Reserves & Resources Update

4 April 2018

Amerisur Resources Plc ("Amerisur" or the "Company")

Reserves & Resources Update

Amerisur Resources Plc ("Amerisur" or the "Company"), the oil and gas producer and explorer focused on South America (LSE: AMER), provides an update on the certified reserves and resources for its production assets in Colombia. 

Following receipt of an independent reserves report for the Platanillo field as at 31 December 2017 undertaken by Petrotech Engineering Ltd, using the standards set by the Oil and Gas Reserves Committee of the Society of Petroleum Engineers, certified 1P (Proven) gross field reserves were 12.84 million barrels of oil ("MMBO") (2016: 15.11 MMBO) after production of 1.76 MMBO during the period and 2P (Proven and Probable) gross field reserves were 18.95 MMBO (2016: 24.47 MMBO). Cumulative total production from the Platanillo field at 31 December 2017 was 9.26 MMBO.

After production, current 1P reserves represent a decrease of approximately 0.5 MMBO from year end 2016. This technical decrease of the Expected Ultimate Recovery ("EUR") (a forward-looking model which assumes a decline factor and projects the volume of oil which will ultimately be recovered from each well) takes account of the wells drilled during the year, including the relatively poor reservoir quality and initial flow rates from wells Platanillo 25 and Platanillo 27. This results in a small decrease in expected EUR. The reduction in 2P reserves is also due to that effect, together with a refined mapping of the field after the reprocessing of the 3D seismic data by Signature Ltd of Calgary, part of our regional reprocessing project which covers our entire Putumayo portfolio.

Since the Mariposa-1 well is currently under Long Term Test, it has not entered the exploitation phase and hence the Operator is not required to report such reserves to the Agencia Nacional de Hidrocarburos (ANH). However, for guidance, the Company also commissioned an evaluation of reserves at the Mariposa discovery in block CPO-5 from Petrotech Engineering Ltd. 1P reserves were certified at 0.79 MMBO and 2P reserves at 1.30 MMBO to Amerisur on a working interest basis (30%).

The Company also commissioned an evaluation of reserves at the Mecaya block related to the well Mecaya-1 from Petrotech Engineering Ltd. 1P reserves were certified at 0.31 MMBO and 2P reserves at 0.45 MMBO to Amerisur on a working interest basis of 58%.

Hence total Amerisur 1P reserves at 31.12.17 are 13.94 MMBO and 2P reserves are 20.70 MMBO.

Reserves

Source: Petrotech Engineering LTD., Reserves Audit at 31 Dec 2017

Resources

John Wardle, CEO of Amerisur Resources said:

"The reduction in reserves at Platanillo over and above production through the year was a result of various factors, including the relatively poor performance of two wells drilled during the period and the latest mapping of the Platanillo structure, part of our wider effort to maximise our understanding of the opportunities within our portfolio. The Board is confident of future reserves growth at Platanillo and that improved mapping will undoubtedly be an advantage as we begin to explore our wider opportunity base in the Putumayo. This reduction was more than compensated for on a 1P basis by new reserves certified at our Mariposa discovery and the recently acquired Mecaya discovery. Amerisur has an extensive growth portfolio with unrisked prospective resources of 1,376MMbl in the mid case scenario. Our fully funded 2018 work programme will see increased drilling across our blocks, including the drilling of up to three N Sand anomaly wells further north on the Platanillo block, three new wells in CPO-5 and a further well in Put-8, all of which have the potential to substantially grow the company's reserves and resources base." 

These assessments are made in accordance with the standard defined in the SPE/WPC Petroleum Resources Management System (2007).

Competent person: Technical information in this announcement has been reviewed by John Wardle Ph.D., the Company's Chief Executive. John Wardle has 32 years' experience in the industry, having worked for BP, Britoil, Emerald Energy and Pebercan, and is a trained drilling engineer. 

The information contained within this announcement is considered to be inside information prior to its release, as defined in Article 7 of the Market Abuse Regulation No. 596/2014, and is disclosed in accordance with the Company's obligations under Article 17 of those Regulations.

Ends

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About Petrotech Engineering Ltd

Petrotech Engineering Ltd. is an independent oil and gas reserve evaluation firm located in Burnaby, British Columbia, Canada. John Yu is a professional Petroleum Engineer with over 40 years of experience in Domestic and International Oil and Gas. He attended the University of Alberta and graduated with a Bachelor of Science in Metallurgical Engineering in 1974. He is a registered Professional Engineer in the Province of British Columbia. Since May of 1981 he has been a Petroleum Engineering Consultant and President of Petrotech Engineering Ltd. of Burnaby, B. C.

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