SLG San Lorenzo Gold Corp

Gran Tierra Energy Inc. ("Gran Tierra") (NYSE American:GTE) (NYSE MKT:GTE) (TSX:GTE), a company focused on oil and gas exploration and production in Colombia, is pleased to announce that it and its indirect wholly-owned subsidiary, Gran Tierra Energy International Holdings Ltd. ("GTEIH"), have entered into a share purchase agreement with PetroTal Ltd. ("PetroTal"), and Sterling Resources Ltd. (TSXV:SLG) ("Sterling") today, pursuant to which GTEIH has agreed to sell all of the issued and outstanding shares of its wholly owned subsidiary, Gran Tierra Energy International Peru Holdings B.V. ("GTEIPH"), subject to the satisfaction of certain conditions (the "SPA").

In connection with the SPA, Sterling and PetroTal have concurrently entered into an arrangement agreement under which they have agreed, subject to certain conditions, that: (a) PetroTal will complete a reverse take-over of Sterling; (b) Sterling and PetroTal will be amalgamated; and (c) the management and board of directors of Sterling will be reconstituted (such transactions being referred to herein as the "Arrangement", and the resulting entity being referred to herein as the "Resulting Issuer").

Subject to the terms of the SPA, the Resulting Issuer has agreed to acquire all of the issued and outstanding shares of GTEIPH from GTEIH as the final step of the Arrangement, in exchange for 187,250,000 common shares of the Resulting Issuer ("Resulting Issuer Shares"), representing approximately 38% of the issued and outstanding Resulting Issuer Shares, plus or minus a cash-settled working capital adjustment.

Gran Tierra will evaluate its investment in the Resulting Issuer from time to time and may, based on such evaluation, market conditions and other circumstances, increase or, subject to applicable escrow periods under the rules of the TSX Venture Exchange ("TSXV"), decrease shareholdings as circumstances require through market transactions, private agreements, or otherwise.

Closing of the Arrangement and the transactions contemplated by the SPA (collectively, the "Peru Transaction") is subject to a number of conditions precedent, including the completion of a minimum US$25 million equity financing by PetroTal, TSXV approval of, inter alia, the reverse take-over of Sterling and the listing of the Resulting Issuer's shares on the TSXV, certain minimum working capital levels of PetroTal and Sterling and other regulatory and customary conditions. There can be no assurance that the conditions will be met or that the transaction will be completed as proposed or at all.

The SPA provides that, at closing, GTEIH and Gran Tierra Resources Limited ("GTRL") will enter into an investor rights agreement with Sterling, pursuant to which, inter alia, GTEIH and GTRL will: (a) be granted the right to nominate two directors to the board of the Resulting Issuer, (b) be granted certain demand and piggy-back registration rights and certain pre-emptive rights and, (c) agree not to exercise their voting rights over more than 30% of the issued and outstanding Resulting Issuer Shares, the whole subject to the terms and conditions set forth therein.

In addition, the SPA provides that, at closing, GTEIH will enter into a carried interest and option agreement with Sterling and a Peruvian subsidiary, pursuant to which GTEIH will be granted a 20% carried working interest in Block 107, located in the Ucayali basin in Peru, which interest will, at the option of GTEIH, either be converted to a non-carried working interest or be forfeited following the drilling of an exploration well in Block 107.

Following the completion of the Peru Transaction, the Purchaser expects that its Resulting Issuer Shares acquired under the Peru Transaction will be deposited with an escrow agent and subject to the terms of an escrow agreement, substantially in the form required by the TSXV.

Contact Information

For investor and media inquiries please contact:

Gary GuidryChief Executive Officer

Ryan EllsonChief Financial Officer

Rodger TrimbleVice President, Investor Relations

403-265-3221info@grantierra.com

About Gran Tierra Energy Inc.

Gran Tierra Energy Inc. together with its subsidiaries is an independent international energy company focused on oil and natural gas exploration and production in Colombia. The Company is focused on its existing portfolio of assets in Colombia and will pursue new growth opportunities throughout Colombia, leveraging our financial strength. The Company’s common shares trade on the NYSE American and the Toronto Stock Exchange under the ticker symbol GTE. Additional information concerning Gran Tierra is available at www.grantierra.com. Information on the Company's website does not constitute a part of this press release. Investor inquiries may be directed to info@grantierra.com or (403) 265-3221.

Gran Tierra'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:

This press release contains opinions, forecasts, projections, and other statements about future events or results that constitute forward-looking statements within the meaning of the United States Private Securities Litigation Reform Act of 1995, Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended, and financial outlook and forward looking information within the meaning of applicable Canadian securities laws (collectively, "forward-looking statements"). The use of the words "will" and "believes", derivations thereof and similar terms identify forward-looking statements. In particular, but without limiting the foregoing, this news release contains forward-looking statements regarding: the satisfaction of the conditions to the closing of the Arrangement, our ability, and the ability of the other parties to the SPA, to complete the Arrangement and the anticipated benefits of the Arrangement to Gran Tierra and its shareholders.

The forward-looking statements contained in this news release are based on certain assumptions made by Gran Tierra based on management's experience and other factors believed to be appropriate. Gran Tierra believes these assumptions to be reasonable at this time, but the forward-looking statements are subject to risk and uncertainties, many of which are beyond Gran Tierra's control, which may cause actual results to differ materially from those implied or expressed by the forward looking statements. These include the factors discussed or referenced in Gran Tierra's reports filed with the Securities and Exchange Commission, including, without limitation, under the caption "Risk Factors" in Gran Tierra's Annual Report on Form 10-K filed March 1, 2017 and its subsequently filed Quarterly Reports on Form 10-Q. These filings are available on a Web site maintained by the Securities and Exchange Commission at http://www.sec.gov and on SEDAR at www.sedar.com. All forward-looking statements are made as of the date of this press release and the fact that this press release remains available does not constitute a representation by Gran Tierra that Gran Tierra believes these forward-looking statements continue to be true as of any subsequent date. Actual results may vary materially from the expected results expressed in forward-looking statements. Gran Tierra 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.