Document:

Exhibit
10.4    

    

    FIRST
PRIORITY OPEN PLEDGE AGREEMENT OVER A COMMERCIAL ESTABLISHMENT

    

    
      	
               
      

            	
              3.

            	
              Edgar
      Louis Dyes of age, domiciled in Bogotá, identified with Id No C.E. 223.325
      de Bogota acting in name and representation of SOLANA PETROLEUM
      EXPLORATION COLOMBIA LIMITED, (hereinafter the “PLEDGOR”) a
      company duly organized and existent under the laws of Cayman Islands, in
      his capacity as Principal Legal Representative authorized to execute this
      agreement, as evidenced in the certified copy of the Resolution of the
      Board of Directors of the PLEDGOR, dated 24 of August, 2009 which is
      attached hereof, and form integral part of this document
    and

            

    

    

    
      	
               
      

            	
              4.

            	
              Jose
      Luis Palacios of age, domiciled in Bogotá, identified with Id No
      80.090.506 of Bogota, D.C. acting in name and representation of STANDARD
      BANK PLC, (hereinafter the “PLEDGEE”) a
      company duly organized and existent under the laws of England and Wales
      (Company No. 2130447) and having its registered office at Cannon Bridge
      House, 25 Dowgate Hill, London EC4R 2SB, with main domicile in the United
      Kingdom, have executed the following Open Pledge
      Agreement  (hereinafter the “Pledge
      Agreement”) :

            

    

     

    WHEREAS:

    

    
      	
               
      

            	
              (A)

            	
              WHEREAS
      an AMENDED AND RESTATED CREDIT AGREEMENT dated  July [---] 2009
      (as amended, restated, supplemented or otherwise modified from time to
      time, the “Credit
      Agreement”; all capitalized terms used and not otherwise defined
      herein have the meanings given to such terms in the Credit Agreement), was
      executed among GRAN TIERRA ENERGY COLOMBIA, LTD. (formerly Argosy Energy
      International), ARGOSY ENERGY LLC (formerly Argosy Energy Corp.), a
      limited liability company organized under the laws of the State of
      Delaware (Registered No. 3234977), the PLEDGOR, SOLANA RESOURCES LIMITED,
      a limited company organized under the laws of Province of Alberta, Canada,
      GRAN TIERRA ENERGY CAYMAN ISLANDS INC., a corporation organized under the
      laws of the Cayman Islands (the “Borrower”),
      each of the Banks party thereto from time to time; and STANDARD BANK PLC
      as Issuing Bank, Arranger and as Administrative Agent (in such capacity,
      together with its successors in such capacity, the “Administrative
      Agent”) by means of which a loan facility for a sum of up to
      US$200,000,000 was granted by the Banks to the Borrower on the terms and
      subject to the conditions set forth
therein;

            

    

     

    
      	
               
      

            	
              (B)

            	
              WHEREAS,
      PLEDGOR is a company dedicated to the exploration and production of
      hydrocarbons in Colombia, and in order to develop its corporate purpose
      has established a commercial establishment (Branch), denominated SOLANA
      PETROLEUM EXPLORATION COLOMBIA LIMITED, (hereinafter the “Commercial
      Establishment”), located in Bogotá, D.C., registered before Bogotá’s
      Chamber of Commerce under trade registration No 00901181 of October 26,
      1998, as evidenced in the certificate issued by said entity, which will be
      attached to this agreement and forms integral part;
  and

            

    

     

    
      	
               
      

            	
              (C)

            	
              WHEREAS,
      in order to secure the prompt payment and performance in full of the
      Secured Obligations, the Parties have agreed to execute this Pledge
      Agreement by virtue of which the PLEDGOR hereby creates an open pledge, in
      favor of PLEDGEE, over its Commercial
  Establishment.

            

    

    

    NOW, THEREFORE, the Parties
have decided to enter into this PLEDGE AGREEMENT which shall
be governed by the following provisions (the “Pledge Agreement”):

    
      
         

      

      
        1

        
          

        

      

      
         

      

    

    

    CLAUSES

    

    FIRST CLAUSE. - PURPOSE:
Considering the recitals mentioned above, the PLEDGOR, acting under the
conditions indicated on this Pledge Agreement, in the terms of articles 532,
1207 to 1220 of the Colombian Commercial Code, hereby creates in favor of
PLEDGEE, a first priority open pledge, without tenancy over the Commercial
Establishment, this being understood as those assets property of the PLEDGOR and
its Branch which are principally located in the city of Bogotá and form part of
its Commercial Establishment, together with its circulating assets along with
the elements, acts and agreements identified in the Third Clause of this
Agreement.

    

    Under
this clause, the PLEDGOR agrees to (i) obtain a duly legalized and apostilled
cancellation of the first priority open pledge over the Commercial
Establishment, dated December 20, 2007 (the “BNP Pledge”), by the
PLEDGOR in favor of BNP PARIBAS, and register the cancellation of the BNP Pledge
in the commercial registry belonging to the Colombian territory within ten (10)
days of the date of this Pledge Agreement or such later date as the PLEDGOR and
the PLEDGEE may agree to in writing, (ii) register this Pledge Agreement in the
commercial registry belonging to the Colombian territory within the three (3)
Business Days following the date of the cancellation and registration of the BNP
Pledge and (iii) to deliver to the PLEDGEE, within five (5) Business Days
following the request of inscription of the present Pledge Agreement in the
commercial registry, a copy of said inscription.

    

    SECOND CLAUSE.- SECURED
OBLIGATIONS: The pledge created by means of this Pledge Agreement is an
open pledge, that secures the payment and performance in full by the Obligors of
all principal of and interest on the Loans made by the Banks to, and the Notes
held by each Bank from, and Reimbursement Obligations in respect of Letters of
Credit issued for the account of, and the Designated Hedging Obligations of, the
Borrower and all other amounts from time to time owing to the Secured Parties by
the Borrower under the Credit Agreement, under the Notes, under each Designated
Hedging Agreement and by any other Obligor under any of the other Loan Documents
to which such Obligor is a party, in each case strictly in accordance with the
terms hereof and thereof (hereinafter the “Secured
Obligations”). For legal purposes,
especially for the provisions of article 58 of Law 788, 2002, it is hereby
stated that at the date of the execution of the Pledge Agreement, no
disbursement has been effectively made under the Credit Agreement since its
execution on [---].

    

    Notwithstanding
the above, the Parties hereto agree that the amount of the Secured Obligations
will correspond to the sum of up to USD$200,000,000 for principal plus any
interest and any other costs, expenses, fees, commissions, indemnifications and
other amounts due from any Obligor pursuant to the Credit Agreement and the
other Loan Documents.

    

    THIRD CLAUSE.- COMMERCIAL
ESTABLISHMENT ASSETS: Pursuant to this Pledge Agreement, the items
provided in article 516 of the Code of Commerce form part of the Commercial
Establishment and are thus subject to this pledge, including but not limited to
the circulating assets and the following assets:

    

    
      	
              3.1.

            	
              All
      present and future rights owned by the PLEDGOR
      over  engineering, designs, blueprints, programs and information
      required for the operation and maintenance of the facilities destined to
      the exploration and production of oil, gas, and any other hydrocarbon,
      conducted by the Commercial
Establishment;

            

    

    

    
      	
              3.2.

            	
              All
      present and future rights owned by the PLEDGOR over the movable goods,
      machinery, equipment, instruments, spare parts, and any other
      inventory,  necessary for the operation and maintenance of the
      facilities destined to the exploration and production of oil, gas and any
      other hydrocarbon, conducted by the Commercial
    Establishment;

            

    

    

    
      	
              3.3.

            	
              All
      present and future authorizations, approvals, concessions, permits, and
      licenses of any nature held by the PLEDGOR for the operation and
      maintenance of the facilities destined to the exploration and production
      of  oil, gas and any other hydrocarbon, conducted
      by  the Commercial
Establishment;

            

    

    
      
         

      

      
        2

        
          

        

      

      
         

      

    

    

    
      	
              3.4.

            	
              All
      present and future easements and transit rights held by the PLEDGOR over
      the real state properties required for the construction, operation and
      maintenance of the facilities destined to the exploration and production
      of oil, gas, or any other hydrocarbon, conducted by the Commercial
      Establishment;

            

    

    

    
      	
              3.5.

            	
              All
      present and future rights held by the PLEDGOR over any oleoduct which
      currently utilizes or may reach to
use;

            

    

    

    
      	
              3.6.

            	
              All
      present and future rights held by the PLEDGOR derived from any oil
      purchase agreements and any oil, gas or any other hydrocarbon
      transportation agreement;

            

    

    

    
      	
              3.7.

            	
              All
      present and future machinery and equipment owned by the PLEDGOR, installed
      by the PLEDGOR for the development of any exploration and production
      activity of oil, gas or any other hydrocarbon, conducted by the Commercial
      Establishment;

            

    

    

    
      	
              3.8.

            	
              All
      present and future movable goods, office equipment, and computer systems
      owned by the PLEDGOR;

            

    

    

    
      	
              3.9.

            	
              All
      present and future trade names, and trademarks of goods and services,
      owned by the PLEDGOR;

            

    

    

    
      	
              3.10.

            	
              All
      present and future patents, utility models, and industrial designs owned
      by the  PLEDGOR;

            

    

    

    
      	
              3.11.

            	
              All
      present and future rights of the  PLEDGOR, different from those
      mentioned above in 3.9 and 3.10 regarding inventions or industrial and
      technical creations used by the  PLEDGOR in the normal
      activities of the Commercial
Establishment;

            

    

    

    
      	
              3.12.

            	
              All
      lease, commodatum, and leasing agreements executed by
      the  PLEDGOR, as well as all rights of the  PLEDGOR to
      lease the offices or premises in which the Commercial Establishment
      operates if those offices or premises are not owned by
      the  PLEDGOR, and the indemnifications which, according to the
      law and the agreements mentioned above, the  PLEDGOR has the
      right to receive and all commodatum, leasing and lease agreements
      executed  by  the  PLEDGOR in the
      future;

            

    

    

    
      	
              3.13.

            	
              All
      present and future engineering, design, construction and services
      agreements executed by the  PLEDGOR for the operation and
      maintenance of the facilities destined to the exploration and production
      of oil, gas, and any other
hydrocarbon;

            

    

    

    
      	
              3.14.

            	
              All
      agreements which grant the  PLEDGOR, direct or indirect
      participation over any hydrocarbon project in Colombia, including but not
      limited to, exploration and production of hydrocarbons agreements executed
      (of any type) with Ecopetrol or the AGENCIA NACIONAL DE HIDROCARBUROS
      (ANH) or private agreements executed by or on behalf of
      the  PLEDGOR with third parties which have contracted areas for
      the exploration and production  of hydrocarbons (of any type)
      with Ecopetrol or the ANH;

            

    

    

    
      	
              3.15.

            	
              All
      credit rights in favor of the  PLEDGOR and any other similar
      values;

            

    

    

    
      	
              3.16.

            	
              All
      rights of the  PLEDGOR,  acquired through its
      Commercial Establishment in Colombia, under every and any kind of
      agreement related to exploration and production of hydrocarbon activities
      in Colombia with the ANH, Ecopetrol or any third party;
  and

            

    

    

    
      	
              3.17.

            	
              All
      other rights of the PLEDGOR derived from the normal operation of the
      Commercial Establishment.

            

    

    
      
         

      

      
        3

        
          

        

      

      
         

      

    

    

    The
Commercial Establishment does not include the rights of the Borrower derived
from any crude oil sales commercial agreements, over which the parties have
constituted a pledge in favor of the PLEDGEE as additional collateral security
to the Secured Obligations pursuant to a separate pledge agreement.

    

    FOURTH CLAUSE.- COMMERCIAL
ESTABLISHMENT LOCATION: The offices in which de Commercial Establishment
operates in Bogotá, D.C. are located at,  Calle 113 No 7 – 80 Floor17.
The PLEDGOR is hereby allowed to change the domicile of the Commercial
Establishment in case of termination of the existing lease agreement, in which
case the PLEDGOR shall inform the PLEDGEE in a prior, express and explicit
manner the new domicile of the Commercial Establishment; provided, however, that
the new domicile shall be kept in the city of Bogotá D.C..

    

    Notwithstanding
the above, the PLEDGOR is expressly authorized to move the items mentioned above
in the following events: a) when the change of location is done inside the
premises of the PLEDGOR; or b) when events of force majeure or acts of god occur
(as defined in Law 95 of 1890) and the mobilization is required in order to
maintain their integrity. The PLEDGOR must return the goods immediately to the
location previously determined, once the events of force majeure and act of god
cease, unless express authorization from the PLEDGEE.

    

    Likewise,
the assets which are of property of the PLEDGOR that were necessary for the
location in which the exploration and production of hydrocarbons are carried out
and can be mobilized pursuant to the business' needs, without affecting in any
way the rights and interests of the PLEDGEE under this document, the Credit
Agreement or any other related document thereto. Notwithstanding, in this case,
the PLEDGOR shall inform the PLEDGEE about the new location of the assets that
have been mobilized.

    

    FIFTH CLAUSE.- SALE OF ASSETS:
The PLEDGOR
may not sell, assign, encumber, or in any form limit, affect, or transfer the
property rights, possession, or any other right it may hold over the Commercial
Establishment encumbered by the present Pledge Agreement, unless prior written
consent has been obtained from the PLEDGEE, subject to any applicable provisions
in the Credit Agreement and the other Loan Documents.

    

    SIXTH CLAUSE. - INSPECTION RIGHTS:
The PLEDGOR
must allow the PLEDGEE or the individuals designated by the PLEDGEE, to inspect
the Commercial Establishment, which includes every single asset of the
Commercial Establishment including its accounting, provided that it is made in
working days, at any time during the term of the Pledge Agreement.

     

    SEVENTH CLAUSE. – TENANCY: The
PLEDGOR, under the condition stated in clause four of this Pledge Agreement,
will maintain the tenancy of the Commercial Establishment, and the assets and
rights that comprise it, being allowed to use them in accordance with their
normal form of use, having to preserve them with due care and diligence, and
agrees to attend with the maximum care and diligence to the custody,
conservation and maintenance of said assets, and will be held responsible for
minimum negligence, in such a manner that during the term of this Pledge
Agreement they are kept in normal conditions, save for the normal wear and tear
derived from its adequate use. Said obligations include those of performing
maintenance work, substitutions and replacements and the repairs that the nature
of the assets and goods require or that the industry advises, without
diminishing the goods or assets.

    

    EIGHTH CLAUSE. –
TERM:  This Pledge Agreement will have the same term as the
Credit Agreement, which is until February 22, 2010, or any of its extensions in
accordance to the Credit Agreement. However, this pledge will serve as a
security for the Secured Obligations until they are cancelled in full. Once all
of the Secured Obligations have been paid or discharged in full, the PLEDGOR
will be entitled, at its sole cost and expense, to receive from the PLEDGEE the
execution of a document canceling the pledge created under this Pledge
Agreement; provided always that
if any payment in respect of the Secured Obligations is avoided or reduced as a
result of the insolvency of the PLEDGOR or any analogous event, such pledge
shall to the fullest extent permitted by law be reinstated as if the payment and
discharge of the Secured Obligations had not occurred, and the liability of the
PLEDGOR will continue as if the payment in respect of the Secured Obligations
had not occurred, and the PLEDGEE shall be entitled to recover the amount of
such payment from the PLEDGOR as if such payment had not been
made.

    
      
         

      

      
        4

        
          

        

      

      
         

      

    

     

    NINTH CLAUSE. – ADDITIONAL
OBLIGATIONS: The PLEDGOR agrees to perform its corporate purpose in
Colombia solely and exclusively by means of the Commercial Establishment and to
not open or establish for such commercial purposes establishments other than the
Commercial Establishment encumbered through this pledge, except the new
Commercial Establishment is included as part of the guaranty under this Pledge
Agreement and the PLEDGEE grants its prior and written consent.

     

    TENTH CLAUSE. – REPRESENTATIONS AND
WARRANTIES OF THE PLEDGOR: The PLEDGOR represents and warranties to the
PLEDGEE the following:

     

    10.1. That the Commercial
Establishment and the assets that it comprises (with the exception of the assets
that have been leased or received by lease or commodatum) are of its exclusive
property, since they have not been previously sold or transferred to any third
party and that they are free of any liens, pledges, civil claims and in general
of any other type of encumbrance or property limitation, except for (i) those
expressly permitted under the Credit Agreement and (ii) the BNP Pledge, provided that the BNP
Pledge shall be cancelled and the cancellation of the BNP Pledge registered
within ten (10) days of the date of this Pledge Agreement or such later date as
the PLEDGOR and PLEDGEE may agree to in writing in accordance with the First
Clause of this Pledge Agreement.

     

    10.2. That the agreements from
which the rights that form part of the Commercial Establishment are derived are
valid and binding for the parties and enforceable against them, in accordance
with the terms and conditions established therein.

     

    10.3. That to the better
understanding of the PLEDGOR it has not neither has any other party of any of
the agreements from which the rights and obligations that form part of the
Commercial Establishment are derived, failed to comply in total or in part, with
any material aspect, any of the terms and conditions established in said
agreements and that the PLEDGOR has not been notified nor has knowledge of any
fact that can cause any breach with any term or condition established in said
agreements.

     

    10.4. The PLEDGOR is legally
empowered to execute and grant this Pledge Agreement and that there are no
legal, contractual o statutory restrictions applicable to the PLEDGOR in order
to execute and grant this Pledge Agreement.

     

    10.5. That all actions and
conditions (statutory or other) that are required in order to validly subscribe
and comply with this Pledge Agreement, have been executed, complied with and
satisfied.

     

    10.6. That this Pledge
Agreement generates valid and binding obligations for the PLEDGOR that are
enforceable against him, in accordance to the terms and conditions stated
herein.

    
      
         

      

      
        5

        
          

        

      

      
         

      

    

     

    10.7 That, except for the
consents and authorizations already received, the granting and execution of this
Pledge Agreement and the compliance with the terms and conditions stated herein,
do not result in a breach nor do they require authorization under: (i) the
by-laws, (b) any law, decree, resolution, agreement, order, judicial decision,
judicial ruling, decision, license or permission applicable to the PLEDGOR or to
which the PLEDGOR is subject to, or (c) any agreement or instrument to which the
PLEDGOR is part to or is obligated by.

     

    ELEVENTH CLAUSE. – EXPENSES AND
TAXES: The registration fees before the Chamber of Commerce, the expenses
related to the issuance of the certificate evidencing the registration of the
pledge to be delivered to the PLEDGEE, the expenses originated from the
notarization of this document, the expenses and taxes caused by the cancellation
of this pledge and the remaining expenses that are caused by the execution and
granting of this Pledge Agreement, shall be fully assumed by the
PLEDGOR.

     

    TWELFTH CLAUSE. – INSURANCE
POLICY: The PLEDGOR agrees to maintain one or more insurance policies
with financially solid insurance companies duly authorized to operate in
Colombia, over the assets that form part of the Commercial Establishment, based
on the ordinary Colombian hydrocarbon sector’s usual amounts, coverages, terms
and conditions. Additionally, the PLEDGOR agrees to maintain the assets that
from part of the Commercial Establishment, insured during the full term of this
Pledge Agreement.

     

    THIRTEENTH.- ENFORCEABILITY OF THE
PLEDGE: The PLEDGEE will only be able to enforce this Pledge following
the established procedures in Colombian legislation and any other regulation, as
well as any of the following events: (i) when an Event of Default occurs as
defined in the Credit Agreement and/or any of the Secured Obligations and/or any
other agreement or document entered into in connection to or as a result of the
Credit Agreement, (ii) when a default occurs under this Pledge Agreement or
(iii) any representation or warranty granted under this Pledge Agreement results
false, inexact or incorrect. (iv) when the value of the Commercial Establishment
is diminished or the goods, assets and rights that conform it are lost or
deteriorated, and so become insufficient to guarantee the Secured Obligations
unless the PLEDGOR provides an additional security reasonably satisfactory to
the PLEDGEE.

    

    FOURTEENTH CLAUSE. – FORECLOSURE
PROCEEDINGS: In case that the PLEDGEE initiates a foreclosure proceeding
against the PLEDGOR for breaches of the Secured Obligations, the parties agree
to the following:

    

    a)
Appoint a suitable person, indicated in good faith by the PLEDGEE, to act as
confiscator in the proceeding and that will continue to administrate the
Commercial Establishment.

    

    b)
Designate the person that the PLEDGEE indicates in good faith, as an expert or
experts for the appraisal of the assets that compose the Commercial
Establishment.

    

    FIRST PARAGRAPH: The PLEDGOR
expressly states that it adheres to the appointment of the confiscator and the
expert or experts made by the PLEDGEE, as provided in letters a) and b) of the
present Clause, in accordance to the Colombian Civil Procedure Code and waives
the right to request the division of the assets into lots in order to hold a
public auction.

    
      
         

      

      
        6

        
          

        

      

      
         

      

    

    

    SECOND PARAGRAPH: In order to
enforce this Pledge Agreement, the PLEDGOR grants a blank promissory note with a
letter of instructions which shall be fulfilled by the PLEDGEE pursuant to the
terms and conditions provided therein and with the owed amounts under the Credit
Agreement. In order to fulfill the owed amount, the PLEDGEE shall discount any
paid amount under any other guaranty granted pursuant to the Credit
Agreement.

    

    FIFTEENTH CLAUSE. – TRANSFER:
The PLEDGOR
accepts from the execution of this Pledge Agreement, any assignment or total or
partial transfer that the PLEDGEE may make of this Pledge Agreement, as a
consequence of the transfer of the Secured Obligations, as long as said transfer
or assignment is made in accordance to what is established in the Credit
Agreement. In the event of a partial transfer of the present Pledge Agreement as
a consequence of the transfer of the Secured Obligations, the PLEDGOR will
expressly be obligated to issue a new original copy of said agreement, with the
corresponding reproduction of the registration stamps before the corresponding
Chamber of Commerce, and deliver them to the PLEDGEE ́s partial assignee or to
deliver a document with the modifications to this pledge, in which the transfer
is referenced and the assignee’s acceptance to all the terms of the present
Pledge Agreement is stated.

    

    SIXTEENTH CLAUSE. – APPLICABLE LAW:
This Pledge Agreement is subject to Colombian law. 

    

    SEVENTEENTH CLAUSE. – HEADERS:
The titles contained in this Pledge Agreement have been inserted for
parties’ convenience and cannot affect in anyway the interpretation and meaning
of any of the provisions of this Pledge Agreement.

    

    EIGHTEENTH CLAUSE. – MODIFICATION:
The present Pledge Agreement, including its Exhibits when the case may
be, can only be modified or amended by mutual agreement between the parties
stated in writing and proof that those who represent the parties are duly
empowered to do so.

    

    NINETEENTH CLAUSE. -
NOTIFICATIONS: Any message, notification or summon required, demanded or
permitted by this Pledge Agreement to be delivered to the PLEDGOR or PLEDGEE
shall be made in writing and shall be given in accordance with Section 12.02 of
the Credit Agreement

    

    TWENTIETH CLAUSE. – TOTAL AGREEMENT:
The present Pledge Agreement, accepted and signed, constitutes the total
agreement between the parties; it has priority and replaces any other agreement
that might have existed previously between them in relation with the object of
this Pledge Agreement.

    

    TWENTY-FIRST CLAUSE. – NULLITY OR
ILLEGALITY OF THE PROVISIONS: In the event that one or more of the
provisions of this Pledge Agreement is declared to be null, inefficient or
contrary to Colombian law, this does not imply the nullity, inefficiency or
illegality of the remaining provisions of this Pledge Agreement, which will
continue to be binding and mandatory for the parties and will remain in force
and in effect. Additionally, the parties agree to cooperate amongst themselves
to replace the null, inefficient or illegal provision, for another provision
that is valid and enforceable and that serves the same purpose and renders the
same effects as the provision that has been declared illegal, null or
inefficient.

    

    TWENTY-SECOND CLAUSE. –WAIVER:
Waivers, by either of the parties to what has been stated in this Pledge
Agreement cannot be interpreted as a waiver to exercise the rights and actions
granted by this Pledge Agreement or by the Law, with the exception of waivers
that have been expressly previously recognized through a written communication.
No omission, delay or action done by the parties while exercising any of its
rights, powers or resources under the present Pledge Agreement will be
considered as a waiver of said rights, powers or resources. No waiver of a
right, power or resources by either of the parties is considered to be valid
except when said party has notified it by writing. The rights and actions in
this Pledge Agreement are cumulative and do not excludes the remaining rights
and actions established in the applicable law. The exercise of any right or
action under this Pledge Agreement, does not exclude the possibility to exercise
another right or resources.

    

    TWENTY-THIRD CLAUSE. – SURVIVAL OF
AGREEMENTS: Each agreement, representation, warranty, and covenant
contained or referred to in this Pledge Agreement shall survive any
investigation at any time made by the PLEDGEE shall survive any disbursement
under the Loans, except for changes permitted hereby and, except as otherwise
provided in this article, shall terminate only when all amounts due or to become
due under the Loan Documents are indefeasibly paid.

    
      
         

      

      
        7

        
          

        

      

      
         

      

    

    

    In
witness whereof, this Pledge Agreement is signed in multiple original copies, of
the same contents by:

    

    
      
        
          
            
              
                
                  
                    
                      
                        
                          
                            
                              
                                
                                  
                                    
                                      
                                        
                                          
                                            
                                              	
                                                      Before
      the Notary Public, in the city of Bogota D.C., on August 24 of two
      thousand and nine (2009).

                                                    	 	
                                                      Before
      the Notary Public, in the city of Bogotá, D.C., on August 24 of two
      thousand and nine (2009).

                                                    
	 
      	 	 
      
	
                                                      By
      PLEDGOR

                                                    	 	
                                                      By
      PLEDGEE

                                                    
	 
      	 	 
      
	
                                                      /s/ Edgar Louis Dyes

                                                    	 	 	
                                                      /s/ Jose Luis Palacios

                                                    	 
	
                                                      EDGAR
      LOUIS DYES

                                                    	 	
                                                      JOSE
      LUIS PALACIOS

                                                    
	
                                                      C.E.
      223.325

                                                    	 	
                                                      C.C.
      No. 80.090.506 Bogota

                                                    
	
                                                      Principal
      Legal Representative

                                                    	 	
                                                      [Proxy]

                                                    

                                            

                                          

                                        

                                      

                                    

                                  

                                

                              

                            

                          

                        

                      

                    

                  

                

              

            

          

        

      

    

    
      
         

      

      
        8Exhibit
10.5    

    

    EXECUTION
VERSION    

     

    AMENDED
AND RESTATED FIRST PRIORITY OPEN PLEDGE AGREEMENT OVER CREDIT RIGHTS DERIVED
FROM CRUDE OIL COMMERCIAL SALES AGREEMENTS (this “Pledge Agreement”)

     

    Between
(i) GRAN TIERRA ENERGY COLOMBIA, LTD. (formerly Argosy Energy International), a
limited partnership organized under the laws of the State of Utah (Registered
No. 2110646-0180) and having its principal office at Calle 114 No. 7 - 80, 17th
Floor, AR Building, Bogota D. C., Colombia with a branch denominated GRAN TIERRA
ENERGY COLOMBIA, LTD., (hereinafter the “PLEDGOR”)
incorporated through Public Deed No. 5323 on October 25, 1983, granted by the
Seventh Notary of Bogotá, registered on November 23, 1983 under Number 2092 of
Book VI, with Mercantile Register No. 00841851, and its main domicile in Bogotá,
D.C.,  represented by EDGAR LOUIS DYES, as evidenced in the
certificate of incumbency and legal representation, of legal age, resident of
Bogotá D.C., bearer of Alien’s Identity Document Number 223.325, acting in his
capacity as legal representative and (ii) STANDARD BANK PLC,
a public limited company organized under the laws of England and Wales (Company
No. 2130447) and having its registered office at 20 Gresham Street,
London  EC2V 7JE with main domicile in the United Kingdom, acting for
and on behalf of the Secured Parties as administrative agent under the Credit
Agreement referred to below (in such capacity, together with its successors and
assigns in such capacity, the “PLEDGEE”),
represented in this act by MARTIN REVOREDO and RODERICK L. FRASER, both of legal
age, domiciled in New York City identified as it appears below their signatures.

     

    WHEREAS:

     

    A. The
PLEDGEE and the PLEDGOR are parties to that certain Credit Agreement, dated as
of February 22, 2007 (the “Original Credit
Agreement”), in connection to which, the PLEDGOR pledged its credit
rights derived from a certain crude oil commercial sales agreement, dated
December 1, 2006 (the “2006 Ecopetrol Offtake
Agreement”), between ECOPETROL (as defined below) and the PLEDGOR,
pursuant to the First Priority Open Pledge Agreement Over Credit Rights Derived
From A Crude Oil Sales Agreement, dated as of February 22, 2007 (the “Original Pledge
Agreement”). 

     

    B. The
Original Credit Agreement was amended and restated by the Amended and Restated
Credit Agreement, dated August 24, 2009 (as amended, restated, supplemented or
otherwise modified from time to time, the “Credit Agreement”),
among the PLEDGOR, ARGOSY ENERGY, LLC, a limited liability company organized
under the laws of the State of Delaware (Registered No. 3234977), SOLANA
PETROLEUM EXPLORATION (COLOMBIA) LIMITED, an exempted company organized under
the laws of the Cayman Islands, SOLANA RESOURCES LIMITED, a limited company
organized under the laws of Province of Alberta, Canada, GRAN TIERRA ENERGY
CAYMAN ISLANDS INC., an exempted company organized under the laws of the Cayman
Islands (together with its successors and assigns, the “Borrower”), each of
the Banks party thereto from time to time and the PLEDGEE, by means of which a
loan facility for a sum of up to US$200,000,000 was granted by the Banks to the
Borrower on the terms and subject to the conditions set forth
therein.

    
      
         

      

      
        1

        
          

        

      

      
         

      

    

    

    C. Under
the Credit Agreement, the PLEDGOR continues to be obligated to create a pledge
over all of the present and future rights, titles and interests of the PLEDGOR
to receivables payable from Crude Oil Commercial Sales Agreements (as defined
below) in order to secure the fulfillment of the obligations stipulated in the
Credit Agreement.

    

    D. On
February 12, 2009, ECOPETROL S.A. (hereinafter, “ECOPETROL”), a
decentralized entity of the national order, established through Law 165 of 1948,
organized as a joint Stock Company pursuant to Decree 1760 of 2003, with Tax
Identification Number 899-999-068-1, attached to the Ministry of Mines and
Energy, with main domicile in Bogotá D.C., whose corporate bylaws are contained
in Public Deed No. 4832 dated October 31, 2005, and Public Deed 4302 of
September 26, 2006, from the Second Notary of the Bogotá D.C. Circle and on the
other hand the PLEDGOR engaged in a crude oil commercial sales agreement for the
purchase of the crude produced under the Chaza block (the “2009 Ecopetrol Offtake
Agreement” and together with the 2006 Ecopetrol Offtake Agreement, the
“Ecopetrol Offtake
Agreements”). 

     

    E. Under
the Ecopetrol Offtake Agreements, the payments made by ECOPETROL to the PLEDGOR
are as follows: (a) one part payable in Colombian pesos, equivalent to
twenty-five (25%) of the volumes determined and delivered, in accordance with
the provisions contained therein; (b) the remaining seventy five percent (75%)
in United States dollars (“U.S. Dollars”).

     

    F. In
order to secure the prompt payment and performance in full of the secured
obligations under the Credit Agreement, the PLEDGOR has agreed to amend and
restate the Original Pledge Agreement to extend its first priority open pledge
in favor of the PLEDGEE to include all the present and future rights, titles and
interests of the PLEDGOR to receivables and credits payable from time to time by
ECOPETROL and other Offtakers under the 2009 Ecopetrol Offtake Agreement and
under all other present and future Offtake Agreements entered into by the
PLEDGOR.

     

    G. The
parties hereto have agreed that the Original Pledge Agreement be amended,
restated and replaced, and pursuant to the terms and conditions
hereto.

     

    NOW,
THEREFORE, the parties agree as follows:

     

    FIRST
CLAUSE. DEFINED TERMS: Capitalized terms used in this Pledge Agreement
(including the preamble and whereas clauses) and not otherwise defined herein,
unless the context otherwise requires, have the respective meanings given to
such terms in the Credit Agreement. 

    
      
         

      

      
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    SECOND
CLAUSE. PURPOSE: The PLEDGOR hereby creates a first priority open pledge
in favor of the PLEDGEE over all the present and future rights, titles and
interests of the PLEDGOR to receivables and credits payable from time to time by
ECOPETROL and other Offtakers under the Ecopetrol Offtake Agreements and each
other offtake agreement entered into by the PLEDGOR in the future, but limited
to those included in the definition of “Offtake Agreements” under the Credit
Agreement (collectively, including the Ecopetrol Offtake Agreements, the “Crude Oil Commercial Sales
Agreements” and each, a “Crude Oil Commercial Sales
Agreement”). The pledge created hereunder, includes the rights of the
PLEDGOR to receive: (i) the full price of the crude oil agreed between the
PLEDGOR and ECOPETROL and any other Offtaker; (ii) all the default interest
derived from the Crude Oil Commercial Sales Agreements, if any; (iii) all the
fines, compensations or indemnifications of any nature to which the PLEDGOR may
be entitled to by virtue of breaches of the Crude Oil Commercial Sales
Agreements; (iv) all the indemnifications paid by insurance companies or banks,
to which the PLEDGOR is entitled to, derived from or related to the Crude Oil
Commercial Sales Agreements; and (v) all and any other amounts to which the
PLEDGOR may be entitled to by virtue of the Crude Oil Commercial Sales
Agreements. 

     

    THIRD
CLAUSE. SECURITY FOR OBLIGATIONS: The pledge created by means of this
Pledge Agreement is an open pledge, that secures the payment and performance in
full by the Obligors of all present and future obligations (including, in the
case of the Guarantors, the Guaranteed Obligations) to the Secured Parties under
the Credit Agreement and the other Loan Documents (hereinafter the “Secured
Obligations”). 

     

    The
PLEDGEE may enforce the pledge created by means of this Pledge Agreement at any
time after (i) an Event of Default under Section 10(f) or 10(g) of the Credit
Agreement has occurred, or (ii) any other Event of Default in respect of which
the PLEDGEE has delivered a notice to the Borrower, terminating the Commitments
and/or declaring all amounts payable by the Obligors as immediately due and
payable pursuant to the Credit Agreement.

     

    Notwithstanding
the above, the Parties hereto agree that the amount of the Secured Obligations
will correspond to the sum of USD$200,000,000 of principal plus any interest and
any other costs, expenses, fees, commissions, indemnifications and other amounts
due by any Obligor pursuant to the Credit Agreement and the other Loan
Documents.

     

    FOURTH
CLAUSE. COLLECTIONS: All and any payments made in U.S. Dollars under the
Crude Oil Commercial Sales Agreements, including, but not limited to, payments
made under the Ecopetrol Offtake Agreements corresponding to the seventy five
percent (75%) portion made in U.S. Dollars, shall be made by ECOPETROL or the
applicable Offtaker by means of transference and deposit of those payments in
account number 103353265 opened by the PLEDGOR with JPMorgan Chase Bank, N.A.
New York, New York the (the “Collection Account”).

    
      
         

      

      
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    FIFTH
CLAUSE. SERVICES AND INSTRUCTIONS TO ECOPETROL: The PLEDGOR shall notify
in writing ECOPETROL and any other Offtaker, within the three (3)
working days following the date of execution of this Pledge Agreement, in the
manner indicated in Annex No. 1 to this Pledge Agreement, that from the date on
which this Pledge Agreement is entered into all the rights of the PLEDGOR to
receive payments under the applicable Crude Oil Commercial Sales Agreement have
been pledged in favor of the PLEDGEE. Additionally, the PLEDGOR shall instruct
irrevocably ECOPETROL and any other Offtaker to transfer and deposit all U.S.
Dollar payments derived from the Ecopetrol Offtake Agreements or any other Crude
Oil Sales Agreements into the Collection Account. Each of the Crude Oil
Commercial Sales Agreements executed by the PLEDGOR after the date hereof will
be deemed to form part of this pledge and the PLEDGOR shall provide notice and
instruction to the Offtaker under such Crude Oil Commercial Sales Agreement in
accordance to this Fifth Clause and the receivables and credits payable under
such Crude Oil Commercial Sales Agreement shall be deposited in the Collection
Account.

     

    SIXTH
CLAUSE. ADDITIONAL OBLIGATIONS: In addition to the obligations stipulated
in all other clauses of this Pledge Agreement and in any applicable regulations,
the PLEDGOR undertakes the following specific obligations: (i) be liable for the
existence, validity and duly and timely compliance of the Crude Oil Commercial
Sales Agreements; (ii)
abstain from fully or partially assigning the Crude Oil Commercial Sales
Agreements or the rights derived therefrom without prior, specific and written
authorization of the PLEDGEE; (iii) promptly inform the PLEDGEE about any breach
of the Crude Oil Commercial Sales Agreements regardless its cause, by the
PLEDGOR, ECOPETROL or any Offtaker; (iv) maintain in force and without any liens
or limitations all its rights under the Crude Oil Commercial Sales Agreements
other than Permitted Liens; (v) promptly inform the PLEDGEE about any claim,
lawsuit, seizure or precautionary measure of any nature instituted or intended
to be instituted by any person in regards to the rights of the PLEDGOR under the
Crude Oil Commercial Sales Agreements; (vi) promptly provide to PLEDGEE a copy
of all of the Crude Oil Commercial Sales Agreements executed to date, or any
future Crude Oil Commercial Sales Agreement executed, which are pledged under
this Pledge Agreement, within the following two (2) working days of the
execution of this Pledge Agreement, or within the following two (2) working days
from the execution of the Crude Oil Commercial Sales Agreement, as applicable,
as well as to keep the documents in the offices located in Bogota D.C.;
and  (vii) not to modify, amend or renegotiate the instructions and
the form of payment under the Crude Oil Commercial Sales Agreements, unless such
amendment, modification or renegotiation increases, in U.S. Dollars, the
returned percentages; consequently the amendments to the Crude Oil Commercial
Sales Agreements may not increase the returned percentage in Colombian
pesos.

     

    SEVENTH CLAUSE. TERM: This
Pledge Agreement shall remain in force and effect until the Maturity Date, which
is February 22, 2010 or such later date as may be determined in accordance with
the Credit Agreement; provided that this
pledge shall continue to serve as security for the Secured Obligations until the
payment and discharge of the Secured Obligations in full and the termination of
all Commitments under the Credit Agreement. Once all of the Secured Obligations
have been paid or discharged in full, the PLEDGOR will be entitled to receive
from the PLEDGEE the execution of a document canceling the pledge created under
this Pledge Agreement; provided always that
if any payment in respect of the Secured Obligations is avoided or reduced as a
result of the insolvency of the PLEDGOR or any analogous event, such pledge
shall to the fullest extent permitted by law be reinstated as if the payment and
discharge of the Secured Obligations had not occurred, and the liability of the
PLEDGOR shall continue as if the payment in respect of the Secured Obligations
had not occurred, and the PLEDGEE shall be entitled to recover the amount of
such payment from the PLEDGOR as if such payment had not been
made.

    
      
         

      

      
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    EIGHTH CLAUSE. REPRESENTATIONS AND
WARRANTEES: PLEDGOR hereby represents and warrants in favor of the
PLEDGEE and for the benefit of all the Secured Parties, the
following:

    (i) That
all the rights of the PLEDGOR under the Crude Oil Commercial Sales Agreements
are of its exclusive property, have not been previously assigned or transferred
and are free from any seizures, pledges, lawsuits, and in general from any other
types of liens and limitations to ownership other than Permitted
Liens.

     

    (ii) That
the Crude Oil Commercial Sales Agreements are valid and binding upon each of the
PLEDGOR and, to its knowledge, ECOPETROL or the applicable Offtaker and
enforceable against each of them, in accordance with the terms and conditions
stipulated therein.

    

    
      	
               
      

            	
              (iii)
      That the PLEDGOR has no knowledge of any fact or event that could imply or
      produce a breach of the Crude Oil Commercial Sales
    Agreements.

            

    

     

    (iv) That
it is legally empowered to enter into and perform this Pledge Agreement and that
for its execution and performance there are no legal, contractual or statutory
restrictions applicable to the PLEDGOR.

     

    (v) That
all the actions and conditions (statutory or of any other type) required for the
execution and performance of this Pledge Agreement, have been duly and fully
obtained, performed, fulfilled with and satisfied.

     

    (vi) That
this Pledge Agreement creates valid and binding obligations upon the PLEDGOR
enforceable against it, according to the terms and conditions provided
herein.

    

    
      	
               
      

            	
              (vii)
      That except for the authorizations already received, the entering into and
      perfecting of this Pledge Agreement as well as its compliance and
      performance, does not breach or imply a non-compliance, neither requires
      any consent or authorization under: (a) the constituent documents of the
      PLEDGOR; (b) any law, decree, resolution, agreement, order, judicial
      decision, writ, administrative decision, license or permit applicable to
      the PLEDGOR or to which the PLEDGOR is bound, or (c) any contract or
      document to which the PLEDGOR is a party or is
  obligated.

            

    

     

    NINTH
CLAUSE. EXPENSES AND TAXES: All the expenses and taxes that may be caused
or derived from the execution and compliance of this Pledge Agreement shall be
fully assumed and paid by the PLEDGOR.  

     

    TENTH
CLAUSE. COSTS AND FEES: The expenses and costs to be incurred by the
PLEDGEE in case this pledge is made effective, including lawyer’s fees, will be
fully assumed by the PLEDGOR.

    
      
         

      

      
        5

        
          

        

      

      
         

      

    

    ELEVENTH
CLAUSE. APPLICABLE LAW: This Pledge Agreement is governed by, and shall
be construed and interpreted in accordance with, the laws of the Republic of
Colombia.

     

    TWELFTH
CLAUSE. USE OF ENGLISH LANGUAGE: The English text of this Pledge
Agreement shall be controlling in all cases, except in connection with any legal
action or proceeding brought in respect of this Pledge Agreement in the
competent courts of Colombia, in which case an official translation into Spanish
of this Pledge Agreement shall be controlling. 

     

    THIRTEENTH
CLAUSE. NOTICES: Any message, notification or summon required, demanded
or permitted by this Pledge Agreement shall be made in writing and shall be
given in accordance with Section 12.02 of the Credit Agreement. 

    

    FOURTEENTH
CLAUSE. MISCELLANEOUS:

     

    14.1.
Survival of Agreements. Each agreement, representation, warranty, and
covenant contained or referred to in this Pledge Agreement shall survive any
investigation at any time made by the PLEDGEE and shall survive any disbursement
under the Loans, except for changes permitted hereby and, except as otherwise
provided in this article, shall terminate only when all amounts due or to become
due under the Loan Documents are indefeasibly paid.

     

    14.2.
Integration; Amendments. This Pledge Agreement and the other Loan
Documents embodies the entire understanding of the parties and supersedes all
prior negotiations, understandings, and agreements between them with respect to
the subject matter hereof. The provisions of this Pledge Agreement and of its
Annexes may be waived, supplemented, or amended only by an instrument in writing
signed by the Parties hereto. 

     

    14.3.
Severability.  If any provision of this Pledge Agreement is
prohibited or held to be invalid, illegal, or unenforceable in any jurisdiction,
then to the fullest extent permitted by law, such invalidity, illegality, or
unenforceability shall not affect the validity, legality, and enforceability of
the other provisions of this Pledge Agreement and shall not render such
provision prohibited, invalid, illegal, or unenforceable in any other
jurisdiction. If, and to the extent that, any obligation of the PLEDGOR is
unenforceable for any reason, the PLEDGOR shall, independent of any other
obligation hereunder, make the maximum contribution to the payment and
satisfaction thereof as is permissible under applicable law. 

     

    14.4.
No Waiver.

     

    (a) No
failure or delay by the PLEDGEE in exercising any right, power, or remedy shall
operate as a waiver thereof or otherwise impair any of its other rights, powers,
or remedies. No single or partial exercise of any such right, power, or remedy
shall preclude any other or further exercise thereof or the exercise of any
other legal right, power, or remedy. No waiver of any right, power, or remedy
shall be effective unless given in writing.

    (b) The
rights, powers or remedies provided for herein are cumulative and are not
exclusive of any other rights, powers, or remedies provided by law. The
assertion or employment of any right, power or remedy hereunder, or otherwise,
shall not prevent the concurrent assertion of any other rights, powers, or
remedies.

    
      
         

      

      
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    14.5. Execution in
Counterparts.

    

    This
Pledge Agreement may be executed in counterparts, each of which when so executed
and delivered shall be deemed an original and all of which together shall
constitute one and the same instrument.

    

    [Remainder
intentionally left blank.]

    
      
         

      

      
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    In
witness whereof, the Pledge Agreement is signed as of August 24,
2009

    

    
      
        	
                GRAN
      TIERRA ENERGY COLOMBIA, LTD.

              
	 
      
	
                By:  Argosy
      Energy, LLC, its General Partner

              
	 
      
	
                By:

              	
                /s/ Edgar Louis Dyes

              	 
      
	
                Name:  Edgar
      Louis Dyes

              
	
                Title:  Manager

              
	 
      
	
                STANDARD
      BANK PLC

              
	 
      
	
                By:

              	
                /s/ Martin Revoredo

              	 
      
	
                Name: 
      Martin Revoredo

              
	
                Title:   
      Director

              
	 
      
	
                By:

              	
                /s/ Roderick L. Fraser

              	 
      
	
                Name:  Roderick
      L. Fraser

              
	
                Title:    
      Global Head of Oil & Gas,
Renewables

              

      

    

    
      
         

      

      
        8

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