Mr. Gary Guidry reports

GRAN TIERRA ENERGY INC. ANNOUNCES STRONG RESERVES REPLACEMENT AND MEANINGFUL RESERVES GROWTH IN 2023

Gran Tierra Energy Inc. has released the company's 2023 year-end reserves as evaluated by the company's independent qualified reserves evaluator McDaniel & Associates Consultants Ltd. in a report with an effective date of Dec. 31, 2023 (the GTE McDaniel reserves report).

• Highest year-end total company reserves in company history -- 90 MMBOE (million barrels of oil equivalent) 1P (proved reserves), 147 MMBOE 2P (proved plus probable reserves) and 207 MMBOE 3P (proved plus probable plus possible reserves);
• Added total company reserves of 18 MMBOE 1P, 29 MMBOE 2P and 36 MMBOE 3P;
• Achieved 154-per-cent 1P, 242-per-cent 2P and 303-per-cent 3P reserves replacement;
• Fifth consecutive year of 1P total company reserves growth;
• Incurred F&D (finding and development) costs, excluding change in FDC, of $11.96 (1P), $7.58 (2P) and $6.06 (3P) per boe;
• Net present value before tax discounted at 10 per cent of $1.9-billion (1P), $3.1-billion (2P) and $4.3-billion (3P);
• Net asset value per share of $18.79 before tax and $10.46 after tax (PDP (proved developed producing)), $44.48 before tax and $24.06 after tax (1P), and $79.13 before tax and $42.71 after tax (2P).

All dollar amounts are in United States (U.S.) dollars and all reserves and production volumes are on a working interest before royalties (WI) basis.

Gary Guidry, president and chief executive officer of Gran Tierra, commented: "During 2023, a combination of our strong reserves growth, ongoing reductions in debt and share buybacks allowed Gran Tierra to achieve net asset values per share** before tax of $44.48 (1P), up 288 per cent from 2020, and $79.13 (2P), up 144 per cent from 2020. With this significant growth in our net asset values per share** over the last three years, we believe Gran Tierra is well positioned to offer exceptional long-term stakeholder value.

"Gran Tierra achieved strong 154-per-cent (1P), 242-per-cent (2P) and 303-per-cent (3P) reserves replacement through our successful results from our development drilling, water-flooding programs, field performance and the Suroriente Block continuation agreement.* This multifaceted success resulted in record highs for the company's year-end 1P, 2P and 3P oil reserves.

"We completed our 2023 development plan on-budget including water-flooding efforts and development drilling in the Acordionero, Costayaco and Moqueta oil fields. We also continued to evaluate our successful ongoing production from key 2022 exploration discoveries in Colombia and Ecuador to plan for 2024 follow-up exploration drilling. We believe our success on multiple fronts during 2023 demonstrates Gran Tierra's ability to be a full-cycle oil and gas exploration, development, and production company focused on value creation for all our stakeholders.

"The success the company achieved in 2023 also reflects our ongoing conversion of reserves from the probable to the proved category. With 147 booked proved plus probable undeveloped future drilling locations, Gran Tierra is well positioned to continue to grow the company's production and reserves in 2024 and beyond.

"We have started 2024 strong with two rigs currently drilling our planned series of development wells in Acordionero and Costayaco. Both rigs began their development campaigns in December, 2023. Later in 2024, we look forward to our planned resumption of exploration drilling in Colombia and Ecuador to build upon our successful exploration results in 2022, and the first development drilling in the Suroriente Block since 2018. Through our ongoing focus on the development of our existing assets, appraisal of our 2022 discoveries and exploration drilling, we plan to continue to strengthen our balance sheet, profitably increase production, grow our reserve base and return capital to shareholders through share buybacks."

* See the section titled "Suroriente continuation agreement."

** See the attached tables for the definitions of net asset values per share.

Highlights

• As of Dec. 31, 2023, Gran Tierra achieved:
  • Before-tax NAV of $1.4-billion (1P), $2.6-billion (2P) and $3.8-billion (3P);
  • After-tax NAV of $800-million (1P), $1.4-billion (2P) and $2.0-billion (3P);
  • Strong reserves replacement ratios of:
    • 154-per-cent 1P, with 1P reserves additions of 18 MMBOE;
    • 242-per-cent 2P, with 2P reserves additions of 29 MMBOE;
    • 303-per-cent 3P, with 3P reserves additions of 36 MMBOE.
  • Meaningful 1P, 2P and 3P reserves additions largely driven by success with development drilling and water-flooding results in the Chaza Block (which contains Costayaco and Moqueta fields) and the Suroriente continuation agreement.
  • Finding and development costs (F&D), including change in future development costs (FDC), on a per boe basis of $20.58 (1P), $16.09 (2P) and $14.67 (3P).
  • F&D costs excluding change in FDC, on a per boe basis of $11.96 (1P), $7.58 (2P) and $6.06 (3P).
  • F&D recycle ratios**, including change in FDC, of 1.8 times (1P), 2.2 times (2P) and 2.5 times (3P).
• Gran Tierra's four major oil assets, Acordionero, Costayaco, Moqueta and Suroriente (all on water flood), represent 83 per cent of the company's 1P reserves and 73 per cent of its 2P reserves.
• The company's PDP reserves account for 48 per cent of 1P reserves and 1P reserves account for 61 per cent of 2P reserves, which demonstrate the strength of Gran Tierra's reserves base via the potential future conversion of probable reserves into 1P reserves and proved undeveloped reserves into PDP reserves.
• FDC are forecast to be $561-million for 1P reserves and $923-million for 2P reserves. Gran Tierra's 2024 base case mid-point guidance for cash flow*** of $300-million is equivalent to 54 per cent of 1P FDC and 33 per cent of 2P FDC, which highlights the company's potential ability to finance future development capital. Increases in FDC relative to 2022 year-end reflect that the GTE McDaniel reserves report now assigns Gran Tierra 95 proved undeveloped future drilling locations (up from 78 at 2022 year-end) and 147 proved plus probable undeveloped future drilling locations (up from 115 at 2022 year-end).

* See the section in this release titled Suroriente continuation agreement.

** F&D recycle ratio is defined as fourth quarter 2023 operating netback per WI sales volume boe divided by the appropriate F&D costs on a per boe basis. Operating netback does not have a standardized meaning under generally accepted accounting principles in the United States (GAAP) and is a non-GAAP measure. Operating netback is defined as oil sales less operating and transportation expenses.

*** Cash flow refers to GAAP line item net cash provided by operating activities. Gran Tierra's 2024 base case guidance is based on a forecast 2024 average Brent oil price of $80/bbl. This forecast price used in Gran Tierra's forecast is higher than the 2024 McDaniel Brent price forecast.

GTE McDaniel reserves report

All reserves values, future net revenue and ancillary information contained in this press release have been prepared by McDaniel and 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) and derived from the GTE McDaniel reserves report, unless otherwise expressly stated.

Future net revenue

Future net revenue reflects McDaniel's forecast of revenue estimated using forecast prices and costs, arising from the anticipated development and production of reserves, after the deduction of royalties, operating costs, development costs, and abandonment and reclamation costs but before consideration of indirect costs such as administrative, overhead and other miscellaneous expenses. The estimate of future net revenue below does not necessarily represent fair market value.

Total company WI reserves

The attached table summarizes Gran Tierra's NI 51-101 and COGEH compliant reserves in Colombia and Ecuador derived from the GTE McDaniel reserves report calculated using forecast oil and gas prices and costs. Gran Tierra has determined that Ecuador reserves, included in the total proved, total probable and total possible reserve categories for light and medium crude oil, are not material enough to present separately on a country basis. Therefore all amounts are presented on a consolidated basis by foreign geographic area.

Net present value summary

Gran Tierra's reserves were evaluated using the average of three independent qualified reserves evaluators' commodity price forecasts at Jan. 1, 2024 (McDaniel, Sproule and GLJ). See "forecast prices" for more information. It should not be assumed that the net present value of cash flow estimated by McDaniel represents the fair market value of Gran Tierra's reserves.

Future development costs

FDC reflects McDaniel's best estimate of what it will cost to bring the proved undeveloped and probable undeveloped reserves on production. Changes in forecast FDC occur annually as a result of development activities, acquisition and disposition activities, and changes in capital cost estimates based on improvements in well design and performance, as well as changes in service costs. FDC for 2P reserves increased to $923-million at year-end 2023 from $677-million at year-end 2022. The increase in FDC in 2023 was predominantly attributed to the increase in the numbers of future development well locations identified by McDaniel in the Suroriente continuation agreement.

Forecast prices

The pricing assumptions used in estimating NI 51-101 and COGEH compliant reserves data disclosed above with respect to net present values of future net revenue are set forth herein. The price forecasts are based on an average of three independent qualified reserves evaluators' commodity price forecasts at Jan. 1, 2024 (McDaniel, Sproule and GLJ). All three of these companies are independent qualified reserves evaluators and auditors pursuant to NI 51-101.

Suroriente continuation agreement

On April 11, 2023, the company announced that it had entered into an agreement with Ecopetrol S.A., the national oil company of Colombia, by which the parties renegotiated the terms and the duration of the contract for the Suroriente Block in the department of Putumayo, which was scheduled to end in mid-2024. The Suroriente continuation agreement provides an opportunity to add significant value, as well as economic life, to the Suroriente Block by continuing its duration for 20 years from the Suroriente continuation agreement's effective date. On Aug. 31, 2023, the company announced that it had satisfied all outstanding conditions precedent to the effectiveness of the Suroriente continuation agreement.

Corporate presentation:

Gran Tierra's corporate presentation has been updated and is available on the company website.

About Gran Tierra Energy Inc.

Gran Tierra Energy, together with its subsidiaries, is an independent energy company currently focused on international oil and natural gas exploration and production in Colombia and Ecuador. The company is currently developing its existing portfolio of assets in Colombia and Ecuador and will continue to pursue additional growth opportunities that would further strengthen the company's portfolio. The company's common stock trades on the New York Stock Exchange American, the Toronto Stock Exchange and the London Stock Exchange under the ticker symbol GTE.

We seek Safe Harbor.