China will soon put its first deepwater survey vessel into use in the South China Sea, an official with China Oilfield Services Ltd (COSL) said, part of an effort by the world's top energy consumer to tap its underexplored deep waters.

Ocean Oil 708, with a capacity to work in water depths of 3,000 metres and a drilling depth of 600 metres below the seabed, is one of the deepwater equipment that leading offshore oil and gas developer CNOOC planned to expand its deepwater capability.

The vessel is owned by COSL, a specialised oil service unit of China National Offshore Oil Corp (CNOOC).

The COSL official said the vessel will be used in early-stage exploration works such as geoprospecting, but declined to specify which area of the South China Sea the vessel would be firstly employed in.

CNOOC Ltd, which runs almost all of CNOOC's oil and gas production assets, is preparing to drill its first-ever deepsea well in the northern part of the South China Sea around the beginning of 2012 by using Ocean Oil 981, China's first home-made semi-submersible deepsea rig.

China has so far drilled less than 15 deepsea exploration wells, all of which have been done by CNOOC's foreign partners.

Baoji Oilfield Machinery Co, a unit of top Chinese oil firm CNPC, manufactured the drilling system for the Ocean Oil 708, the China Petroleum Daily reported.