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<P STYLE="border-top: Black 4.5pt double; font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>UNITED STATES</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>SECURITIES AND EXCHANGE COMMISSION</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>WASHINGTON, DC 20549</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: bold 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"></P>

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<P STYLE="font: bold 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>FORM 8-K&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>CURRENT REPORT</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>PURSUANT TO SECTION 13 OR 15(d) OF</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>THE SECURITIES EXCHANGE ACT OF 1934</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">Date of Report (Date of earliest event reported):
<B>August 6, 2012</B></P>

<P STYLE="font: bold 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: bold 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"></P>

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<P STYLE="font: bold 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 18pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Gran Tierra Energy Inc.</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">(Exact name of Registrant as specified in
its charter)</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: bold 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"></P>

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<P STYLE="font: bold 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"></P>

<P STYLE="font: bold 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" ALIGN="CENTER" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 32%; padding-right: 0.1in; padding-left: 0.1in; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">Nevada</P></TD>
    <TD STYLE="width: 2%">&nbsp;</TD>
    <TD STYLE="width: 32%; padding-right: 0.1in; padding-left: 0.1in; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">001-34018</P></TD>
    <TD STYLE="width: 2%">&nbsp;</TD>
    <TD STYLE="width: 32%; padding-right: 0.1in; padding-left: 0.1in; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">98-0479924</P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="padding-right: 0.1in; padding-left: 10.1pt; font-size: 10pt; text-align: center">(State or other jurisdiction</TD>
    <TD>&nbsp;</TD>
    <TD STYLE="padding-right: 0.1in; padding-left: 0.1in; font-size: 10pt; text-align: center">(Commission</TD>
    <TD>&nbsp;</TD>
    <TD STYLE="padding-right: 0.1in; padding-left: 0.1in; font-size: 10pt; text-align: center">(IRS Employer</TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="padding-right: 0.1in; padding-left: 20.2pt; font-size: 10pt; text-align: center">of incorporation)</TD>
    <TD>&nbsp;</TD>
    <TD STYLE="padding-right: 0.1in; padding-left: 0.1in; font-size: 10pt; text-align: center">File Number)</TD>
    <TD>&nbsp;</TD>
    <TD STYLE="padding-right: 0.1in; padding-left: 0.1in; font-size: 10pt; text-align: center">Identification No.)</TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><FONT STYLE="font-weight: normal">300, 625
- 11th Avenue S.W. </FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><FONT STYLE="font-weight: normal">Calgary,
Alberta, Canada T2R 0E1</FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>(Address of principal executive offices)
</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt; text-align: center"><B>(403) 265-3221 </B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">(Registrant&rsquo;s telephone number, including
area code)</P>

<P STYLE="font: bold 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: bold 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"></P>

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<P STYLE="font: bold 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"></P>

<P STYLE="font: bold 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Check the appropriate box below if the Form 8-K filing is intended
to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction
A.2. below):</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><FONT STYLE="font-family: Wingdings 2">&#163;</FONT> Written
communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><FONT STYLE="font-family: Wingdings 2">&#163;</FONT> Soliciting
material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><FONT STYLE="font-family: Wingdings 2">&#163;</FONT> Pre-commencement
communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><FONT STYLE="font-family: Wingdings 2">&#163;</FONT> Pre-commencement
communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify"><B>Item 1.01. Entry into a Material Definitive
Agreement.</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify"><I>Background</I></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">As previously announced,
Gran Tierra Energy Colombia Ltd. (&ldquo;<B><I>Gran Tierra Colombia</I></B>&rdquo;) and Solana Petroleum Exploration Colombia Ltd.
(&ldquo;<B><I>Solana Colombia</I></B>&rdquo;), both wholly owned indirect subsidiaries of Gran Tierra Energy Inc., each have an
agreement with Ecopetrol S.A. (each, a &ldquo;<B><I>Purchase Agreement</I></B>&rdquo;). The Purchase Agreements provided that Gran
Tierra Colombia and Solana Colombia agreed to sell to Ecopetrol, and Ecopetrol agreed to purchase from Gran Tierra Colombia and
Solana Colombia, all of the volume of crude oil production produced in the Chaza Block, Santana Block and Guayuyaco Block owned
by Gran Tierra Colombia and Solana Colombia (the &ldquo;<B><I>Putamayo Production</I></B>&rdquo;).&nbsp;&nbsp;The volume of crude
oil does not include the volume of oil owned by the National Hydrocarbons Agency (ANH) corresponding to royalties.&nbsp;&nbsp;In
the event that Ecopetrol does not accept a full delivery, Gran Tierra Colombia and Solana Colombia may sell to another party the
crude oil not accepted.&nbsp;&nbsp; On February 7, 2012, Gran Tierra Colombia and Solana Colombia each entered into an amendment,
dated as of January 30, 2012, to its respective Purchase Agreement, pursuant to which: (1) for Putamayo Production that is to be
exported through the Port of Tumaco on the Pacific coast of Colombia, the sales point is designated as the Tumaco Port rather than
a point in the Putamayo basin and the price received is determined based on a &ldquo;marker&rdquo; price (based on the average
export price of Ecopetrol of the South Blend mix by the Port of Tumaco for the month of the crude delivery) less a port operation
fee and a commercialization fee; (2) for Putamayo Production sold for export through Ecuador, the price received is determined
based on a &ldquo;marker&rdquo; price (based on the weighted average price of exports by Ecopetrol of Crude Oriente through the
port of Balao) less a transportation fee, transportation tax and commercialization fee; and (3) for Putamayo Production sold at
the DINA station in the Putamayo Basin for export by the Port of Cove&ntilde;as or for refining, the price received is determined
based on a &ldquo;marker&rdquo; (based on the average price of export of Grupo Empresarial crude mix Vasconia by the Port of Cove&ntilde;as
during the month of delivery) with adjustments for quality and less transportation fees, transportation tax, a commercialization
fee and port operation fee. Pursuant to the amendments, the expiry dates of each of the Purchase Agreements were extended to July
31, 2012.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">Also as previously
announced, as a result of the shift of the point of sale to the end of Ecopetrol&rsquo;s pipeline, on February 16, 2012, Gran Tierra
Colombia and Solana Colombia each entered into an agreement (each, a &ldquo;<B><I>Transportation Agreement</I></B>&rdquo;) with
Ecopetrol, dated as of January 30, 2012, pursuant to which the Putamayo Production to be exported through the Port of Tumaco was
transported by Ecopetrol through Ecopetrol&rsquo;s pipeline and Gran Tierra Colombia and Solana Colombia pay to Ecopetrol a transportation
tariff for this transportation through its pipeline. The estimated value of each Transportation Agreement<B><I> </I></B>was approximately
$6.75 million. Under these Transportation Agreements, Ecopetrol is liable for risk of loss of oil during transportation only if
Ecopetrol fails to take reasonable measures to operate the pipeline or is grossly negligent. The Transportation Agreements<B><I>
</I></B>had expiration dates of July 29, 2012.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in"></P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify"><I>August 6, 2012, Amendments</I></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">On August 6, 2012,
each of Gran Tierra Colombia<B><I> </I></B>and Solana Colombia entered the following agreements with Ecopetrol:</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">1.&#9;An Addendum No.
2 to its respective Purchase Agreement with Ecopetrol, effective July 31, 2012, which amended and restated the Purchase Agreement,
providing for: the extension of the term of the Purchase Agreement from July 31, 2012, to November 30, 2012; and the revision of
certain of the invoicing and pricing terms, in some cases as required by Colombian law; and</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">2.&#9;An Addendum
No. 1 to its respective Transportation Agreement with Ecopetrol, effective July 29, 2012, providing for: the extension of the
term of the Transportation Agreement from July 30, 2012, to December 31, 2012; a restriction on heavy crude up to a maximum of
12% of light crude received on the day at the Orito Plant; and a requirement to meet any changing product specification on the
pipeline.&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in"><B>&nbsp;</B></P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in"><B></B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify; text-indent: 0.5in">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">S<B>IGNATURES</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 0.1pt; text-indent: 35.9pt">Pursuant to the requirements
of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned
hereunto duly authorized.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD COLSPAN="3">Gran Tierra Energy Inc.</TD></TR>
<TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD COLSPAN="2">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>By:</TD>
    <TD COLSPAN="2" STYLE="border-bottom: windowtext 1pt solid">&nbsp;/s/ David Hardy&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 55%">&nbsp;</TD>
    <TD STYLE="width: 5%">&nbsp;</TD>
    <TD STYLE="width: 6%">Name:</TD>
    <TD STYLE="width: 34%; padding-left: 4.9pt">David Hardy</TD></TR>
<TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>Title:</TD>
    <TD STYLE="padding-left: 4.9pt">General Counsel, Vice President, Legal and Secretary</TD></TR>
</TABLE>


<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;Dated:&nbsp;August 9&#9;, 2012</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

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{"company-data": {"conformed-name": "GRAN TIERRA ENERGY, INC.", "cik": "0001273441", "assigned-sic": "1311", "irs-number": "000000000", "state-of-incorporation": "NV", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "8-K", "act": "34", "file-number": "001-34018", "film-number": "121020840"}, "business-address": {"street1": "300, 611-10TH AVENUE S.W.", "city": "CALGARY", "state": "A0", "zip": "T2R 0B2", "phone": "(403) 265-3221"}, "mail-address": {"street1": "300, 611-10TH AVENUE S.W.", "city": "CALGARY", "state": "A0", "zip": "T2R 0B2"}, "former-company": [{"former-conformed-name": "GOLDSTRIKE INC", "date-changed": "20040113"}, {"former-conformed-name": "GOLKSTRIKE INC", "date-changed": "20031216"}]}
UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, DC 20549
FORM 8-K
CURRENT REPORT
PURSUANT TO SECTION 13 OR 15(d) OF
THE SECURITIES EXCHANGE ACT OF 1934
Date of Report (Date of earliest event reported):
August 6, 2012
Gran Tierra Energy Inc.
(Exact name of Registrant as specified in
its charter)
Nevada
001-34018
98-0479924
(State or other jurisdiction
(Commission
(IRS Employer
of incorporation)
File Number)
Identification No.)
300, 625
- 11th Avenue S.W.
Calgary,
Alberta, Canada T2R 0E1
(Address of principal executive offices)
(403) 265-3221
(Registrant's telephone number, including
area code)
Check the appropriate box below if the Form 8-K filing is intended
to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction
A.2. below):
£
Written
communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)
£
Soliciting
material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)
£
Pre-commencement
communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))
£
Pre-commencement
communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))
1
Item 1.01. Entry into a Material Definitive
Agreement.
Background
As previously announced,
Gran Tierra Energy Colombia Ltd. ("
Gran Tierra Colombia
") and Solana Petroleum Exploration Colombia Ltd.
("
Solana Colombia
"), both wholly owned indirect subsidiaries of Gran Tierra Energy Inc., each have an
agreement with Ecopetrol S.A. (each, a "
Purchase Agreement
"). The Purchase Agreements provided that Gran
Tierra Colombia and Solana Colombia agreed to sell to Ecopetrol, and Ecopetrol agreed to purchase from Gran Tierra Colombia and
Solana Colombia, all of the volume of crude oil production produced in the Chaza Block, Santana Block and Guayuyaco Block owned
by Gran Tierra Colombia and Solana Colombia (the "
Putamayo Production
").  The volume of crude
oil does not include the volume of oil owned by the National Hydrocarbons Agency (ANH) corresponding to royalties.  In
the event that Ecopetrol does not accept a full delivery, Gran Tierra Colombia and Solana Colombia may sell to another party the
crude oil not accepted.   On February 7, 2012, Gran Tierra Colombia and Solana Colombia each entered into an amendment,
dated as of January 30, 2012, to its respective Purchase Agreement, pursuant to which: (1) for Putamayo Production that is to be
exported through the Port of Tumaco on the Pacific coast of Colombia, the sales point is designated as the Tumaco Port rather than
a point in the Putamayo basin and the price received is determined based on a "marker" price (based on the average
export price of Ecopetrol of the South Blend mix by the Port of Tumaco for the month of the crude delivery) less a port operation
fee and a commercialization fee; (2) for Putamayo Production sold for export through Ecuador, the price received is determined
based on a "marker" price (based on the weighted average price of exports by Ecopetrol of Crude Oriente through the
port of Balao) less a transportation fee, transportation tax and commercialization fee; and (3) for Putamayo Production sold at
the DINA station in the Putamayo Basin for export by the Port of Coveñas or for refining, the price received is determined
based on a "marker" (based on the average price of export of Grupo Empresarial crude mix Vasconia by the Port of Coveñas
during the month of delivery) with adjustments for quality and less transportation fees, transportation tax, a commercialization
fee and port operation fee. Pursuant to the amendments, the expiry dates of each of the Purchase Agreements were extended to July
31, 2012.
Also as previously
announced, as a result of the shift of the point of sale to the end of Ecopetrol's pipeline, on February 16, 2012, Gran Tierra
Colombia and Solana Colombia each entered into an agreement (each, a "
Transportation Agreement
") with
Ecopetrol, dated as of January 30, 2012, pursuant to which the Putamayo Production to be exported through the Port of Tumaco was
transported by Ecopetrol through Ecopetrol's pipeline and Gran Tierra Colombia and Solana Colombia pay to Ecopetrol a transportation
tariff for this transportation through its pipeline. The estimated value of each Transportation Agreement
was approximately
$6.75 million. Under these Transportation Agreements, Ecopetrol is liable for risk of loss of oil during transportation only if
Ecopetrol fails to take reasonable measures to operate the pipeline or is grossly negligent. The Transportation Agreements
had expiration dates of July 29, 2012.
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August 6, 2012, Amendments
On August 6, 2012,
each of Gran Tierra Colombia
and Solana Colombia entered the following agreements with Ecopetrol:
1.	An Addendum No.
2 to its respective Purchase Agreement with Ecopetrol, effective July 31, 2012, which amended and restated the Purchase Agreement,
providing for: the extension of the term of the Purchase Agreement from July 31, 2012, to November 30, 2012; and the revision of
certain of the invoicing and pricing terms, in some cases as required by Colombian law; and
2.	An Addendum
No. 1 to its respective Transportation Agreement with Ecopetrol, effective July 29, 2012, providing for: the extension of the
term of the Transportation Agreement from July 30, 2012, to December 31, 2012; a restriction on heavy crude up to a maximum of
12% of light crude received on the day at the Orito Plant; and a requirement to meet any changing product specification on the
pipeline.
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S
IGNATURES
Pursuant to the requirements
of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned
hereunto duly authorized.
Gran Tierra Energy Inc.
By:
/s/ David Hardy
Name:
David Hardy
Title:
General Counsel, Vice President, Legal and Secretary
Dated: August 9	, 2012
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