Thombo Petroleum has announced the start of 3D seismic acquisition over the A-J1 graben in Block 2B, off the west coast of South Africa. The survey, by WesternGeco, aims to reveal the extent of the A-J1 oil discovery, drilled by Soekor in 1988, and to look at other prospects and leads in the graben which have been identified from existing 2D seismic data.