Gran Tierra Energy Announces Record 2012 Year-End Reserves

          Gran Tierra Energy Announces Record 2012 Year-End Reserves

PR Newswire

CALGARY, Feb. 4, 2013

Reserve Additions Replace 205% of Production* on a 1P Company Interest Basis
After Producing a Record 8.4 Million Barrels of Oil*

CALGARY, Feb. 4, 2013 /PRNewswire/ -  Gran Tierra Energy Inc. (NYSE MKT: GTE;
TSX: GTE) ("Gran Tierra Energy"), a company focused on oil exploration and
production in South America, today announced the results of a qualified
independent reserve evaluation of the company's reserves by GLJ Petroleum
Consultants Ltd. ("GLJ") effective December 31, 2012.

Year-end  2012  Highlights,  calculated  in  accordance  with  United   States 
Securities and  Exchange Commission  ("SEC") rules  (comparisons are  to  2011 
year-end amounts):

  *Total Proved ("1P") reserves net after royalty ("NAR") increased 20% to
    approximately 40.6 million barrels of oil equivalent ("MMBOE")
    (approximately 95% light and medium oil and liquids; an increase compared
    to 91% at year-end 2011);
  *Total Proved plus Probable ("2P") reserves NAR increased 15% to
    approximately 56.2 MMBOE (approximately 95% light and medium oil and
    liquids; an increase compared to 85% at year-end 2011);
  *Total Proved plus Probable plus Possible ("3P") reserves NAR increased 1%
    to approximately 86.3 MMBOE (approximately 87% light and medium oil and
    liquids; an increase compared to 69% at year-end 2011);
  *Reservoir performance expectations were exceeded at the Costayaco field in
    Colombia. Costayaco 1P reserves increased to 19.7 million barrels of oil
    ("MMBO") NAR at year-end 2012 from 16.4 MMBO NAR at year-end 2011 despite
    total production of 3.8 MMBO NAR before inventory adjustments in 2012;
  *Appraisal drilling in the Moqueta field in Colombia resulted in 1P
    reserves increasing 45% to approximately 8.7 MMBO, 2P reserves increasing
    54% to 14.9 MMBO and 3P reserves increasing 108% to 26.9 MMBO on a company
    interest basis, and 1P reserves increasing to approximately 6.8 MMBO, 2P
    reserves increasing to 11.2 MMBO and 3P reserves increasing to 19.4 MMBO
    on a NAR basis. The limits of the field have not yet been defined;
  *Gran Tierra Energy produced approximately 8.4 MMBO of working interest oil
    before royalties and inventory adjustments or 6.4 MMBO NAR before
    inventory adjustments and 1.7 billion cubic feet ("Bcf") of company
    interest gas before royalties or 1.5 Bcf NAR in 2012;
  *Based on Gran Tierra Energy's 2012 year-end SEC company interest reserves
    and Gran Tierra Energy's 2012 total working interest production, Gran
    Tierra Energy's 1P, 2P, and 3P reserves life indices are 6.4 years, 8.9
    years, and 13.6 years respectively.
  *Annual production for 2012 averaged a record of approximately 23,600 
    company interest barrels of oil equivalent per day ("BOEPD") before
    royalties, or 18,000 BOEPD NAR, both before inventory adjustments.
    Production in the fourth quarter of 2012 increased to approximately 18,600
    BOEPD NAR before inventory adjustments. Production for the month of
    January 2013, before inventory adjustments, increased further to average
    approximately 21,000 BOEPD NAR.

All reserves values contained in the 2012 Highlights provided above have  been 
calculated using SEC rules. For reserves values calculated in compliance with
Canadian National Instrument 51-101 - Standards of Disclosure for Oil and  Gas 
Activities ("NI  51-101") and  the Canadian  Oil and  Gas Evaluation  Handbook 
("COGEH"), see  "Reserves  Reported  in  Accordance  with  Canadian  Reporting 
Requirements" below in this press release.

* Before royalties and inventory adjustments

"Through  continued  strong  reservoir  management,  appraisal  drilling   and 
exploration success,  Gran  Tierra  Energy had  another  outstanding  year  in 
growing reserves  and  production  to  record  levels  from  our  projects  in 
Colombia,  Brazil  and   Argentina.  The  company   has  been  successful   at 
consistently growing land, reserves and production  over the past 8 years  and 
is focused on continuing to add value for our shareholders through  successful 
exploration and  development  drilling in  the  future," said  Dana  Coffield, 
President and CEO. "In 2012, we produced  a record volume of oil, in spite  of 
unexpected challenges  posed by  substantial  transportation downtime  due  to 
pipeline disruptions on  the OTA pipeline  in Colombia. Our  team has  worked 
vigorously to put into place  alternative transportation measures to  mitigate 
possible future downtime impacts to crude transportation. These measures  are 
now in place and operational. As  a result, even with recent disruptions,  the 
company  achieved  near   record  levels  of   production,  before   inventory 
adjustments, in January of this year."

"In 2013, we  are focused  on continuing  to grow  reserves through  continued 
appraisal  drilling  in  the  Moqueta  and  Ramiriqui  oil  discoveries,   and 
additional exploration drilling  in Colombia,  testing new  oil resource  play 
concepts in  Brazil  and Argentina,  and  evaluating a  very  high-impact  oil 
exploration target at the  recently drilled Bretaña Norte  well in Peru.  Gran 
Tierra Energy's 2013 capital budget is expected to be funded through available
cash on hand, cash flow from  operations and with potential periodic draws  on 
our credit  facility  at  current commodity  prices  and  production  levels," 
concluded Coffield.

Reserves Reported in Accordance with United States Reporting Requirements

The following reserves are reported  consistent with United States  Securities 
and Exchange Commission rules.

Total Company

The following two tables summarize Gran Tierra Energy's year-end 2012  company 
interest reserves and  NAR reserves (calculated  using average  start-of-month 
2012 oil prices). Also shown in  the following table are Gran Tierra  Energy's 
NAR reserves for year-end 2011  (calculated using average start-of-month  2011 
oil prices).

Total Company                2012 Year-End    2012 Year-End    2011 Year-End

Light and Medium Oil and      Gran Tierra      Gran Tierra      Gran Tierra
Liquids                         Energy            Energy           Energy
                           Company Interest    NAR Reserves     NAR Reserves
(SEC Compliant)               Reserves
Reserves Category               MBO **             MBO              MBO
Proved                                                            
 Developed Producing           35,644            26,817           21,317
 Developed Nonproducing          778              666             1,554
 Undeveloped                   14,280            11,011           8,051
Total Proved                    50,702            38,494           30,922
Total Probable                  19,641            14,784           10,489
Total Proved plus Probable      70,343            53,278           41,411
Total Possible                  28,418            21,456           17,626
Total PPP                       98,761            74,734           59,037

**MBO (thousand barrels of oil).

Total Company                2012 Year-End    2012 Year-End    2011 Year-End

Gas                           Gran Tierra      Gran Tierra      Gran Tierra
                                Energy            Energy           Energy
(SEC Compliant)           Company Interest    NAR Reserves     NAR Reserves
                               Reserves
Reserves Category              MMSCF***           MMSCF            MMSCF
Proved                                                            
 Developed Producing           11,572            10,515           16,968
 Developed Nonproducing         1,014             813              310
 Undeveloped                    1,624            1,448            1,044
Total Proved                    14,210            12,776           18,322
Total Probable                   6,087            5,136            25,716
Total Proved plus Probable      20,297            17,912           44,038
Total Possible                  59,375            51,667          116,509
Total PPP                       79,672            69,579          160,547

***MMSCF (million standard cubic feet)

Total Company                2012 Year-End    2012 Year-End    2011 Year-End

BOE                           Gran Tierra      Gran Tierra      Gran Tierra
                                Energy            Energy           Energy
(SEC Compliant)            Company Interest    NAR Reserves     NAR Reserves
                               Reserves
Reserves Category               BOE****            BOE              BOE
Proved                                                            
 Developed Producing           37,572            28,569           24,145
 Developed Nonproducing          947              802             1,606
 Undeveloped                   14,551            11,252           8,225
Total Proved                    53,070            40,623           33,976
Total Probable                  20,656            15,640           14,775
Total Proved plus Probable      73,726            56,263           48,751
Total Possible                  38,314            30,068           37,044
Total PPP                       112,040           86,331           85,795

****BOE (barrel of oil equivalent).

  *1P, 2P and 3P reserves NAR (on an oil equivalent basis) increased largely
    due to positive technical adjustment to Costayaco reserves based on
    reservoir performance and additional appraisal drilling at Moqueta in
    Colombia.
  *Reserves were added through the Ramiriqui-1 exploration well in Colombia.
  *Reserves were added through development drilling in the Tiê field in the
    Recôncavo Basin, Brazil.
  *The Proa-2 development well on the Surubi Block, Argentina, successfully
    added reserves.
  *Partially offsetting reserve additions was 2012 full year production of
    8.4 MMBO of company interest oil before royalties and 1.7 Bcf of company
    interest gas before royalties.

Colombia

Gran Tierra Energy's Colombia year-end 2012 company interest and NAR  reserves 
are shown in the following two tables (calculated using average start-of-month
2012 oil  prices). Also  shown in  the  following two  tables is  Gran  Tierra 
Energy's Colombian NAR  reserves for year-end  2011 (calculated using  average 
start-of-month 2011 oil prices).

Colombia                     2012 Year-End    2012 Year-End    2011 Year-End

Light and Medium Oil and      Gran Tierra      Gran Tierra      Gran Tierra
Liquids                         Energy            Energy           Energy
                           Company Interest    NAR Reserves     NAR Reserves
(SEC Compliant)               Reserves
Reserves Category                 MBO              MBO              MBO
Proved                                                            
 Developed Producing           32,838            24,360           19,497
 Developed Nonproducing          380              317             1,402
 Undeveloped                    8,989            6,432            4,526
Total Proved                    42,207            31,109           25,425
Total Probable                  15,178            10,915           5,913
Total Proved plus Probable      57,385            42,024           31,338
Total Possible                  18,839            13,167           9,749
Total PPP                       76,224            55,191           41,087



Colombia                     2012 Year-End    2012 Year-End    2011 Year-End

Gas                           Gran Tierra      Gran Tierra      Gran Tierra
                                Energy            Energy           Energy
(SEC Compliant)            Company Interest    NAR Reserves     NAR Reserves
                               Reserves
Reserves Category                MMSCF            MMSCF            MMSCF
Proved                                                            
 Developed Producing            8,370            7,757            13,927
 Developed Nonproducing          993              794               0
 Undeveloped                    1,012             921              713
Total Proved                    10,375            9,472            14,640
Total Probable                   3,929            3,300            21,155
Total Proved plus Probable      14,304            12,772           35,795
Total Possible                   5,353            4,239            72,026
Total PPP                       19,657            17,011          107,821

  *The increase in 1P, 2P and 3P NAR oil reserves is mainly associated with
    positive technical adjustments in Costayaco reserves due to reservoir
    performance, additional development drilling in Costayaco, the appraisal
    drilling program in Moqueta field in Colombia, and the Ramiriqui-1
    exploration well.

The Costayaco and Moqueta fields 2012  year-end NAR reserves are shown in  the 
following  two  tables  (calculated  using  average  start-of-month  2012  oil 
prices). Also  shown  in the  following  two tables  is  a comparison  of  the 
Costayaco and Moqueta  fields 2012 year-end  gross lease reserves  (calculated 
using average  start-of-month 2012  oil prices)  to the  gross lease  reserves 
estimated in December 31, 2011  (calculated using average start-of-month  2011 
oil prices).

Costayaco                  2012 Year-End  2012 Year-End   2011 Year-End

Light and Medium Oil       Costayaco NAR Costayaco Gross Costayaco Gross
                             Reserves    Lease Reserves  Lease Reserves
(SEC Compliant) 
Reserves Category               MBO            MBO             MBO
Proved                                                       
 Developed Producing         17,240         24,803          20,281
Total Proved                  19,716         28,424          23,517
Total Probable                 3,740          5,420           2,503
Total Proved plus Probable    23,456         33,844          26,020
Total Possible                 2,642          3,867           7,528
Total PPP                     26,098         37,711          33,548



Moqueta                    2012 Year-End    2012 Year-End    2011 Year-End

Light and Medium Oil        Moqueta NAR  Moqueta Gross Lease Moqueta Gross
                             Reserves         Reserves       Lease Reserves
(SEC Compliant) 
Reserves Category               MBO              MBO              MBO
Proved                                                          
 Developed Producing          3,745            4,250            2,137
Total Proved                   6,849            8,683            5,973
Total Probable                 4,314            6,252            3,727
Total Proved plus Probable    11,163           14,935            9,700
Total Possible                 8,262           11,922            3,243
Total PPP                     19,425           26,857            12,943

  *Gran Tierra Energy successfully completed development drilling at
    Costayaco-15, Costayaco-16 and Costayaco-17 in 2012.
  *Approximately 3.8 MMBO NAR before inventory adjustments was produced from
    the Costayaco field in 2012. Through a successful field development and
    reservoir management program in 2012, Gran Tierra Energy was able to
    successfully mitigate reserve declines at the Costayaco field.
  *Gran Tierra Energy successfully drilled the Moqueta-7 and Moqueta-8
    appraisal wells in 2012.

Argentina

Gran Tierra Energy's Argentina company interest and NAR reserves are shown  in 
the following two  tables (calculated  using average  start-of-month 2012  oil 
prices). Also  shown in  the  following two  tables  is Gran  Tierra  Energy's 
Argentina  NAR   reserves  for   year-end  2011   (calculated  using   average 
start-of-month 2011 oil prices).

Argentina                    2012 Year-End    2012 Year-End    2011 Year-End

Light and Medium Oil and      Gran Tierra      Gran Tierra      Gran Tierra
Liquids                         Energy            Energy           Energy
                           Company Interest    NAR Reserves     NAR Reserves
(SEC Compliant)               Reserves
Reserves Category                 MBO              MBO              MBO
Proved                                                            
 Developed Producing            2,407            2,110            1,766
 Developed Nonproducing          398              349              152
 Undeveloped                    3,868            3,335            3,226
Total Proved                     6,673            5,794            5,144
Total Probable                   2,929            2,530            3,389
Total Proved plus Probable       9,602            8,324            8,533
Total Possible                   7,211            6,219            5,842
Total PPP                       16,813            14,543           14,375

Argentina                    2012 Year-End    2012 Year-End    2011 Year-End

Gas                           Gran Tierra      Gran Tierra      Gran Tierra
                                Energy            Energy           Energy
(SEC Compliant)           Company Interest    NAR Reserves     NAR Reserves
                               Reserves
Reserves Category                MMSCF            MMSCF            MMSCF
Proved                                                            
 Developed Producing            3,202            2,758            3,041
 Developed Nonproducing          21                19              310
 Undeveloped                     612              527              331
Total Proved                     3,835            3,304            3,682
Total Probable                   2,158            1,836            4,561
Total Proved plus Probable       5,993            5,140            8,243
Total Possible                  54,022            47,428           44,483
Total PPP                       60,015            52,568           52,726

  *The 1P and 3P NAR liquid reserve additions are largely associated with
    positive adjustments at Puesto Morales and Surubi.

Brazil

Gran Tierra Energy's Brazil company interest and NAR reserves are shown in the
following table  (calculated using  average start-of-month  2012 oil  prices). 
Also shown in the following table is Gran Tierra Energy's Brazil NAR  reserves 
for year-end 2011 (calculated using average start-of-month 2011 oil prices).

Brazil                       2012 Year-End    2012 Year-End    2011 Year-End

Light and Medium Oil and      Gran Tierra      Gran Tierra      Gran Tierra
Liquids                         Energy            Energy           Energy
                           Company Interest    NAR Reserves     NAR Reserves
(SEC Compliant)               Reserves
Reserves Category                 MBO              MBO              MBO
Proved                                                            
 Developed Producing             399              347               54
 Developed Nonproducing           0                0                0
 Undeveloped                    1,423            1,244             299
Total Proved                     1,822            1,591             353
Total Probable                   1,534            1,339            1,187
Total Proved plus Probable       3,356            2,930            1,540
Total Possible                   2,368            2,070            2,035
Total PPP                        5,724            5,000            3,575

  *1P, 2P and 3P reserves were added through development drilling in Brazil
    and increasing working interest to 100% from 70% in Blocks REC-T-129,
    -142, -155 and -224 located in Brazil's Recôncavo Basin.

Reserves Reported in Accordance with Canadian Reporting Requirements

The following reserves estimates are compliant with NI 51-101 and COGEH  (with 
forecasted oil price and costs):

Total Company

Total company                2012 Year-End    2012 Year-End    2011 Year-End

Light and Medium Oil and      Gran Tierra      Gran Tierra      Gran Tierra
Liquids                         Energy            Energy           Energy
                           Company Interest    NAR Reserves     NAR Reserves
(NI 51-101 compliant)         Reserves
Reserves Category                 MBO              MBO              MBO
Proved                                                            
 Developed Producing           35,242            26,892           21,232
 Developed Nonproducing          510              444             1,293
 Undeveloped                   13,996            10,920           8,448
Total Proved                    49,748            38,256           30,973
Total Probable                  19,528            15,006           10,601
Total Proved plus Probable      69,276            53,262           41,574
Total Possible                  28,755            22,105           18,224
Total PPP                       98,031            75,367           59,798

Total Company                2012 Year-End    2012 Year-End    2011 Year-End

Gas                           Gran Tierra      Gran Tierra      Gran Tierra
                                Energy            Energy           Energy
(NI-51-101 Compliant)     Company Interest    NAR Reserves     NAR Reserves
                               Reserves
Reserves Category                MMSCF            MMSCF            MMSCF
Proved                                                            
 Developed Producing           11,572            10,515           16,971
 Developed Nonproducing         1,014             812              306
 Undeveloped                    1,483            1,327            1,045
Total Proved                    14,069            12,654           18,322
Total Probable                   6,480            5,550            25,721
Total Proved plus Probable      20,549            18,204           44,043
Total Possible                  59,086            51,529          116,519
Total PPP                       79,635            69,733          160,562



Total Company                2012 Year-End    2012 Year-End    2011 Year-End

BOE                           Gran Tierra      Gran Tierra      Gran Tierra
                                Energy            Energy           Energy
(NI-51-101 Compliant)     Company Interest    NAR Reserves     NAR Reserves
                               Reserves
Reserves Category                 BOE              BOE              BOE
Proved                                                            
 Developed Producing           37,171            28,645           24,061
 Developed Nonproducing          679              579             1,344
 Undeveloped                   14,243            11,141           8,622
Total Proved                    52,093            40,365           34,027
Total Probable                  20,608            15,931           14,888
Total Proved plus Probable      72,701            56,296           48,915
Total Possible                  38,603            30,693           37,644
Total PPP                       111,304           86,989           86,558

Colombia

Gran Tierra Energy's year-end  2012 Colombia company  interest and NAR  liquid 
reserves are shown in the following  table (NI 51-101 compliant with  forecast 
oil price  and  cost). Also  shown  in the  following  table are  Gran  Tierra 
Energy's Colombian NAR reserves  for year-end 2011  (NI 51-101 compliant  with 
forecast oil price and cost).

Colombia                     2012 Year-End    2012 Year-End    2011 Year-End

Light and Medium Oil and      Gran Tierra      Gran Tierra      Gran Tierra
Liquids                         Energy            Energy           Energy
                           Company Interest    NAR Reserves     NAR Reserves
(NI 51-101 compliant)         Reserves
Reserves Category                 MBO              MBO              MBO
Proved                                                            
 Developed Producing           32,437            24,436           19,373
 Developed Nonproducing          112               96             1,141
 Undeveloped                    8,805            6,427            4,934
Total Proved                    41,354            30,959           25,448
Total Probable                  14,966            11,055           6,029
Total Proved plus Probable      56,320            42,014           31,477
Total Possible                  19,175            13,820           10,196
Total PPP                       75,495            55,834           41,673

Gran Tierra  Energy's year-end  2012  Colombia company  interest and  NAR  gas 
reserves are shown in the following  table (NI 51-101 compliant with  forecast 
gas price  and  cost). Also  shown  in the  following  table are  Gran  Tierra 
Energy's Colombian NAR reserves  for year-end 2011  (NI 51-101 compliant  with 
forecast gas price and cost).

Colombia                     2012 Year-End    2012 Year-End    2011 Year-End

Gas                           Gran Tierra      Gran Tierra      Gran Tierra
                                Energy            Energy           Energy
(NI-51-101 Compliant)     Company Interest    NAR Reserves     NAR Reserves
                               Reserves
Reserves Category                MMSCF            MMSCF            MMSCF
Proved                                                            
 Developed Producing            8,371            7,757            13,926
 Developed Nonproducing          993              794               0
 Undeveloped                     980              892              714
Total Proved                    10,344            9,443            14,640
Total Probable                   4,213            3,621            21,156
Total Proved plus Probable      14,557            13,064           35,796
Total Possible                   5,063            4,102            72,026
Total PPP                       19,620            17,166          107,822

The Costayaco and Moqueta fields 2012  year-end NAR reserves are shown in  the 
following two tables  (with forecast oil  price and cost).  Also shown in  the 
following two tables is a comparison of the Costayaco and Moqueta fields  2012 
year-end gross lease reserves (with forecast oil price and cost) to the  gross 
lease reserves estimated  at December 31,  2011 (with forecast  oil price  and 
cost).

Costayaco                     2012 Year-End     2012 Year-End   2011 Year-End

Light and Medium Oil         Costayaco Gran    Costayaco Gross Costayaco Gross
                                 Tierra        Lease Reserves  Lease Reserves
(NI 51-101 compliant)     Energy NAR Reserves
Reserves Category                  MBO               MBO             MBO
Proved                                                             
 Developed Producing            17,415            24,535          19,855
Total Proved                     19,929            28,139          23,216
Total Probable                    3,572             5,067           2,496
Total Proved plus Probable       23,501            33,206          25,712
Total Possible                    2,655             3,799           7,836
Total PPP                        26,156            37,005          33,548



Moqueta                       2012 Year-End     2012 Year-End  2011 Year-End

Light and Medium Oil       Moqueta NAR Reserves Moqueta Gross  Moqueta Gross
                                                Lease Reserves Lease Reserves
(NI 51-101 compliant) 
Reserves Category                  MBO               MBO            MBO
Proved                                                            
 Developed Producing             3,709             4,190          2,137
Total Proved                      6,794             8,478          5,973
Total Probable                    4,586             6,457          3,727
Total Proved plus Probable        11,380            14,935         9,700
Total Possible                    8,501             11,922         3,243
Total PPP                         19,881            26,857         12,943

Argentina

Gran Tierra Energy's Argentina year-end  2012 company interest and NAR  liquid 
reserves are shown in the following  table (NI 51-101 compliant with  forecast 
oil price and cost). Also shown in the following table is Gran Tierra Energy's
Argentina NAR reserves for  year-end 2011 (NI  51-101 compliant with  forecast 
oil price and cost).

Argentina                    2012 Year-End    2012 Year-End    2011 Year-End

Light and Medium Oil and      Gran Tierra      Gran Tierra      Gran Tierra
Liquids                         Energy            Energy           Energy
                           Company Interest    NAR Reserves     NAR Reserves
(NI 51-101 compliant)         Reserves
Reserves Category                 MBO              MBO              MBO
Proved                                                            
 Developed Producing            2,406            2,109            1,803
 Developed Nonproducing          398              348              152
 Undeveloped                    3,768            3,251            3,226
Total Proved                     6,572            5,708            5,181
Total Probable                   3,028            2,615            3,420
Total Proved plus Probable       9,600            8,323            8,601
Total Possible                   7,212            6,220            5,977
Total PPP                       16,812            14,543           14,578

Gran Tierra  Energy's Argentina  year-end 2012  company interest  and NAR  gas 
reserves are shown in the following  table (NI 51-101 compliant with  forecast 
oil price and cost). Also shown in the following table is Gran Tierra Energy's
Argentina NAR reserves for  year-end 2011 (NI  51-101 compliant with  forecast 
oil price and cost).

Argentina                    2012 Year-End    2012 Year-End    2011 Year-End

Gas                           Gran Tierra      Gran Tierra      Gran Tierra
                                Energy            Energy           Energy
(NI-51-101 Compliant)      Company Interest    NAR Reserves     NAR Reserves
                               Reserves
Reserves Category                MMSCF            MMSCF            MMSCF
Proved                                                            
 Developed Producing            3,201            2,758            3,045
 Developed Nonproducing          21                18              306
 Undeveloped                     503              435              331
Total Proved                     3,725            3,211            3,682
Total Probable                   2,267            1,929            4,565
Total Proved plus Probable       5,992            5,140            8,247
Total Possible                  54,023            47,427           44,493
Total PPP                       60,015            52,567           52,740

Brazil

Gran Tierra  Energy's Brazil  year-end 2012  company interest  and NAR  liquid 
reserves are shown in the following  table (NI 51-101 compliant with  forecast 
oil price and cost).

Brazil                       2012 Year-End    2012 Year-End    2011 Year-End

Light and Medium Oil and      Gran Tierra      Gran Tierra      Gran Tierra
Liquids                         Energy            Energy           Energy
                           Company Interest    NAR Reserves     NAR Reserves
(NI 51-101 compliant)         Reserves
Reserves Category                 MBO              MBO              MBO
Proved                                                            
 Developed Producing             399              347               56
 Developed Nonproducing           0                0                0
 Undeveloped                    1,423            1,242             288
Total Proved                     1,822            1,589             344
Total Probable                   1,534            1,336            1,152
Total Proved plus Probable       3,356            2,925            1,496
Total Possible                   2,368            2,065            2,051
Total PPP                        5,724            4,990            3,547

About Gran Tierra Energy Inc.

Gran Tierra  Energy Inc.  is  an international  oil  and gas  exploration  and 
production company,  headquartered in  Calgary,  Canada, incorporated  in  the 
United States, trading on  the NYSE MKT Exchange  (GTE) and the Toronto  Stock 
Exchange (GTE),  and operating  in  South America.  Gran Tierra  Energy  holds 
interests in producing and prospective properties in Argentina, Colombia, 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.

Additional information concerning Gran Tierra Energy is available at
www.grantierra.com, on SEDAR (www.sedar.com and with the SEC www.sec.gov).

Cautionary Statements:

Possible reserves are those  additional reserves that are  less certain to  be 
recovered than  Probable  reserves.  There  is  a  10%  probability  that  the 
quantities actually recovered  will equal  or exceed  the sum  of Proved  plus 
Probable plus  Possible  reserves. The  estimate  of reserves  for  individual 
properties may not reflect the same confidence level as estimates of  reserves 
for all properties, due  to the effects of  aggregation. A BOE is  calculated 
using the conversion factor of six thousand cubic feet ("Mcf") of natural  gas 
being equivalent to one barrel of oil. BOEs may be misleading, particularly if
used in isolation. A BOE conversion ratio of 6 Mcf : 1 barrel of oil is based
on an energy equivalency conversion method primarily applicable at the  burner 
tip and does not represent a value equivalency at the wellhead.

Forward-Looking Statements

The  statements  in  this  press   release  regarding  Gran  Tierra   Energy's 
expectations, plans, projections  and actions including,  reserve life  index, 
Gran  Tierra  Energy's  expectations   regarding  its  2013  exploration   and 
development  drilling  campaign,  reservoir  management  and  production,  and 
expected  funding  of   Gran  Tierra   Energy's  2013   capital  program   are 
"forward-looking statements"  within  the  meaning of  the  U.S.  federal  and 
Canadian  securities  laws,  including  Canadian  Securities   Administrators' 
National Instrument 51-102  - Continuous Disclosure  Obligations and the  U.S. 
Private Securities Litigation  Reform Act of  1995. Statements containing  the 
words "estimates", "expects", "continue", "will", "may", "grow", "anticipated"
and variations of these words are forward-looking statements.

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 the  accuracy of  its 
reserves estimates, the continuity of certain industry conditions, the ability
of Gran Tierra Energy to execute its current business and operational plans in
the manner currently planned.  Although Gran Tierra  Energy believes that  the 
assumptions underlying, and expectations  reflected in, these  forward-looking 
statements are reasonable, it can give no assurance that these assumptions and
expectations will prove to be correct.

The forward-looking statements contained in this press 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.Factors that could cause results to differ materially from those
described in the forward-looking statements include:Gran Tierra Energy's
operations are located in South America, and unexpected problems can arise due
to guerilla activity, technical difficulties and operational difficulties
which impact the production, transportation or sale of oil and gas; changing
prices for crude oil may cause some scheduled projects or actions to become
uneconomical, or may change Gran Tierra Energy's focus to other projects or
actions which could be of more benefit to Gran Tierra Energy, which could
cause projects or actions currently contemplated to be postponed or cancelled;
unexpected problems due to technical difficulties, operational difficulties,
and weather conditions; risks associated with not being able to fund the 2013
capital program through cash flow and cash on hand; and those other risks
found in the periodic reports filed by Gran Tierra Energy with the SEC,
including in the section entitled "Risk Factors" in its Quarterly Report on
Form 10-Q filed with the SEC on November 7, 2012, and available at the SEC's
internet site www.sec.gov and on SEDAR at www.sedar.com.

All forward-looking statements in this  press release are expressly  qualified 
by information  contained  in Gran  Tierra  Energy's filings  with  regulatory 
authorities and, subject to its obligations under applicable securities  laws, 
Gran Tierra  Energy  does not  undertake  to publicly  update  forward-looking 
statements,  whether  as  a  result  of  new  information,  future  events  or 
otherwise.

SOURCE Gran Tierra Energy Inc.

Contact:

Contact Information

For investor and media inquiries please contact:
Jason Crumley
Director, Investor Relations
403-265-3221
info@grantierra.com.
 
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