The firm said the rig would be operational Wednesday and called the launch "a substantial step," as it is the first independent deep-water platform developed in China.
Xinhua reported the semi-submersible rig would be put to use 200 miles southeast of Hong Kong in waters about 1 mile deep.
Oil reserves under the South China Sea are estimated at 23 billion metric tons to 30 billion with natural gas reserves of 16 trillion cubic meters.
The area contains about a third of China's oil and gas reserves.
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