AMER.L Regulatory News (AMER)

11 December 2012

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

Colombia Update

Amerisur Resources Plc, the oil and gas producer and explorer focused on South America, is pleased to announce an update on its operations in Colombia.

·; Platanillo-9 well currently producing approximately 730 bopd, taking total current controlled production to 4,342 bopd

·; Following optimisation and workover of Platanillo-3 the year end production target of 5,000 bopd remains on track

·; Additional drilling rig secured

·; Gained 60% WI and operatorship in block Put-12 contract, adjacent to Platanillo field

·; New reserves report due in 1Q13 to reflect the results of the first four wells

Platform 9 South, Platanillo field update

As announced on 28 November 2012, Platanillo-9, the fourth well in a planned campaign of eight wells in the Platanillo field (Amerisur 100%), located on Platform 9 South (9S) has been successfully drilled to a total depth of 8,689ft, achieving an offset of 1,485ft to the west of the bottom hole location of Platanillo-3. The reservoir section was logged and initial log analysis indicated the presence of a 71ft gross, 45ft net oil column in the U sand formation, 7ft net pay in the N sand formation and pay intervals in the B/T formation, in line with the pre-drill prognosis.

Additionally, pressure data and fluid samples were acquired using logging tools from the N sand interval. The pressures indicated an oil gradient and the samples recovered from the interval contain 17.9° API oil together with mud filtrate. The flow characteristics during sample acquisition indicated a good quality reservoir rock.

The well was perforated using Tubing Conveyed Perforating guns over a 31ft interval in the U sand, and produced up to 440 bopd while choked back in natural flow with 60 psi well head pressure, significantly below expectations. Investigative pressure testing found that the completion packer had failed with respect to pressure integrity. Rig D-10 was therefore skidded back over the well to perform a corrective work over. The failed completion packer was pulled and a replacement hydraulic packer run and set. The well was subsequently placed on production, and is currently producing approximately 730 bopd with a down hole jet pump, taking current controlled production for the field to approximately 4,300 bopd. The well has been damaged by the failure of the original packer and requires a corrective chemical stimulation using a Coiled Tubing Unit.

The Serinco D-10 is now being moved to perform a work over on Platanillo-3 within the Pad 9 location, with the objective of re-configuring the well to repair poor zonal isolation behind the 7" casing.

Once that work over is completed the Company will mobilise a Coiled Tubing Unit to Platform 9S and perform chemical stimulation work on Platanillo-4 and Platanillo-9.

Forthcoming Operations

Civil works have been completed at Platform 5 South (5S), a drilling location constructed approximately 1.2 km north of Platform 9S. The location has been prepared with 4 drilling cellars on a single concrete base, which facilitates the skidding of a drilling rig between the cellars.

The Company is pleased to announce that it has entered into a Day Work Drilling Contract with Latco Drilling SA for the use of the Latco 01 1000HP drilling rig in the Platanillo field. The unit is currently being rigged up on Platform 5S to begin the drilling of Platanillo-6, the fifth well in the planned 8 well drilling programme. The rig is expected to be ready for inspection and acceptance checks during the course of December. Platanillo-6 is a directional well whose bottom hole location is approximately 1,490ft south east of the surface location.

After the work over of Platanillo-3, rig D-10 will be moved to the location of well Platanillo-1, located on Platform 1N, 2.5km north of the wells Alea-1R and Platanillo-2. Platanillo-1, drilled in 2007, was never tested by the previous operator, ECOPETROL, however Amerisur's log analysis indicates that an oil column exists in the U sand at this location. Platanillo-1 will be re-entered and sidetracked to a location approximately 2,000ft to the east. The objective of the sidetrack is to further delineate the oil columns in the Platanillo reservoirs and potentially to provide a water injection facility for the field. Depending on the results from this well, provisionally named Platanillo-1ST1, further wells may be drilled from Platform 1N.

The Company is also considering options for the re-entry and sidetracking of the wells Alea-1R and Platanillo-2, aiming to increase production from those wells by placing them in more advantageous reservoir positions based on the 3D seismic data and confirmed by results from the southern wells.

The Company has developed options for the export of oil production to various reception points, including Orito, Rio Loro and Dina. This has been necessary to reduce dependence upon the OTA pipeline, and also to reduce the impact of a comprehensive maintenance and upgrade programme being performed by ECOPETROL at its Orito facilities. However some constraints are being experienced on total reception capacity available, which may affect the output in the field for a period of approximately three months.

2012 Reserves

As previously reported, the Company targeted a 2P reserves objective of 35mmbo from the 8 well drilling programme. The certified reserves report for Agencia Nacional de Hidrocarburos (ANH) is required to be prepared based upon a cut-off date of 31 December 2012, with only the results from 4 of the planned 8 wells likely to be reflected in the analysis. That report will be presented to ANH on or before 31 March 2013.

Update on ANH Ronda 2012

Amerisur is pleased to announce that the application made with partner Pluspetrol in the competitive bid round "Ronda 2012" for block Put-12 was ratified by ANH and the contract has now been signed. Amerisur holds 60% working interest in the contract and is operator. Put-12 is a 54,433Ha (134,507 Acres) Exploration and Production contract area located east of and contiguous to the Platanillo field. The contract is of the latest ANH form, and contemplates 2 exploration phases of 36 months each, preceded by a "Phase 0" of up to 15 months during which local scouting and access agreements can be made.

Dr. John Wardle, Chief Executive commented: "We are pleased to report further progress towards realising the potential of our acreage. While the technical setbacks in the completion of Platanillo-9 are disappointing, the reservoir quality is high and our structure is developing faithfully to the seismic model, which augurs very well for the future field development. Securing the Latco-01 rig will allow us to both expand and improve our operational delivery, bringing forward the exciting programme in Platanillo. Our focus is to create value in all of our assets within the field, as well as to access high value acreage in the same setting. The re-entry of Platanillo-1 is particularly important, since it will add much information about the field, thus assisting us to define ever more closely the ultimate potential of the accumulation. We are also delighted to report that Amerisur has gained a participation in the Put-12 block. This area shares a common geology with Platanillo and is five times larger than the Platanillo block, with strong prospectivity. As operator we look forward to the start of this exciting campaign alongside our partner Pluspetrol."

ENDS

Competent person: Technical information in this announcement has been reviewed by John Wardle Ph.D., the Company's Chief Executive. John Wardle has 28 years' experience in the industry, having worked for BP, Britoil, Emerald Energy and Pebercan, and is a trained drilling engineer.

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