AMER.L Regulatory News (AMER)

19 October 2017

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

Operational Update

Amerisur Resources Plc, the oil and gas producer and explorer focused on South America, is pleased to provide an operational update on activities in Colombia.

Platanillo

Drilling of Platanillo-25, a medium step out directional well drilled to the south west of Pad 2N partially to determine the extent of the inferred permeability barrier between Pad 2N and the main structure of the Platanillo field, is complete.

Platanillo-25 was drilled to a planned total depth of 8,699ft, logged using logging-while-drilling tools which indicated 10ft of pay in the U sand. Although the reservoir levels were encountered close to prognosis, overall pay thickness was reduced by increased shale content within the upper part of the U sands. This result will help increase our understanding of the location and make-up of the inferred permeability barrier.

The Company is now side tracking Platanillo-25 to locate a production well further up dip and nearer to Platanillo-21 where better reservoir quality and additional pay thickness is expected and which has the potential to deliver more sustainable production. The side track is expected to be completed before the end of October.

In addition to the discovery of the U sands the well also intersected 3ft of pay in the N sands, a more positive result than expected for the planned drilling campaign in the north/central part of the field targeting 18.8 MMBOE.

Once the side track is complete, Platanillo-27, a planned well to the north of Pad 2N will be drilled in place of Platanillo-23 while analysis of the data from Platanillo-25 continues. Platanillo-27 is targeting a bottom hole location to the north of Platanillo-22 in a structural position similar to Platanillo-21.

As part of its low-cost optimisation work programme across the Platanillo field, routine well service operations have been undertaken on Platanillo 10, 11 and 20 including down hole pump changes and production string optimisation. In addition the Company has perforated a 4ft section of the Upper U sand in Platanillo-21 and the well is now being brought back onto production to test the effect of this additional perforation. Production from the Platanillo-21 well has been managed carefully in order to minimise water production arising from the incomplete cementation of the 7" casing. The management of Platanillo-21 and routine maintenance are likely to have a modest impact on production in October but are part of the production optimisation plan aimed at securing the Company´s 7,000 BOPD exit rate target for 2017.

CPO-5

The operator of the Mariposa discovery in the CPO-5 block has informed the Company that the equipment to initiate the Long Term Test (LTT) of the Mariposa-1 well is 95% mobilised to location and 80% installed. The LTT will commence after the inspection visit by the National Hydrocarbons Agency (ANH) to approve the facilities and begin the LTT. The Company will make a further announcement on commencement of the LTT.

John Wardle, Chief Executive Officer, commented:

"We are very encouraged by the results of Platanillo-25 which supports the view that there is significant further upside in the Platanillo field, both in the separate northern structure targeting 7.82 MMBO of recoverable reserves and in the N Sand Anomaly in the north/central part of the field targeting 18.8 MMBOE.

"The net pay observed in the U sands of Platanillo-25 may well be associated with the inferred permeability barrier which we believe has resulted in the deeper oil-water contact we discovered at Pad 2N. These subtle changes in lithology are usually not possible to detect in seismic data. To manage risk, we will focus on drilling to the north of Pad 2N with Platanillo-27 post the Platanillo-25 side track and meanwhile continue to analyse the data we have obtained.

"We are pleased to report that the LTT off Mariposa-1 is on track to begin at the end of October, which will not only diversify Amerisur's production base from one to two fields, but also adds further material production to Amerisur in the near term."

ENDS

Enquiries:

Glossary

Competent person

Technical information in this announcement has been reviewed by John Wardle Ph.D., the Company's Chief Executive. John Wardle has 31 years' experience in the industry, having worked for BP, Britoil, Emerald Energy and Pebercan, and is a trained drilling engineer.

Standard

Estimates of reserves and resources contained in this announcement were prepared using the standards set by the Oil and Gas Reserves Committee of the Society of Petroleum Engineers / World Petroleum Congress Petroleum Resources Management System (2007).

Inside Information

This announcement contains inside information as defined in EU Regulation No. 596/2014 and is in accordance with the Company's obligations under Article 17 of that Regulation.

Important notice

Forward looking statements and dates referenced in this announcement, in relation to Amerisur's production, development and exploration assets, are estimates and subject to change. Oil and gas operations are subject to varying inputs that may impact timing, including, inter alia, permitting; environmental regulation; changes to regulators and regulation; third party manufacturers and service providers, social issues and the weather. The Company's estimates of timing for forward looking operations are based on the best information it has to hand at the time, however these timings may change with little or no notice to the Company. The Company will update the market as and when it becomes aware of a material change to any of the operations or timings referenced in this announcement.

Notes to editors

Amerisur Resources is an independent full-cycle oil and gas company focused on South America, with assets in Colombia and Paraguay and production from the Platanillo field in southern Colombia. In 2016 Amerisur successfully built and is 100% owner of the strategic OBA oil transfer line into Ecuador.

In Colombia, the Company is operator and has a 100% working interest in the Platanillo block which includes the Platanillo field, which is currently producing circa 6,400 BOPD. The Company has a strong position in the Putumayo basin and has a cluster of near term activity assets around the OBA export line including the Platanillo block, Put-8, Put-12 and Coati. Additionally, the Company holds a 100% working interest in contract Put-9, 100% of Tacacho and 100% of Terecay acquired from Talisman and Pacific. These acquisitions have now been approved by ANH. It has a diverse portfolio of longer term exploration assets.

www.amerisurresources.com