Afren plc (“Afren” or the “Company”) and Partners Optimum Petroleum Development Ltd and Lekoil Limited announce the suspension of current drilling operations at the Ogo prospect located on the OPL 310 licence offshore Nigeria and an update on estimated gross mean recoverable resources, significantly ahead of pre-drill expectations.
OPL 310 is located in the Upper Cretaceous fairway that runs along the West African Transform Margin. Extending from the shallow water continental shelf to deep water, the block represented a wild cat exploration opportunity in an under-explored basin. Detailed pre-drill evaluation of the block identified several prospects lying in the same Turonian, Cenomanian and Albian sandstone intervals that have yielded significant discoveries in Ghana and Côte d’Ivoire. The first exploration well drilled by the Partners was the Ogo prospect, a four-way dip-closed structure in the Turonian to Albian sandstone reservoirs, which was targeting 78 mmboe of gross P50 prospective resources. The drilling programme included a planned side-track, testing a new play of stratigraphically trapped sediments that pinch-out onto the basement high targeting 124 mmboe of gross P50 prospective resources. In total, the Partners were targeting 202 mmboe of gross P50 prospective resources.
The Ogo-1 well was drilled to a total measured depth of 10,518 ft (10,402 ft true vertical depth subsea), and encountered a gross hydrocarbon section of 524 ft, with 216 ft of net stacked pay. The Ogo-1ST reached a total measured depth (TD) of 17,987 ft (12,050 ft true vertical depth) and encountered hydrocarbon intervals in the same Turonian, Cenomanian and Albian reservoirs that were successfully drilled and logged at the Ogo-1 well. In addition, the syn-rift section encountered a 280 ft true vertical thickness gross hydrocarbon interval.
Based on the well data, the Partners estimate the P50 to P10 gross recoverable resources range to be significantly ahead of pre-drill expectations at 774 to 1,180 mmboe across the Ogo four-way dipped closed and syn-rift structures. Additional upside potential is expected in the syn-rift play. In addition, the latest PVT (Pressure-Volume-Temperature) analysis confirms excellent reservoir fluid properties with a 40 deg API, 600 GOR, 0.42 cp viscosity oil in the Turonian, a 39 deg API, 870 GOR, 0.40 cp viscosity oil in the Cenomanian and a condensate rich gas in the Albian of up to 115 bbls / mmscf. The partners expect the syn-rift to contain a light oil or a condensate rich gas.
Whilst circulating bottoms up at TD, the drill string parted at 3,390 ft and during good progress towards recovery of the drill string from the well bore, the well took a hydrocarbon kick. After the kick was safely controlled, the partners considered it prudent to move to permanently secure the well. The Partners intend to drill an appraisal well in H2 2014, ahead of development planning and will also increase 3D coverage on the block, currently covering only 25 per cent. of the block, to define further prospectivity.