Block 2B covers 4,360 square kilometers of the South African Western offshore about 300 kilometers north of Cape Town. Water depths over the block are 50 meters to 200 meters. Over the main area of interest in the block, the A-J rift graben, water depth ranges from 140 meters to 160 meters.
Oil was discovered and tested by Soekor in the A-J1 borehole drilled in 1988. Thick reservoir sandstones were intersected between 2,985 meters and 3,350 meters. The well was tested and flowed 191 barrels of oil per day of 36 degree API oil from a 10 meters sandstone interval at about 3,250 meters. At the time the discovery was considered to be of limited economic significance. However, significant upside potential within six prospect areas at depths of up to 800 meters shallower than the reservoirs in A-J1 has been identified on the 686 square kilometers of 3-D seismic data that covers the whole of the A-J graben area. Follow-up wells will target this potential.
The A-J graben is typical a rift basin, similar to others in which major oil accumulations have recently been discovered such as the South Lokichar basin in Kenya. The oil was generated in lacustrine source rocks that are present in the deepest parts of the basin. The oil migrated and accumulated in fluvial and lacustrine sandstone reservoirs around the basin flanks.
There is also significant potential in other rift graben to the north and south of the A-J graben and potential for significant gas discoveries in the shallower sequences above the rift graben succession over the whole block.