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Vice-Presidency for Supply and Marketing
Addendum No. 2 Contract VSM-GPS-030-2011

Exhibit 10.1
ADDENDUM No. 2

CONTRACT:    VSM-GPS-030-2011
PURPOSE:
SALE & PURCHASE OF CHAZA, SANTANA AND GUAYUYACO CRUDE

SELLER:        GRAN TIERRA ENERGY COLOMBIA LTD
VALUE:        UNDETERMINED
The contracting parties, namely: ECOPETROL S.A., a decentralized entity of
national order, created by Law 165 of 1948, with NIT 899.999.068-1, organized as
a Mixed Company pursuant to the provisions of Article 2 of Law 1118 of 2006,
attached to the Ministry of Mines and Energy, with its head office in Bogotá,
D.C., whose Bylaws are contained entirely in Public Deed No. 5314 of December
14, 2007, granted by the Second Notary Public of the Circuit of Bogotá D.C. and
registered with the Chamber of Commerce of Bogotá D.C., hereinafter and for the
effects of this Addendum referred to as the “BUYER”, represented herein by JUAN
PABLO OSPINA., of legal age and domiciled in this city, bearer of Citizen
Identity Card Number 98.542.872 issued in Envigado, who in his capacity of Vice
President of Supply and Marketing (acting) and in exercise of the authorization
contained in the Manual of Authorizations to Contract, acts on behalf of and in
representation of this Company, and on the other, GRAN TIERRA ENERGY COLOMBIA
LTD., with NIT 860.516.431-7, hereinafter the “SELLER” and represented herein by
ALEJANDRA ESCOBAR HERRERA, bearer of ID No. 52.646.943, and IVAN TOBON GARCIA,
bearer of ID No. 79.731.294, acting in their capacity of Joint Legal
Representatives and duly authorized to enter into this Contract, as evidenced by
Certificate of Incorporation and Legal Representation attached hereto and who
states that neither he nor the Company he represents is affected by any cause of
disqualification or incompatibility provided in the Political Constitution or in
the Law that could prevent the execution of this Addendum.
Pursuant to the aforementioned conditions, BUYER and SELLER, who shall be
referred to jointly as the Parties and individually as a Party, agree to enter
into this Addendum, subject to the following:
CONSIDERATIONS AND REPRESENTATIONS
1.
That on June 27, 2011, ECOPETROL S.A. and GRAN TIERRA ENERGY COLOMBIA LTD
entered into Contract VSM-GPS-030-2011 whose purpose is the purchase of crude
produced under the Santana Risk-Sharing Contract (CPR-Santana), under the
Guayuyuco Association Agreement, and in Bloque Chaza, hereinafter the
“Contract”.

2.
That on January 30, 2012, ECOPETROL S.A. and GRAN TIERRA ENERGY COLOMBIA LTD
entered into Addendum No. 1 of Contract VSM-GPS-030-2011, whose purpose is the
change of the Delivery Points.

Cra. 7a No. 37-69 Piso 5, Bogotá, D.C. Colombia. Telephone:
(571) 2344606

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Vice-Presidency for Supply and Marketing
Addendum No. 2 Contract VSM-GPS-030-2011

3.
That bearing in mind that the parties wish to continue the sale and purchase of
the crude produced under the Santana Risk-Sharing Contract (CPR-Santana), under
the Guayuyuco Association Agreement, and in Bloque Chaza for the next four (4)
months, it is necessary to sign this Addendum No. 2, hereinafter the “Addendum”.

4.
That only for documentary, evidentiary and invoicing effects it is deemed
pertinent to modify the pricing and invoicing formulae of Contract
VSM-GPS-030-2011, for which reason they are included in this Addendum No. 2.

5.
That the Administrator and Manager of Contract VSM-GPS-030-2011 have evaluated
in coordination the need to modify and clarify the original Contract and its
Addendum No. 1 by entering into this Addendum. Moreover, in compliance with the
Contractor Management Procedure (ECP-DAB-P-032), the latest partial performance
assessment of SELLER was duly presented.

6.
That for the effects of entering into this Addendum BUYER previously verified in
the Fiscal Liabilities Bulletin prepared and published by the
Comptroller-General of the Republic that SELLER does not appear in such Bulletin
as one of the persons against whom a definitive ruling on fiscal liability has
been issued and who have failed to satisfy the obligation contained therein.
Moreover, BUYER implemented the control mechanisms related to the laundering of
assets and developed the instruments for the adequate application of such
mechanisms, pursuant to the Policy of Prevention of Laundering of Assets and of
the Financing of Terrorism.

7.
That pursuant to the provisions of the Manual of Authorizations to Contract of
ECOPETROL S.A., the Vice-President for Supply and Marketing is the person
competent to enter into this Addendum.

8.
That in its expense budget BUYER has the respective budgetary availability for
the execution of the Addendum referred to herein.

9.
That pursuant to the provisions of the Contracting Manual of BUYER and after
analyzing the nature and manner of execution of the services rendered by the
Parties under this Addendum, the Authorized Official has qualified the risk as
low and therefore dispensed with requiring a guarantee by SELLER.

10.
That in attention to the contractual scheduling performed, the area of Tax
Management of ECOPETROL S.A. was consulted in order to avoid any tax risk that
might arise for the Company as a result of entering into and executing this
Addendum.

Cra. 7a No. 37-69 Piso 5, Bogotá, D.C. Colombia. Telephone:
(571) 2344606

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Vice-Presidency for Supply and Marketing
Addendum No. 2 Contract VSM-GPS-030-2011

11.
That in compliance with the Policy of Prevention of Laundering of Assets and of
the Financing of Terrorism adopted by BUYER, the Legal Representative of SELLER
declares, under oath and subject to the sanctions established in the Penal Code:

I.
That my resources (or the resources of the entity I represent) come from legal
activities and are associated with the normal development of my activities (or
the activities that are typical of the social purpose of the company I
represent) and that, on the other hand, such resources do not come from any
illegal activity among those contemplated in the Colombian Penal Code or in any
regulation that may substitute, be added to or modify such Code.

II.
That I (or the entity I represent) have (has) not executed transactions or
operations intended for any illegal activity that is contemplated in the
Colombian Penal Code or in any regulation that may substitute, be added to or
modify such Code, or in favor of persons involved in such activities.

III.
That the resources committed to Contract VSM-GPS-030-2011 or to the legal
relationship with BUYER do not come from any illegal activity that is
contemplated in the Colombian Penal Code or in any regulation that may
substitute, be added to or modify such Code.

IV.
That in the execution of Contract VSM-GPS-030-2011 or the legal relationship
with BUYER I will not contract nor will I have any contact with third parties
who conduct operations or whose resources come from any illegal activity that is
contemplated in the Colombian Penal Code or in any regulation that may
substitute, be added to or modify such Code.

V.
That the entity I represent observes the regulations on prevention and control
of the laundering of assets and financing of terrorism (LA/FT) that may be
applicable to it (as the case may be), having implemented the LA/FT policies,
procedures and prevention and control mechanisms that derive from such legal
provisions. Certification model is attached in Exhibit 1.

VI.
That neither I nor the entity I represent, nor its shareholders, associates or
partners who directly or indirectly hold FIVE PERCENT (5%) or more of the
capital stock, contribution or participation, their legal representatives and
members of the Board of Directors, figure on the international lists that are
binding on Colombia according to international law (the United Nations lists) or
on the OFAC lists, BUYER being empowered to conduct the investigations it deems
appropriate and to terminate any commercial or legal relationship if it
determines that any of such persons figures on the above-mentioned lists.
Certification model is attached in Exhibit 2.

VII.
That no investigations or criminal procedures FOR INTENTIONAL CRIMES are under
way against myself or the entity I represent, or its shareholders, associates or
partners who directly or indirectly hold FIVE PERCENT (5%) or more of the
capital stock, contribution or participation, their legal representatives and
members of the Board of Directors, BUYER being empowered to conduct the
verifications it deems appropriate

Cra. 7a No. 37-69 Piso 5, Bogotá, D.C. Colombia. Telephone:
(571) 2344606

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Vice-Presidency for Supply and Marketing
Addendum No. 2 Contract VSM-GPS-030-2011

in public national or international databases or information and to terminate
any commercial or legal relationship if it determines that there are ongoing
investigations or procedures or there is information on such public databases
that may place BUYER in a position of legal or reputational risk.
VIII.
That in the event that any of the situations described in the above two
paragraphs occurs, I undertake to communicate same immediately to BUYER.

IX.
That by signing this document it is understood that both I and the natural or
legal person I represent grant our informed consent, and we therefore authorize
BUYER to communicate to the national authorities or those of any of the
countries with which BUYER conducts operations, regarding any of the situations
described in this document, as well as to provide the competent authorities of
such countries with all the personal, public, private or semi-private
information on me or on the natural or legal person I represent, that they may
require. Furthermore, that BUYER submit any reports to the competent authorities
that it deems appropriate pursuant to its regulations and manuals in relation to
the system of prevention and/or administration of the risk of laundering of
assets and financing of terrorism, releasing it from any liability in such
regard.

X.
That all the documentation and information provided for the entering into and
execution of the contract or legal business with BUYER is true and exact, BUYER
being empowered to conduct the verifications it deems appropriate and to
terminate the contract or the legal business if it determines or becomes aware
that the above is not so.

XI.
That no other natural or legal person has an illegitimate interest in the
Contract or legal business that is the reason for the signing of this
declaration.

XII.
That I know, declare and accept that BUYER is under the legal obligation to
request the clarifications that it considers appropriate in the event that
circumstances arise based upon which BUYER may have reasonable doubts regarding
my operations or the operations of the natural or legal person I represent, or
the origin of our assets, in which case we undertake to provide the respective
clarifications. If these are not satisfactory, in the opinion of BUYER, we
authorize it to terminate any commercial or legal relationship.

Based on the above, the Parties

HEREBY AGREE

FIRST CLAUSE. Modify the SECOND CLAUSE. PRICE of Contract VSM-GPS-030-2011,
which will now read as follows:

“SECOND CLAUSE. PRICE: The price to be paid for the crude that is the subject of
this Contract, delivered at the Delivery Point(s) indicated in the Sixth Clause
of the Addendum

Cra. 7a No. 37-69 Piso 5, Bogotá, D.C. Colombia. Telephone:
(571) 2344606

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Vice-Presidency for Supply and Marketing
Addendum No. 2 Contract VSM-GPS-030-2011

No. 1, shall be established as indicated below for the different components that
form part of the following formula(s):
A.
For crude exported as South Blend through the port at Tumaco and received in the
Tumaco Plant:

Crude Price =         Marker – Port Operation Fee – Commercialization Fee
Each of the above elements is defined below:
Marker: Corresponds to the average export price for South Blend Crude in USD/bbl
achieved by the International Trade Management of Ecopetrol S.A. (including
crudes negotiated for the affiliates) in the month of deliveries through the
Port at Tumaco. This price shall be reported by BUYER. The reference quality for
South Blend is 29.3° API and 0.62% Sulfur (S). If no exports are made for the
delivery month, the Parties shall apply as a provisional and definitive price
the price defined in the First Paragraph of the Second Clause of this Document.
Port Operation Fee: Corresponds to a value of zero point seven zero one six
United States Dollars (US$ 0.7016) per barrel.
Commercialization Fee: Corresponds to a value of one United States Dollar and
fifty cents (US$ 1.50) per barrel
B.
For crude exported as Oriente Crude through Ecuador received at the Orito
Station:

Crude Price =
Marker – Transportation (Delivery Site/Port of Shipment) – Transportation Tax –
Commercialization Fee

Each of the above elements is defined below:
Marker: Corresponds to the real weighted average price of the exports made by
BUYER of Oriente Crude in the month of deliveries or in those that include the
crude dispatched by BUYER, through the Port of Balao associated with the
deliveries. If no exports are made for the delivery month through the Port of
Balao, the Parties shall apply the next export price which includes crude owned
by BUYER.
Transportation (Delivery Site/Port of Shipment): Determined as the sum of the
following fees:
Section
Resolution of the MME
100% Base Rate
MME US$/BBL
Orito – San Miguel (OSO)
124572
2.3472
La Ye – Orito (OMO)
124560
0.5387
Total Transport
 
2.8859

•
Additionally, the fee charged by PETROECUADOR for the transportation of crude
between San Miguel and the Port of Balao.

Transportation Tax: Determined as set forth in Article 52 of the Petroleum Code
of Colombia for the national transport systems indicated in the above
subsection. For the Ecuadorian section the respective tax, if applicable, shall
be taken into account from the delivery site to the port of shipment.

Cra. 7a No. 37-69 Piso 5, Bogotá, D.C. Colombia. Telephone:
(571) 2344606

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Vice-Presidency for Supply and Marketing
Addendum No. 2 Contract VSM-GPS-030-2011

Transportation System
100% Base Rate
MME US$/BBL
Transport Tax %
Transport Tax US$/BBL
Orito – San Miguel (OSO)
2.3472
2%
0.0469
La Ye – Orito (OMO)
0.5387
2%
0.0108
Total Transport Tax
2.8859
2%
0.0577

Commercialization Fee: Corresponds to a value of one United States Dollar and
fifty cents (US$ 1.5) per barrel

C.
For crude delivered to the Estación Dina to be exported through the port at
Coveñas or for refining:

Crude Price =
Marker – Transportation (Delivery Site/Port of Shipment) – Transportation Tax –
Commercialization Fee – Port Operation Fee – Unloading Fee

Each of the above elements is defined below:
Marker: Corresponds to the average export price of the Grupo Empresarial of the
Vasconia export blend crude through the Port of Coveñas negotiated for the month
of deliveries of crude. This price shall be reported by BUYER. The reference
quality for Vasconia export blend crude is 24.8° API and 0.97% Sulfur (S). In
the event that Grupo Empresarial Ecopetrol fails to export during the month of
the deliveries, the marker shall correspond to the export average of Vasconia
Crude reported by Argus and Platts for the month of the deliveries. This value
shall be reported monthly by BUYER.
Transportation (Delivery Site/Port of Shipment): Determined as the sum of the
fees established by the Ministry of Mines and Energy for the pipelines between
Tenay and Coveñas. The pipeline transport fees will be adjusted yearly for the
“Phi” factor in accordance with what is established by the Ministry of Mines and
Energy. The fees to be applied for the year 2012 are:
Section
Approval Resolution
100% Base Rate
MME US$/BBL
Tenay – Vasconia
OAM
2.6035
Vasconia – Coveñas ODC
ODC
1.7053
Total Transport
 
4.3088

Transportation Tax: Determined as set forth in Article 52 of the Petroleum Code
of Colombia (or the regulation that modifies same) for the national transport
systems indicated in the above subsection, as detailed below:

Cra. 7a No. 37-69 Piso 5, Bogotá, D.C. Colombia. Telephone:
(571) 2344606

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Vice-Presidency for Supply and Marketing
Addendum No. 2 Contract VSM-GPS-030-2011

Section
MME Fee
US$/bbl.
% Transport tax
Transport Tax US$/bbl.
Tenay – Vasconia
2.6035
2%
0.0521
Vasconia – Coveñas ODC
1.7053
2%
0.0341
Total Tax
4.3088
 
0.0862

Commercialization Fee: Corresponds to a value of one United States Dollars and
fifty cents (US$ 1.5) per barrel
Port Operation Fee: Corresponds to a value of zero point six one one zero United
States Dollars (US$ 0.6110) per barrel.
Unloading Fee: Corresponds to the value charged by the Vice-presidency of
Production or the corresponding area for the unloading and handling service at
Estación Dina. While this value is not available a value of zero US Dollars
shall be applied per barrel (US$ 0.00/BBL).
PARAGRAPH ONE: The price determined using the above-mentioned formula comprises
the different costs of transport, handling, metering and transport taxes for
account of SELLER caused up until the delivery of the crude subject to this
Contract at the Delivery Point(s); therefore BUYER shall not deduct or recognize
any additional amount for the above concepts.
PARAGRAPH TWO: When the Parties agree on Delivery Point(s) other than those
established in the Sixth Clause of this Contract, the price formula established
in this Clause shall be modified in the transportation item, taking into account
the crude transport fees and taxes per pipeline in force between the Delivery
Point(s) and the exportation point that may apply. The marker will also be
modified when applicable, by prior agreement between the Parties.
PARAGRAPH THREE: The reception and fiscal control costs in the case of the
stations agreed upon between the Parties and which are not operated by ECOPETROL
S.A. shall be directly recognized by SELLER to the respective operating company.
BUYER will recognize no additional charge for such concepts.
PARAGRAPH FOUR: RENEGOTIATION OF PRICES. The Parties may request a review of the
price established in this Clause provided the following events arise:
a)
A change of more or less two (2) degrees API in the quality of the crude oil
produced in the contracted field/area/block/contract.

b)
A change of more or less two (2) degrees API in the quality of the Marker Crude
during three (3) consecutive months. In such event the request for review shall
be submitted during the month following the period of three (3) consecutive
months.

c)
In the event that the Marker Crude disappears or it becomes necessary to define
a new Marker.

The Parties shall have a term of thirty (30) business days to negotiate. If they
reach an agreement, this shall be evidenced in an addendum signed by BUYER and
SELLER and its content shall apply as of the day following the date on which
such addendum is signed.

Cra. 7a No. 37-69 Piso 5, Bogotá, D.C. Colombia. Telephone:
(571) 2344606

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Vice-Presidency for Supply and Marketing
Addendum No. 2 Contract VSM-GPS-030-2011

If, upon expiry of the thirty (30) business day period, an agreement has not
been reached, BUYER or SELLER may inform the other its intention to terminate
the Contract pursuant to its Twenty-Second Clause of this Contract.
The termination shall not release the Parties from performance of any
obligations that may have already been caused.
PARAGRAPH FIVE: QUALITY SPECIFICATIONS. The quality of the crude received shall
be certified by BUYER at the Delivery Point indicated in the Fifth Clause and
shall meet the following quality specifications:
Field/Contract
Minimum API°
Maximum SULFUR (% weight)
Maximum BS&W (% volume)
Maximum SALT (lb./1000 bbl.)
Santana and Guayuyaco
29.0°
0.7
0.5
20.0
Chaza
29.0°
0.41
0.5
20.0

1.
The density of the crudes shall be determined using the ASTM-D-1298 laboratory
method (Method for determining density, specific density (Specific Gravity) or
API Gravity of the crude and liquid petroleum products by the Hydrometer
method).

2.
The water and sediment content, BS&W shall be determined using the following
methods:

Water in suspension ASTM-D4377 “Standard Test Method for Water in Crude Oils by
Potentiometric Karl Fischer Titration” and Sediments ASTM-D473 “Standard Test
Method for Sediment in Crude Oils and Fuel Oils by the Extraction Method”, for
the content of water and sediment in the crude maximum individual values will be
accepted of: 0.5% volume for water and 0.01% volume for sediments.
3.
The sulfur content shall be determined using the ASTM-D4294 ”Standard Test
Method for Sulfur in Petroleum and Petroleum Products by Energy Dispersive X-ray
Fluorescence Spectrometry”.

4.
The salt content shall be determined using the ASTM-D3230 method “Standard Test
Method for Salts in Crude Oil (Electrometric Method)” 

When the BS&W and Salt specifications of the crudes received at Estación Dina
and at Estación Orito for crude exported as Oriente Crude through Ecuador
indicated herein are not within the allowed margin, BUYER reserves the right to
receive the crude and purchase it at a BS&W and Salt adjusted price. In such
cases the crude price shall be adjusted according to the following tables:

Cra. 7a No. 37-69 Piso 5, Bogotá, D.C. Colombia. Telephone:
(571) 2344606

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Vice-Presidency for Supply and Marketing
Addendum No. 2 Contract VSM-GPS-030-2011

BS&W Content
% Volume
Correction
(US$/bbl.)
Charged to
0.51 to 0.80
0.1
SELLER
0.81 to 1.00
0.2
SELLER
1.01 to 1.20
0.3
SELLER
1.21 to 1.50
0.4
SELLER
> 1.51
Will not be received
 
Salt Content
Pounds per one hundred thousand barrels
Correction
(US$/bbl.)
Charged to
20.1 to 30.0
 
SELLER
30.1 to 40.0
 
SELLER
40.1 to 60.0
 
SELLER
60.1 to 80.0
 
SELLER
80.1 to 100.0
 
SELLER
> 100.0
Will not be received
 

It shall be understood that SELLER shall make every effort possible to deliver
the crudes subject to this Contract with the BS&W and Salt contents within the
agreed parameters. Such corrections shall be applied to daily deliveries and for
each batch delivered.
In the event that the deliveries of crude exceed the maximum values in the table
(1.51% BS&W and 100 pounds of salt per one hundred thousand barrels) and if
BUYER decides to opt to receive the crude, the Parties shall agree on the
corresponding correction value and this shall be evidenced in an addendum signed
by the Parties. In the event that an agreement is not reached, BUYER may reject
the crude.

PARAGRAPH SIX: Reimbursable expenses: Reimbursable expenses shall not be more
than forty million pesos (COP $ 40,000,000) without VAT per year and shall be
previously authorized and approved by BUYER. For this concept solely and
exclusively the cost of the independent inspector mentioned in the Second
Paragraph of the Second Paragraph of the Fifth Clause of Contract
VSM-GPS-030-2011 will be recognized.

The amount of the reimbursable expenses shall not form part of the value of
Contract VSM-GPS-030-2011. The management of the reimbursable expenses shall be
performed pursuant to the procedure that BUYER has in force for such type of
expenditure (Exhibit 3).”

SECOND CLAUSE: Modify the THIRD CLAUSE. INVOICING AND PAYMENT of Contract
VSM-GPS-030-2011, which shall now read:

Cra. 7a No. 37-69 Piso 5, Bogotá, D.C. Colombia. Telephone:
(571) 2344606

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Vice-Presidency for Supply and Marketing
Addendum No. 2 Contract VSM-GPS-030-2011

“THIRD CLAUSE. INVOICING AND PAYMENT: SELLER shall invoice and collect from
BUYER the value of the crude sold pursuant to the terms of this document, in the
Bogota Accounts Payable office, within the first ten (10) working days of the
month following the month of the delivery(-ies) of crude to BUYER. Within the
first six (6) working days of the month following the deliveries, BUYER shall
provide SELLER with the information that latter requires to prepare the
corresponding invoicing. The invoices shall be submitted to the Accounts Payable
office of BUYER in Bogotá and their valid presentation date for payment effects
shall be that which is indicated as their date of reception in the Accounts
Payable office of the BUYER in Bogotá. Invoicing shall be made based on the net
volumes, free of water and sediment, corrected to sixty (60) degrees Fahrenheit
received at the Delivery Point(s). The presentation of official forms Table N° 4
and/or Form N° 9SH of the Ministry of Mines and Energy shall be required for
approval of invoices. In the event that the Ministry of Mines and Energy has
failed to deliver Tables N° 4 and/or Form N° 9SH corresponding to the month
being invoiced, Tables N° 4 and/or Form N° 9SH submitted to the Ministry of
Mines and Energy that are pending signing shall be temporarily accepted, but
every quarter SELLER shall send BUYER copies of Tables N° 4 and/or Form N° 9SH
for the immediately preceding quarter duly processed and signed by the Ministry
of Mines and Energy.

Bearing in mind the authorization of payments in foreign currency contained in
Article 51 of External Resolution Number 8 of 2000 of the Board of Directors of
the Banco de la República, which provides that the sale-purchases of
nationally-produced crude oil and natural gas executed by BUYER and other
entities dedicated to the industrial activity of petroleum refining may be paid
in foreign currency, the invoicing that SELLER issues for the supply of crude to
BUYER may be made in United States Dollars.

In all cases, payment shall be made 100% in Dollars at thirty (30) calendar days
following the submission of the invoices duly processed, prior legal
withholdings, if applicable. SELLER shall previously inform BUYER in writing the
bank account where the respective payment is to be deposited.

FIRST PARAGRAPH: Deliveries to Port of Tumaco: Deliveries of crude shall be
provisionally invoiced, based on the volumes and prices reported by the Crude
Purchasing Coordination of Ecopetrol S.A. during the first six (6) business days
following the end of the month of the deliveries; the final invoicing shall be
made based on the volumes compensated in the official volumetric compensation
document prepared by the Vice-presidency of Transport and Logistics of Ecopetrol
or whoever takes its place.

Once the volumetric compensation is received, SELLER is responsible for
invoicing and submitting to the Accounts Payable office of BUYER the respective
adjustments, within the

Cra. 7a No. 37-69 Piso 5, Bogotá, D.C. Colombia. Telephone:
(571) 2344606

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Vice-Presidency for Supply and Marketing
Addendum No. 2 Contract VSM-GPS-030-2011

following three (3) business days after receipt of the volumetric compensation,
taking into account the date of receipt at the Accounts Payable office of
Ecopetrol.

For the months when there are no exports of South Blend crude through the Port
of Tumaco, the provisional price shall correspond to the weighted average by
volume reported in the trade balance corresponding to the last month in which
there has been exports of South Blend crude or the blend exported through the
Port of Tumaco.

For the final invoicing, the final volumes volumetrically compensated by the
Vice-presidency of Transport and Logistics (VIT) or whoever takes it place shall
be invoiced at the weighted average export price per volume of South Blend or
the blend exported through the Port of Tumaco for the month of deliveries or in
the event no exports were made in the month of deliveries for the following
month in which exports are made.

Pursuant to the conditions established in this Contract, no payments shall be
made for volumes not received at the Tumaco plant.

SECOND PARAGRAPH. For deliveries to the Estación Orito for export through
Ecuador: In the event that at the date of invoicing of the crude for export
through the Port of Balao, there is no information on final export price,
exported volumes or fees charged by Petroecuador, invoicing shall be done
provisionally with the volume of crude dispatched from Estación Orito prorated
according to the volumes delivered by each operator. The price used shall
correspond to the arithmetical average of the daily quotes for Oriente crude
reported by Platts for the days on which crude was pumped towards Lago Agrio.

THIRD PARAGRAPH. BUYER shall have a period of ten (10) business days, counted as
of receipt of the crude sales invoices, to review or challenge them. If there
are objections to the invoices, the reception date shall be that of the
submission of the new invoice. BUYER shall inform SELLER, within the term
provided, regarding any invoice that is objected in order that it be adjusted
and corrected, clearly specifying the items that are to be adjusted and
corrected and the corresponding reasons. SELLER shall respond to the objection
within the ten (10) business days following its receipt, counted as of the
moment that BUYER submits to SELLER all the documents that gave rise to the
objection, unless the Parties decide by mutual agreement to extend such term due
to the complexity of the objection or any other reasonable circumstance that so
merits.

In the event that SELLER fails to respond to the objection within the specified
term, the objection shall be deemed accepted by SELLER. If SELLER resolves the
objection in favor of BUYER it will be understood that there was no payment
obligation over the invoice originally submitted and which was subject to
objection. If SELLER resolves the objection

Cra. 7a No. 37-69 Piso 5, Bogotá, D.C. Colombia. Telephone:
(571) 2344606

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Vice-Presidency for Supply and Marketing
Addendum No. 2 Contract VSM-GPS-030-2011

in its favor, BUYER shall take the necessary steps to resolve the dispute as
quickly as possible, based on the provisions of this Contract, for the purpose
of making the payment of the sum left unpaid. To resolve any discrepancy, each
of the Parties shall send the other Party copies of the documents that gave rise
to the invoice and to the challenge. In the event that BUYER disagrees with the
decision of SELLER, the provisions of the Seventeenth Clause of this document
may be applied.

FOURTH PARAGRAPH: In the event of unjustified delay in the payment of invoices
not timely challenged by BUYER pursuant to the provisions in the Third Paragraph
of this Clause, BUYER shall accept to pay SELLER, as interest payable in Pesos,
the maximum interest on arrears authorized by the Financial Superintendent of
Colombia over the days of arrears effectively elapsed.

In order to assess the late-payment interest, the amount of the invoice(s) in US
Dollars that is(are) in arrears shall first be converted into Colombian Pesos at
the representative market exchange rate of the date of issue, as certified by
the Financial Superintendent of Colombia.

The invoices for collection of interest shall be paid by BUYER thirty (30)
calendar days following their receipt by BUYER.

Both BUYER and SELLER acknowledge that the invoices issued, as well as this
Contract shall have right of execution and BUYER and SELLER expressly waive
private or judicial requirements for constitution of arrears.

FIFTH PARAGRAPH: In the event that SELLER is interested in factoring the
invoices issued in relation to this Addendum, it shall first offer such option
to BUYER.

THIRD CLAUSE: Modify the FOURTH CLAUSE. TERMS of Contract VSM-GPS-030-2011,
which shall now read:

“FOURTH CLAUSE. TERMS OF THE CONTRACT: The term of the Addendum shall commence
upon its signing date and shall include the term of execution and that of
liquidation.

The term of execution of the Contract shall be computed as of the signing of
this document and shall terminate on the thirtieth (30th) of November, two
thousand and twelve (2012).

Within a period of four (4) months counted as of the date of termination of the
execution term of the Addendum, the Parties shall sign the respective
liquidation minutes.

Cra. 7a No. 37-69 Piso 5, Bogotá, D.C. Colombia. Telephone:
(571) 2344606

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Vice-Presidency for Supply and Marketing
Addendum No. 2 Contract VSM-GPS-030-2011

In the event that SELLER fails to appear at the liquidation or has not agreed to
its content within the above-mentioned term, SELLER expressly authorizes BUYER
to proceed to unilaterally liquidate within a period of two (2) months.”

FOURTH CLAUSE: This Addendum does not constitute novation of Modify of Contract
VSM-GPS-030-2011 and its Addendum 1, whose clauses, the content of which has not
been expressly clarified and specified in this document, shall remain in force.

FIFTH CLAUSE: TAXES: All the taxes that are caused by reason of the signing,
development, execution and liquidation of this Addendum, except for those that
correspond strictly to BUYER, are for the exclusive account of SELLER. BUYER
shall make the tax withholdings established by Law over the accounts of SELLER.

SIXTH CLAUSE: The Parties agree to attribute the scope of transaction to the
agreements contained in this document, pursuant to the provisions established in
the regulations currently in force, thus maintaining the contractual, economic
and financial balance of Contract VSM-GPS-030-2011.

SEVENTH CLAUSE: This Addendum is formalized by its signing by the Parties.

In evidence, two counterparts of the same tenor are signed in Bogotá D.C. on the
thirty-first (31st) day of July, two thousand and twelve (2012)

THE SELLER
THE BUYER

/s/ Alejandra Escobar H.
ALEJANDRA ESCOBAR H.
Legal Representative

/s/ Ivan Tobon G.
IVAN TOBON G.
Legal Representative

/s/ Juan Pablo Ospina
JUAN PABLO OSPINA
Vice-President for Supply and Marketing

EXHIBIT 1. Model certification of application of the LA/FT regulations for
companies obliged to adopt the LA/FT prevention systems.
EXHIBIT 2. Certificate of shareholdings of associates, shareholders and partners
with a participation of more than five percent (5%) in the capital stock.

Cra. 7a No. 37-69 Piso 5, Bogotá, D.C. Colombia. Telephone:
(571) 2344606

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Vice-Presidency for Supply and Marketing
Addendum No. 2 Contract VSM-GPS-030-2011

EXHIBIT No. 1

MODEL CERTIFICATION OF APPLICATION OF THE LA/FT REGULATIONS FOR COMPANIES
OBLIGED TO ADOPT THE LA/FT PREVENTION SYSTEMS

ONLY OBLIGATORY FOR COUNTERPARTIES WHO BY REASON OF LEGAL REGULATIONS ARE
OBLIGED TO ADOPT LA/FT PREVENTION SYSTEMS

The purpose of this document is to certify before ECOPETROL S.A. that our entity
has a SYSTEM FOR THE PREVENTION AND CONTROL OF LAUNDERING OF ASSETS AND FINDING
OF TERRORISM, which fully complies with applicable Colombian regulations.

I, the undersigned, ___________, in my capacity of legal representative of Gran
Tierra Energy Colombia Ltd. (THE ENTITY) hereby CERTIFY that:

1.
THE ENTITY complies with the Colombian rules and regulations related to the
prevention and control of laundering of assets and financing of terrorism that
are applicable to it.

Yes __         No ___
2.
THE ENTITY has in place the appropriate policies, manuals and procedures for the
prevention and control of laundering of assets and financing of terrorism that
are in full compliance with the regulations in force that are applicable to it.

Yes __         No ___
3.
Has THE ENTITY been involved in investigations for violation of the laws related
to the Laundering of Assets and Financing of Terrorism?

Yes ___         No __
4.
Has THE ENTITY or any of its employees or directors been sanctioned for
violation of the laws related to the Laundering of Assets and Financing of
Terrorism?

Yes ___         No __
Please fill out the following details of the complying officer or employee:
Name:_____ __________________________________________________
Telephone:______________________________
Email:__________________________________
Address:_________________________________________________________________________
                         
We declare that we authorize ECOPETROL S.A., either directly or through the
persons it appoints, to verify and confirm the information provided herein
including the effective application of the SYSTEM FOR THE PREVENTION AND CONTROL
OF LAUNDERING OF ASSETS AND FINDING OF TERRORISM within our entity.

Comments:____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Cra. 7a No. 37-69 Piso 5, Bogotá, D.C. Colombia. Telephone:
(571) 2344606

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Vice-Presidency for Supply and Marketing
Addendum No. 2 Contract VSM-GPS-030-2011

EXHIBIT No. 2

CERTIFICATE OF SHAREHOLDINGS OF ASSOCIATES, SHAREHOLDERS AND PARTNERS WITH A
PARTICIPATION OF MORE THAN FIVE PERCENT (5%) IN THE CAPITAL STOCK

THIS CERTIFICATION IS ONLY REQUIRED IN THE CASE OF LEGAL ENTITIES WHICH, BY
THEIR NATURE, THEIR SHAREHOLDERS OR ASSOCIATES DO NOT FIGURE IN THE CERTIFICATE
OF THE CHAMBER OF COMMERCE

I hereby certify that the associates, shareholders or partners who have more
than a FIVE PERCENT (5%) participation in the capital stock of the entity that I
represent are the individuals or legal entities that appear in the list below:

NAME OF SHAREHOLDER, PARTNER OR ASSOCIATE
IDENTIFICATION
NUMBER OF SHARES, QUOTAS OR OUTSTANDING INTEREST
PARTICIPATION IN THE CAPITAL STOCK (%)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

I hereby certify that the real and controlling beneficiaries of the entity that
I represent are the following individuals:

Name
Identification
 
 
 
 
 
 

Name of the
entity:_________________________________________________________________________
NIT:____________________________________________________________________________________
Name of the legal
representative:____________________________________________________________
Identification
Number______________________________________________________________________
Signature of the legal representative

__________________________________________________________________________________

Cra. 7a No. 37-69 Piso 5, Bogotá, D.C. Colombia. Telephone:
(571) 2344606