FOSUN International subsidiary Roc Oil has started drilling the second of two planned exploration wells in the Bohai Bay basin, offshore China.

Project partner AWE, which holds a 40 per cent stake in Block 09/05, told the Australian Securities Exchange the well, named QK12 3 1D, was expected to take 26 days to complete.

To be drilled to a planned total depth of 3,600 metres, the QK12 3 1D well is designed to test the oil potential of a three way dip closed structure matured by 3D seismic data, AWE said.

QK12 3 1D has two primary stacked objectives in the Miocene-age Guantao reservoirs and Pliocene-age Minghuazhen reservoirs and a secondary objective in the Oligocene-age Dongying reservoir.

Several prospects with similar geological structures have been mapped in the close proximity to the QK12 3 1D prospect, the group said.

Block 09/05, in which Roc holds the 60% operating stake, is located in the western part of the Bohai Bay basin in China, about 10 kilometres southeast of Chinese port city Tanggu.

Covering an area of 335 square kilometres with water depths from about 5 metres to 10 metres, the block has low drill and development costs and is close to existing infrastructure AWE said.