Last updated on April 21, 2014 at 5:04 EDT

Gran Tierra Energy Announces Increased Working Interest and Contingent Resource Estimate for Block 95, Peru

June 11, 2012

Operations Update, With New 3-D Seismic Data Increasing Moqueta
Structural Closure Area

CALGARY, June 11, 2012 /PRNewswire/ – Gran Tierra Energy Inc. (“Gran Tierra Energy”) (NYSE MKT: GTE, TSX:
a company focused on oil exploration and production in South America,
today provided updates for its operations in Colombia, Argentina and


Block 95, Marañon Basin (Gran Tierra Energy 100% WI and operator subject to PeruPetro S.A. and
Peruvian Government approvals)

Gran Tierra Energy Peru S.R.L. has entered into an agreement to purchase
the remaining 40% working interest in Block 95 from Global Energy
Development PLC.  Subject to PeruPetro S.A. and Peruvian Government
approvals, Gran Tierra Energy will have a 100% working interest in
Block 95.

In addition, Gran Tierra Energy announces the results of a contingent
gross lease resource estimate for an oil discovery on Block 95,
provided by its independent reserves auditor, GLJ Petroleum Consultants
(“GLJ“) effective June 1, 2012. The resource estimate has been prepared in
compliance with National Instrument 51-101 – Standards of Disclosure for Oil and Gas Activities and the Canadian Oil and Gas Evaluation Handbook.

        --  Low estimate "1C" contingent resources of 11.5 million stock
            tank barrels of oil ("MMSTB")
        --  Best estimate "2C" contingent resources of 31.6 MMSTB
        --  High estimate "3C" contingent resources of 88.1 MMSTB

There is no certainty that it will be commercially viable to produce any
portion of the resources.  Contingent resources are those quantities of
petroleum estimated, as of a given date, to be potentially recoverable
from known accumulations using established technology or technology
under development, but which are not currently considered to be
commercially recoverable due to one or more contingencies. 
Contingencies may include factors such as economic, legal,
environmental, political, and regulatory matters, or a lack of
markets.  It is also appropriate to classify as contingent resources
the estimated discovered recoverable quantities associated with a
project in the early evaluation stage. Contingent resources are further
classified in accordance with the level of certainty associated with
the estimates and may be subclassified based on project maturity and/or
characterized by their economic status. The recoverable resources
attributed to the Block 95 discovery were considered sub-commercial
(contingent resources) due to the absence of a commitment to proceed
with development and the fact that development is in the very early
stages as considered from the point of view of both regulatory
requirements, and development strategy. It is premature to determine
the economic status; the economic status is undetermined until
additional fluid samples confirm the market for the crude and Gran
Tierra Energy has done additional work on the oil market, development
capital and environmental/regulatory matters.

The oil field discovered on Block 95, with the Bretaña 10-16-1X
discovery well drilled in 1974, flowed 807 barrels of oil per day
naturally without pumps for approximately six hours from the Vivian
Formation.  Well records indicate inconsistent oil gravity values of
13.1° API and 17.6° API. As the Bretaña well is located in a remote
location, an oil gravity of 13.1° API will make this project
challenging to develop in the current economic environment.  If the oil
gravity is 17.6° API, this project will likely be economic to develop
in the current economic environment.  Gran Tierra Energy is planning to
drill a new exploration well in the fourth quarter of this year to
further delineate this field and to explore deeper reservoir horizons
not penetrated by the discovery well. A drilling site location has been
identified and civil construction initiated for the Bretaña Norte
95-2-1X exploration well on this structure.


Chaza Block, Putumayo Basin (Gran Tierra Energy 100% WI and operator)

A 3-D seismic program has now been acquired over the Moqueta Field. The
new maps over the field indicate the eastern flank of the structure
extends more than 2.5 kilometers to the northeast at the level of the
lowest known oil in existing well bores in the field, implying
additional reserve potential may exist on the east flank of the
structure that had not previously been recognized. A new well to
evaluate this additional potential is being designed for drilling late
this year.

Mobilization for a drilling rig is underway for the Moqueta-7 appraisal
well in the Moqueta field, which is expected to be spud in early July.
 This well is targeting additional appraisal of the down-dip extent of
the oil columns encountered in the Villeta U, Villeta T and Caballos
reservoirs in the field approximately 960 meters west-southwest of the
Moqueta-4 appraisal well.  Gran Tierra Energy intends to target the
interpreted oil-water contact, which has not yet been encountered by
drilling, approximately 225 feet below the lowest known oil in existing
well bores in the field; Moqueta-7 could be used as an oil producer or
water injector for pressure support depending on the well results. 

The Costayaco-16 development well spud on June 6, 2012; this well is
intended to be a producing well to assist with maintaining plateau
production in the Costayaco Field.

Azar Block, Putumayo Basin (Gran Tierra Energy 40% WI and Operator,
Lewis Energy Colombia Inc. 40% WI, Gold Oil 20% WI subject to Agencia
Nacional de Hidrocarburos

The La Vega Este-1 oil exploration well spud on May 14, 2012 and is
targeting the same Cretaceous sandstone intervals present in the
Costayaco and Moqueta discoveries.  Gran Tierra Energy expects the La
Vega Este well to reach total depth at the end of June, with results
expected in July.

Garibay Block, Llanos Basin (Gran Tierra Energy 50% WI, CEPSA 50% WI and

The Bordon-1 oil exploration well spud on June 6, 2012 and is expected
to reach total depth in late July, with results expected in August.


Puesto Guevara Block, Neuquen Basin (Gran Tierra Energy 100% WI and

The Los Incas x-1 oil exploration well in the Puesto Guevara Block has
been drilled and is being plugged and abandoned after encountering only
minor oil shows.

Production Update

May production and sales have been impacted by additional disruptions on
the Ecopetrol-operated Oleoducto Transandino (“OTA“) pipeline in Colombia. Gran Tierra Energy continued production at a
reduced rate while the OTA pipeline was down, selling a portion of its
crude through trucking and storing excess crude. Production, net after
royalties and before changes in inventory and losses for the months of
April and May averaged approximately 18,000 barrels of oil equivalent
per day.  Production is expected to return to normal levels mid-June.

About Gran Tierra Energy Inc.

Gran Tierra Energy is an international oil and gas exploration and
production company, headquartered in Calgary, Canada, incorporated in
the United States, trading on the NYSE MKT (GTE) and the Toronto Stock
Exchange (GTE), and operating in South America. Gran Tierra Energy
holds interests in producing and prospective properties in Colombia,
Argentina, Peru, and Brazil. Gran Tierra Energy has a strategy that
focuses on establishing a portfolio of producing properties, plus
production enhancement and exploration opportunities to provide a base
for future growth.

Gran Tierra Energy’s Securities and Exchange Commission filings are
available on a web site maintained by the Securities and Exchange
Commission at http://www.sec.gov and on SEDAR at http://www.sedar.com.

Forward Looking Statements and Advisories

This news release contains certain forward-looking information and
forward-looking statements (collectively, “forward-looking statements”)
under the meaning of applicable securities laws, including Canadian
Securities Administrators’ National Instrument 51-102 – Continuous Disclosure Obligations and the United States Private Securities Litigation Reform Act of 1995.
The use of the words “expected”, “intends”, “will”, “targeting”,
“planning”, “could”, “estimate”, “potential”, “scheduled”, and
derivations thereof and similar terms identify forward-looking
statements. In particular, but without limiting the foregoing, this
news release contains forward-looking statements regarding Gran Tierra
Energy’s intended and expected drilling operations in Colombia,
Argentina and Peru including, without limitation, anticipated  well
uses, drilling targets and timelines, estimated additional reserves and
resource potential and estimated contingent resources and expectations
respecting the resumption of service of the OTA pipeline.

Statements relating to “resources” are forward-looking statements as
they involve the implied assessment, based on estimates and
assumptions, that the resources described exist in the quantities
predicted or estimated and can be profitably produced in the future.

The forward-looking statements contained in this news release reflect
several material factors and expectations and assumptions of Gran
Tierra Energy including, without limitation: assumptions relating to
log evaluations; that Gran Tierra Energy will continue to conduct its
operations in a manner consistent with past operations; the accuracy of
testing and production results and seismic data; the effects of certain
drilling techniques; and the general continuance of current or, where
applicable, assumed operational, regulatory and industry conditions.
Gran Tierra Energy believes the material factors, expectations and
assumptions reflected in the forward-looking statements are reasonable
at this time but no assurance can be given that these factors,
expectations and assumptions will prove to be correct.

The forward-looking statements contained in this news release are
subject to risks, uncertainties and other factors that could cause
actual results or outcomes to differ materially from those contemplated
by the forward-looking statements, including, among others: unexpected
technical difficulties and operational difficulties may occur, or the
obtaining of environmental permits may be delayed, which could impact
or delay the commencement of drilling; geographic, political and
weather conditions can interrupt drilling, which could impact or delay
the commencement or continuation of drilling, service of the OTA
pipeline may not resume on the timeline or to the capacity currently
expected by Gran Tierra Energy; and the risk that current global
economic and credit market conditions may impact oil prices and oil
consumption more than Gran Tierra Energy currently predicts, which
could cause Gran Tierra Energy to change its current drilling,
production and testing plans. Although Gran Tierra Energy’s plans for
its ongoing exploration and development and the funding thereof are
based upon the current expectations of the management of Gran Tierra
Energy, there may be circumstances where, for unforeseen reasons, a
change in such plans may be necessary as may be determined at the
discretion of Gran Tierra Energy. Should any one of a number of issues
arise, Gran Tierra Energy may find it necessary to alter its current
business strategy. Further information on potential factors that could
affect Gran Tierra Energy are included in risks detailed from time to
time in Gran Tierra Energy’s Securities and Exchange Commission
filings, including, without limitation, under the caption “Risk
Factors” in Gran Tierra Energy’s Quarterly Report on Form 10-Q filed
May 7, 2012. These filings are available on a Web site maintained by
the Securities and Exchange Commission at http://www.sec.gov and on SEDAR at www.sedar.com.  The forward-looking statements contained herein are expressly
qualified in their entirety by this cautionary statement. The
forward-looking statements included in this press release are made as
of the date of this press release and Gran Tierra Energy disclaims any
intention or obligation to update or revise any forward-looking
statements, whether as a result of new information, future events or
otherwise, except as expressly required by applicable securities

Barrels of oil equivalent (“BOE“) may be misleading, particularly if used in isolation. A BOE
conversion ratio of 6 Mcf: 1 bbl is based on an energy equivalency
conversion method primarily applicable at the burner tip and does not
represent a value equivalency at the wellhead. In addition, given that
the value ratio based on the current price of oil as compared to
natural gas is significantly different from the energy equivalent of
six to one, utilizing a BOE conversion ratio of 6 Mcf: 1 bbl would be
misleading as an indication of value.

SOURCE Gran Tierra Energy Inc.

Source: PR Newswire