Exhibit 10.2

ENGLISH TRANSLATION — EXECUTED DOCUMENT IS IN SPANISH

AMENDMENT NO.1 TO THE CONTRACT RESULTING FROM THE ACCEPTANCE OF THE COMMERCIAL
OFFER DATED DECEMBER 17, 2009 FOR THE PURCHASE OF CHAZA OIL

The contracting parties: ECOPETROL S.A., decentralized entity of national order,
incorporated by means of Law 165 of 1948, with Tax ID No.  899-999-068-1,
organized as a Mixed Economy Company according to the dispositions of article
No. 2 of Law 1118 of 2006, linked/related to the Ministry of Mines and Energy,
with domicile in Bogota D.C., whose bylaws are totally contained in Public Deed
No. 5314 of December 14, 2007 given before Notary Second of Bogota D.C. and
registered before the Chamber of Commerce, hereinafter referred in this
Amendment as THE BUYER,  represented by CLAUDIA L. CASTELLANOS R., of age and
domiciled in this city, identified with citizenship card No. 63.314.635 issued
in Bucaramanga, who in capacity of Vice-president of Supply and Marketing and
with authorization contained in the Delegation Manual, acts on behalf of this
company, and on the other hand, GRAN TIERRA ENERGY COLOMBIA LTD, with Tax Id No.
860.516.431-7, hereinafter THE SELLER represented by JULIAN GARCIA SALCEDO,
identified with citizenship card No. 19.421.914 who acts in his capacity as
legal representative and is duly authorized to execute this Amendment according
to the incorporation and representation certificate issued by the Chamber of
Commerce,  who states that neither he nor the company he represents are
disqualified on grounds of disability or any inconsistency according to the
Constitution or the law, that might prevent them from entering into this
Amendment.

In the conditions listed, THE BUYER and THE SELLER, who jointly and individually
will be referred to as the Parties or the Party, agree to execute this Amendment
to the contract resulting from the acceptance by GRAN TIERRA ENERGY COLOMBIA LTD
of the commercial offer dated December 17 2009 for the purchase of crude oil
produced in Chaza Block, taking into account the following:

CONSIDERATIONS

1.  
That by means of Purchase Order No. SOL-01-2009 issued on December 18, 2009 GRAN
TIERRA ENERGY COLOMBIA LTD accepted the Commercial Offer dated December 17, 2009
issued by ECOPETROL S.A., for the purchase of 100% of the crude oil of property
of THE SELLER, produced in Chaza Block.

2.  
That the expiration date for the contract resulting from the acceptance of the
Commercial Offer dated December 17, 2009 for the purchase of crude oil is
December 31st, 2010.

3.  
That THE SELLER has expressed its interest in selling to third parties different
from THE BUYER a portion of the crude oil produced in Chaza Block.

4.  
That ECOPETROL S.A. has no objection with THE SELLER commercializing a part of
the crude oil produced in the Chaza Block with third parties, provided that The
SELLER complies with the strict delivery to ECOPETROL S.A. of the volumes
according to the final schedule approved by THE BUYER according to the
provisions contained in CLAUSE TWO – PROGRAM SCHEDULE of this document.

5.  
Taking into account the above, ECOPETROL and GRAN TIERRA ENERGY COLOMBIA LTD
require to enter into an Amendment by means of which the purpose of the contract
is modified, allowing THE SELLER to commercialize with third parties other than
ECOPETROL SA part of the crude oil produced in the Chaza Block.

 
 
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6.  
That for purposes of the execution of this Amendment, THE BUYER previously
verified the Bulletin of Fiscal Responsibility developed and published by the
General Comptroller of the Republic, in which THE SELLER does not appear as one
of the people who have been determined by a judicial and firm decision as
fiscally responsible. Additionally, THE BUYER implemented the control mechanisms
in relation to the prevention of money laundering, and developed the appropriate
tools for implementing such mechanisms, pursuant to the general policy for the
prevention and control of money laundering

7.  
That in accordance with the Delegations Manual, the Vice-President of Supply and
Marketing is competent to enter into this Amendment.

8.  
That in accordance with the dispositions contained in the Contracting Manual of
THE BUYER and having analyzed the nature and manner of implementing the
performance of the Parties on the occasion of this Amendment to the sales of
crude oil, the Authorized Officer has classified the risk as low, and therefore
dispenses the need to require a guarantee from THE SELLER.

9.  
That considering the contractual planning, the areas of Labor Relations Risk,
Coordination of Risks, Coordination of Budget and Accounting and Tax
Coordination of ECOPETROL S.A. were consulted, in order to avoid any labor, tax,
environmental, and other risks that may be generated for Ecopetrol as a result
of the execution and implementation of this Amendment.

10.  
That the Contract Administrator, after support it before the Manager, has
recommended that the Authorized Official sign this document.

11.  
That in compliance with the policy for preventing of money laundering and
terrorist financing adopted by THE BUYER, the legal representative of THE SELLER
declares under oath, subject to the penalties provided in the Penal Code:

a.  
That my resources (or the resources of the institution that I represent) come
from lawful activities and are linked to the normal development of my activities
(or the activities contained in the purpose of the company I represent), and
that, in the same sense, such resources do not come from any unlawful activity
contained in the Colombian Criminal Code or any law that substitutes, amends or
modifies it.
 
That I (or the entity I represent) have not made transactions or operations
destined to illicit activities referred to in the Colombian Criminal Code or any
law that substitutes, amends or modifies it, or to people connected with such
activities.

 
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b.  
That the resources compromised to the contract or legal relationship with THE
BUYER do not come from any unlawful activity referred to in the Colombian
Criminal Code or any law that substitutes, amends or modifies it.
 
That in the execution of the contract or legal relationship with THE BUYER, I
will not hire or have links to third parties that perform operations or whose
resources come from illicit activities referred to in the Colombian Criminal
Code or any law that substitutes, amends or modifies it.

c.  
That the institution I represent complies with the regulations on the prevention
and control money laundering and terrorist financing (ML / FT) that are
applicable (if any), having implemented the policies, procedures and mechanisms
to prevent and control of ML/FT arising from such laws. Certification model is
attached in Annex 1.
 
That neither I nor the institution I represent, or its shareholders, partners or
associates that directly or indirectly have FIVE PERCENT (5%) or more of the
capital, contribution or participation, legal representatives and members of the
Board of Directors, are on international lists binding for Colombia under
international law (United Nations lists) or in OFAC lists, being THE BUYER is
entitled to check if it deems appropriate and to terminate any business or legal
relationship if it verifies that any of those people are on these lists.
Certification model is attached in Annex 2.

d.  
That there is not against me or the entity I represent and its shareholders,
associates or partners that directly or indirectly have the FIVE PERCENT (5%) or
more of the capital, contribution or participation, their legal representatives
and members of the Board Directors, any  investigations or criminal proceedings
for a felony, THE BUYER is entitled to check if it deems appropriate in
databases or in national or international public information and to terminate
any legal relationship if it verifies that any of those people have
investigations or proceedings or have information is such public databases that
may place THE BUYER in legal or reputational risk.

e.  
That in the event that any of the circumstances described in the preceding two
paragraphs, I agree to immediately notify THE BUYER.

f.  
That with the signature of this document it is understood that I as well as the
person or legal entity that I represent, give our informed consent, and
therefore authorize THE BUYER to inform national authorities of any country in
which THE BUYER performs operations about any of the situations described
herein, and to provide to the relevant authorities of those countries, all
personal information, public, private or semiprivate that about me or the person
or company I represent, they require. Also, for THE BUYER to report to the
relevant authorities, taking into account its rules and manuals related to its
system of prevention and / or management of risk of money laundering and
terrorist financing, exonerating it from any liabilities derived from said act.

g.  
That all documents and information provided for the conclusion and execution of
the contract or legal transaction with THE BUYER is truthful and accurate, being
THE BUYER entitled to verify if it deems appropriate and to terminate the
contract or legal transaction, if verified, or has knowledge that it is not so.

h.  
Than any other person or legal entity has illegitimate interest in the contract
or legal transaction that encourages the execution of this declaration.

i.  
That I am aware, declare and accept that THE BUYER is under a legal obligation
to seek clarification as it considers appropriate in the event that
circumstances arise on the basis in which THE BUYER may have reasonable doubts
about my operations or the operations of the person or legal entity I represent,
as well as the origin of our assets, event in which we commit to provide the
corresponding clarifications. If these are not satisfactory, according to THE
BUYER, we authorize to terminate any legal or business relationship.

 
Taking into account the above, the Parties
 
 
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AGREE

FIRST CLAUSE. Modify article No. 1 (SOURCES OF SUPPLY AND VOLUME) of the
contract resulting from the acceptance of the Commercial Offer dated December
17, 2009 accepted by means of Purchase Order No. SOL-01-2009 issued on December
18, 2009, as follows:

“1. SOURCES OF SUPPLY AND VOLUME

THE BUYER agrees to acquire ninety percent (90%) of the volume of crude produced
and which is property of THE SELLER in Chaza Block, and THE SELLER agrees to
sell and deliver a volume equivalent to ninety percent (90%) of crude oil of its
property of the production of Chaza Block. The contract resulting from
acceptance of the commercial offer does not include the volume of crude oil
which is owned by the National Hydrocarbons Agency (ANH) corresponding to
royalties.

The obligations of THE BUYER and THE SELLER will last during the term set forth
in article No. 4 of the present document.

For purposes of this commercial offer and the contract arising from acceptance
of it, one barrel equals to one hundred and fifty-eight point nine hundred
eighty-eight (158.988) liters.

FIRST PARAGRAPH: DESTINATION OF CRUDE OIL. THE BUYER will destine the oil
purchase for exportation through the port of Tumaco. THE BUYER, upon prior
written notice to THE SELLER may allocate additional crude oil subject to the
present crude oil purchase for refinery in the country.

SECOND CLAUSE. Modify article No. 7 (DELIVERY PROGRAM) of the contract resulting
from the acceptance of the Commercial Offer dated December 17, 2009 accepted by
means of Purchase Order No. SOL-01-2009 issued on December 18, 2009, as follows:

“7. DELIVERY PROGRAM: THE SELLER shall deliver THE BUYER not later than the
third day (03) calendar day of each month copies of the nomination of delivery
for the following trimester. The final volume to receive by THE BUYER at the
point of delivery defined in the article No. 6 shall be drawn up every month in
accordance to the final schedule made by THE BUYER in accordance with paragraph
first and second of article No. six, and returned to THE SELLER before the tenth
(10) calendar day of each month.

Given that the above information is the basic premise for the planning process
of THE BUYER, the latter may refrain from receiving the crude oil if THE SELLER
does not provide the program within the established deadline.

THE SELLER is obliged to provide and carry information from the field on
production, liquidation of royalties, shipping by trucks (carrrotanque) and/or
pipeline indicating the participation and ownership of each and the official
receipt in the receipt station. To this end, THE BUYER shall send to THE SELLER
daily information requested through the volumetric integrator available via the
website, which’s User Manual is attached as Annex 1.

FIRST PARAGRAPH: Without prejudice of the dispositions contained in article No.
15 (ACTS OF GOD AND EXCULPATORY EVENTS), shall be considered exculpatory events:
1. In the event that within the agreed period THE BUYER cannot receive the
entire crude oil delivery at the Delivery Point, it shall inform THE SELLER with
a minimum of three (3) calendar days and as soon the contingency is overcome it
shall announce the date for the reactivation of the receipts. 2. Additionally,
in the event that for reasons specifically related to the operation of the
field, THE SELLER cannot deliver to THE BUYER the crude oil in any of the dates
specified in the program, it will inform THE BUYER in writing, with three (3)
calendar days prior to the respective deadline, and as soon as the contingency
is overcome, it shall announce the date for the resumption of deliveries.”
 
 
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THIRD CLAUSE.  Include article 26 (PENALTY CLAUSE) to the Contract, as follows:

“26. PENALTY CLAUSE

THE BUYER, based on the provisions contained in Articles 867 and 949 of the Code
of Commerce, and during the term of the contract arising from acceptance of the
commercial offer, may enforce the penalty clause to THE SELLER in the event of
default of any of the obligations that the latter assumes, or due to imperfect
or inappropriate compliance equal to or greater than five percent (5%) of the
obligation to deliver in one calendar month, if THE BUYER deems as relevant and
necessary.

In accordance to the provisions of the preceding paragraph, in the event of a
failure attributable to THE SELLER, THE SELLER agrees to pay to THE BUYER, as a
penalty, a sum equivalent to three point zero percent (3.0%) of the amount
corresponding to the final schedule for the month in which the breach occurs, a
value that is calculated using the actual export price for that month.

The value may be charged for each situation or act constituting infringement,
and its value will be compensated from the bill for the month following that one
in which it is notified by the Contract Administrator. THE SELLER expressly
authorizes THE BUYER to offset from the balances in their favor or any amounts
due by THE BUYER, the amount of the penalty clause.

In order for the offset to apply, the following procedure must be followed:

(i) The Contract Manager will notice THE BUYER of the events occurred.

(ii) Within the three (3) business days following receipt of notice, THE BUYER
may render explanations and indicate the reasons why it does not consider that
the infringement is attributable to THE BUYER.

 (iii) The Contract Manager will analyze the explanations provided by THE SELLER
and in case of being acceptable, will proceed to notice said decision; on the
contrary, will notice that the compensation or offtake foreseen in this clause
will apply (the same will apply in case THE SELLER does not provide any
justification).

If there is no balance in favor of THE SELLER, THE BUYER may collect the amounts
by means of a legal proceeding for which the contract arising from acceptance of
the commercial offer, together with the communications through which the penalty
clause becomes effective, will be considered to have merit to enforce the action
(prestarán mérito de título ejecutivo)

To make effective the penalty clause the report of the Contract Manager will be
enough.

By executing the penalty clause the rest of the obligations that have arisen in
virtue of the contract will not be considered to be extinct nor will exempt THE
SELLER from indemnifying any damages caused.”

FORTH CLAUSE.  This Amendment does not imply a novation to the contract arising
from acceptance of the commercial offer dated December 17, 2009 for the purchase
of crude oil produced in Chaza Block, which’s provisions remain intact except
for what was modified in this Amendment.
 
 
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FIFTH CLAUSE. This Amendment will be completed with the execution by the
Parties. For the performance of the dispositions within, the accreditation by
THE SELLER of the payment of the publication of this Amendment in the Public
Contracts Newspaper (Diario Único de Contratación Pública).

SIXTH CLAUSE. Each of the Parties acknowledges and accepts the taxes and/or
deductions that apply in accordance to the Law. The payment of all national,
departmental and municipal taxes, fees, charges, or similar that are caused or
will be cause by this Amendment, including but not limited to those incurred by
the celebration, formalization, implementation and termination or liquidation of
this Amendment or arising after the date of signature of this Amendment, shall
be borne by the taxpayer of the relevant tax, who must pay under the laws and
regulations.

In witness whereof, the Parties hereto have caused this Amendment to be duly
executed in Bogotá D.C. on the 8th day of November of 2010, in two copies of
equal value.

THE SELLER
 
THE BUYER
 
/s/ Julian Garcia Salcedo 

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JULIAN GARCIA SALCEDO
Legal Representative
 
 
/s/ Claudia L. Castellanos R.

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CLAUDIA L. CASTELLANOS R.
Vice-president of Supply and Marketing

 
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