Unassociated Document


    Exhibit
10.1

    


    ENGLISH TRANSLATION — EXECUTED
DOCUMENT IS IN SPANISH

    


    Bogotá
D.C., December 17, 2009


    


    Mister

    EDGAR
LOUIS DYES

    Legal
Representative

    GRAN
TIERRA ENERGY COLOMBIA LTD.

    Carrera 7
No. 113-43 Of. 1502


    


    Subject: Commercial Offer to Purchase “Chaza”
Crude Oil

    


    By means
of this Commercial Offer, ECOPETROL S A, a company with mixed capital (private
and public) authorized by Law 1118 of 2006, linked to the Ministry of Mines and
Energy, acting pursuant to its by-laws with domicile in the city of Bogotá, with
Tax ID No. 899.999.068-1, hereinafter and for purposes of this Offer, referred
to as ECOPETROL or THE BUYER, represented in this act by CLAUDIA L CASTELLANOS,
of legal age and resident of this city, identified with citizenship card number
63.314.635 issued in Bucaramanga, in her capacity as Vice-president of Supply
and Marketing and exercising the authorization contained in the Delegations
Manual, acting on behalf of, and representing this Company, presents to GRAN
TIERRA ENERGY COLOMBIA LTD, hereinafter THE SELLER, a Commercial Offer for the
purchase of crude oil as defined in article one (1) of the terms and conditions
of this offer.

     

    TERMS
AND CONDITIONS OF THE OFFER

    


    
      	
              1.  

            	
              SOURCES
      OF SUPPLY AND VOLUME

            


    

    


    THE BUYER
undertakes the obligation to acquire and pay 100% of all the crude oil owned by
THE SELLER produced in the “Chaza” Block, and THE SELLER on the other hand
undertakes the obligation to sell and deliver 100% of the crude oil of its
property, pursuant to the terms and conditions of this document. This contract
does not include the volume of crude whose owner is the “Agencia Nacional de
Hidrocarburos (ANH)” (National  Hydrocarbons
Agency) corresponding to royalties.

    


    The
obligations of the BUYER and seller shall be extended during the term of
execution set forth in article four (4) of the document hereof.

    


    For
purposes of this Offer and the Contract resulting from the acceptance of it, one
barrel is equivalent to one hundred fifty eight point nine hundred eighty eight
(158.988) liters.

    


    FIRST PARAGRAPH: DESTINATION
OF THE CRUDE OIL. THE BUYER shall destine the crude purchased for export 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.

     

    
      
        
        

      

      
        1

        
          

        

      

      
        
        

      

    

    


    
      	
              2.  

            	
              PRICE

            


    

    


    The price
to be paid for the crude oil purpose of this Offer, placed in the Delivery Point
(s) indicated in article six of this document shall be established as the
monthly average corresponding to the month of the delivery of crude oil for the
different components which comprise the following formula(s):

    


    
      	
              A.  

            	
              For
      crude oil exported as Southblend by the port of Tumaco and received at the
      Orito Station:

            


    

    


    Crude
Price = WTI – Marker Discount +/- Adjustment for Quality – Transportation (Site
of Delivery/Port of Loading) – Transportation Tax – Handling and
Commercialization Fee.

    


    Each of
the above terms is defined as follows:

    


    WTI: Corresponds to the
arithmetic average of the daily quote of the West Texas Intermediate crude, WTI
NYMEX, in dollars per barrel of the month of deliveries.

    


    Marker Discount: Corresponds
to the average discount of export of THE BUYER of South Blend Crude by the Port
of Tumaco negotiated for the month after the month of delivery of crude. THE
BUYER shall report this discount. The reference quality of the South Blend Crude
is 30.3° API and 0.59%
Sulfur (S), and the same shall be monthly updated with real average data of the
exports made by THE BUYER by the Port of Tumaco.

    


    Adjustment for Quality: Shall
be established in accordance with the provisions in the Fifth Paragraph of this
article.

    


    Transportation (Site of Delivery/Port
of Loading): This is determined as the sum of the fees established by the
Ministry of Mines and Energy for pipelines between the Orito Station and the
Port of Tumaco. The transportation fees for pipelines are updated at the
beginning of each year by the “F” Factor as indicated by the Ministry of Mines
and Energy. The applicable fees for the year 2009 are:

    


    
      	
              Section

            	 	
              MME
      

              US$/BI
      100% 

              Base
      Fee

            	 
	
              Orito
      – Tumaco

            	 	 	2.8786	 
	
              Total
      Transportation

            	 	 	2.8786	 


    

    


    


    Transportation Tax: It is
determined according to the provisions in Article 52 of the Petroleum Code of
Colombia for transportation systems indicated in the previous point based on the
following detail:

    


    
      	
              Section

            	 	
              MME
      

              US$/BI
      Fee

            	 	 	
              %
      

              Transportation
      

              Tax

            	 	 	
              US$/BI
      

              Transportation
      

              Tax

            	 
	
              Orito
      – Tumaco

            	 	 	2.8786	 	 	 	2	%	 	 	0.0576	 
	
              Total
      Tax

            	 	 	 	 	 	 	 	 	 	 	0.0576	 


    

     

    Handling and Commercialization
Fee: Corresponds to the value of one dollar and fifty cents of US dollars
per barrel (US$/Bl 1.50) to cover expenses related to refining and/or export of
crude such as: Storage at the Port of Tumaco, use of the Submarine Line, vessel
docking, administration, commercialization fee, insurances, guarantees, hedging
of risks related to market variations and operational conditions including,
without being limited to the risk circumstances that may occur form the time of
delivery at the Delivery Point until the loading of crude at the port, among
others.

     

    
      
        
        

      

      
        2

        
          

        

      

      
        
        

      

    

    


    
      	
              B.  

            	
              For
      crude oil exported as Southblend by the port of Tumaco and received at the
      Santana Station:

            


    

    


    Crude
Price = WTI – Marker Discount +/- Adjustment for Quality – Transportation (Site
of Delivery/Port of Loading) – Transportation Tax – Handling and
Commercialization Fee.

    


    Each of
the above terms is defined as follows:

    


    WTI: Corresponds to the
arithmetic average of the daily quote of the West Texas Intermediate crude, WTI
NYMEX, in dollars per barrel of the month of deliveries.

    


    Marker Discount: Corresponds
to the average discount of export of THE BUYER of South Blend Crude by the Port
of Tumaco negotiated for the month after the month of delivery of crude. THE
BUYER shall report this discount. The reference quality of the South Blend Crude
is 30.3° API and 0.59%
Sulfur (S), and the same shall be monthly updated with real average data of
exports made by THE BUYER by the Port of Tumaco.

    


    Adjustment for Quality: Shall
be established in accordance with the provisions in the Fifth Paragraph of this
article.

    


    Transportation (Site of Delivery/Port
of Loading): This is determined as the sum of the fees established by the
Ministry of Mines and Energy for pipelines between the Santana Station and the
Port of Tumaco. The transportation fees for pipelines are updated at the
beginning of each year by the “F” Factor as indicated by the Ministry of Mines
and Energy. The applicable fees for the year 2009 are:

    


    
      	
              Section

            	 	
              MME
      

              US$/BI
      100% 

              Base
      Fee

            	 
	
              Orito-Tumaco

            	 	 	2.8786	 
	
              La
      Ye – Orito

            	 	 	0.2924	 
	
              Total
      Transportation

            	 	 	3.1710	 


    

    


    


    Transportation Tax: It is
determined according to the provisions in Article 52 of the Petroleum Code of
Colombia for transportation systems indicated in the previous point based on the
following detail:

    


    
      	
              Section

            	 	
              MME
      

              US$/BI
      Fee

            	 	 	
              %
      

              Transportation
      

              Tax

            	 	 	
              US$/BI
      

              Transportation

               Tax

            	 
	
              Orito
      – Tumaco

            	 	 	2.8786	 	 	 	2	%	 	 	0.0576	 
	
              La
      Ye – Orito

            	 	 	0.2924	 	 	 	2	%	 	 	0.0055	 
	
              Total
      Tax

            	 	 	 	 	 	 	 	 	 	 	0.0631	 


    

    


    Handling and Commercialization
Fee: Corresponds to the value of one dollar and fifty cents of US dollars
per barrel (US$/Bl 1.50) to cover expenses related to refining and/or export of
crude such as: Storage at the Port of Tumaco, use of the Submarine Line, vessel
docking, administration, commercialization fee, insurances, guarantees, hedging
of risks related to market variations and operational conditions including,
without being limited to the risk circumstances that may occur form the time of
delivery at the Delivery Point until the loading of crude at the port, among
others.

     

    
      
        
        

      

      
        3

        
          

        

      

      
        
        

      

    

    


    
      	
              C.  

            	
              For
      crude oil exported as “Oriente” Crude by the port
  Ecuador:

            


    

    


    Crude
Price = Marker Discount – Transportation (Site of Delivery/Port of Loading) –
Transportation Tax – Handling and Commercialization Fee.

    


    Each of
the above terms is defined as follows:

    


    Marker: Corresponds to the
weighted average real price of exports made by THE BUYER of Oriente crude by the
port of Balao.

    


    Transportation (Site of Delivery/Port
of Loading): This is determined as the sum of the fees:

    


    
      	
              ·  

            	
              Fee
      Santana Station – Orito (established by the Ministry of Mines and
      Energy)

            
	 	 


    

    
      	
              ·  

            	
              Fee
      Orito – San Miguel (established by the Ministry of Mines and
      Energy)

            
	 	 


    

    
      	
              ·  

            	
              Fee
      charged by PETROECUADOR  for the transportation of
      crude.

            


    

    


    Transportation Tax: It is
determined according to the provisions in Article 52 of the Petroleum Code of
Colombia for transportation systems indicated in the previous point. For the
Ecuador trench the respective tax, if applicable, shall be taken into account
from the delivery site to the loading port.

    


    Handling and Commercialization
Fee: Corresponds to the value of one dollar and fifty cents of US dollars
per barrel (US$/Bl 1.50) to cover expenses related to refining and/or export of
crude such as: Storage at the Port of Balao, use of the Submarine Line, vessel
docking, administration, commercialization fee, insurances, guarantees, hedging
of risks related to market variations and operational conditions including,
without being limited to the risk circumstances that may occur form the time of
delivery at the Delivery Point until the loading of crude at the port, among
others.

    


    
      	
              D.  

            	
              For
      crude oil delivered at the DINA Station for export by the port of Coveñas
      or for refining:

            


    

    


    Crude
Price  = WTI – Marker Discount +/- Adjustment for Quality –
Transportation (Site of Delivery/Port of Loading) – Transportation Tax –
Handling and Commercialization Fee.

    


    Each of
the above terms is defined as follows:

    


    WTI: Corresponds to the
arithmetic average of the daily quote of the West Texas Intermediate crude, WTI
NYMEX, in dollars per barrel of the month of deliveries.

    


    Marker Discount: Corresponds
to the monthly average discount of export Vasconia Crude reported by Argus for
the month minus 1 of the deliveries. THE BUYER shall report this discount. The
reference quality of the Vasconia crude is 24.8° API and 0.97% Sulfur
(S).

    


    Adjustment for Quality: Shall
be established in accordance with the provisions in the Fifth Paragraph of this
article.

     

    
      
        
        

      

      
        4

        
          

        

      

      
        
        

      

    

    


    Transportation (Site of Delivery/Port
of Loading): This is determined as the sum of the fees established by the
Ministry of Mines and Energy for pipelines between the Santana Station and the
Port of Tumaco. The transportation fees for pipelines are updated at the
beginning of each year by the “F” Factor as indicated by the Ministry of Mines
and Energy. The applicable fees for the year 2009 are:

    


    
      	
              Section

            	 	
              MME
      

              US$/BI
      100% 

              Base
      Fee

            	 
	
              Tenay
      – Vasconia

            	 	 	1.7175	 
	
              Vasconia
      – Coveñas ODC

            	 	 	1.5282	 
	
              Total
      Transportation

            	 	 	3.1710	 


    

    


    Transportation Tax: It is
determined according to the provisions in Article 52 of the Petroleum Code of
Colombia for transportation systems indicated in the previous point based on the
following detail:

    


    
      	
              Section

            	 	
              MME
      

              US$/BI
      100%
      

              Base
      Fee

            	 	 	
              %
      

              Transportation
      

              Tax

            	 	 	
              US$/BI
      

              Transportation

               Tax

            	 
	
              Tenay
      –Vasconia

            	 	 	1.7175	 	 	 	6	%	 	 	0.1031	 
	
              Vasconia
      - Coveñas

            	 	 	1.5282	 	 	 	6	%	 	 	0.0917	 
	
              Total
      Tax

            	 	 	 	 	 	 	 	 	 	 	0.1948	 


    

    


    Handling and Commercialization
Fee: Corresponds to the value of one dollar and fifty cents of US dollars
per barrel (US$/Bl 1.50) to cover expenses related to refining and/or export of
crude such as: Storage at the Port of Coveñas, use of the Submarine Line, vessel
docking, administration, commercialization fee, insurances, guarantees, hedging
of risks related to market variations and operational conditions including,
without being limited to the risk circumstances that may occur form the time of
delivery at the Delivery Point until the loading of crude at the port, among
others.

    


    FIRST PARAGRAPH: The price
determined by the aforementioned formula comprises the different costs of
transportation, handling, measurement and transportation taxes bore by THE
SELLER and generated until the delivery of the crudes being the purpose of this
purchase-sale at the Delivery Point(s); therefore THE BUYER shall not make any
additional acknowledgement on such items.

    


    SECOND PARAGRAPH: When the
parties agree on Delivery Point(s) different from those established in article
six (6) of this document, the price formula set out in this article shall be
modified in the transportation item, taking into account the fees and
transportation tax of crude for the pipeline in force between the Delivery
Point(s) and the export port that applies. Additionally, the marker shall be
modified as the case may be.

    


    THIRD PARAGRAPH: The reception
and inspection costs in the case of stations agreed between the parties and not
operated by THE BUYER, shall be recognized directly by THE SELLER to the
respective operating company. THE BUYER shall not make any additional
acknowledgment on said items.

    


    FOURTH PARAGRAPH: PRICE RENEGOTIATION. The
parties may request a review of the price established in this article provided
that any of the following events occur:

    


    
      	
              a)  

            	
              A
      change of more or less two (2) API grades in the quality of Crude oil
      produced in the Contracted Area

            


    

     

    
      
        
        

      

      
        5

        
          

        

      

      
        
        

      

    

     

    
      	
              b)  

            	
              A
      change of more or less two (2) API grades in the quality of Marker Crude
      during six (6) consecutive months. In this event the request for review
      shall be made during the following month to the period of six (6)
      consecutive months.

            


    

     

    
      	
              c)  

            	
              In
      the event the Marker Crude disappears and becomes necessary to define a
      new marker.

            


    

    


    The
Parties shall have a term of thirty (30) business days to negotiate. In case of
reaching an agreement, this shall be stated for the record by signing an
amendment between THE BUYER and THE SELLER and its contents shall apply starting
of the following date in which said amendment is executed.

    


    If, at
the end of thirty (30) business days there is not an agreement, THE BUYER or THE
SELLER may inform to the other, its intention to terminate the contract pursuant
to the provisions in article 25 of this document.

    


    The
termination is not a waiver for the Parties to fulfill the obligations that may
have been caused.

    


    FIFTH PARAGRAPH: ADJUSTMENT FOR
QUALITY. The adjustments for quality (API Gravity and Sulfur) shall be
made if the following two conditions are met:

    


    
      	
              1.  

            	
              That
      the average of daily deliveries of crude owned by THE SELLER (in volume)
      be higher than 10% of the daily average of:

            
	 	 


    

    
      	
              a.  

            	
              The
      total current of SouthBlend dispatched by the “Trasandino” Pipeline for
      the month of deliveries, for the case of deliveries at Orito and
      Santana.

            
	 	 


    

    
      	
              b.  

            	
              For
      total exports of Vasconia Mix by the port of Coveñas for the month of
      deliveries, for the case of deliveries at Dina.

            
	 	 


    

    
      	
              2.  

            	
              That
      the quality of marker crude for the case of deliveries at Orito and
      Santana, monthly updated pursuant to the provisions in this document has
      to be:

            
	 	 


    

    
      	
              a.  

            	
              higher
      than 31°API or
      lower than 29°API
      and/or

            
	 	 


    

    
      	
              b.  

            	
              higher
      than 0.7% Sulfur or lower than 0.5%
Sulfur

            


    

    


    If the
two previous conditions are met, it shall be compared monthly in terms of API
and % of sulfur the qualities of the marker, monthly updated as set out in this
document, and the crude being the purpose of this purchase-sale, applying
bonuses or penalties to the price if better or worse quality than the marker is
delivered as follows:

    


    
      	
              ·  

            	
              Correction for
      API: +/- 0.62 US$/Unit of API or proportionally by fraction. Price
      adjustments shall be positive for API gravities of crude above the
      reference value for marker crude and negative for lower
      gravities.

            


    

    


    
      	
              ·  

            	
              Correction for
      sulfur: +/- 2.01 US$/Unit of % of sulfur in weight or
      proportionally by fraction. Price adjustments shall be positive for
      percentage of sulfur in the crude below the reference value for marker
      crude and negative for higher
values.

            


    

    


    
      	
              3.  

            	
              INVOICING
      AND PAYMENT

            


    

    


    THE
SELLER shall invoice and charge THE BUYER the value of the crude sold according
to the terms of this document, at the Planning and Supply Management Office in
Bogotá, within the first ten (10) business days of the month, after the month of
the delivery of crude to THE BUYER. Within the first seven (7) calendar days of
the month after the deliveries, THE BUYER shall provide THE SELLER the
information the latter may require to make the corresponding invoice. Invoices
shall be filed at the Planning and Supply Management Offices of THE BUYER in
Bogotá and its date of presentation valid for the payment shall be the date of
reception at the accounts payable office of THE BUYER in Bogotá. The invoicing
shall be made based on the net volumes, free of water and sediment, corrected at
sixty (60) Fahrenheit degrees received at the Delivery Point. For invoice
approval it is necessary to present the official forms Table No. 4 and/or Form
No. 9SH from the Ministry of Mines and Energy.   Provisional
Table No. 4 and forms may be accepted, but quarterly, THE SELLER shall submit to
THE BUYER copy of Tables No. 4 and/or Form No. 9SH of the previous quarter duly
filled in and signed by the Ministry of Mines and Energy.

     

    
      
        
        

      

      
        6

        
          

        

      

      
        
        

      

    

    


    Considering
the authorization of payments in foreign exchange stated in article 51 of
External Resolution Number 8 of 2000 of the Board of Directors of the Central
Bank, which provides that the purchase-sales of crude oil and natural gas
produced in the country may be paid in foreign exchange by THE BUYER and all
other entities engaged in the industrial activity of refining oil, the invoicing
made by THE SELLER for the provision of crude to THE BUYER shall be made 100% in
dollars of the United States of America.

    


    Payment
shall be made thirty (30) calendar days after the filing of the invoices duly
filled in, and after any legal withholdings, if applicable. THE SELLER shall
communicate to THE BUYER in advance, and in writing, the bank account in which
the respective payment shall be made.

    


    FIRST PARAGRAPH: THE BUYER
shall have a period of ten (10) calendar days, counted as of the reception of
the invoices for the sale of crude oil, to review or object them. In case of any
objections on the invoices, the date of reception shall be the date of filing of
the new invoice. THE BUYER shall inform THE SELLER within the term established
of any invoice objected, so that it may be adjusted and corrected, clearly
specifying the items to be adjusted or corrected and the corresponding motives.
THE SELLER shall respond any objection within ten (10) business days after
reception of the same, counted as of the time in which THE BUYER submits to THE
SELLER all documents supporting the objection, unless the Parties determine by
common agreement to extend this term, if the complexity of the objection or any
other circumstance thus requires so.

    


    In case
THE SELLER does not respond the objection within the term described, the
objection shall be understood as accepted by THE SELLER. If THE SELLER resolves
the objection in favor of THE BUYER, it shall be understood that there was no
payment obligation on the invoice originally filed, being the purpose of the
objection. If THE SELLER resolves the objection in its favor, THE BUYER shall be
obliged to pay the amount unpaid. In order to resolve any discrepancy, each of
the Parties shall submit to the other Party copy of the documents, which
originated the invoice and the objection. In the event THE BUYER is in
disagreement with the decision of THE SELLER, the former may apply the
provisions in article 19 of this document.

    


    SECOND PARAGRAPH: In case of
any unjustified delay in the payment of invoices not objected on time by THE
BUYER, in accordance with the provisions in the first paragraph of this article,
THE BUYER shall recognize to THE SELLER, as interest payable in pesos, the
highest interest rate authorized by the Superintendence of Finance during the
default days effectively elapsed.

    


    THIRD PARAGRAPH: In case THE
SELLER is interested in any factoring with the invoices issued in connection
with this Commercial Offer, the option in first instance shall be offered to THE
BUYER.

    


    In order
to calculate the late interests, the overdue amount of the invoice shall be
first converted to Colombian pesos, at the market representative exchange rate
of its issuance date, certified by the Superintendence of Finance of
Colombia.

    


    THE BUYER
shall pay invoices charging default interests thirty (30) calendar days after
their reception by THE BUYER.

     

    
      
        
        

      

      
        7

        
          

        

      

      
        
        

      

    

    


    Any
invoices issued, as well as the contract derived from the acceptance of the
offer shall constitute a writ of execution and THE BUYER and THE SELLER
expressly wave any private or judicial requirements to file as
default.

    


    
      	
              4.  

            	
              VALIDITY,
      TERMS OF EXECUTION AND SPECIAL MOTIVES FOR TERMINATION IN
      ADVANCE

            


    

    


    The term
of the contract resulting from the acceptance of the Offer hereto, shall
commence with its acceptance and will conclude with its
liquidation.

    


    The
duration or term of execution of the contract shall be counted as of January
1st,
2010 (with the previous fulfillment of the requirement of execution established
in article 18 of this document) and shall end on December 31st,
2010.

    


    The
parties shall carry out the respective liquidation within a term of four (4)
months counted as of the date of termination of the term of execution of the
contract derived from the acceptance of the Offer hereof.

    


    In case
THE SELLER fails to attend the liquidation, or if there is no agreement on the
content of the same within the term previously mentioned, THE SELLER expressly
authorizes THE BUYER to proceed and carry out the unilateral liquidation in a
term of two (2) months.

    


    
      	
              5.  

            	
              QUALITY
      SPECIFICATIONS

            


    

    


    THE BUYER
shall certify the quality of the product received at the reception stations
indicated in article six (6) of the document hereof, which shall comply with the
following quality specifications:

    
      	
              API

            	 	
              SULFUR

            	 	 	
              Maximum
      Vol.
      

              BSW%

            	 	 	
              Maximul
      SAL 

              Lb/100Bls

            	 
	
              29.6°

            	 	 	0.41	 	 	 	0.5	 	 	 	20.0	 


    

    


    
      	
              1.  

            	
              The
      crude gravity shall be determined by the ASTM-D-287 lab method (API
      Gravity).

            
	 	 


    

    
      	
              2.  

            	
              BSW,
      content of water and sediment shall be determined by the ASTM-D4377
      methods “Water in oil products and bituminous materials by Karl Fisher”,
      last version and ASTM-D473 “Sediment in crude oil and fuels by
      extraction”, last version. For the content of water and sediments in crude
      oil the following maximum individual values shall be accepted: 0.49 % in
      volume for water and 0.01% in volume for sediments.

            
	 	 


    

    
      	
              3.  

            	
              The
      content of sulfur shall be determined by the ASTM-D4294 method “Sulfur
      analysis by X rays”, last revision.

            
	 	 


    

    
      	
              4.  

            	
              The
      content of salt shall be determined by the ASTM-D3230 method “salts in
      crudes (electrometric method)”, last
revision.

            


    

    


    Once the
crude oil is delivered and received by THE BUYER, it shall be understood that
the same was delivered under the quality conditions offered and
accepted.

     

    
      
        
        

      

      
        8

        
          

        

      

      
        
        

      

    

    


    FIRST PARAGRAPH: When any of
the specifications indicated are not within the margins permitted, THE BUYER
reserves the right to receive the crudes and purchase them with an adjusted
price. In such cases the price of crude oil shall be adjusted as
follows:

    


    BSW and
Salt corrections – shall be applied according to the following
tables:

    


    
      	
              BSW
      Content

              %
      in Volume

            	 	
              Penalty
      In
      

              United
      States 

              Dollars
      per 

              Barrel

              (US$/Barrel)

            	 	
              In
      charge of:

            
	
              0.51
      to 0.80

            	 	 	0.10	 	
              THE
      SELLER

            
	
              0.81
      to 1.00

            	 	 	0.20	 	
              THE
      SELLER

            
	
              1.01
      to 1.20

            	 	 	0.30	 	
              THE
      SELLER

            
	
              1.21
      to 1.50

            	 	 	0.40	 	
              THE
      SELLER

            
	
              >
      than 1.51

            	 	 	0.50	 	
              THE
      SELLER

            


    

    


    
      	
              Salt
      contents

              Pounds
      per thousand barrels

            	 	
              Penalization

              United
      States 

              Dollars
      per barrel 

              (US$/Barrel)

            	 	
              In
      charge of

            
	
              20.1
      to 30.0

            	 	 	0.160	 	
              THE
      SELLER

            
	
              30.1
      to 40.0

            	 	 	0.180	 	
              THE
      SELLER

            
	
              40.1
      to 60.0

            	 	 	0.200	 	
              THE
      SELLER

            
	
              60.1
      to 80.0

            	 	 	0.220	 	
              THE
      SELLER

            
	
              80.1
      to 100.0

            	 	 	0.240	 	
              THE
      SELLER

            
	
              >
      than 100.0

            	 	 	0.300	 	
              THE
      SELLER

            


    

    


    It is
understood that THE SELLER will make the best efforts to deliver the crudes with
BSW and salt contents within the agreed parameters. These corrections will be
applied to the daily deliveries or to each batch delivered. Any variation in
regards to the quality specifications mentioned above, which is accepted by the
parties, shall be recorded in a previous minutes signed by the representatives
of THE BUYER and THE SELLER.

    


    6.  DELIVERY
POINTS

    


    The
Delivery Point(s) and the transfer of the crude oil property right, purpose of
this sales agreement, will be the inlet flange to the crude oil receipt tank(s)
of SANTANA station, municipality of Puerto Asis, in the LACT UNIT/LAFERT UNIT,
property of the CPR_SANTANA joint operation, the Dina Station tanks and/or the
Orito Station tanks, with measurement of tanks and/or flow meter, following THE
BUYER’S operational procedures established in the Measurement Manual (attached
herein as Annex 2).

    


    THE
SELLER transfers to THE BUYER the crude oil property right at the Delivery
Point(s). THE SELLER guarantees at the moment of delivery that the crude oil is
free of any liens or financial claims by any government entity of any level, or
of any natural or legal person of private law, in every respect, including those
arising from taxes, rates, contributions, participation or royalties, domain
limitation or any other judicial or extrajudicial measure that may restrict or
limit the use or availability of the crude oil by THE BUYER. The costs
associated with the transportation of the crude oil to the Delivery Point, along
with the costs associated to the delivery of the crude oil, will be borne by THE
SELLER.

    


    FIRST PARAGRAPH: THE BUYER
shall inform in advance to THE SELLER of any change at the Delivery Point to a
station different than those established in this article, and such change will
be subject to the previous acceptance by THE SELLER. Without prejudice of the
aforementioned, the designation of the capacity of the Receiving Stations of
crude oil will be a discretionary power of Ecopetrol S.A., subject to the
operational capacity thereof, and without the obligation to receive the crude
oil on a permanent basis at any Station. The volumes to be received at each of
the stations established in this article will be established and informed
according to the schedule provided by THE BUYER, regardless of the nominations
provided by THE SELLER.

     

    
      
        
        

      

      
        9

        
          

        

      

      
        
        

      

    

    


    SECOND PARAGRAPH: The volumes
to be received at each of the stations established in this clause will be
determined on a monthly basis according to the transportation official schedule
established by THE BUYER.

    


    7.
SCHEDULE OF DELIVERIES

    


    THE
SELLER shall deliver to THE BUYER at the latest on the twentieth (20th) day of
each month, a schedule of the estimated production and deliveries (nominations)
for the following month.

    


    THE
SELLER is bound to supply and keep track of the information of production on the
field, liquidation of royalties, shipment by tank truck and/or pipelines, and
indicate the participation and the property right on each, and the official
receipt of the receiving station. For this purpose, THE SELLER shall send to THE
BUYER on a daily basis the information requested, through THE BUYER’S volumetric
integrator, which is available at THE BUYER’S web site. Copy of the Users Manual
is attached herein as Annex 1.

    


    In the
event that within the agreed term THE BUYER cannot receive at the Delivery
Point(s) the total amount of crude oil, THE SELLER will be informed with at
least three (3) calendar days in advance, (or as soon as possible, if the cause
could not be foreseen or known within the aforementioned term), and as soon as
the contingency is overcome, THE BUYER will inform the date to resume the
receiving.

    


    In the
same way, in the event that for reasons associated to the operation of the
filed, THE SELLER cannot deliver the crude oil to THE BUYER on any of the dates
established in the schedule, THE SELLER shall inform THE BUYER in writing with
three (3) calendar days in advance to the corresponding delivery date (or as
soon as possible, if the cause could not be foreseen or known within the
aforementioned term), and as soon as the contingency is overcome, THE SELLER
will inform the date to resume the deliveries.

    


    8.
THE INSPECTION AND MEASUREMENT

    


    The
determination of the quality parameters will be performed at the Delivery Point,
following the operational procedures established in the Measurement Manual of
ECOPETROL S.A., attached herein as Annex 2. THE BUYER’S or its associates
stations or departments where the crude oil is received, shall certify the
volume and quality (API, BSW and Salt) of the crude oil received
daily.

    


    For
billing purposes, the sulfur contents of the crude oil will be the value
reported by the Colombian Petroleum Institute (CPI) in accordance with the
analysis made by semester that such institute performs for each crude oil. THE
BUYER will update this information on a half-yearly basis to be delivered to THE
SELLER. In the event that such sulfur contents analysis is not available, the
sulfur contents for billing purposes will be the one established in the fifth
paragraph herein this document, which will be in force until the CPI performs a
new analysis, which will be informed to THE SELLER by THE BUYER. From the day
following the receipt by THE SELLER of the analysis performed by CPI, the sulfur
contents for billing purposes will be the one established by THE BUYER in such
report. When any of the parties deem appropriate, may request the performance by
CPI of a new analysis of sulfur contents.

    


    When deem
appropriate, any of the parties may appoint an independent inspector to certify
the quality and quantity and verify the capacity of the tanks or the calibration
of the measurement and volume instruments. The costs of such analysis or
inspections will be shared equally between THE BUYER and THE
SELLER.

     

    
      
        
        

      

      
        10

        
          

        

      

      
        
        

      

    

    


    9. INDUSTRIAL SAFETY – HSE:
THE SELLER is bound to keep in force all HSE programs for the
transportation of the crude oil to the Point of Delivery.

    


    10.
GUARANTY

    


    According
to the provisions of ECOPETROL’S Contracting Manual and taking into account the
nature of the services arising from the acceptance of this commercial offer by
the parties, the Authorized Official has determined the risk as low; therefore,
THE SELLER is not required to submit the corresponding guaranty in the event of
acceptance of this Commercial Offer.

    


    11.
TAXES

    


    All
taxes, whether national, regional, municipal, liens, rates, contributions,
shares or any others arising from or that may arise from the acceptance of this
Offer, including without limit, those incurred during the formalization,
execution, termination or winding-up of the Contract as a result of the
acceptance of this Offer will be borne by the taxpayer of the relevant tax, and
shall be paid pursuant to the laws and regulations in force.

    


    12.
LEGAL REQUIREMENTS

    


    Prior to
the submission of this Offer, the Management of Supply and Planning has verified
that it is not listed in the Fiscal Responsibility Bulletin prepared and
published by the General Comptroller of the Republic, as a legal person with a
ruling for unpaid taxes.

    


    Prior to
the preparation of this Commercial Offer, the Management of Supply and Planning
has implemented the control mechanisms associated to the prevention of money
laundering, and has developed the policies for the proper implementation
thereof, in compliance with the general policy for the prevention and control of
money laundering.

    


    13.
ADMINISTRATION AND MANAGEMENT

    


    The
Authorized Official of THE BUYER will appoint the administrator and manager of
the contract arising out of the acceptance of this Offer among the officers of
the Vice Presidency of Supply and Marketing or the Management of Supply and
Planning who will be empowered to enforce the obligations provided in the Manual
for THE BUYER’S administration and management of Contracts, attached herein as
Annex 3.

    


    THE BUYER
will perform the performance evaluation as Contractor to THE SELLER, according
to the “Contractors Performance Evaluation” policy, which will be supplied by
THE BUYER to THE SELLER upon the acceptance of this Offer.

    


    14.
ASSIGNMENT

    


    THE
SELLER shall not assign, sell or transfer the whole or part of its rights and
obligations under the contract that may arise upon the acceptance of the offer
to any third party, without the previous written consent of THE
BUYER.

    


    15.
FORCE MAJEURE, ACT OF NATURE AND FORTUITOUS EVENTS

    


    The
obligations of any of the parties in connection with the acceptance of this
Offer that cannot be performed due to Force Majeure, Acts of Nature or
Exculpatory Events, whether total or partial, will be suspended during the
occurrence of the effects of such events.

     

    
      
        
        

      

      
        11

        
          

        

      

      
        
        

      

    

    


    The Party
announcing the occurrence of a Force Majeure, Act of Nature or Exculpatory
Events shall inform immediately by phone the other Party about the situation,
with the date and start time, and the next day following the occurrence of such
event, in writing along with the evidence that prove the occurrence of such
event. The Party notified of the Force Majeure, Act of Nature or Exculpatory
Events, may request further information that supports such announcement, and the
affected Party shall send it within the next three (3) business days following
the request. Any differences between the Parties in connection with such event
will be solved in accordance with the mechanisms for dispute resolutions
provided in article nineteenth (19th).

    


    The Party
announcing the occurrence of a Force Majeure, Act of Nature or Exculpatory
Events shall use their best efforts to remedy the cause that gave rise to the
announcement, and shall inform the other Party the date and time when such event
was overcome.

    


    For all
the purposes, the contract arising out of the acceptance of this Offer, Force
Majeure or Act of Nature event means, any event that can be qualified as such
according to the Colombian laws, which is unforeseeable and overpowering, duly
proved, provided always that it is external to the Parties and it occurs without
their fault or negligence.

    


    Exculpatory
Events are the following: a) the inability to operate and function, whether
total or partial of the oil pipe, the tank trucks for the transportation of the
crude oil; the connections or the facilities of any of the Parties caused by
malicious acts beyond the direct control of THE SELLER and THE BUYER, without
their fault, such as: terrorists or guerrilla attacks, sabotage, serious
disturbances of public order that may result in, directly or indirectly, the
inability of any of the parties to comply with their obligations; b) industry
disturbance acts, including work stoppage and strike, when such acts may result
in the inability of THE SELLER to comply with their obligations, and c) industry
disturbance acts, including work stoppage and strike, when such acts may result
in the inability of THE SELLER to comply with their obligations .

    


    PARAGRAPH: Under no
circumstances, any changes in the financial situation of THE BUYER or THE SELLER
may be considered as Exculpatory Events under the contract arising out of the
acceptance of this Offer.

    


    Neither
THE BUYER nor THE SELLER shall be held responsible for non compliance or partial
compliance of any or all of the obligations established in this agreement, when
such failure to comply is caused by force majeure, act of nature or exculpatory
events duly proven.

    


    Any Force
Majeure, Acts of Nature and/or Exculpatory Events do not relieve THE BUYER of
their obligations to pay THE SELLER the invoices related to the supply of crude
oil that have been delivered by THE SELLER, according to the terms established
in this Offer.

    


    The
occurrence of any of the events provided in this article shall not relieve under
any circumstance to any of the Parties of the compliance with their contractual
obligations, and/or those obligations incurred prior to the occurrence of the
events mentioned in this article.

    


    16.
ENFORCEABILITY OF THE COLOMBIAN LAWS

    


    The
Colombian laws govern this Commercial Offer and the Contract that may arise upon
the acceptance of this Offer.

     

    
      
        
        

      

      
        12

        
          

        

      

      
        
        

      

    

    


    17.
PUBLICATION

    


    THE
SELLER is responsible for the payment of the publication of the contract
associated with this Offer on the Public Contracts Newspaper (Diario Único de Contratación
Pública). THE SELLER must send to ECOPETROL copy of the receipt
corresponding to the deposit of such payment within three (3) business days
following the acceptance of the Offer. THE BUYER shall send to the Colombian
National Printing the Sole Summary for Publication (Extracto Único de
Publicación).

    


    18.
COMPLETION AND EXECUTION

    


    The
contract arising out of the acceptance of this Offer will be considered as
completed with the acceptance of this Offer by THE SELLER. For the purpose of
the execution, it is required the proof of payment of the publication on the
Public Contracts Newspaper (Diario Único de Contratación
Pública).

    


    19.
DISPUTE RESOLUTION

    


    In the
event of any controversy, any of the Parties may request a direct resolution to
such controversy. The Party having a controversy shall notify the other Party
with the purpose to meet and amicably resolve the controversy within the five
(5) days following the notification, and reach an agreement in a term of ten
(10) business days. Upon the expiration of such term, if no agreement intended
to resolve the controversy has been reached, or that partial agreements have
been made, the Parties shall immediately resort to the dispute or controversies
resolution mechanisms provided by the law, as follows:

    


    Legal Disputes. The disputes
of legal nature, and in general, any dispute different than a technical or
accounting dispute, derived from or in connection with the contract arising out
of the acceptance of this Offer, which have not been resolved according to the
procedure provided in the aforementioned paragraph, shall be resolved by an
arbitration court comprised by three (3) Colombian lawyers. The Parties shall
make their best efforts to agree on the appointment of the three (3)
arbitrators, as the case may be, within a term no longer than twenty (20)
business days from the expiration of the term for direct resolution. If the
Parties do not agree on the appointment of one of the arbitrators, it is
understood that the Parties delegate the appointment to the Center of
Arbitration and Conciliation of the Chamber of Commerce of Bogotá, D.C., from
their list at the request of either Party. The arbitrators will decide in law;
the seat of the court is the Center of Arbitration and Conciliation of the
Chamber of Commerce of Bogotá, D.C. The sessions and functioning of the court
will be in accordance with the Regulations of such Center, and the fees
established by the Center, and in matters not provided here, according to the
law.

    


    In the
event of controversy related to the controversy, it shall be considered a legal
dispute.

    


    Disputes of Technical and/or
Accounting Nature. Any controversy of technical or accounting nature that
may arise between the Parties in regards to the construal, execution or
termination of the contract that may arise out of the acceptance of this Offer,
shall be subject to the ruling of three (3) experts appointed by the Parties by
common agreement. If within thirty (30) days following the date when the
controversy was submitted in writing by any of the Parties, no agreement has
been reached in regards to the appointment of one of the experts, the expert not
being appointed along with all the other experts will be appointed by the Board
of Directors of the Colombian Engineering Society, CES, with seat in Bogotá,
D.C. at the request of any of the Parties. Any controversy of accounting nature
that may arise between the Parties in regards to the construal and performance
of the contract that may arise upon the acceptance of this Offer, shall be
subject to the ruling of three (3) experts appointed by the Parties by common
agreement; such experts shall be Certified Public Accountants. If the Parties do
not reach an agreement for the appointment of one expert or all the experts, the
expert or experts not being appointed will be appointed by the Central Board of
Public Accountants of Bogotá, D.C. at the request of any of the
Parties.

     

    
      
        
        

      

      
        13

        
          

        

      

      
        
        

      

    

    


    The
ruling of the experts will be final and shall be issued in a term no longer than
ninety (90) days from the date of appointment of the three experts. The Parties
may agree in writing to the extension of this term.

    


    PARAGRAPH: The costs, fees and
expenses associated with the necessary procedure to resolve the controversies
herein established, shall be paid by the Party or Parties according to the
decision of the Arbitration Court or the Experts, as the case may
be.

    


    20.
LANGUAGE: SPANISH

    


    This
Offer is written in Spanish and is the only form of obligations between the
Parties. Any translation to any other language will only be valid for reference
purposes for the Parties, and under no circumstance may affect the meaning and
construal of the Spanish version.

    


    21.
CONTRACT VALUE

    


    The value
of the Contract associated with this Offer is undetermined.

    


    22.
CONFIDENTIALITY

    


    For the
purposes of this article, the Party that discloses or reveals the information is
called hereinafter the Disclosing Party, and the party that receives the
information is called the Receiving Party. The Parties herein agree that all the
information of technical, commercial, industrial or financial nature given and
interchanged or prepared by the Parties during the development of the contract
that may arise upon the acceptance of this Offer, or that any of the Parties may
develop, receive or obtain in regards to the Contract derived from this Offer
(hereinafter “Confidential Information” or “the information”) are subject to
strict discretion and confidentiality during the term of the Contract and three
(3) years following the expiration thereof.

    


    For the
purposes of the contract that may arise upon the acceptance of this Offer, it is
not considered “Confidential Information” the information that: (i) is of public
knowledge at the moment of its disclosure, or that may be of public knowledge
after its disclosure through means different that the action or omission of the
Receiving Party; (ii) is known by the Receiving Party before or at the receiving
moment, or obtained under this Offer, without such knowledge being the cause of
breach of any obligation of confidentiality; (iii) is developed by the Receiving
Party independently, or based on information or documentation received from a
third party, without this being in breach of any obligation of confidentiality;
(iv) is received or obtained in good faith, by the Receiving Party, from a third
party without this being in breach of any obligations of confidentiality; (v)
its disclosure or revelation is required to the Receiving Party by the
application of the legislation in force, administrative act, judicial order and
or by any competent government entity with jurisdiction on the Party or its
affiliates, or by the standards of any stock exchange in which the stocks of the
Parties or corporations related are registered, in the terms and to the extent
that this is required.

    


    The
Receiving Party may reveal the Confidential Information to their managers,
officials, employees, agents, partners, representatives or associates,
affiliates and subordinated (in general, the Representatives).

    


    If any
judicial or administrative authority requires that the Receiving Party, under
the law, regulations or judicial ruling delivers any part of the Information,
such Receiving Party may request the cooperation of the Disclosing Party, and if
deemed appropriate, consult with the Disclosing Party about the measures to be
taken in order to keep the confidentiality.

     

    
      
        
        

      

      
        14

        
          

        

      

      
        
        

      

    

    


    23.
EXPIRATION AS PENALTY (caducidad)

    


    THE BUYER
may declare the expiration of the Contract derived from the acceptance of this
Offer, as a penalty, and order the liquidation at any moment, when THE SELLER
engage in conducts prohibited by Article 25 of Law 40, 1993 (payment of sums of
money to profiteers, or when hiding or cooperating on behalf of any manager or
delegate of THE SELLER in the payment for the release of a kidnapped person that
may be an official or employee of THE SELLER or any of its
affiliates).

    


    In the
event of announcement of expiration as penalty of the contract, there will be no
compensation for THE SELLER, who will be made subject to the penalties and
inabilities provided in the law. The statement of lapse is a breach of the
contract. THE BUYER will announce the lapse through a resolution, and THE SELLER
will be notified timely. THE SELLER may file an appeal. THE SELLER will have the
right, subject to the corresponding deductions according to the provisions of
this document, to get paid for the part or the goods or services received at the
satisfaction of THE BUYER until the date of the administrative act stating the
expiration as penalty.

    


    24.
VALIDITY OF THE OFFER

    


    The Offer
contained in this document is valid until December 22, 2009 at 4:30 PM; upon the
expiration of this term, and if the Offer is not accepted, the Offer will be
declared void.

    


    The
acceptance of the Offer shall be made by means of a single sales order sent to
the Management of Supply and Planning of the Vice Presidency of Supply and
Marketing, located at Carrrera 7 No. 37-69, fifth floor, Edificio Teusacá,
Bogotá, Colombia, accompanied by a Certificate of the Chamber of Commerce that
allows the confirmation that the persons signing is fully empowered to accept
the Offer, and a certificate of good standing and compliance of all payments to
the integral system of social security.

    


    25.
EARLY TERMINATION

    


    Either
THE SELLER or THE BUYER may early terminate, at any moment, the contract derived
from the acceptance of this Offer without the obligation to compensate for any
loss or damage to the other party, provided that the decision to early terminate
is notified to the other party with at least thirty (30) calendar days in
advance with respect to the termination date of the Contract.

    


    Sincerely,

    


    /s/
Claudia L. Castellanos R.

    


    CLAUDIA
L. CASTELLANOS R.

    Vice
President


    


    Annex 1:
Users Manual of the Volumetric Integrator of ECOPETROL S.A.

     

    Annex 2:
Measurement Manual of ECOPETROL S.A.

     

    Annex 3:
Contracts Management and Administration Manual of ECOPETROL S.A.

     

    
      
        
        

      

      
        15

        
          

        

      

      
        
        

      

    

     

    Purchase
Order No. GTEC.02-2009

    Date:
December 18, 2009

    


    
      	
              Client:             ECOPETROL
      S.A.

            	
              Issuance
      date:             
      December 18, 2009

            
	
              Tax
      ID:            899.999.068-1

            	
              Delivery
      date:               According
      to commercial offer

            
	
              Attention:     
       Dr. Claudia L. Castellanos R.

                                     Vice-president
      of Supply and Marketing

                                     Carrera
      7 no. 37-69 Floor 4

                                     Tel:
      2344120

                                     Fax:
      2344671

                                     Bogota

            	
              Currency:                     According
      to commercial offer

              Payment
      date:              According
      to commercial offer

            


    

    


    
      	
              ITEM

            	 	
              QUANTITY

            	 	
              UND.

            	 	
              DESCRIPTION

            	 	
              UNITARY
      VALUE

            	 	
              TOTAL
      VALUE

            
	
              1

            	 	
              According
      to the commercial offer for the purchase of crude oil from
      Chaza

            	 	
              BLS

            	 	
              API
      29.6° Crude oil; Sulfur 0.41%, BSW Maximum 0.5%, SAL
      Maximum  20.00 Lb/1000

            	 	
              According
      to the commercial offer for the purchase of crude oil from
      Chaza

            	 	
              According
      to the commercial offer for the purchase of crude oil from
      Chaza

            


    

    


    Observations

     

    All the
conditions of delivery, terms, prices, compliance, operation, etc., are
contained in the commercial offer dated December 17 of 2009.

    


    
      	
              Drafted:

               

              /s/
      Margarita Reyes

            	 	
              Reviewed:

               

              (Illegible
      Signature)

            	 	
              Approved:

               

              (Illegible
      Signature)

            
	
              Margarita
      Reyes

            	 	
              Iván
      Ernesto Tobón G.

            	 	
              Álvaro
      Camacho

            
	
              Operations
      Assistant

            	 	
              Operations
      Senior Manager

            	 	
              Legal
      Representative

            


    

     

    
      
        
        

      

      
        16