; and

                  (b)      all other securities and all rights, monies
                           (including, without limitation, dividends) and
                           property whatsoever which may from time to time at
                           any time be derived from, accrued on or be offered in
                           respect of the Original Shares whether by way of
                           redemption, exchange, conversion, rights, bonus,
                           capital reorganisation or otherwise howsoever.

3.       CONTINUING AND PRIMARY SECURITY

         3.1      This Deed of Mortgage shall be a continuing security, and
                  shall be in addition to and shall not affect any continuing
                  liens or other Security Interests to which the Mortgagee is or
                  will be otherwise entitled over the Mortgaged Property, which
                  liens and other Security Interests shall remain in force
                  independently of this Deed of Mortgage.

         3.2      The Original Securities and other Mortgaged Property are
                  hereby mortgaged to the Mortgagee as primary and not as
                  collateral security.

         3.3      The Mortgagor's liability hereunder shall not be discharged or
                  impaired by:

                  (a)      the existence or validity of any other security taken
                           by the Mortgagee in relation to the Financing
                           Documents or any enforcement of or failure to enforce
                           or the release of any such security;


<PAGE>   60


                  (b)      any amendment to or variation of the Financing
                           Documents or any security relating to the Financing
                           Documents or any assignment thereof or hereof;

                  (c)      any release of or granting of time or any other
                           indulgence to the Mortgagor or any third party;

                  (d)      any invalidity, irregularity, unenforceability,
                           imperfection or avoidance of or any defect in any
                           security granted by, or any obligations of, the
                           Mortgagor or any other person hereunder or under the
                           Financing Documents or any amendment to or variation
                           thereof or of any other document or security
                           comprised therein;

                  (e)      the insolvency, liquidation, bankruptcy or
                           dissolution (or proceedings analogous thereto) of the
                           Mortgagor, the Companies or any other person or the
                           appointment of a receiver or administrative receiver
                           or administrator (whether by administration order or
                           otherwise) or trustee or similar officer of any of
                           the assets of the Mortgagor, the Companies or any
                           other person or the occurrence of any circumstances
                           whatsoever affecting the Mortgagor, or any other
                           person's liability to discharge its obligations under
                           the Financing Documents;

                  (f)      any release, renewal, exchange or realisation of any
                           security or obligation provided under or by virtue of
                           this Deed of Mortgage or the other Financing
                           Documents or the provision of any further security to
                           the Mortgagee at any other time; or

                  (g)      any other act, event, neglect or omission which would
                           or might but for this clause operate to impair or
                           discharge the Mortgagor's liability hereunder.

         3.4      Any release, compromise or discharge of the obligations of the
                  Mortgagor shall be deemed to be made subject to the condition
                  that it will be void if any payment or security which the
                  Mortgagee may receive or have received is set aside or proves
                  invalid for whatever reason.

         3.5      Rights may be exercised and demands may be made under this
                  Deed of Mortgage from time to time, and the liabilities and
                  obligations of the Mortgagor and the rights and security or
                  other consideration contained in this Deed of Mortgage may be
                  exercised and enforced, irrespective of

                  (a)      whether any demands, steps or proceedings are being
                           or have been taken against the Mortgagor or any third
                           party; or

                  (b)      whether or in what order any security to which the
                           Mortgagee may be entitled in respect of the Secured
                           Amounts is enforced.


<PAGE>   61

4.       WARRANTIES AND UNDERTAKING

         4.1      The Mortgagor represents and warrants to the Mortgagee and
                  undertakes that:

                  (a)      it is the absolute legal and beneficial owner of all
                           of the Original Securities free of all Security
                           Interests, encumbrances, trusts, equities, proxies
                           and claims whatsoever (save under this Deed of
                           Mortgage or the other Financing Documents) and that
                           all of the Original Securities are fully paid up and
                           are non-assessable;

                  (b)      except as limited by the Financing Documents,
                           Mortgagor has the full legal and unlimited right to
                           vote the Original Securities in its sole discretion;

                  (c)      the Original Securities of each of the Companies
                           constitute 100% of the issued and outstanding equity
                           capital of each of the Companies and are all
                           currently registered in the name of the Mortgagor
                           (subject to the registration of the Original
                           Securities in the name of the Mortgagee as Collateral
                           Agent concurrently with the execution and delivery of
                           this Deed of Mortgage);

                  (d)      each of the Mortgagor and the Companies are duly
                           incorporated and in good standing under the
                           respective laws of the jurisdiction in which each of
                           them is incorporated and the Mortgagor has and will
                           at all times have the necessary power to enter into
                           and perform its obligations under this Deed of
                           Mortgage and has duly authorized the execution and
                           delivery of this Deed of Mortgage;

                  (e)      neither this Deed of Mortgage or the transfer of the
                           Original Securities to the Mortgagee is subject to
                           any stamp or other tax under the laws of the State of
                           Oklahoma, the State of Delaware or the Cayman
                           Islands, as the case may be, and this Deed of
                           Mortgage is capable of being enforced without being
                           subject to any stamp or other tax under the laws of
                           the State of Oklahoma, the State of Delaware or the
                           Cayman Islands;

                  (f)      pursuant to amendments to the articles of
                           incorporation of each of the Companies within 45 days
                           after the date of this Agreement, the Companies will
                           not be permitted to issue any equity capital other
                           than the Original Securities;

                  (g)      the Companies have no contractual or other business
                           relationship with any Inactive Subsidiary;

                  (h)      No Inactive Subsidiary has any operations, assets or
                           liabilities, direct, indirect or contingent;

                  (i)      the Mortgagor holds no rights or Security Interests
                           with respect to present or future revenues and
                           assets, tangible or intangible, relating to the


<PAGE>   62


                           exploration, development, production, transportation
                           and sale of petroleum in and from the Republic of
                           Colombia, directly, by assignment, or otherwise,
                           except as a shareholder of companies whose shares are
                           pledged to Mortgagee pursuant to the Financing
                           Documents;

                  (j)      this Deed of Mortgage constitutes its legal, valid,
                           binding and enforceable obligation and is a first
                           priority security interest over the Mortgaged Shares
                           effective in accordance with its terms;

                  (k)      the execution, delivery, observance and performance
                           by the Mortgagor of this Deed of Mortgage will not
                           require the Mortgagor to obtain any licenses,
                           consents or approvals and will not result in any
                           violation to the best of the Mortgagor's knowledge,
                           of any law, statute, ordinance, rule or regulation
                           applicable to it or any other agreements;

                  (l)      the Companies are not a party or otherwise bound to
                           any employment, management or other agreement, the
                           effect of which would be to limit the ability of the
                           Mortgagee to manage the Companies upon an event of
                           Default under the Financing Documents or give rise to
                           any payment or penalty to terminate any such
                           arrangement;

                  (m)      it has obtained all the necessary authorizations and
                           consents to enable it to enter into this Mortgage and
                           the necessary authorizations and consents will remain
                           in full force and effect at all times during the
                           existence of the security constituted by this Deed of
                           Mortgage;

                  (n)      the execution, delivery, observance and performance
                           by the Mortgagor of the Deed of Mortgage will not
                           constitute an event of default or trigger any
                           enforcement under any Security Interest in the
                           Mortgagor's assets nor will it result in the creation
                           of any Security Interest over or in respect of the
                           present or future assets of the Companies;

                  (o)      the Mortgagor has fully disclosed in writing to the
                           Mortgagee all facts relating to the Mortgagor and the
                           Companies which the Mortgagor knows or should
                           reasonably know and which are material for disclosure
                           to the Mortgagee in the context of the Financing
                           Documents; and

                  (p)      no agreement to which the Mortgagor or the Companies
                           or its Colombian branch, as the case may be, is a
                           party, or law, decree or regulation to which either
                           is subject, including without limitation any
                           agreement with Empresa Colombiana de Petroleos or
                           imposition by the Ministro de Minas y Energia de
                           Colombia or any other instrumentality of the Republic
                           of Colombia requires the consent of any such person
                           to the execution, delivery or performance of this
                           Deed of Mortgage and the other Financing Documents
                           and each obligation and covenant contained herein and
                           therein.

<PAGE>   63


4.2      The Mortgagor undertakes that, for so long as any Secured Amounts
         remain outstanding:

         (a)      the Mortgagor shall pay to the Mortgagee, upon demand, the
                  amount of all reasonable expenses which the Mortgagee may
                  incur in, about or with a view to perfecting or enforcing this
                  security or otherwise in connection with this security;

         (b)      the Mortgagor shall promptly pay (and shall indemnify the
                  Mortgagee on demand against) all calls, installments and other
                  payments which may be made or become due in respect of the
                  Mortgaged Property and so that, in the event of default by the
                  Mortgagor, the Mortgagee may do so on behalf of the Mortgagor
                  and clause 4.2(a) shall apply accordingly;

         (c)      to the extent any Mortgaged Property is at any time not vested
                  in the Mortgagee or its nominee as Collateral Agent the
                  Mortgagor shall forthwith and from time to time deposit with
                  the Mortgagee all certificates and other documents of title
                  relating to the Mortgaged Property and signed share transfer
                  forms;

         (d)      the Mortgagor will maintain the Companies in good standing
                  under the laws of their respective jurisdictions and will not
                  do anything that would cause the completion of transactions or
                  enforcement actions contemplated hereunder to incur any stamp
                  or other tax under the laws of the Cayman Islands, the State
                  of Oklahoma or the State of Delaware;

         (e)      the Mortgagor will not permit the Company to enter into or
                  become bound by any employment, management or other agreement,
                  the effect of which would be to limit the ability of the
                  Mortgagee to manage the Company upon an event of Default under
                  the Financing Documents or give rise to any payment or penalty
                  to terminate any such arrangement;

         (f)      the Mortgagor will not permit any Inactive Subsidiary to
                  conduct operations or own any asset or incur any liability,
                  direct, indirect or contingent;

         (g)      Mortgagor will not permit the Company to engage in any
                  transaction, contractual or otherwise, with any affiliate of
                  Mortgagor except with Mortgagor and Active Subsidiaries and as
                  may otherwise be permitted by the Financing Documents;
                  provided however, that in no event shall the Company engage in
                  any transaction, contractual or otherwise, with an Inactive
                  Subsidiary;

         (h)      the Mortgagor shall deliver to the Mortgagee undated letters
                  of resignation executed by all persons now or hereafter
                  serving as Directors of the Companies from time to time, which
                  letters the Mortgagee shall be entitled to date and cause to
                  be given immediate effect as of the date of an Enforcement
                  Notice;


<PAGE>   64


         (i)      the Mortgagor shall forthwith sign, seal, deliver and complete
                  all transfers, renunciations, proxies (including irrevocable
                  proxies if the Mortgagee so requests) mandates, assignments,
                  deeds and documents and do all acts and things which the
                  Mortgagee may, in its absolute discretion, at any time and
                  from time to time specify for enabling or assisting the
                  Mortgagee:

(i) to perfect or improve its title to and security over the Mortgaged Property
including, without limitation, obtaining such approvals or consents to the
rights and remedies granted to the Mortgagee herein as the Mortgagee requests in
the Mortgagee's sole discretion;

(ii) to vest the Mortgaged Property (including without limitation the
registration thereof in the applicable share registry) in the Mortgagee or its
nominee or nominees as Collateral Agent as of the date of execution of this Deed
of Mortgage;

(iii) to exercise (or enable its nominee or nominees to exercise) any rights or
powers attaching to the Mortgaged Property;

(iv) after the service of an Enforcement Notice to sell or dispose of the
Mortgaged Property; or

(v) otherwise to enforce any of the rights of the Mortgagee under or in
connection with this Deed of Mortgage;

         (j)      the Mortgagor shall not (without the written consent of the
                  Mortgagee):

(i) create or permit to exist over all or part of the Mortgaged Property (or any
interest therein) any Security Interest (other than created or expressly
permitted to be created under this Deed of Mortgage or under other Financing
Documents) whether ranking prior to, pari passu with or behind the security
contained in this Deed of Mortgage;

(ii) sell, transfer or otherwise dispose of the Mortgaged Property or any
interest therein or attempt or agree to so dispose;

(iii) permit any person other than the Mortgagee or its nominee to be registered
as or become the holder of the Mortgaged Property as Collateral Agent; or

(iv) vote in favour of a resolution or amend, modify or change the articles of
incorporation or bylaws of either of the Companies or authorize the issuance by
any of the Companies of any shares or any other equity security.

(v) except as otherwise permitted by the Financing Documents permit the
Companies to transfer, assign, dispose of or encumber any rights or interests of
the Companies, direct or indirect, with respect to petroleum exploration,
development, production, transportation, sale or other disposition or with
respect to any association or other contract under which the Companies have such
rights or interests;


<PAGE>   65


(vi) permit the Companies to grant any Security Interest in, or otherwise
encumber, any of its assets, tangible or intangible, except as may be expressly
permitted by the Financing Documents;

(vii) permit the Companies to make any distribution or payment to or for the
benefit of Mortgagor, whether directly or otherwise, if the effect of that
distribution or payment is to render the Companies insolvent or unable to pay
its obligations as they mature; or

(viii) take any other action that would have as its effect a breach of a
Financing Document.

                  (k)      to the extent received by the Mortgagor, it shall
                           forward to the Mortgagee all notices, reports,
                           accounts and other documents relating to the
                           Mortgaged Property or which are sent to the holders
                           of any of the Mortgaged Property as soon as they are
                           received;

                  (l)      no further shares or equity securities of any kind in
                           the Companies (or any options or other rights with
                           respect thereto) will be issued and the authorized
                           shares shall at no time exceed the issued shares;

                  (m)      at any time after the service of an Enforcement
                           Notice, it shall exercise all voting and other rights
                           and powers which may at any time be exercisable by
                           the holder of the Mortgaged Property as the Mortgagee
                           may in its absolute discretion direct, it being
                           understood that the Mortgagee has reserved the right
                           to exercise all such voting rights directly for any
                           proper purpose, including without limitation the
                           immediate removal of Directors of the Companies and
                           their replacement;

                  (n)      the Mortgagor shall not take or accept any Security
                           Interest from the Companies or, in relation to the
                           Secured Amounts, from any third party, without first
                           obtaining the Mortgagee's written consent or permit
                           any Security Interest to be granted by the Companies
                           to any third party, except as may be expressly
                           permitted by the Financing Documents;

                  (o)      the Mortgagor shall not prove in a liquidation or
                           winding up of the Companies in competition with the
                           Mortgagee for any amount whatsoever owing to the
                           Mortgagee by the Mortgagor on any account whatsoever;
                           and

                  (p)      the Mortgagor shall not claim payment whether
                           directly or by set-off, lien, counterclaim or
                           otherwise of any amount which may be or has become
                           due to the Mortgagor by the Companies.

5.       POWER OF ATTORNEY

         5.1      The Mortgagor hereby irrevocably and by way of security for
                  the payment by it of the Secured Amounts and the performance
                  of its obligations under this Deed of Mortgage appoints the
                  Mortgagee as its true and lawful attorney (with full power to
                  appoint substitutes and to subdelegate) on behalf of the
                  Mortgagor and in the


<PAGE>   66


                  Mortgagor's own name or otherwise, at any time and from time
                  to time, to sign, seal, deliver and complete all transfers,
                  renunciations, proxies, mandates, assignments, deeds and
                  documents and do all acts and things which the Mortgagee may,
                  in its sole and absolute discretion, consider to be necessary
                  or advisable to perfect or improve its security over the
                  Mortgaged Property or to give proper effect to the intent and
                  purposes of this Deed of Mortgage or, after delivery of an
                  Enforcement Notice to enable or assist in any way in the
                  exercise of any power of sale of the Mortgaged Property
                  (whether arising under this Deed of Mortgage or implied by
                  statute or otherwise).

6.       ENFORCEMENT

         6.1      The Mortgagee may at any time after the occurrence of an event
                  of Default (as defined in the Note Purchase and Loan
                  Agreement) which has not been timely cured but including,
                  without limitation, the breach of any representation, warranty
                  or covenant contained in this Deed of Mortgage and the other
                  Financing Documents) serve an Enforcement Notice on the
                  Mortgagor. Unless and until the Mortgagee shall have served an
                  Enforcement Notice, but not thereafter:

                  (a)      Mortgagee agrees to the fullest extent permitted by
                           applicable law that the Mortgagor has the right to
                           receive payments distributed in respect of the
                           Original Securities and all other securities which
                           may from time to time at any time be derived from the
                           Original Securities; and

                  (b)      Appoints Mortgagor as Mortgagee's agent and proxy to
                           vote all of the securities described in clause (a)
                           above and exercise all rights and privileges
                           attributable to such securities as permitted under
                           applicable law. Prior to default, if the Mortgagee
                           shall receive any dividend or money described in
                           clause (a) above, the Mortgagee shall receive the
                           same as agent for Mortgagor and upon receipt shall
                           promptly pay or remit the same, without reduction, to
                           Mortgagor. At the request of Mortgagor, Mortgagee
                           shall give such reasonable assurances, confirmations
                           and advice to any third party as may be necessary for
                           Mortgagor to enjoy the full benefit of the rights and
                           privileges described in clauses (a) and (b) above

         6.2      If the Mortgagee shall serve an Enforcement Notice, the
                  Mortgagee shall, without prejudice to any other right or
                  remedy available hereunder or under applicable law, forthwith
                  become entitled:

                  (a)      solely and exclusively to exercise all voting rights
                           attaching to the Mortgaged Property or any thereof
                           and shall exercise such rights in such manner as the
                           Mortgagee may in its absolute discretion determine;
                           and/or

                  (b)      solely and exclusively to exercise any and all other
                           rights and/or powers and/or discretions of the
                           Mortgagor in, to and under the Mortgaged Property
                           pursuant to the constitutional documents of the
                           Company; and/or


<PAGE>   67


                  (c)      to receive and retain all dividends and other
                           distributions made on or in respect of the Mortgaged
                           Property or any thereof and any such dividends and
                           other distributions received by the Mortgagor after
                           such time shall be held in trust by the Mortgagor for
                           the Mortgagee and be paid or transferred to the
                           Mortgagee on demand; and/or

                  (d)      without notice to, or further consent or concurrence
                           by, the Mortgagor to sell the Mortgaged Property or
                           any part thereof by such method, at such place and
                           upon such terms as the Mortgagee may in its absolute
                           discretion determine, with power to postpone any such
                           sale and in any such case the Mortgagee may exercise
                           any and all rights attaching to the Mortgaged
                           Property as the Mortgagee in its discretion may
                           determine and without being answerable for any loss
                           occasioned by such sale or resulting from
                           postponement thereof or the exercise of such rights;
                           upon any sale of the Mortgaged Property or any part
                           thereof the purchaser thereof shall not be bound to
                           see or enquire whether the power of sale of the
                           Mortgagee has arisen in the manner herein provided
                           and the sale shall be deemed to be within the power
                           of the Mortgagee and the receipt of the Mortgagee for
                           the purchase money shall effectively discharge the
                           purchaser of the Mortgaged Property, or any part
                           thereof, who shall not be concerned or be in any way
                           answerable therefor; and/or

                  (e)      to appoint a receiver in respect of the Mortgaged
                           Property and the provisions of Clause 7 shall apply
                           thereto.

         6.3      The Mortgagee shall not be liable for any loss or damage
                  occasioned by any sale or disposal of the Mortgaged Property
                  (or interest therein) or arising out of the exercise of or
                  failure to exercise any of its powers under this Deed of
                  Mortgage or for any neglect or default to pay any instalment
                  or accept any offer or notify the Mortgagor of any such matter
                  or for any other loss of any nature whatsoever in connection
                  with the Mortgaged Property.

7.       MORTGAGEE'S RIGHTS AS TO MORTGAGED PROPERTY

         If the Mortgagee shall serve an Enforcement Notice, the Mortgagee
         shall, without prejudice to any other right or remedy available
         hereunder or under applicable law, forthwith become entitled:

         7.1      solely and exclusively to exercise all voting rights attaching
                  to the Mortgaged Property or any thereof and shall exercise
                  such rights in such manner as the Mortgagee may in its
                  absolute discretion determine; and/or

         7.2      solely and exclusively to exercise all other rights and/or
                  powers and/or discretions of the Mortgagor in, to and under
                  the Mortgaged Property pursuant to the memorandum and articles
                  of association of the Company; and/or

         7.3      to receive and retain all dividends and other distributions
                  made on or in respect of the Mortgaged Property or any thereof
                  and any such dividends and other


<PAGE>   68


                  distributions received by the Mortgagor after such time shall
                  be held in trust by the Mortgagor for the Mortgagee and be
                  paid or transferred to the Mortgagee on demand to be applied
                  towards the discharge of the Secured Obligations; and/or

         7.4      without notice to, or further consent or concurrence by, the
                  Mortgagor to sell or otherwise dispose of the Mortgaged
                  Property or any part thereof by such method, at such place and
                  upon such terms as the Mortgagee may in its absolute
                  discretion determine, with power to postpone any such sale and
                  in any such case the Mortgagee may exercise any and all rights
                  attaching to the Mortgaged Property as the Mortgagee in its
                  absolute discretion may determine and without being answerable
                  for any loss occasioned by such sale or resulting from
                  postponement thereof or the exercise of such rights; and/or

         7.5      to date and deliver the documents delivered to it pursuant to
                  this Mortgage as it considers appropriate and to take all
                  steps not already taken to register the Mortgaged Property in
                  the name of the Mortgagee or its nominee or nominees as
                  Collateral Agent and to assume control as registered owner of
                  the Mortgaged Property.

8.       OTHER SECURITY

         8.1      This security is in addition to and shall not affect or be
                  merged in any bills, notes, guarantees, indemnities,
                  undertakings, Security Interests, or other security whatsoever
                  which the Mortgagee may hold now or hereafter in connection
                  with the Financing Documents or the obligations of any other
                  person liable for any of the Secured Amounts.

9.       FURTHER PROVISIONS

         9.1  (a) This security is in addition to, and shall neither be merged
                  in, nor in any way exclude or prejudice, any other Security
                  Interest or right of recourse or other right whatsoever which
                  the Mortgagee may now or at any time hereafter hold or have
                  (or would apart from this security hold or have) as regards
                  the Mortgagor or any other, person in respect of the Secured
                  Amounts.

              (b) The powers which this Deed of Mortgage confer on the Mortgagee
                  are cumulative, without prejudice to its powers under the
                  general law, and may be exercised as often as the Mortgagee
                  thinks appropriate; the Mortgagee may, in connection with the
                  exercise of its powers, join or concur with any person in any
                  transaction, scheme or arrangement whatsoever; and the
                  Mortgagor acknowledges that the respective powers of the
                  Mortgagee shall in no circumstances whatsoever be suspended,
                  waived or otherwise prejudiced by anything other than an
                  express waiver or variation in writing.

              (c) The rights of the Mortgagee in relation to the Mortgaged
                  Property and the recovery of the Secured Amounts (whether
                  arising under this Deed of


<PAGE>   69


                  Mortgage, the other Financing Documents or under the general
                  law) shall not be capable of being waived or varied otherwise
                  than by an express waiver or variation in writing; and in
                  particular any failure to exercise or any delay in exercising
                  any of such rights shall not operate as a waiver or variation
                  of that or any other such right; any defective or partial
                  exercise of any such right shall not preclude any other or
                  further exercise of that or any other such right; and no act
                  or course of conduct or negotiation on its part or on its
                  behalf shall in any way preclude it from exercising any such
                  right or constitute a suspension or any variation of any such
                  right.

              (d) If any of the provisions of this Deed of Mortgage becomes
                  invalid, illegal or unenforceable in any respect under any
                  law, the validity, legality and enforceability of the
                  remaining provisions shall not in any way be affected or
                  impaired.

              (e) In any proceedings relating to this Deed of Mortgage a
                  statement as to any amount due to the Mortgagee or the Trustee
                  under the Financing Documents which is certified as being
                  correct by an officer or agent of the Mortgagee shall, save in
                  the case of manifest error, be conclusive evidence that such
                  amount is in fact due and payable.

9.2      Assignment

         9.2.1    This Deed of Mortgage shall be binding upon and inure to the
                  benefit of each party hereto and its successors in title and
                  permitted assigns.

         9.2.2    The Mortgagor shall not be entitled to assign or transfer any
                  of its rights, benefits or obligations hereunder without the
                  prior written consent of the Mortgagee.

         9.2.3    The Mortgagee may assign or transfer all or any part of its
                  rights, benefits or obligations under this Deed of Mortgage to
                  any other person which is its successor under the Financing
                  Documents. Where the Mortgagee assigns or transfers its
                  obligations or any part thereof, the Mortgagor shall execute
                  such documents as the Mortgagee may specify to release the
                  Mortgagee to the extent of the assignment or transfer or with
                  a view to perfecting such assignment or transfer, or where
                  necessary, shall execute further security documentation in
                  favour of the assignee or transferee in like form to this Deed
                  of Mortgage.

9.3      Release of Security

         Upon final and unconditional repayment of the Secured Amounts in full
         and provided that no event of Default has occurred, the Mortgagee shall
         promptly assign the Mortgaged Property to the Mortgagor free of all
         Security Interests, encumbrances, trusts, equities and claims
         whatsoever imposed by the Mortgagee and the Mortgagee shall forthwith
         sign, seal, deliver and complete all transfers, renunciations, proxies,
         mandates, assignments, deeds and documents and do all


<PAGE>   70


         acts and things which the Mortgagor may reasonably specify to vest all
         of the Mortgaged Property in the name of the Mortgagor or its nominee.

9.4      This Deed of Mortgage is governed by, and shall be construed in
         accordance with, the laws of the Cayman Islands.

9.5      (a) The parties agree that the courts of the Cayman Islands are to have
             exclusive jurisdiction to settle any disputes which may arise in
             connection with the legal relationships established by this Deed of
             Mortgage (including, without limitation, claims for set-off or
             counterclaim) or otherwise arising in connection with this Deed of
             Mortgage.

         (b) The parties irrevocably waive any objections on the grounds of
             venue of forum non conveniens or any similar grounds. The parties
             irrevocably consent to service of process by mail or in any other
             manner permitted by the relevant law.

10.      NOTICES, ENGLISH LANGUAGE

         (a) Each notice or other communication to be given or made hereunder
             shall be in the English language and shall, unless otherwise stated
             be made in writing as provided below.

         Any notice or other communication or document to be made or delivered
         by one person to another pursuant to this Deed of Mortgage shall
         (unless that other person has by fifteen days' written notice to the
         other specified another address and/or fax or telex number) be made or
         delivered to that other person at the following address, fax or telex
         number:

             The Mortgagor:
             -------------

             SEVEN SEAS PETROLEUM INC.
             5555 San Felipe, Suite 1700
             Houston, Texas 77056
             Attention: Larry A. Ray
             Fax No. (713) 621-9770


             The Mortgagee:
             -------------

             CHESAPEAKE ENERGY CORPORATION
             6100 North Western Avenue
             Oklahoma City, Oklahoma 73118
             Attention: M. Rowland
             Fax No. (405) 879-9580


<PAGE>   71


                  and shall be deemed to have been made or delivered when such
                  communication or document has been dispatched and the
                  appropriate answer back received (in the case of any
                  communication made by telex) or sent by fax to the fax number
                  of the party set out herein and when receipt is confirmed by
                  facsimile or telephone (in the case of any communication by
                  fax) or (in the case of any communication made by letter) when
                  left at that address or, as the case may be, three days after
                  being deposited in the post first class postage prepaid in an
                  envelope addressed to it at that address; Provided that any
                  communication or document to be made or delivered to the
                  Mortgagee shall be effective only when received by the
                  Mortgagee.

11.      COUNTERPARTS

This Deed of Mortgage may be executed in any number of counterparts and all such
counterparts taken together shall be deemed to constitute one and the same
instrument.

IN WITNESS WHEREOF this Deed of Mortgage has been executed and delivered as a
Deed the day and year first above written.

EXECUTED AS A DEED by                   )
the duly authorised representative      )/s/ LARRY A. RAY
of SEVEN SEAS PETROLEUM INC.,           )
in the presence of:                     )

EXECUTED AS A DEED by                   )
the duly authorised representative      )
of CHESAPEAKE ENERGY CORPORATION        )/s/ TOM L. WARD
as Collateral Agent                     )
in the presence of:                     )

<PAGE>   72



                                   SCHEDULE 1
                               ORIGINAL SECURITIES


<Table>
<Caption>
                                    Amount or number of
         Company                    Original Securities       Description of Original Securities
         -------                    -------------------       ----------------------------------
<S>                                 <C>                       <C>
Seven Seas Petroleum USA Inc.,      100                       Common Shares
a Delaware corporation

GHK Company Columbia, an            1000                      Common Shares
Oklahoma corporation
</Table>




<PAGE>   73






                                  July 23, 2001





                            SEVEN SEAS PETROLEUM INC
                                 (as Mortgagor)


                          CHESAPEAKE ENERGY CORPORATION
                                 (as Mortgagee)




                     -------------------------------------
                           LEGAL MORTGAGE OVER SHARES






<PAGE>   74


THIS DEED OF MORTGAGE ("Deed of Mortgage") is made as of July 23, 2001

BETWEEN

(1)      SEVEN SEAS PETROLEUM INC., a Cayman Islands exempted company limited by
         shares, the registered office of which is at Walker House, Mary Street,
         George Town, Grand Cayman, Cayman Islands (the "Mortgagor"); and

(2)      CHESAPEAKE ENERGY CORPORATION, an Oklahoma corporation, whose principal
         place of business is at 6100 North Western Avenue, Oklahoma City,
         Oklahoma, 73118 (the "Mortgagee") as Collateral Agent under the
         Collateral Sharing Agreement (as hereinafter defined) for itself and
         United States Trust Company of New York, ("Trustee") under that certain
         Indenture dated July 23, 2001 (the "Indenture"), pursuant to which the
         Trustee is trustee for the holders of the Mortgagor's 12% Senior
         Secured Series A Notes (the "Series A Notes") and the Mortgagor's 12%
         Senior Secured Series B Notes (the "Series B Notes").

WHEREAS

(A)      Pursuant to a Note Purchase and Loan Agreement dated as of July 9, 2001
         (the "Note Purchase and Loan Agreement") the Mortgagee agreed to
         advance to the Mortgagor the sum of Twenty-two Million Five Hundred
         Thousand United States Dollars (US$22,500,000.00), evidenced by a 12%
         Senior Secured Note due 2004 in the principal amount of TWENTY-TWO
         MILLION FIVE HUNDRED THOUSAND DOLLARS ($22,500,000.00) (the "CEC Note")
         subject to the terms and conditions stated in: (a) the Note Purchase
         and Loan Agreement; (b) the CEC Note; (c) the detachable Warrants to
         purchase twelve million six hundred twelve thousand one hundred forty
         (12,612,140) shares of the Mortgagor's ordinary shares (the
         "Warrants"); (d) the Shareholder's Rights Agreement dated July 23, 2001
         between the Mortgagor and the Mortgagee (the "Shareholder's
         Agreement"); (e) the Registration Rights Agreement dated July 23, 2001
         between the Mortgagor and the Mortgagee (the "Registration Agreement");
         (f) the Security Agreement dated July 23, 2001 between the Mortgagor
         and the Mortgagee as Collateral Agent for itself and the Trustee (the
         "Security Agreement"); (g) certain other Deeds of Mortgage Over Shares
         of the subsidiaries of the Mortgagor other than the Company (as
         hereinafter defined) dated July 23, 2001 (the "Other Deeds of
         Mortgage"); (h) the Collateral Sharing and Agency Agreement dated as of
         July 23, 2001 between the Mortgagee and the Trustee pursuant to which
         the Mortgagee agrees to act as collateral agent for itself and the
         Trustee (the "Collateral Sharing Agreement"); and (i) any and all other
         documents and instruments executed and delivered in connection with the
         Note Purchase and Loan Agreement, the Indenture and any of the other
         documents executed in connection with the Note Purchase and Loan
         Agreement or the Indenture.

Upon satisfaction of certain conditions set forth in the Note Purchase and
         Loan Agreement, the CEC Note, the Warrants, and the other Related
         Agreements, the CEC Note issued under the Note Purchase and Loan
         Agreement may be exchanged by the Mortgagee in part for ordinary shares
         of the Mortgagor.



<PAGE>   75


The Note Purchase and Loan Agreement was executed on the agreement that the
         Mortgagor shall enter into this mortgage over shares in the capital of
         Petrolinson S.A., a company organized under the laws of Panama.

The Mortgagor has agreed to secure the Secured Amounts (as defined below)
         by entering into this Deed of Mortgage, as well as the other Financing
         Documents (as defined below).

IT IS AGREED as follows

1.       INTERPRETATION

         1.1      Except where the context otherwise requires, words and
                  expressions defined in the Note Purchase and Loan Agreement or
                  the recitals above shall have the same meaning where used
                  herein and the further words and expressions set out below
                  shall have the following meanings;

                  ACTIVE SUBSIDIARIES means Seven Seas Petroleum USA Inc., a
                  Delaware corporation, Seven Seas Petroleum Colombia Inc., a
                  Cayman Islands company, Petrolinson SA, a Panamanian
                  corporation, and GHK Company Colombia, an Oklahoma
                  corporation.

                  COLLATERAL AGENT means the Mortgagee as collateral agent under
                  the certain Collateral Sharing Agreement;

                  COMPANY means the company specified in Schedule 1;

                  ENFORCEMENT NOTICE means an enforcement notice served by the
                  Mortgagee on the Mortgagor pursuant to the terms of this Deed
                  of Mortgage;

                  FINANCING DOCUMENTS means the Note Purchase and Loan
                  Agreement, the Indenture, the CEC Note, the Series A Notes,
                  the Series B Notes, the Security Agreement, the Other Deeds of
                  Mortgage, this Deed of Mortgage, the Related Agreements, the
                  Collateral Sharing Agreement and any and all other documents
                  and instruments executed and delivered in connection with the
                  Note Purchase and Loan Agreement or the Indenture.

                  INACTIVE SUBSIDIARIES means Seven Seas Petroleum Holdings
                  Inc., a Cayman Islands company, Seven Seas Petroleum Turkey
                  Inc., a British Colombia corporation, Seven Seas Resources
                  Australia Inc., a British Colombia corporation, Seven Seas
                  Petroleum Australia Inc., a Cayman Islands company, Seven Seas
                  Petroleum PNG Inc., a Cayman Islands company, Seven Seas
                  Petroleum Argentina, a Cayman Islands company, Seven Seas
                  Mediterranean Inc., a Cayman Islands company, Seven Seas
                  Petroleum Turkey Inc., a Cayman Islands company, and Guaduas
                  Pipeline Company, a Cayman Islands company.





                                       2
<PAGE>   76


                  INDENTURE means the Indenture for the Series A Notes and the
                  Series B Notes as referred to in paragraph (2) above.

                  MORTGAGED PROPERTY means the Original Securities and all and
                  any other shares, securities, rights, moneys and property for
                  the time being mortgaged or charged to the Mortgagee pursuant
                  to Clause 2;

                  NOTE PURCHASE AND LOAN AGREEMENT means the facility referred
                  to in recital A;

                  ORIGINAL SECURITIES means the securities listed in Schedule 1
                  which are all registered in the name of the Mortgagor and
                  following execution of this Deed of Mortgage will be
                  transferred into the name of the Mortgagee or its nominee as
                  Collateral Agent;

                  OTHER DEEDS OF MORTGAGE means each Legal Mortgage Over Shares
                  between Mortgagor and Mortgagee delivered concurrently
                  herewith or hereafter delivered;

                  RELATED AGREEMENTS means the Warrants, the warrants granted to
                  the holders of the Series A Notes, the Shareholder's
                  Agreement, the Registration Agreement and any other documents
                  or instruments executed in connection with any of the
                  foregoing;

                  SECURED AMOUNTS means all and any amounts of any kind now or
                  in the future, actual or contingent, due and payable by the
                  Mortgagor to the Mortgagee under the CEC Note or to the
                  Trustee for the benefit of the holders of the Series A Notes
                  or the Series B Notes or under or in connection with this Deed
                  of Mortgage or the other Financing Documents and references to
                  the Secured Amounts include references to any part of them;
                  and

                  SECURITY INTEREST means any mortgage, charge, pledge, lien,
                  encumbrance, right of set off or any security interest,
                  howsoever created or arising.

         1.2      In this Deed of Mortgage:

                  (a)      references to the Mortgagor or the Mortgagee include
                           references to any person for the time being deriving
                           title under each of them respectively;

                  (b)      references to this Deed of Mortgage and the Financing
                           Documents are references to the same as from time to
                           time varied, supplemented or amended in any manner or
                           respect whatsoever;

                  (c)      references to the Original Securities or to the
                           Mortgaged Property include references to any property
                           included in such term;

                  (d)      "mortgage" includes a transfer or assignment by way
                           of mortgage;

                  (e)      Unless the context otherwise indicates, words
                           importing the singular shall include the plural and
                           vice versa, and the use of the neuter, masculine, or




                                       3
<PAGE>   77

                           feminine gender is for convenience only and shall be
                           deemed to mean and include the neuter, masculine or
                           feminine gender; and

                  (f)      Clause headings are for ease of reference only.

2.       COVENANT TO PAY SECURED AMOUNTS AND CHARGE

         2.1      The Mortgagor covenants with the Mortgagee for the benefit of
                  the Mortgagee and the Trustee that it shall, whether or not
                  the Mortgagor shall have received an Enforcement Notice in
                  accordance with this Deed of Mortgage or notice of demand in
                  respect of the Secured Amounts, pay and discharge any moneys
                  and liabilities in respect of the Secured Amounts whatsoever
                  which are now or at any time hereafter may be due, owing or
                  payable by the Mortgagor in any currency, actually or
                  contingently, solely and/or jointly and/or severally with
                  another or others, as principal or surety on any account
                  whatsoever pursuant to this Deed of Mortgage or the other
                  Financing Documents or as a consequence of any breach,
                  non-performance, disclaimer or repudiation by the Mortgagor of
                  any of its obligations, covenants, representations or
                  warranties under this Deed of Mortgage, the other Financing
                  Documents or otherwise.

         2.2      The Mortgagor hereby transfers absolutely by way of mortgage
                  to the Mortgagee as a continuing security for the payment and
                  discharge of the Secured Amounts, all its rights, title,
                  interest and benefit, present and future in, to and under:

                  (a)      the Original Securities; and

                  (b)      all other securities and all rights, monies
                           (including, without limitation, dividends) and
                           property whatsoever which may from time to time at
                           any time be derived from, accrued on or be offered in
                           respect of the Original Shares whether by way of
                           redemption, exchange, conversion, rights, bonus,
                           capital reorganisation or otherwise howsoever.

3.       CONTINUING AND PRIMARY SECURITY

         3.1      This Deed of Mortgage shall be a continuing security, and
                  shall be in addition to and shall not affect any continuing
                  liens or other Security Interests to which the Mortgagee is or
                  will be otherwise entitled over the Mortgaged Property, which
                  liens and other Security Interests shall remain in force
                  independently of this Deed of Mortgage.

         3.2      The Original Securities and other Mortgaged Property are
                  hereby mortgaged to the Mortgagee as primary and not as
                  collateral security.

         3.3      The Mortgagor's liability hereunder shall not be discharged or
                  impaired by:

                  (a)      the existence or validity of any other security taken
                           by the Mortgagee in relation to the Financing
                           Documents or any enforcement of or failure to enforce
                           or the release of any such security;




                                       4
<PAGE>   78

                  (b)      any amendment to or variation of the Financing
                           Documents or any security relating to the Financing
                           Documents or any assignment thereof or hereof;

                  (c)      any release of or granting of time or any other
                           indulgence to the Mortgagor or any third party;

                  (d)      any invalidity, irregularity, unenforceability,
                           imperfection or avoidance of or any defect in any
                           security granted by, or any obligations of, the
                           Mortgagor or any other person hereunder or under the
                           Financing Documents or any amendment to or variation
                           thereof or of any other document or security
                           comprised therein;

                  (e)      the insolvency, liquidation, bankruptcy or
                           dissolution (or proceedings analogous thereto) of the
                           Mortgagor, the Company or any other person or the
                           appointment of a receiver or administrative receiver
                           or administrator (whether by administration order or
                           otherwise) or trustee or similar officer of any of
                           the assets of the Mortgagor, the Company or any other
                           person or the occurrence of any circumstances
                           whatsoever affecting the Mortgagor, or any other
                           person's liability to discharge its obligations under
                           the Financing Documents;

                  (f)      any release, renewal, exchange or realisation of any
                           security or obligation provided under or by virtue of
                           this Deed of Mortgage or the other Financing
                           Documents or the provision of any further security to
                           the Mortgagee at any other time; or

                  (g)      any other act, event, neglect or omission which would
                           or might but for this clause operate to impair or
                           discharge the Mortgagor's liability hereunder.

         3.4      Any release, compromise or discharge of the obligations of the
                  Mortgagor shall be deemed to be made subject to the condition
                  that it will be void if any payment or security which the
                  Mortgagee may receive or have received is set aside or proves
                  invalid for whatever reason.

         3.5      Rights may be exercised and demands may be made under this
                  Deed of Mortgage from time to time, and the liabilities and
                  obligations of the Mortgagor and the rights and security or
                  other consideration contained in this Deed of Mortgage may be
                  exercised and enforced, irrespective of

                  (a)      whether any demands, steps or proceedings are being
                           or have been taken against the Mortgagor or any third
                           party; or

                  (b)      whether or in what order any security to which the
                           Mortgagee may be entitled in respect of the Secured
                           Amounts is enforced.




                                       5
<PAGE>   79

4.       WARRANTIES AND UNDERTAKING

         4.1      The Mortgagor represents and warrants to the Mortgagee and
                  undertakes that:

                  (a)      it is the absolute legal and beneficial owner of all
                           of the Original Securities free of all Security
                           Interests, encumbrances, trusts, equities, proxies
                           and claims whatsoever (save under this Deed of
                           Mortgage or the other Financing Documents) and that
                           all of the Original Securities are fully paid up and
                           are non-assessable;

                  (b)      except as limited by the Financing Documents,
                           Mortgagor has the full legal and unlimited right to
                           vote the Original Securities in its sole discretion;

                  (c)      the Original Securities constitute 100% of the issued
                           and outstanding equity capital of the Company and are
                           all currently registered in the name of the Mortgagor
                           (subject to the registration of the Original
                           Securities in the name of the Mortgagee as Collateral
                           Agent concurrently with the execution and delivery of
                           this Deed of Mortgage);

                  (d)      the Mortgagor and the Company are duly incorporated
                           and in good standing under the respective laws of the
                           jurisdiction in which each of them is incorporated
                           and the Mortgagor has and will at all times have the
                           necessary power to enter into and perform its
                           obligations under this Deed of Mortgage and has duly
                           authorized the execution and delivery of this Deed of
                           Mortgage;

                  (e)      neither this Deed of Mortgage or the transfer of the
                           Original Securities to the Mortgagee is subject to
                           any stamp or other tax under the laws of Panama or
                           the Cayman Islands and this Deed of Mortgage is
                           capable of being enforced without being subject to
                           any stamp or other tax under the laws of Panama or
                           the Cayman Islands;

                  (f)      pursuant to amendments to the organization documents
                           within 45 days after the date of this Agreement, the
                           Company will not be permitted to issue any equity
                           capital other than the Original Securities;

                  (g)      the Company has no contractual or other business
                           relationship with any Inactive Subsidiary;

                  (h)      No Inactive Subsidiary has any operations, assets or
                           liabilities, direct, indirect or contingent;

                  (i)      the Mortgagor holds no rights or Security Interests
                           with respect to present or future revenues and
                           assets, tangible or intangible, relating to the
                           exploration, development, production, transportation
                           and sale of petroleum in and from the Republic of
                           Colombia, directly, by assignment, or






                                       6
<PAGE>   80

                           otherwise, except as a shareholder of companies whose
                           shares are pledged to Mortgagee pursuant to the
                           Financing Documents;

                  (j)      this Deed of Mortgage constitutes its legal, valid,
                           binding and enforceable obligation and is a first
                           priority security interest over the Mortgaged Shares
                           effective in accordance with its terms;

                  (k)      the execution, delivery, observance and performance
                           by the Mortgagor of this Deed of Mortgage will not
                           require the Mortgagor to obtain any licenses,
                           consents or approvals and will not result in any
                           violation to the best of the Mortgagor's knowledge,
                           of any law, statute, ordinance, rule or regulation
                           applicable to it or any other agreements;

                  (l)      the Company is not a party or otherwise bound to any
                           employment, management or other agreement, the effect
                           of which would be to limit the ability of the
                           Mortgagee to manage the Company upon an event of
                           Default under the Financing Documents or give rise to
                           any payment or penalty to terminate any such
                           arrangement;

                  (m)      it has obtained all the necessary authorizations and
                           consents to enable it to enter into this Mortgage and
                           the necessary authorizations and consents will remain
                           in full force and effect at all times during the
                           existence of the security constituted by this Deed of
                           Mortgage;

                  (n)      the execution, delivery, observance and performance
                           by the Mortgagor of the Deed of Mortgage will not
                           constitute an event of default or trigger any
                           enforcement under any Security Interest in the
                           Mortgagor's assets nor will it result in the creation
                           of any Security Interest over or in respect of the
                           present or future assets of the Company;

                  (o)      the Mortgagor has fully disclosed in writing to the
                           Mortgagee all facts relating to the Mortgagor and the
                           Company which the Mortgagor knows or should
                           reasonably know and which are material for disclosure
                           to the Mortgagee in the context of the Financing
                           Documents; and

                  (p)      no agreement to which the Mortgagor or the Company or
                           its Colombian branch is a party, or law, decree or
                           regulation to which either is subject, including
                           without limitation any agreement with Empresa
                           Colombiana de Petroleos or imposition by the Ministro
                           de Minas y Energia de Colombia or any other
                           instrumentality of the Republic of Colombia requires
                           the consent of any such person to the execution,
                           delivery or performance of this Deed of Mortgage and
                           the other Financing Documents and each obligation and
                           covenant contained herein and therein.

         4.2      The Mortgagor undertakes that, for so long as any Secured
                  Amounts remain outstanding:




                                       7
<PAGE>   81

                  (a)      the Mortgagor shall pay to the Mortgagee, upon
                           demand, the amount of all reasonable expenses which
                           the Mortgagee may incur in, about or with a view to
                           perfecting or enforcing this security or otherwise in
                           connection with this security;

                  (b)      the Mortgagor shall promptly pay (and shall indemnify
                           the Mortgagee on demand against) all calls,
                           installments and other payments which may be made or
                           become due in respect of the Mortgaged Property and
                           so that, in the event of default by the Mortgagor,
                           the Mortgagee may do so on behalf of the Mortgagor
                           and clause 4.2(a) shall apply accordingly;

                  (c)      to the extent any Mortgaged Property is at any time
                           not vested in the Mortgagee or its nominee as
                           Collateral Agent the Mortgagor shall forthwith and
                           from time to time deposit with the Mortgagee all
                           certificates and other documents of title relating to
                           the Mortgaged Property and signed share transfer
                           forms;

                  (d)      the Mortgagor will maintain the Company in good
                           standing under the laws of Panama and will not do
                           anything that would cause the completion of
                           transactions or enforcement actions contemplated
                           hereunder to incur any stamp or other tax under the
                           laws of Panama or the Cayman Islands;

                  (e)      the Mortgagor will not permit the Company to enter
                           into or become bound by any employment, management or
                           other agreement, the effect of which would be to
                           limit the ability of the Mortgagee to manage the
                           Company upon an event of Default under the Financing
                           Documents or give rise to any payment or penalty to
                           terminate any such arrangement;

                  (f)      the Mortgagor will not permit any Inactive Subsidiary
                           to conduct operations or own any asset or incur any
                           liability, direct, indirect or contingent;

                  (g)      Mortgagor will not permit the Company to engage in
                           any transaction, contractual or otherwise, with any
                           affiliate of Mortgagor except with Mortgagor and
                           Active Subsidiaries and as may otherwise be permitted
                           by the Financing Documents; provided however, that in
                           no event shall the Company engage in any transaction,
                           contractual or otherwise, with an Inactive
                           Subsidiary;

                  (h)      the Mortgagor shall deliver to the Mortgagee undated
                           letters of resignation executed by all persons now or
                           hereafter serving as Directors of the Company from
                           time to time, which letters the Mortgagee shall be
                           entitled to date and cause to be given immediate
                           effect as of the date of an Enforcement Notice;

                  (i)      the Mortgagor shall forthwith sign, seal, deliver and
                           complete all transfers, renunciations, proxies
                           (including irrevocable proxies if the Mortgagee so
                           requests) mandates, assignments, deeds and documents
                           and do all acts and






                                       8
<PAGE>   82

                           things which the Mortgagee may, in its absolute
                           discretion, at any time and from time to time specify
                           for enabling or assisting the Mortgagee:

(i) to perfect or improve its title to and security over the Mortgaged Property
including, without limitation, obtaining such approvals or consents to the
rights and remedies granted to the Mortgagee herein as the Mortgagee requests in
the Mortgagee's sole discretion;

(ii) to vest the Mortgaged Property (including without limitation the
registration thereof in the applicable share registry) in the Mortgagee or its
nominee or nominees as Collateral Agent as of the date of execution of this Deed
of Mortgage;

(iii) to exercise (or enable its nominee or nominees to exercise) any rights or
powers attaching to the Mortgaged Property;

(iv) after the service of an Enforcement Notice to sell or dispose of the
Mortgaged Property; or

(v) otherwise to enforce any of the rights of the Mortgagee under or in
connection with this Deed of Mortgage;

                  (j)      the Mortgagor shall not (without the written consent
                           of the Mortgagee):

(i) create or permit to exist over all or part of the Mortgaged Property (or any
interest therein) any Security Interest (other than created or expressly
permitted to be created under this Deed of Mortgage or under other Financing
Documents) whether ranking prior to, pari passu with or behind the security
contained in this Deed of Mortgage;

(ii) sell, transfer or otherwise dispose of the Mortgaged Property or any
interest therein or attempt or agree to so dispose;

(iii) permit any person other than the Mortgagee or its nominee to be registered
as or become the holder of the Mortgaged Property as Collateral Agent; or

(iv) vote in favour of a resolution or amend, modify or change organization
documents of the Company or authorize the issuance by the Company of any shares
or any other equity security.

(v) except as otherwise permitted by the Financing Documents permit the Company
to transfer, assign, dispose of or encumber any rights or interests of the
Company, direct or indirect, with respect to petroleum exploration, development,
production, transportation, sale or other disposition or with respect to any
association or other contract under which the Company has such rights or
interests;

(vi) permit the Company to grant any Security Interest in, or otherwise
encumber, any of its assets, tangible or intangible, except as may be expressly
permitted by the Financing Documents;




                                       9
<PAGE>   83

(vii) permit the Company to make any distribution or payment to or for the
benefit of Mortgagor, whether directly or otherwise, if the effect of that
distribution or payment is to render the Company insolvent or unable to pay its
obligations as they mature; or

(viii) take any other action that would have as its effect a breach of a
Financing Document.

                  (k)      to the extent received by the Mortgagor, it shall
                           forward to the Mortgagee all notices, reports,
                           accounts and other documents relating to the
                           Mortgaged Property or which are sent to the holders
                           of any of the Mortgaged Property as soon as they are
                           received;

                  (l)      no further shares or equity securities of any kind in
                           the Company (or any options or other rights with
                           respect thereto) will be issued and the authorized
                           shares shall at no time exceed the issued shares;

                  (m)      at any time after the service of an Enforcement
                           Notice, it shall exercise all voting and other rights
                           and powers which may at any time be exercisable by
                           the holder of the Mortgaged Property as the Mortgagee
                           may in its absolute discretion direct, it being
                           understood that the Mortgagee has reserved the right
                           to exercise all such voting rights directly for any
                           proper purpose, including without limitation the
                           immediate removal of Directors of the Company and
                           their replacement;

                  (n)      the Mortgagor shall not take or accept any Security
                           Interest from the Company or, in relation to the
                           Secured Amounts, from any third party, without first
                           obtaining the Mortgagee's written consent or permit
                           any Security Interest to be granted by the Company to
                           any third party, except as may be expressly permitted
                           by the Financing Documents;

                  (o)      the Mortgagor shall not prove in a liquidation or
                           winding up of the Company in competition with the
                           Mortgagee for any amount whatsoever owing to the
                           Mortgagee by the Mortgagor on any account whatsoever;
                           and

                  (p)      the Mortgagor shall not claim payment whether
                           directly or by set-off, lien, counterclaim or
                           otherwise of any amount which may be or has become
                           due to the Mortgagor by the Company.

5.       POWER OF ATTORNEY

         5.1      The Mortgagor hereby irrevocably and by way of security for
                  the payment by it of the Secured Amounts and the performance
                  of its obligations under this Deed of Mortgage appoints the
                  Mortgagee as its true and lawful attorney (with full power to
                  appoint substitutes and to subdelegate) on behalf of the
                  Mortgagor and in the Mortgagor's own name or otherwise, at any
                  time and from time to time, to sign, seal, deliver and
                  complete all transfers, renunciations, proxies, mandates,
                  assignments, deeds and documents and do all acts and things
                  which the Mortgagee may, in its sole and absolute discretion,
                  consider to be necessary or








                                       10
<PAGE>   84

                  advisable to perfect or improve its security over the
                  Mortgaged Property or to give proper effect to the intent and
                  purposes of this Deed of Mortgage or, after delivery of an
                  Enforcement Notice to enable or assist in any way in the
                  exercise of any power of sale of the Mortgaged Property
                  (whether arising under this Deed of Mortgage or implied by
                  statute or otherwise).

6.       ENFORCEMENT

         6.1      The Mortgagee may at any time after the occurrence of an event
                  of Default (as defined in the Note Purchase and Loan
                  Agreement) which has not been timely cured but including,
                  without limitation, the breach of any representation, warranty
                  or covenant contained in this Deed of Mortgage and the other
                  Financing Documents) serve an Enforcement Notice on the
                  Mortgagor. Unless and until the Mortgagee shall have served an
                  Enforcement Notice, but not thereafter:

                  (a)      Mortgagee agrees to the fullest extent permitted by
                           applicable law that the Mortgagor has the right to
                           receive payments distributed in respect of the
                           Original Securities and all other securities which
                           may from time to time at any time be derived from the
                           Original Securities; and

                  (b)      Appoints Mortgagor as Mortgagee's agent and proxy to
                           vote all of the securities described in clause (a)
                           above and exercise all rights and privileges
                           attributable to such securities as permitted under
                           applicable law. Prior to default, if the Mortgagee
                           shall receive any dividend or money described in
                           clause (a) above, the Mortgagee shall receive the
                           same as agent for Mortgagor and upon receipt shall
                           promptly pay or remit the same, without reduction, to
                           Mortgagor. At the request of Mortgagor, Mortgagee
                           shall give such reasonable assurances, confirmations
                           and advice to any third party as may be necessary for
                           Mortgagor to enjoy the full benefit of the rights and
                           privileges described in clauses (a) and (b) above

         6.2      If the Mortgagee shall serve an Enforcement Notice, the
                  Mortgagee shall, without prejudice to any other right or
                  remedy available hereunder or under applicable law, forthwith
                  become entitled:

                  (a)      solely and exclusively to exercise all voting rights
                           attaching to the Mortgaged Property or any thereof
                           and shall exercise such rights in such manner as the
                           Mortgagee may in its absolute discretion determine;
                           and/or

                  (b)      solely and exclusively to exercise any and all other
                           rights and/or powers and/or discretions of the
                           Mortgagor in, to and under the Mortgaged Property
                           pursuant to the constitutional documents of the
                           Company; and/or

                  (c)      to receive and retain all dividends and other
                           distributions made on or in respect of the Mortgaged
                           Property or any thereof and any such dividends and
                           other distributions received by the Mortgagor after
                           such time shall be





                                       11
<PAGE>   85

                           held in trust by the Mortgagor for the Mortgagee and
                           be paid or transferred to the Mortgagee on demand;
                           and/or

                  (d)      without notice to, or further consent or concurrence
                           by, the Mortgagor to sell the Mortgaged Property or
                           any part thereof by such method, at such place and
                           upon such terms as the Mortgagee may in its absolute
                           discretion determine, with power to postpone any such
                           sale and in any such case the Mortgagee may exercise
                           any and all rights attaching to the Mortgaged
                           Property as the Mortgagee in its discretion may
                           determine and without being answerable for any loss
                           occasioned by such sale or resulting from
                           postponement thereof or the exercise of such rights;
                           upon any sale of the Mortgaged Property or any part
                           thereof the purchaser thereof shall not be bound to
                           see or enquire whether the power of sale of the
                           Mortgagee has arisen in the manner herein provided
                           and the sale shall be deemed to be within the power
                           of the Mortgagee and the receipt of the Mortgagee for
                           the purchase money shall effectively discharge the
                           purchaser of the Mortgaged Property, or any part
                           thereof, who shall not be concerned or be in any way
                           answerable therefor; and/or

                  (e)      to appoint a receiver in respect of the Mortgaged
                           Property and the provisions of Clause 7 shall apply
                           thereto.

         6.3      The Mortgagee shall not be liable for any loss or damage
                  occasioned by any sale or disposal of the Mortgaged Property
                  (or interest therein) or arising out of the exercise of or
                  failure to exercise any of its powers under this Deed of
                  Mortgage or for any neglect or default to pay any instalment
                  or accept any offer or notify the Mortgagor of any such matter
                  or for any other loss of any nature whatsoever in connection
                  with the Mortgaged Property.

7.       MORTGAGEE'S RIGHTS AS TO MORTGAGED PROPERTY

         If the Mortgagee shall serve an Enforcement Notice, the Mortgagee
         shall, without prejudice to any other right or remedy available
         hereunder or under applicable law, forthwith become entitled:

         7.1      solely and exclusively to exercise all voting rights attaching
                  to the Mortgaged Property or any thereof and shall exercise
                  such rights in such manner as the Mortgagee may in its
                  absolute discretion determine; and/or

         7.2      solely and exclusively to exercise all other rights and/or
                  powers and/or discretions of the Mortgagor in, to and under
                  the Mortgaged Property pursuant to the memorandum and articles
                  of association of the Company; and/or

         7.3      to receive and retain all dividends and other distributions
                  made on or in respect of the Mortgaged Property or any thereof
                  and any such dividends and other distributions received by the
                  Mortgagor after such time shall be held in trust by the
                  Mortgagor for the Mortgagee and be paid or transferred to the
                  Mortgagee on demand to be applied towards the discharge of the
                  Secured Obligations; and/or




                                       12
<PAGE>   86

         7.4      without notice to, or further consent or concurrence by, the
                  Mortgagor to sell or otherwise dispose of the Mortgaged
                  Property or any part thereof by such method, at such place and
                  upon such terms as the Mortgagee may in its absolute
                  discretion determine, with power to postpone any such sale and
                  in any such case the Mortgagee may exercise any and all rights
                  attaching to the Mortgaged Property as the Mortgagee in its
                  absolute discretion may determine and without being answerable
                  for any loss occasioned by such sale or resulting from
                  postponement thereof or the exercise of such rights; and/or

         7.5      to date and deliver the documents delivered to it pursuant to
                  this Mortgage as it considers appropriate and to take all
                  steps not already taken to register the Mortgaged Property in
                  the name of the Mortgagee or its nominee or nominees as
                  Collateral Agent and to assume control as registered owner of
                  the Mortgaged Property.

8.       OTHER SECURITY

         8.1      This security is in addition to and shall not affect or be
                  merged in any bills, notes, guarantees, indemnities,
                  undertakings, Security Interests, or other security whatsoever
                  which the Mortgagee may hold now or hereafter in connection
                  with the Financing Documents or the obligations of any other
                  person liable for any of the Secured Amounts.

9.       FURTHER PROVISIONS

         9.1      (a)      This security is in addition to, and shall
                           neither be merged in, nor in any way exclude or
                           prejudice, any other Security Interest or right of
                           recourse or other right whatsoever which the
                           Mortgagee may now or at any time hereafter hold or
                           have (or would apart from this security hold or have)
                           as regards the Mortgagor or any other, person in
                           respect of the Secured Amounts.

                  (b)      The powers which this Deed of Mortgage confer on the
                           Mortgagee are cumulative, without prejudice to its
                           powers under the general law, and may be exercised as
                           often as the Mortgagee thinks appropriate; the
                           Mortgagee may, in connection with the exercise of its
                           powers, join or concur with any person in any
                           transaction, scheme or arrangement whatsoever; and
                           the Mortgagor acknowledges that the respective powers
                           of the Mortgagee shall in no circumstances whatsoever
                           be suspended, waived or otherwise prejudiced by
                           anything other than an express waiver or variation in
                           writing.

                  (c)      The rights of the Mortgagee in relation to the
                           Mortgaged Property and the recovery of the Secured
                           Amounts (whether arising under this Deed of Mortgage,
                           the other Financing Documents or under the general
                           law) shall not be capable of being waived or varied
                           otherwise than by an express waiver or variation in
                           writing; and in particular any failure to exercise or




                                       13
<PAGE>   87

                           any delay in exercising any of such rights shall not
                           operate as a waiver or variation of that or any other
                           such right; any defective or partial exercise of any
                           such right shall not preclude any other or further
                           exercise of that or any other such right; and no act
                           or course of conduct or negotiation on its part or on
                           its behalf shall in any way preclude it from
                           exercising any such right or constitute a suspension
                           or any variation of any such right.

                  (d)      If any of the provisions of this Deed of Mortgage
                           becomes invalid, illegal or unenforceable in any
                           respect under any law, the validity, legality and
                           enforceability of the remaining provisions shall not
                           in any way be affected or impaired.

                  (e)      In any proceedings relating to this Deed of Mortgage
                           a statement as to any amount due to the Mortgagee or
                           the Trustee under the Financing Documents which is
                           certified as being correct by an officer or agent of
                           the Mortgagee shall, save in the case of manifest
                           error, be conclusive evidence that such amount is in
                           fact due and payable.

         9.2      Assignment

                  9.2.1    This Deed of Mortgage shall be binding upon and inure
                           to the benefit of each party hereto and its
                           successors in title and permitted assigns.

                  9.2.2    The Mortgagor shall not be entitled to assign or
                           transfer any of its rights, benefits or obligations
                           hereunder without the prior written consent of the
                           Mortgagee.

                  9.2.3    The Mortgagee may assign or transfer all or any part
                           of its rights, benefits or obligations under this
                           Deed of Mortgage to any other person which is its
                           successor under the Financing Documents. Where the
                           Mortgagee assigns or transfers its obligations or any
                           part thereof, the Mortgagor shall execute such
                           documents as the Mortgagee may specify to release the
                           Mortgagee to the extent of the assignment or transfer
                           or with a view to perfecting such assignment or
                           transfer, or where necessary, shall execute further
                           security documentation in favour of the assignee or
                           transferee in like form to this Deed of Mortgage.

         9.3      Release of Security

                  Upon final and unconditional repayment of the Secured Amounts
                  in full and provided that no event of Default has occurred,
                  the Mortgagee shall promptly assign the Mortgaged Property to
                  the Mortgagor free of all Security Interests, encumbrances,
                  trusts, equities and claims whatsoever imposed by the
                  Mortgagee and the Mortgagee shall forthwith sign, seal,
                  deliver and complete all transfers, renunciations, proxies,
                  mandates, assignments, deeds and documents and do all acts and
                  things which the Mortgagor may reasonably specify to vest all
                  of the Mortgaged Property in the name of the Mortgagor or its
                  nominee.




                                       14
<PAGE>   88

         9.4      This Deed of Mortgage is governed by, and shall be construed
                  in accordance with, the laws of the Cayman Islands.

         9.5      (a)      The parties agree that the courts of the Cayman
                           Islands are to have exclusive jurisdiction to settle
                           any disputes which may arise in connection with the
                           legal relationships established by this Deed of
                           Mortgage (including, without limitation, claims for
                           set-off or counterclaim) or otherwise arising in
                           connection with this Deed of Mortgage.

                  (b)      The parties irrevocably waive any objections on the
                           grounds of venue of forum non conveniens or any
                           similar grounds.

                  The parties irrevocably consent to service of process by mail
                  or in any other manner permitted by the relevant law.

10.      NOTICES, ENGLISH LANGUAGE

                  (a)      Each notice or other communication to be given or
                           made hereunder shall be in the English language and
                           shall, unless otherwise stated be made in writing as
                           provided below.

                  Any notice or other communication or document to be made or
                  delivered by one person to another pursuant to this Deed of
                  Mortgage shall (unless that other person has by fifteen days'
                  written notice to the other specified another address and/or
                  fax or telex number) be made or delivered to that other person
                  at the following address, fax or telex number:

                           The Mortgagor:

                           SEVEN SEAS PETROLEUM INC.
                           5555 San Felipe, Suite 1700
                           Houston, Texas 77056
                           Attention: Larry A. Ray
                           Fax No. (713) 621-9770


                           The Mortgagee:

                           CHESAPEAKE ENERGY CORPORATION
                           6100 North Western Avenue
                           Oklahoma City, Oklahoma 73118
                           Attention: M. Rowland
                           Fax No. (405) 879-9580


                  and shall be deemed to have been made or delivered when such
                  communication or document has been dispatched and the
                  appropriate answer back received (in the





                                       15
<PAGE>   89

                  case of any communication made by telex) or sent by fax to the
                  fax number of the party set out herein and when receipt is
                  confirmed by facsimile or telephone (in the case of any
                  communication by fax) or (in the case of any communication
                  made by letter) when left at that address or, as the case may
                  be, three days after being deposited in the post first class
                  postage prepaid in an envelope addressed to it at that
                  address; Provided that any communication or document to be
                  made or delivered to the Mortgagee shall be effective only
                  when received by the Mortgagee.

11.      COUNTERPARTS

This Deed of Mortgage may be executed in any number of counterparts and all such
counterparts taken together shall be deemed to constitute one and the same
instrument.

IN WITNESS WHEREOF this Deed of Mortgage has been executed and delivered as a
Deed the day and year first above written.

EXECUTED AS A DEED by                       )
the duly authorised representative          )/s/ LARRY A. RAY
of SEVEN SEAS PETROLEUM INC.,               )
in the presence of:                         )

EXECUTED AS A DEED by                       )
the duly authorised representative          )
of CHESAPEAKE ENERGY CORPORATION            )/s/ TOM L. WARD
as Collateral Agent                         )
in the presence of:                         )



                                       16
<PAGE>   90




                                   SCHEDULE 1

                               ORIGINAL SECURITIES


Company: Petrolinson S.A., a company organized under the laws of Panama.




<Table>
<Caption>
Amount or number of
Original Securities                 Description of Original Securities
-------------------                 ----------------------------------

<S>                                 <C>
5000                                Common Shares of 10 Balboas or Dollars
                                    par value
</Table>