12 December 2017

Early Warning Report of Gran Tierra Resources Limited

This news release is issued pursuant to National Instrument 62-104 – Take-Over Bids and Issuer Bids and National Instrument 62-103 – The Early Warning System and Related Take-Over Bid and Insider Reporting Issues in connection with the filing of an early warning report.

CALGARY, Alberta, Dec. 12, 2017 (GLOBE NEWSWIRE) — Gran Tierra Resources Limited (the “Purchaser“) an indirect wholly-owned subsidiary of Gran Tierra Energy Inc. (NYSE American:GTE) (NYSE MKT:GTE) (TSX:GTE) (“Gran Tierra“) hereby announces that the Purchaser has purchased 11,000,000 subscription receipts (“Subscription Receipts“) of PetroTal Ltd. (“PetroTal“) at a price of US $1.00 per Subscription Receipt, for a total consideration paid to PetroTal of US $11,000,000. The Subscription Receipts were acquired as part of a non-brokered private placement offering of 34,000,000 Subscription Receipts (the “Offering“). Pursuant to a subscription receipt agreement entered into between PetroTal, Eight Capital Corp. and Computershare Trust Company, dated December 12, 2017, each Subscription Receipt is exchangeable for one common share in the share capital of PetroTal (“PetroTal Shares“) in connection with the closing of the Peru Transaction (as defined below), without payment of additional consideration or further action on behalf of the holder thereof.

The Purchaser acquired the Subscription Receipts in connection with an arrangement agreement entered into between PetroTal and Sterling Resources Ltd. (TSXV:SLG)(the “Issuer“) effective November 9, 2017 (the “Arrangement Agreement“) and a share purchase agreement between the Issuer, PetroTal, Gran Tierra and an indirect subsidiary of Gran Tierra, Gran Tierra Energy International Holdings Ltd. (“GTEIH“), effective November 9, 2017 (collectively the “Peru Transaction“) pursuant to which GTIEH has agreed to sell certain assets to PetroTal in exchange for 187,250,000 common shares of the Issuer (“Common Shares“) issuable under the Arrangement (as defined below), the whole as further described in the press release of the Gran Tierra dated November 9, 2017. Pursuant to the Arrangement Agreement and the related plan of arrangement (the “Arrangement“), each PetroTal Share is expected to be exchanged for 5.35 Common Shares on or around December 14, 2017.

Immediately after giving effect to the Offering, the Purchaser does not hold any Common Shares, but holds 11,000,000 Subscription Receipts, which are expected to be exchanged for 11,000,000 PetroTal Shares, which in turn are expected to be exchanged for 58,850,000 Common Shares, which are expected to represent approximately 10.94% of the Common Shares immediately following the completion of the Peru Transaction.

Following the completion of the Peru Transaction, the Purchaser expects that it and GTEIH together will hold 246,100,000 Common Shares, which the Purchaser expects will represent approximately 45.77% of the issued and outstanding Common Shares at that time.

In connection with the completion of the Peru Transaction, the Purchaser expects to enter into an investor rights agreement with the Issuer and GTEIH, pursuant to which, inter alia, the Purchaser and GTEIH will together be granted the right to nominate two directors to the board of the Issuer as well as certain demand and piggy-back registration rights and certain pre-emptive rights and the Purchaser and GTEIH will agree not to exercise its voting rights over more than 30% of the issued and outstanding Common Shares, the whole subject to the terms and conditions set forth therein.

Following the completion of the Peru Transaction, the Purchaser expects that its 187,250,000 Common 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 TSX Venture Exchange.

The Purchaser may, depending on market and other conditions, or as future circumstances may dictate, from time to time, increase or dispose of some or all of the existing or additional securities it holds or will hold in the Issuer or may continue to hold its position in the Issuer.

A copy of the early warning report filed by the Purchaser in connection with the Offering is available on SEDAR, located at www.sedar.com.

Contact Information
For investor and media inquiries please contact:

Gary Guidry
Chief Executive Officer

Ryan Ellson
Chief Financial Officer

Rodger Trimble
Vice President, Investor Relations


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 continues to pursue new growth opportunities, leveraging its 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”, “expects” 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 Peru Transaction and the acquisition or disposition of the shares of PetroTal and the Issuer.

The forward-looking statements contained in this news release are based on certain assumptions made by the Purchaser based on management’s experience and other factors believed to be appropriate. The Purchaser 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 the Purchaser’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 the Purchaser that the Purchaser 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. The Purchaser 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.