Gran Tierra Energy Inc. Announces Second Quarter 2013 Results and Production Guidance Increase

 Gran Tierra Energy Inc. Announces Second Quarter 2013 Results and Production
                              Guidance Increase

PR Newswire

CALGARY, Aug. 6, 2013

Moqueta Field Size Extended with Additional Drilling and Successful Brazil
Acreage Bid Contribute to Another Strong Quarter

CALGARY, Aug. 6,  2013 /PRNewswire/ -  Gran Tierra Energy  Inc. ("Gran  Tierra 
Energy") (NYSE  MKT:  GTE,  TSX:  GTE),  a company  focused  on  oil  and  gas 
exploration and production in South America, today announced its financial and
operating results for the quarter ended June30, 2013.All dollar amounts  are 
in United States ("U.S.") dollars unless otherwise indicated.

Financial and operating highlights for the quarter include:

  *Quarterly oil and natural gas production net after royalty ("NAR") and
    adjusted for inventory changes, was 22,131 barrels of oil equivalent per
    day ("BOEPD"), an increase of 57% from the comparable period in 2012.
    Production before adjustment for inventory changes in July 2013 averaged
    approximately 23,000 BOEPD NAR. As a result of strong production
    performance in the first half of 2013, including continued plateau
    production at the Costayaco field in Colombia, guidance for 2013 has been
    increased from 20,000 BOEPD NAR to a range between 21,000 and 22,000 BOEPD
    NAR and before adjustment for inventory changes;
  *Revenue and other income for the quarter was $168.8 million, a 47%
    increase over the comparable period in 2012;
  *Net income for the quarter was $47.8 million, representing $0.17 per share
    basic and diluted, an increase of 265% compared with net income of $13.1
    million, or $0.05 per share basic and diluted, in the comparable period in
    2012;
  *Funds flow from operations increased to $200.1 million in the first half
    of 2013 from $116.6 million in the comparable period in  2012;
  *Cash and cash equivalents were $282.0 million at June30, 2013, compared
    with $212.6 million at December31, 2012;
  *In Colombia, continued the successful development of the Moqueta field in
    the Putumayo Basin. The Moqueta-10 well was drilled and tested at 952
    barrels of oil per day ("BOPD"); the well was intended to be a water
    injector, but will now be brought on as a producing well and converted to
    a water injector at a later date. The Moqueta-11 well was successfully
    drilled and testing has been initiated. The well discovered additional
    oil column in a new area to the south of the field's existing proved
    reserves, with positive additional reserve implications subject to testing
    results. No oil-water contact has yet to be found, the limits of the
    field have yet to be defined;
  *In Peru, successfully tested the horizontal sidetrack of the Bretaña Norte
    95-2-1XD exploration well in Block 95 at 3,095 BOPD. A 382 kilometer
    ("km") 2D seismic acquisition program has been initiated to provide a more
    detailed map of the Bretaña structure and an independent exploration
    prospect to the south of the Bretaña structure;
  *In Brazil, Gran Tierra Energy successfully bid on three blocks in the
    recently completed 2013 Brazil Bid Round administered by Brazil's Agência
    Nacional de Petróleo, Gás Natural e Biocombustíveis ("ANP"), thus
    increasing its land position in Brazil to 47,734 gross acres. Gran Tierra
    Energy's ongoing three-well horizontal drilling campaign results to date
    have been inconclusive, but data gathered continues to support the
    exploration play concept on our expanded land base.
  *In Argentina, plans are underway to drill a second horizontal multi-stage
    fracture stimulated well in the third quarter of 2013 after the successful
    production test of the PMN-1117 horizontal multi-stage fracture stimulated
    well in late 2012.

"Gran Tierra Energy achieved an outstanding  first half of 2013, with  average 
production levels exceeding  our expectations  leading to an  increase in  our 
2013 production  projections," commented  Dana Coffield,  President and  Chief 
Executive Officer of  Gran Tierra  Energy. "Operationally,  the Moqueta  field 
continues to  grow  with the  Moqueta-10  and Moqueta-11  wells  now  drilled. 
Ongoing testing on the  Moqueta-11 well increases the  known aerial extent  of 
the oil  field and  significantly  increases the  oil column  thickness,  with 
positive implications for additional reserves in the field. In Brazil,  Gran 
Tierra  Energy  successfully  bid  on   three  new  onshore  Recôncavo   Basin 
exploration blocks,  which will  enable  Gran Tierra  Energy to  leverage  its 
growing knowledge  of the  basin. Our  horizontal drilling  has not  provided 
conclusive test results to  date, but we remain  encouraged with the  positive 
data gathered  and  are  aggressively continuing  our  drilling  program.  In 
Argentina, we are  continuing to build  on the success  of our first  fracture 
stimulated horizontal  well by  planning a  second similar  well in  the  Loma 
Montosa formation for  this year. And  finally, in Peru,  Gran Tierra  Energy 
successfully transported by barge and sold  its first Bretaña test oil to  the 
Petroperu S.A.  refinery in  the  city of  Iquitos.  We are  working  towards 
booking reserves on the Bretaña structure at or before December 31, 2013,  and 
we intend to  initiate long-term testing  from Bretaña Norte  95-2-1XD in  the 
first quarter of 2014," concluded Coffield.

Production review

                  Three Months Ended June 30, 2013                Three Months Ended June 30, 2012      
(Barrels of   Colombia    Argentina    Brazil       Total       Colombia   Argentina   Brazil      Total
Oil
Equivalent)
Gross         2,275,972   321,286    87,792    2,685,050   1,498,875   392,388   15,360  1,906,623 
production
Royalties     (590,032)  (38,081)  (10,771)    (638,884)   (375,506)  (45,672)  (1,579)  (422,757) 
Inventory      (18,640)   (3,556)  (10,062)     (32,258)   (185,330)  (10,674)  (2,288)  (198,292) 
adjustment
Production,   1,667,300   279,649    66,959    2,013,908     938,039   336,042   11,493  1,285,574 
NAR
                                                                                                  
Production       18,322     3,073       736       22,131      10,308     3,693      126     14,127 
per day,
NAR (BOEPD)
                                                                                          
                                                                                          
                   Six Months Ended June 30, 2013                  Six Months Ended June 30, 2012       
(Barrels of   Colombia    Argentina    Brazil       Total       Colombia   Argentina   Brazil      Total
Oil
Equivalent)
Gross         4,459,463   652,502   167,705    5,279,670   3,364,523   685,716   29,266  4,079,505 
production
Royalties   (1,166,971)  (77,880)  (20,477)  (1,265,328)   (861,364)  (79,393)  (3,407)  (944,164) 
Inventory       121,134     3,040  (16,435)      107,739   (313,960)  (10,402)  (1,843)  (326,205) 
adjustment
Production,   3,413,626   577,662   130,793    4,122,081   2,189,199   595,921   24,016  2,809,136 
NAR
                                                                                                  
Production       18,860     3,192       723       22,775      12,029     3,274      132     15,435 
per day,
NAR (BOEPD)

Financial review

          Three Months Ended June 30,          Six Months Ended June 30,     
          2013         2012        %        2013         2012        %    
                                    Change                               Change
Revenue $ 168,810   $ 115,150       47  $ 374,181   $ 271,101       38 
and
Other
Income
($000s)
Net     $  47,783   $  13,104      265  $ 105,696   $  12,791      726 
Income
($000s)
Net     $    0.17   $    0.05      240  $    0.37   $    0.05      640 
Income
Per
Share -
Basic
Net     $    0.17   $    0.05      240  $    0.37   $    0.05      640 
Income
Per
Share -
Diluted

Net income reconciled to funds flow from operations^(1) is as follows:

                        Three Months Ended June 30, Six Months Ended June 30,
Funds Flow From              2013           2012       2013         2012
Operations - Non-GAAP
Measure ($000s)
                                                                       
Net income                $  47,783     $ 13,104  $ 105,696   $  12,791 
Adjustments to reconcile                                                
net income to funds flow
from operations
Depletion, depreciation,     63,022       32,571    121,434      92,938 
accretion and impairment
    Deferred tax           (8,299)      (4,800)   (15,749)    (10,050) 
     recovery
    Stock-based              2,349        3,730      4,416       6,922 
     compensation
    Unrealized foreign    (11,622)      (5,187)   (18,366)      16,164 
     exchange (gain)
     loss
    Settlement of asset          —            —          —       (404) 
     retirement
     obligation
Equity tax                  (1,718)      (1,785)    (1,718)     (1,785) 
Other loss                        —            —      4,400           — 
Funds flow from           $  91,515     $ 37,633  $ 200,113   $ 116,576 
operations

^(1) Funds flow from operations is a non-GAAP measure which does not have  any 
standardized meaning prescribed under generally accepted accounting principles
in the  United States  of  America ("GAAP").  Management uses  this  financial 
measure to  analyze operating  performance and  the income  generated by  Gran 
Tierra Energy's principal  business activities prior  to the consideration  of 
how non-cash  items  affect that  income,  and believes  that  this  financial 
measure is  also  useful supplemental  information  for investors  to  analyze 
operating performance and  Gran Tierra Energy's  financial results.  Investors 
should  be  cautioned  that  this  measure  should  not  be  construed  as  an 
alternative to  net  income or  other  measures of  financial  performance  as 
determined  in  accordance  with  GAAP.   Gran  Tierra  Energy's  method   of 
calculating this measure may differ from other companies and, accordingly,  it 
may not be comparable to similar measures used by other companies. Funds  flow 
from  operations,  as  presented,  is  net  income  adjusted  for   depletion, 
depreciation,  accretion  and  impairment  ("DD&A"),  deferred  tax  recovery, 
stock-based compensation, unrealized foreign exchange gain or loss, settlement
of asset retirement obligation, equity tax and other loss.

Second Quarter 2013 Financial Highlights:

For the three and  six months ended  June 30, 2013,  revenue and other  income 
increased by 47% to $168.8 million and by 38% to $374.2 million, respectively,
compared with $115.2 million and  $271.1 million in the corresponding  periods 
in 2012. The positive contribution from higher production levels was partially
offset by  lower  realized  prices. In  Colombia,  alternative  transportation 
arrangements to minimize the impact  of pipeline disruptions, production  from 
new wells and a decrease in oil inventory had a positive impact on  production 
in 2013. The net inventory reduction accounted for 595 BOEPD of the production
increase for the six months ended June 30, 2013. Production during the  second 
quarter of 2013reflected approximately 70  days of oil delivery  restrictions 
in Colombia.

Average realized oil prices decreased by  8% to $85.03 per barrel ("bbl")  for 
the three months ended June  30, 2013, from $92.48  per bbl in the  comparable 
period in 2012, and decreased by 7% to $92.26 per bbl for the six months ended
June 30, 2013, from $99.49 per bbl  in the comparable period in 2012.  Average 
Brent oil  prices for  the three  and six  months ended  June 30,  2013,  were 
$102.58 and $107.54 per bbl,  respectively, compared with $108.43 and  $113.50 
per bbl in  2012. West Texas  Intermediate oil  prices for the  three and  six 
months ended June 30, 2013, averaged $94.22 and $94.31 per bbl,  respectively, 
compared with $93.48 and $98.19 per bbl in 2012.

During  the  three  and  six  months  ended  June  30,  2013,  51%  and   40%, 
respectively, of the company's oil and gas volumes sold were to a customer for
which the realized price is adjusted for trucking costs related to a 1,500  km 
route. The effect on the Colombian realized price for the three and six months
ended June 30, 2013, was a reduction of approximately $11.30 and $9.85 per BOE
as compared with  delivering all of  our Colombian oil  through the  Ecopetrol 
S.A. ("Ecopetrol") operated Trans-Andean oil pipeline (the "OTA pipeline").

Operating expenses increased by 17% to $31.9 million and 41% to $72.9  million 
for the  three and  six months  ended June  30, 2013,  respectively, from  the 
comparable periods in  2012. The increase  in operating expenses  in 2013  was 
primarily due to increased production, partially  offset by a decrease in  the 
operating cost  per barrel  of oil  equivalent ("BOE").  On a  per BOE  basis, 
operating expenses decreased by 25% to $15.84  and 4% to $17.69 for the  three 
and six months ended  June 30, 2013, respectively,  from $21.26 and $18.45  in 
the comparable periods in 2012.

In the three months ended June 30, 2013, operating expenses per BOE  decreased 
primarily due to lower transportation  costs associated with the OTA  pipeline 
and  increased   volumes,   partially   offset  by   increased   general   and 
administrative ("G&A") allocations  to operating  costs. Transportation  costs 
were lower due to the absence of OTA pipeline charges for volumes sold at  the 
Costayaco battery. The trucking costs associated with the volumes sold at  the 
Costayaco battery were a reduction of the realized price rather than  recorded 
as  transportation  expenses.  The  estimated  net  effect  of  OTA   pipeline 
disruptions on Colombian transportation costs for the three months ended  June 
30, 2013, was  a saving of  $2.20 per BOE.  In the six  months ended June  30, 
2013, lower transportation costs associated with OTA pipeline disruptions were
offset by increased  trucking costs  to an alternate  pipeline, increased  G&A 
allocations to  operating costs  and  other fixed  costs. The  estimated  net 
effect of OTA pipeline disruptions  on Colombian transportation costs for  the 
six months ended June 30, 2013, was a saving of $1.05 per BOE.

DD&A expenses for  the three months  ended June 30,  2013, increased to  $63.0 
million from $32.6 million in the comparable period in 2012, primarily due  to 
increased production and a ceiling test impairment loss of $2.0 million in the
Brazil cost center  related to lower  realized prices and  an increase in  the 
estimate of operating costs. On a per BOE basis, the depletion rate  increased 
by 23% to $31.29 from $25.34. The  increase was mainly due to increased  costs 
in the depletable  base only partially  offset by increased  reserves and  the 
Brazil impairment loss of $0.99 per BOE in 2013.

DD&A expenses for  the six  months ended June  30, 2013,  increased to  $121.4 
million from $92.9  million in the  comparable period in  2012. The impact  of 
increased production  was partially  offset  by a  reduction in  ceiling  test 
impairment losses. As noted above, DD&A expenses for the six months ended June
30, 2013, included a $2.0 million  ceiling test impairment loss in our  Brazil 
cost center. DD&A expenses for the six months ended June 30, 2012, included  a 
$20.2 million ceiling test impairment loss  in the Brazil cost center  related 
to seismic and  drilling costs on  Block BM-CAL-10.  On a per  BOE basis,  the 
depletion rate decreased by 11% to $29.46 from $33.08. The decrease was mainly
due to  reduced Brazil  cost  center impairment  losses, partially  offset  by 
increased costs in the depletable base. Increased costs were partially  offset 
by increased reserves.

G&A expenses for the three  and six months ended  June 30, 2013, decreased  by 
33% to $11.7  million and by  31% to $23.2  million, respectively, from  $17.6 
million and $33.5 million,  compared with the  corresponding periods in  2012. 
Increased employee related costs reflecting expanded operations were more than
offset by  increased  recoveries  and  higher  G&A  allocations  to  operating 
expenses and capital projects in all  business units. G&A expenses per BOE  in 
the  three  and  six  months  ended  June  30,  2013,  of  $5.83  and   $5.62, 
respectively, were 57% and 53% lower  compared with $13.69 and $11.92 in  2012 
due  to  increased  production,  and  increased  recoveries  and  higher   G&A 
allocations to operating expenses and capital projects in all business units.

For the three and six  months ended June 30,  2013, the foreign exchange  gain 
was $12.0 million and $17.2 million, respectively, comprising an $11.6 million
and $18.4  million  unrealized non-cash  foreign  exchange gain.  The  foreign 
exchange gain was a  result of a net  monetary liability position in  Colombia 
combined with the weakening of the Colombian Peso, partially offset by foreign
exchange losses resulting from a net monetary asset position in Argentina  and 
the weakening of the Argentina Peso. For the three months ended June 30, 2012,
there was a foreign exchange loss  of $4.8 million, comprising a $5.2  million 
unrealized non-cash foreign exchange gain and realized foreign exchange losses
of $10.0  million. The  realized foreign  exchange loss  primarily arose  upon 
payment of the 2011 Colombian income tax liability during the quarter. For the
six months ended June  30, 2012, there  was a foreign  exchange loss of  $29.2 
million, comprising a $16.2 million unrealized non-cash foreign exchange  loss 
and realized foreign exchange losses of $13.0 million. The unrealized non-cash
foreign exchange loss  was a result  of a net  monetary liability position  in 
Colombia combined  with  the  strengthening  of the  Colombian  Peso  and  the 
realized foreign  exchange  loss primarily  arose  upon payment  of  the  2011 
Colombian income tax liability during the second quarter of 2012.

Other loss of $4.4 million in the six months ended June 30, 2013, relates to a
contingent loss  accrued in  connection with  a legal  dispute in  which  Gran 
Tierra Energy received an adverse legal judgment in the first quarter of 2013.
Gran Tierra Energy has filed an appeal against the judgment.

Income tax expense was $26.3 million and  $63.8 million for the three and  six 
months ended  June 30,  2013, respectively,  compared with  $19.7 million  and 
$50.9 million in the comparable periods in 2012. The increases were  primarily 
due to higher income before tax.

Net income for the three and six months ended June 30, 2013, was $47.8 million
and $105.7  million,  respectively,  compared with  $13.1  million  and  $12.8 
million in the comparable periods  in 2012. On a  per share basis, net  income 
increased to $0.17 per share basic and diluted for the three months ended June
30, 2013, and $0.37 per share basic and diluted for the six months ended  June 
30, 2013, from $0.05 per share basic and diluted in the comparable periods  in 
2012. Increased  oil and  natural  gas sales,  decreased  G&A expenses  and  a 
foreign exchange gain were partially  offset by increased operating, DD&A  and 
income tax expenses.

Balance Sheet Highlights:

Cash and cash equivalents were $282.0 million at June30, 2013, compared  with 
$212.6 million at December31, 2012. The increase in cash and cash equivalents
during the first six  months of 2013  was primarily the  result of funds  flow 
from operations of $200.1 million, and a $48.7 million decrease in assets  and 
liabilities  from   operating   activities,  partially   offset   by   capital 
expenditures of $184.6 million.

Working capital (including cash  and cash equivalents)  was $237.5 million  at 
June30, 2013, a $15.0 million increase from December31, 2012.

Production Highlights:

Production for the second quarter of 2013 averaged approximately 22,485  BOEPD 
NAR before adjustment for inventory changes  or 22,131 BOEPD NAR adjusted  for 
inventory changes (97% oil),  an increase of  approximately 57% versus  14,127 
BOEPD NAR adjusted for inventory changes  in 2012. Production for the  second 
quarter of 2013 consisted  of 18,322 BOEPD NAR  in Colombia (100% oil),  3,073 
BOEPD NAR in Argentina (82% oil) and 736 BOPD NAR in Brazil, all adjusted  for 
inventory changes. Production in July 2013 averaged approximately 23,000 BOEPD
NAR before adjustment for inventory changes.

Production for the second  quarter of 2013 was  above expectations due to  the 
continued  successful  execution  of  measures  to  mitigate  the  impact   of 
disruptions in  the OTA  pipeline  in Colombia.  In  addition, in  Colombia  a 
decrease in oil inventory and production from new wells had a positive  impact 
on production in  the first half  of 2013.  As a result,  Gran Tierra  Energy 
anticipates 2013 average production to  range between 21,000 and 22,000  BOEPD 
NAR before adjustment for  inventory changes, an  increase from the  company's 
prior projections of 20,000 BOEPD NAR before adjustment for inventory changes.
Approximately 96% of this production is expected to consist of light oil, with
the balance consisting of natural gas.

Second Quarter 2013 Operational Highlights

Colombia 

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

Moqueta Field

The Moqueta-10 appraisal  well was spud  on April 7,  2013, and reached  total 
depth ("TD") on May 7, 2013. The well was intended as a water injection  well 
targeting the far  western flank of  the Moqueta field  to assist in  pressure 
support. The Moqueta-10 well  discovered oil in  the T-Sandstone and  Caballos 
formations. The T-Sandstone formation consisted of 65 feet true vertical depth
("TVD") gross reservoir  or 58  feet TVD of  net reservoir  thickness. It  was 
perforated and tested from 6,105 feet to 6,180 feet measured depth ("MD")  for 
81 hours at a rate  of 609 BOPD of  26.2° API oil with  a 0.3% water cut.  The 
underlying Caballos formation consisted of 178 feet TVD gross reservoir or 113
feet TVD net reservoir thickness. It was perforated and tested from 6,276 feet
to 6,470 feet MD for 202 hours at a  rate of 343 BOPD of 27.5° API oil with  a 
0.3% water cut. The  well was tested  with a hydraulic jet  pump and will  be 
completed as an oil producer until water breakthrough occurs, and then will be
converted to a water injector as originally planned.

The Moqueta-11 appraisal well,  drilled to the southern  flank of the  Moqueta 
structure, was spud on June 19, 2013 and reached TD on July 15, 2013.  Initial 
drilling and logging results indicate oil through the Villeta T-Sandstone  and 
the Caballos formations. Initial  log interpretations suggest  the top of  the 
Villeta T-Sandstone is  approximately 290  feet lower in  the Moqueta-11  well 
compared to the  lowest known oil  encountered in the  field at the  Moqueta-7 
well, suggesting the oil column is 290 feet thicker than previously  defined. 
The gross oil column in the Villeta T-Sandstone has now grown to 765 feet  and 
the gross oil column in the underlying Caballos reservoir has now grown to 960
feet. No oil-water  contact is evident  on logs, which,  subject to  testing, 
indicates additional  oil  potential exists  further  down the  flank  of  the 
Moqueta structure.

Gran Tierra  Energy  continues  to anticipate  receiving  the  Moqueta  global 
environmental permit  in the  first quarter  of 2014,  which will  enable  the 
company to  pursue  delineation  of  the north-east  portion  of  the  Moqueta 
structure later that year.

Costayaco Field

The Costayaco-18 development well was spud on March 19, 2013, and reached a TD
of 8,857 feet MD  on April 13, 2013.  This well was put  on production in  the 
second quarter to assist  in maintaining plateau  production at the  Costayaco 
field.

Llanos-22 Block, Llanos  Basin (Gran  Tierra Energy 45%  WI CEPSA  55% WI  and 
non-operated)

The Ramiriqui-1 oil discovery is located in the Andean foothills trend of  the 
Llanos Basin. Gran Tierra Energy,  along with its operating partner  Compania 
Espanola de  Petroleos  Colombia, S.A.U.  ("CEPCOLSA"),  previously  completed 
initial testing of the Mirador  formation. Long-term test of the  Ramiriqui-1 
well started on  April 22, 2013,  with Gran Tierra  Energy's share of  current 
production at approximately 410 BOPD NAR.

The Mayalito-1 exploration  well was spud  on June 19,  2013. This well  will 
explore a  shallow prospect  and further  test additional  deeper  hydrocarbon 
bearing zones encountered  but not  tested in the  successful Ramiriqui-1  oil 
discovery well. This well is expected to reach total depth in late September.

Guayuyaco Block (70% WI and operator, Ecopetrol 30% WI)

The next exploration well  in Colombia is expected  to be the Miraflor  West-1 
oil exploration well on the Guayuyaco Block. The well is expected to spud  in 
the third quarter of 2013.

Argentina

Puesto Morales Block, Neuquen Basin (100% WI and operator)

With the previous announcement of the  successful flow test for the  PMN-1117, 
the first fracture stimulated horizontal well in the Loma Montosa formation of
Argentina,  Gran  Tierra  Energy  plans  to  replace  two  development  wells, 
originally planned for the second half of 2013, with a second horizontal  well 
into the Loma Montosa  formation. Gran Tierra Energy  has secured a  drilling 
rig and expects to begin drilling the PMN-1135 horizontal multi-stage fracture
stimulated well in August 2013.

Peru

Block 95 (100% WI and operator)

Following the successful first quarter  2013 production tests from the  Vivian 
formation sandstone reservoir in the Bretaña Norte 95-2-1XD exploration  well, 
Gran Tierra Energy announced the successful production test from a  horizontal 
sidetrack of the Bretaña  Norte 95-2-1XD well on  May 28, 2013. A  production 
test was conducted  over the  1,595 foot  horizontal length  of the  sidetrack 
penetrating approximately 25 vertical feet of the top of the Vivian  formation 
in the  Bretaña  structure. A  final  rate  of approximately  1,699  BOPD  was 
produced on natural flow with  0% water cut, through  a 32/64 inch choke.  The 
choke size was then increased  to a 64/64 inch and  the oil flow increased  to 
approximately 3,095 BOPD on natural flow  with 0% water cut. Wellhead  flowing 
pressure was increasing  during the  first test indicating  the formation  was 
cleaning up. Cumulative production for both testing periods was  approximately 
3,552 barrels of oil  and testing was concluded  when full usage of  available 
storage capacity  had  been  achieved.  Gran Tierra  Energy  has  initiated  a 
preliminary  Front  End  Engineering  Design  study  for  the  Bretaña   field 
development. In addition, a  382 km 2D seismic  program has been initiated  to 
provide a more detailed map of the Bretaña structure, in addition to  maturing 
separate independent exploration lead on Block 95.

Gran Tierra Energy successfully transported by  barge and sold its first  test 
oil to the Petroperu  S.A. refinery in  the city of Iquitos.  This is one  of 
several monetization options for crude from Bretaña under evaluation.

Gran Tierra  Energy  is  working  towards  booking  reserves  on  the  Bretaña 
structure at or before  December 31, 2013, and  intends to initiate  long-term 
testing from Bretaña Norte 95-2-1XD in the first quarter of 2014.

In its press  release dated June  11, 2012, Gran  Tierra Energy announced  the 
results of a contingent gross lease resource estimate for the oil discovery on
Block  95,  provided  by  its  independent  reserves  auditor,  GLJ  Petroleum 
Consultants, effective June 1, 2012, before the drilling of the Bretaña  Norte 
95-2-1XD exploration well.  The resource estimate  was prepared in  compliance 
with National Instrument  51-101 -  Standards of  Disclosure for  Oil and  Gas 
Activities and the  Canadian Oil  and Gas Evaluation  Handbook. The  estimates 
included a low estimate "1C" contingent  resources of 11.5 million stock  tank 
barrels of oil ("MMSTB"),  a best estimate "2C"  contingent resources of  31.6 
MMSTB and a high estimate "3C" contingent resources of 88.1 MMSTB. There is no
certainty that it will be commercially viable to produce any portion of  these 
resources.  Additional   information  respecting   such  contingent   resource 
estimates is  included in  the June  11,  2012, press  release and  under  the 
heading "Forward-Looking Statements and Legal Advisories" below.

Brazil

Recôncavo Basin

The  data  collected  during   the  ongoing  three-well  horizontal   drilling 
exploration campaign  targeting  two  separate  unconventional  plays  in  the 
Recôncavo Basin continues to be evaluated, but results remain inconclusive  to 
date.

The first horizontal  sidetrack well,  GTE-05HP-BA, on Block  REC-T-142 was  a 
re-entry sidetrack well  into 1-GTE-1-BA  pilot well which  encountered a  121 
foot tight oil-saturated  Gomo Sandstone. The  1-GTE-5HP-BA sidetrack  drilled 
1,739 feet of gross  horizontal section in the  target Gomo Sandstone and  was 
completed with  a four  stage  fracture stimulation.  The well  tested  water, 
suggesting that the oil saturations were not sufficiently high enough to  flow 
oil. Despite this, Gran  Tierra Energy remains confident  that the concept  is 
still  promising  and  future  wells   will  target  areas  with  higher   oil 
saturations.

The second horizontal well, 1-GTE-6HP-BA,  was also a re-entry sidetrack  well 
into the 1-GTE-2-BA pilot well on Block REC-T-129. The 1-GTE-6HP-BA horizontal
well was targeting an oil  bearing interval in the  Gomo Shale. A 1,870  foot 
horizontal  section  was  successfully   drilled  with  excellent  oil   shows 
throughout. A six stage fracture stimulation was completed and based on  micro 
seismic monitoring data, the  final two fracture  stages had greater  fracture 
heights than planned and were inadvertently fracked into a lower saline  water 
bearing zone.  Gran  Tierra  Energy  is currently  planning  to  re-enter  the 
wellbore to isolate the final two stages in order to test the shale interval.

The third horizontal  well, 1-GTE-7HPC-BA, was  sidetracked from the  original 
wellbore on Block  REC-T-155 and is  drilling ahead, targeting  the shale  oil 
interval. The intent is to drill a  1,640 foot horizontal section and test  it 
with multi-stage fracture stimulation. Gran Tierra Energy anticipates drilling
and setting the completion  string by the first  week of August with  fracture 
stimulation planned for September.

The next  well  planned is  the  1-GTE-8-BA, which  will  be a  deviated  well 
targeting the oil saturated shales. The primary objective for the well will be
to cut and retrieve  up to 177 feet  of core to be  utilized for detailed  oil 
shale special core analysis studies to gain critical information regarding the
oil shale play.

Based on the growing  volume of technical data  acquired to date, Gran  Tierra 
Energy believes the tight oil sandstone and shale oil reservoir targets in the
Recôncavo Basin  represent  a valuable  and  material opportunity  for  future 
development. As a result, Gran Tierra Energy successfully bid on three blocks
in the recently completed 2013 Brazil Bid Round administered by Brazil's ANP.
The three blocks,  REC-T-86,-117 and -118,  are located north  of Gran  Tierra 
Energy's core existing areas in the Recôncavo Basin onshore Brazil and  offers 
additional potential on the company's current exploration play trend that will
enable Gran Tierra Energy to leverage its growing knowledge of the basin.  The 
three blocks encompasses  20,658 gross acres  of land under  an initial  three 
year exploration period, during which Gran Tierra Energy is committed to drill
five exploration wells, acquire  84 square kilometers  ("km^2") of 3D  seismic 
data and pay a signature bonus  of approximately 33.3 million Brazilian  Reals 
($14.5 million at current exchange  rate) upon finalization of the  concession 
agreement. Upon  final approvals  from the  ANP, Gran  Tierra Energy's  total 
acreage in the Recôncavo Basin will be 47,734 gross acres.

2013 Work Program and Capital Expenditure Program Update

Gran Tierra Energy's planned capital  expenditure program for its  exploration 
and production operations in Colombia, Brazil, Peru and Argentina for 2013 has
been revised to $454  million from $424 million.  This includes: $216  million 
for Colombia; $94 million for Brazil; $33 million for Argentina; $109  million 
for Peru; and $2 million  associated with corporate activities. The  majority 
of the  increase to  Gran Tierra  Energy's capital  spending is  due to  bonus 
payments relating  to successful  land bids  in Brazil,  the addition  of  the 
Proa-3 well in Argentina  and increased costs  associated with the  horizontal 
sidetrack well in  the Bretaña  structure in  Peru. The  increase in  capital 
spending is  partially offset  by the  deferral of  two exploration  wells  in 
Colombia.  The  capital  expenditure  program  allocates  $235  million   for 
drilling, $72 million for  facilities, pipelines and  other, $129 million  for 
geological and geophysical expenditures, $16  million for acquisitions and  $2 
million for corporate activities. Of  the $235 million allocated to  drilling, 
approximately $124 million is for exploration and the balance is for appraisal
and development drilling.  The 2013  work program  currently contemplates  the 
drilling of seven  gross wells  in Colombia,  four gross  wells in  Argentina, 
three gross wells in  Brazil and two  gross wells in  Peru. The approved  2013 
capital expenditure program  also includes funds  for 1,302 km  of 2D and  200 
km^2 of  3D seismic  acquisition  programs in  Colombia, Peru,  Argentina  and 
Brazil, primarily  in preparation  for additional  exploration and  production 
drilling operations in  2013 and beyond.  The 2013 work  program and  capital 
expenditure program are expected to be funded primarily from cash on hand  and 
cash flows from operations at current production and commodity price levels.

Conference Call Information:

Gran Tierra Energy Inc. will host  its second quarter 2013 results  conference 
call on Wednesday, August7, 2013, at 2:00 p.m. Mountain Time.

President and Chief Executive Officer, Dana Coffield, Chief Operating Officer,
Shane O'Leary, and  Chief Financial  Officer, James Rozon,  will discuss  Gran 
Tierra Energy's financial and operating results for the quarter and then  take 
questions from securities analysts and institutional shareholders.

Interested parties may  access the conference  call by dialing  1-866-318-8615 
(domestic) or  1-617-399-5134 (international),  pass code  27854553. The  call 
will    also    be    available    via    webcast    at    www.grantierra.com, 
www.streetevents.com, or www.fulldisclosure.com. The webcast will be available
on Gran Tierra Energy's website until the next earnings call.

For interested parties unable to participate, an audio replay of the call will
be available beginning two hours after the call until 11:59 p.m. on August 21,
2013.To access the replay  dial 1-888-286-8010 (domestic) or  1-617-801-6888 
(international) pass code 38133878.

Please connect at  least 15  minutes prior to  the conference  call to  ensure 
adequate time  for any  software download  that may  be required  to join  the 
webcast.

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 (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.  Investor 
inquiries may be directed to info@grantierra.com or (403) 265-3221.

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

Forward Looking Statements and Legal Advisories:

Readers are cautioned that the well-flow test results disclosed in this  press 
release are not necessarily indicative of long term performance or of ultimate
recovery.

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  sub-classified 
based on project maturity and/or characterized by their economic status.

This   news    release   contains    certain   forward-looking    information, 
forward-looking   statements    and    forward-looking    financial    outlook 
(collectively, "forward-lookingstatements") 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 
"expect", "plan", "estimate",  "believe", "anticipate", "will",  "potential", 
"may", "indicate,"  "intend", "projection",  derivations  of these  words  and 
similar expressions are  intended to identify  forward-looking statements.  In 
particular, but  without limiting  the foregoing,  forward-looking  statements 
include statements regarding: drilling,  testing and production  expectations, 
including without  limitation,  the  timing  of  operations,  the  oil-bearing 
potential of certain reservoirs and  expectations with respect to the  results 
of drilling, testing and exploration activities; Gran Tierra Energy's  planned 
capital program and  the allocation  of capital, including  under the  caption 
"2013 Work Program and Capital Expenditure Program Update" expected funding of
the capital program out of  cash flow and cash  on hand at current  production 
and commodity price levels; Gran Tierra Energy's 2013 production  expectations 
and projections; expected benefits from the three new blocks in the  Recôncavo 
Basin; Gran Tierra Energy's planned  operations, including as described  under 
the captions  "Colombia",  "Peru", "Brazil"  and  "Argentina" in  the  section 
"Second  Quarter  2013  Operational   Highlights"  together  with  all   other 
statements regarding  expected  or  planned  development,  testing,  drilling, 
production, expenditures or  exploration, or that  otherwise reflect  expected 
future  results   or   events.   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 resource  estimates,  the 
accuracy of testing and production results and seismic data, pricing and  cost 
estimates, rig availability, the effects of drilling down-dip, the effects  of 
waterflood and  multi-stage fracture  stimulation operations  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:  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 may impact
its testing and  drilling operations,  and the  production, transportation  or 
sale of its products; geographic, political, regulatory and weather conditions
can impact testing and drilling operations and the production,  transportation 
or sale  of  its  products;  the  OTA  pipeline  may  continue  to  experience 
disruptions and if further disruptions occur, service at the OTA pipeline  may 
not continue on the time lines or to the capacity expected by or favorable  to 
Gran Tierra Energy; attempts to mitigate the effect of disruptions of the  OTA 
pipeline may not have the impact currently anticipated by Gran Tierra  Energy; 
waterflood and multi-stage  fracture stimulation operations  may not have  the 
impact, including  with respect  to reserve  recovery improvements,  currently 
anticipated by Gran Tierra Energy;  permits and approvals from regulatory  and 
governmental authorities may  not be  received in the  manner or  on the  time 
lines expected or at all; 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 
modify its exploration, drilling and/or construction activities. Although  the 
current capital  spending program  of Gran  Tierra Energy  is based  upon  the 
current expectations of  the management of  Gran Tierra Energy,  there may  be 
circumstances in which, for unforeseen reasons, a reallocation of funds may be
necessary as may  be determined at  the discretion of  Gran Tierra Energy  and 
there can be no assurance as at the date of this press release as to how those
funds may be reallocated.  Should any one  of a number  of issues arise,  Gran 
Tierra Energy may  find it necessary  to alter its  current business  strategy 
and/or capital spending program.

Accordingly, readers should  not place undue  reliance on the  forward-looking 
statements contained  herein. 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  6, 2013. These filings  are 
available on a website 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 legislation.

BOE's 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  with 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.

Basis of Presentation of Financial Results:

Gran Tierra Energy's financial results  are reported in United States  dollars 
and prepared in  accordance with generally  accepted accounting principles  in 
the United States.

Gran Tierra Energy Inc.
Condensed Consolidated Statements of Operations and Retained Earnings
(Unaudited)
(Thousands of U.S. Dollars, Except Share and Per Share Amounts)

                 Three Months Ended June 30,     Six Months Ended June 30,
                    2013           2012           2013           2012
REVENUE AND                                                            
OTHER INCOME
 Oil and         $  168,181    $  114,542    $  372,961    $  269,790 
  natural gas
  sales
 Interest               629           608         1,220         1,311 
  income
                    168,810       115,150       374,181       271,101 
EXPENSES                                                               
Operating             31,902        27,333        72,917        51,820 
 Depletion,          63,022        32,571       121,434        92,938 
  depreciation,
  accretion and
  impairment
 General and         11,746        17,599        23,167        33,498 
  administrative
 Foreign           (11,980)         4,807      (17,209)        29,182 
  exchange
  (gain) loss
Other loss                 —             —         4,400             — 
                     94,690        82,310       204,709       207,438 
                                                                      
INCOME BEFORE         74,120        32,840       169,472        63,663 
INCOME TAXES
 Income tax        (26,337)      (19,736)      (63,776)      (50,872) 
  expense
NET INCOME AND        47,783        13,104       105,696        12,791 
COMPREHENSIVE
INCOME
RETAINED             342,586       184,701       284,673       185,014 
EARNINGS,
BEGINNING OF
PERIOD
RETAINED          $  390,369    $  197,805    $  390,369    $  197,805 
EARNINGS, END OF
PERIOD
                                                                      
NET INCOME PER    $     0.17    $     0.05    $     0.37    $     0.05 
SHARE — BASIC
NET INCOME PER    $     0.17    $     0.05    $     0.37    $     0.05 
SHARE — DILUTED
WEIGHTED AVERAGE 282,822,383   280,714,786   282,482,343   279,726,434 
SHARES
OUTSTANDING -
BASIC
WEIGHTED AVERAGE 285,449,708   284,141,287   285,646,763   283,500,228 
SHARES
OUTSTANDING -
DILUTED

Gran Tierra Energy Inc.
Condensed Consolidated Balance Sheets (Unaudited)
(ThousandsofU.S.Dollars, Except Share and Per Share Amounts)

                                            June 30, 2013  December 31, 2012
ASSETS                                                                   
Current Assets                                                           
         Cash and cash equivalents          $   281,978     $    212,624  
         Restricted cash                          2,549            1,404  
         Accounts receivable                    114,128          119,844  
         Inventory                               14,720           33,468  
         Taxes receivable                         7,562           39,922  
         Prepaids                                 3,866            4,074  
         Deferred tax assets                      1,445            2,517  
Total Current Assets                             426,248          413,853  
                                                                        
Oil and Gas Properties (using the full cost               
method of accounting)                                                      
         Proved                                 801,255          813,247  
         Unproved                               445,994          383,414  
Total Oil and Gas Properties                   1,247,249        1,196,661  
         Other capital assets                     9,610            8,765  
Total Property, Plant and Equipment            1,256,859        1,205,426  
                                                                        
Other Long-Term Assets                                                   
         Restricted cash                          3,924            1,619  
         Deferred tax assets                      2,950            1,401  
         Taxes receivable                        13,054            1,374  
         Other long-term assets                   6,972            6,621  
         Goodwill                               102,581          102,581  
Total Other Long-Term Assets                     129,481          113,596  
                                                                        
Total Assets                                 $ 1,812,588     $  1,732,875  
LIABILITIES AND SHAREHOLDERS' EQUITY                                     
Current Liabilities                                                      
         Accounts payable                   $    66,228     $    102,263  
         Accrued liabilities                     79,122           66,418  
         Taxes payable                           41,784           22,339  
         Deferred tax liabilities                 1,599              337  
         Asset retirement obligation                  —               28  
Total Current Liabilities                        188,733          191,385  
                                                                        
Long-Term Liabilities                                                    
         Deferred tax liabilities               190,866          225,195  
         Equity tax payable                       1,632            3,562  
         Asset retirement obligation             19,615           18,264  
         Other long-term liabilities              7,421            3,038  
Total Long-Term Liabilities                      219,534          250,059  
                                                                        
Shareholders' Equity                                                     
Common Stock (271,747,587 and 268,482,445                                  
shares of Common Stock
and 11,323,499 and 13,421,488 exchangeable
shares, par value $0.001
per share, issued and outstanding as at June
30, 2013 and December 31,
2012, respectively)                                9,750              7,986
         Additional paid in capital           1,004,202          998,772  
         Warrants                                     —                —  
         Retained earnings                      390,369          284,673  
Total Shareholders' Equity                     1,404,321        1,291,431  
                                                                        
Total Liabilities and Shareholders' Equity   $ 1,812,588     $  1,732,875  

Gran Tierra Energy Inc.
Condensed Consolidated Statements of Cash Flows (Unaudited)
(ThousandsofU.S.Dollars)

                        Three Months Ended June 30, Six Months Ended June 30,
                            2013          2012        2013         2012
Operating Activities                                                    
Net income                $   47,783   $  13,104  $ 105,696   $  12,791 
Adjustments to reconcile                                                
net income to net cash
provided
by (used in) operating
activities:
   Depletion,                63,022      32,571    121,434      92,938 
    depreciation,
    accretion and
    impairment
   Deferred tax             (8,299)     (4,800)   (15,749)    (10,050) 
    recovery
   Stock-based                2,349       3,730      4,416       6,922 
    compensation
   Unrealized foreign      (11,622)     (5,187)   (18,366)      16,164 
    exchange (gain) loss
   Settlement of asset            —           —          —       (404) 
    retirement
    obligation
   Equity tax               (1,718)     (1,785)    (1,718)     (1,785) 
Other loss                         —           —      4,400           — 
Net change in assets and                                                
liabilities from
operating activities
   Accounts receivable       33,113      55,197      3,726    (17,668) 
    and other long-term
    assets
   Inventory                  1,917     (8,985)     13,560    (13,485) 
   Prepaids                     467         772        209         154 
   Accounts payable and       5,417       5,468    (9,314)    (28,567) 
    accrued and other
    liabilities
   Taxes receivable and       6,560   (101,857)     40,486    (82,262) 
    payable
Net cash provided by         138,989    (11,772)    248,780    (25,252) 
(used in) operating
activities
                                                                       
Investing Activities                                                    
   Increase in              (2,712)       8,031    (3,450)    (23,006) 
    restricted cash
   Additions to            (97,208)   (100,661)  (184,586)   (178,644) 
    property, plant and
    equipment
   Proceeds from oil          5,597           —      5,597           — 
    and gas properties
Net cash used in            (94,323)    (92,630)  (182,439)   (201,650) 
investing activities
                                                                       
Financing Activities                                                    
   Proceeds from              1,402       2,854      3,013       3,745 
    issuance of shares
    of Common Stock
Net cash provided by           1,402       2,854      3,013       3,745 
financing activities
                                                                       
Net increase (decrease)       46,068   (101,548)     69,354   (223,157) 
in cash and cash
equivalents
Cash and cash                235,910     230,076    212,624     351,685 
equivalents, beginning
of period
Cash and cash             $  281,978   $ 128,528  $ 281,978   $ 128,528 
equivalents, end of
period
                                                                       
Cash                      $  279,377   $  78,929  $ 279,377   $  78,929 
Term deposits                  2,601      49,599      2,601      49,599 
Cash and cash             $  281,978   $ 128,528  $ 281,978   $ 128,528 
equivalents, end of
period







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
www.grantierra.com
 
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