The West African Transform Margin remains “highly prospective” despite two Anadarko Petroleum Corp.-operated exploratory wells that encountered water-bearing reservoirs with oil shows offshore Sierra Leone and Ivory Coast, said Tullow Oil PLC.
Mercury-2, on Block SL-07B-11 off Sierra Leone 12 km northwest of the Mercury-1 oil discovery, targeted an area where the extensive 3D seismic coverage indicated a high probability of finding thick reservoir quality sandstones. It intersected more than 270 m of reservoir quality sandstones that were water bearing with oil shows at this location, Tullow said.
Mercury-2 went to 5,142 m in 1,815 m of water. Anadarko operates the block with 55% interest, Repsol YPF has 25%, and Tullow has 20%.
Kosrou-1 went to 5,241 m in 2,275 m of water on Block CI-105 off Ivory Coast 17 km east-southeast of the previous South Grand Lahou-1 well. Kosrou-1 targeted a channel system identified on 3D seismic survey shot in 2010. The well cut 90 m of reservoir quality sandstones with oil shows in the primary target and more than 120 m in total in the well.
On completion of operations the rig will return to the Paon-1 location to finish drilling that well. Paon-1 is a high-impact prospect geologically independent from Kosrou and closer to recent discoveries in Ghana. Anadarko operates CI-105 with 50% interest. Tullow has 22%, Petroci 15%, and Thani 13%.
Tullow said it will integrate data from the two wells into its regional models to improve the chances of making a hub-class discovery with the ongoing exploratory campaign that includes the Strontium-1 well off Liberia and Paon-1 off Ivory Coast.