Gran Tierra Energy Increases Proved, Probable and Possible Oil Reserves 361% with 2007 Exploration Drilling Campaign



    Proved Reserves Increase 197%

    CALGARY, CANADA, August 13 /CNW/ - Gran Tierra Energy Inc. (OTC Bulletin
Board: GTRE), a company focused on oil exploration and production in South
America, today announced that results from the independent reserve auditors
report of Gaffney, Cline & Associates (GCA) and internal assessments relating
to Gran Tierra Energy's exploration drilling program in the first half of
2007, have increased the company's reported proved, probable, and possible
reserves 361%, and have increased the company's reported proved reserves 197%.

    Dana Coffield, President and CEO, stated, "Gran Tierra Energy has
attained extraordinary oil reserve growth in the first half of 2007 as a
result of our operated drilling activity. We believe these results affirm our
strategy of acquiring underdeveloped lands and adding value by drilling. In
the last two years, since inception of Gran Tierra Energy, our focus has been
on identifying and acquiring underdeveloped lands; our focus in 2007 has been
on developing these lands by drilling. As a result, we have now more than
tripled our acquired proved, probable and possible oil reserve base and almost
doubled our acquired proved oil reserve base by executing our drilling program
in the first half of 2007."

    The discovery of the Costayaco field in the Chaza Block, located in the
Putumayo Basin of Colombia and operated by Gran Tierra Energy, was the result
of drilling the Costayaco-1 exploration well in the second quarter of 2007.
GCA has evaluated the well data and associated geoscience data, and has
allocated to Gran Tierra Energy proved reserves of 3.0 million barrels of oil,
with additional probable reserves of 6.0 million barrels of oil, and
additional possible reserves of 8.2 million barrels of oil (all net after
royalty).

    The discovery of the Juanambu field in the Guayuyaco Block, also located
in the Putumayo Basin of Colombia and operated by Gran Tierra Energy, was the
result of drilling the Juanambu-1 exploration well earlier in 2007. GCA has
evaluated the well data and associated geoscience data, and has allocated to
Gran Tierra Energy proved reserves of 0.1 million barrels of oil, with
additional probable reserves of 0.3 million barrels of oil, and additional
possible reserves of 1.1 million barrels of oil (all net after royalty).

    The Puesto Climaco-2D sidetrack well in the Vinalar Block, located in the
Noroeste Basin of Argentina, tested a deeper undeveloped reservoir beneath the
existing Puesto Climaco field at the beginning of 2007. Gran Tierra Energy
internally evaluated the well data and associated geoscience data, and has
reallocated reserves associated with this well from existing proved
undeveloped reserves to new proved producing reserves. This reallocation does
not impact total proved reserves.

    In the first half of 2007, Gran Tierra Energy has produced approximately
206 thousand barrels of oil, net after royalty, reducing its proved producing
reserves reported at December 31, 2006 by that amount. Incorporating oil
produced and adding the new reserves reported above, Gran Tierra Energy's
estimate of proved reserves, net after royalty, as of June 30, 2007, stands at
5.9 million barrels of oil, with additional probable reserves at 7.5 million
barrels of oil, and additional possible reserves of 12.2 million barrels of
oil, for a total of 25.6 million barrels of proved, probable and possible oil
reserves. This contrasts to Gran Tierra Energy's December 31, 2006, proved
reserves of 3.0 million barrels of oil, probable reserves of 1.2 million
barrels of oil, and possible reserves of 2.9 million barrels of oil, or a
total of 7.1 million barrels of proved, probable and possible oil reserves.

    Production for the first half of 2007 has been stable, averaging 1,140
barrels of oil per day, net after royalty, as a result of successful well
workovers and production from Puesto Climaco-2D. Gran Tierra Energy has begun
initial production from testing and production optimization programs at
Juanambu-1 and Costayaco-1. Gran Tierra Energy expects production to grow
through the balance of 2007 and into 2008. The new oil production is currently
being trucked to existing production facilities.

    New field development planning is in progress for the Costayaco and
Juanambu fields, and is expected to continue into early 2008. This planning
will include the design of oil processing facilities, oil transportation
requirements, and field development drilling requirements. Gran Tierra Energy
has currently scheduled two additional wells for the Costayaco field, with the
objective to increase early production capacity and to further delineate the
size of the oil accumulation in the field. Drilling is to begin in the fourth
quarter of 2007.

    Dana Coffield continued "Our immediate attention going forward will be to
develop these new reserves by converting them into production and cash flow in
the coming years through additional drilling and infrastructure development.
Simultaneously, we are continuing to add additional underdeveloped lands to
our base and developing additional exploration drilling opportunities. The
balance of 2007 and 2008 will see a mix of both development drilling and
exploration drilling in our portfolio, in contrast to the activity of the
first half of this year, which was focused on exploration."

    About Gran Tierra Energy Inc.

    Gran Tierra Energy Inc. is an international oil and gas exploration and
production company, headquartered in Calgary, Canada, incorporated and traded
in the United States and operating in South America. Gran Tierra Energy holds
interests in producing and prospective properties in Argentina, Colombia and
Peru. To date, Gran Tierra Energy has pursued a strategy that focuses on
establishing a portfolio of producing properties, and development and
exploration opportunities, through selective acquisitions, to provide a base
for future growth. Additional information concerning Gran Tierra Energy is
available at http://www.grantierra.com. Investor inquiries may be directed to
info@grantierra.com or 1-800-916-GTRE (4873).

    General Statements

    GCA's statement of Proved reserves have been prepared in accordance with
the definitions set out in Rule 4-10 of Regulation S-X of the United States
Securities and Exchange Commission. GCA's statement of Probable and Possible
reserves have been prepared in accordance with generally accepted petroleum
engineering principles provided for in the document entitled Standards
Pertaining to the Estimating and Auditing of Oil and Gas Reserves Information,
promulgated by the Society of Petroleum Engineers (SPE). Reserve definitions
utilized are those approved by the Society of Petroleum Engineers, World
Petroleum Council, American Association of Petroleum Geologists and the
Society of Petroleum Evaluation Engineers in March 2007 and issued under the
name of Petroleum Resources Management System in March of 2007.

    Forward Looking Statements

    The statements in this press release regarding Gran Tierra Energy's
expectations for the balance of 2007 and 2008 with respect to growth of
production, new field development and increase in development drilling, are
'forward-looking statements' within the meaning of Section 27A of the United
States Securities Act of 1933, as amended, and Section 21E of the United
States Securities Exchange Act of 1934. Although these forward-looking
statements reflect the good faith judgment of management, forward-looking
statements are inherently subject to known and unknown risks and uncertainties
that may cause actual results to be materially different from those discussed
in these forward-looking statements including, but not limited to, in the case
of these forward-looking statements, unexpected delays in drilling due to
equipment failure or other unforeseen reasons; unforeseen events, such as
unexpected difficulties in drilling or unexpected discoveries, may cause Gran
Tierra Energy to reallocate resources, which may delay drilling and production
and/or alter the mix of development drilling and exploration drilling in Gran
Tierra Energy's portfolio; and unexpected costs may decrease funds available
to carry out drilling plans, which could delay or prevent production and/or
development. Readers are urged not to place undue reliance on these
forward-looking statements, which speak only as of the date of this release.
Gran Tierra Energy assumes no obligation to update these forward-looking
statements to reflect any event or circumstance that may arise after the date
of this release, other than as may be required by applicable law or
regulation. Readers are urged to carefully review and consider the various
disclosures, including the risk factors, made by Gran Tierra Energy in its
reports filed with the Securities and Exchange Commission, in particular its
quarterly report on Form 10-Q filed on May 15, 2007, which attempt to advise
interested parties of the risks and factors that may affect Gran Tierra
Energy's business. If one or more of these risks or uncertainties materialize,
or if the underlying assumptions prove incorrect, Gran Tierra Energy's actual
results may vary materially from those expected or projected.




For further information:

For further information: Gran Tierra Energy Inc. Dana Coffield,
800-916-4873 President & Chief Executive Officer info@grantierra.com or
Cameron Associates Al Palombo, 212-245-8800 Ext. 209 Investor Relations
al@cameronassoc.com

Organization Profile

Gran Tierra Energy Inc.

More on this organization


Custom Packages

Browse our custom packages or build your own to meet your unique communications needs.

Start today.

CNW Membership

Fill out a CNW membership form or contact us at 1 (877) 269-7890

Learn about CNW services

Request more information about CNW products and services or call us at 1 (877) 269-7890