BEIJING, Feb 8 (Reuters) - China's $1-billion deepsea drilling rig, the first of its kind designed and built at home, is being repaired after leaks in a pump room while it was being worked in the South China Sea, state giant the China National Offshore Oil Company said on Friday.
The rig, "Offshore Oil 981", was being chartered by Canada's Husky Energy, operator of the Liwan project in the western part of South China Sea, a major offshore gas discovery, industry officials said.
"Minor leaks were found at one water pump room of 'Offshore Oil 981' during routine checks ... The company decided to deal with this issue promptly to ensure safe deep-water operations," CNOOC, China's top offshore oil and gas producer, said in an e-mail.
The leaks were found on Dec 31 and maintenance will finish by the end of February, CNOOC, the parent of CNOOC Ltd said, adding that preliminary analysis showed the leaks were caused by the release of structural stress in the early days of the rig's operation.
An industry official with knowledge of the matter said cracks found in one of the rig's four steel columns led to water leaks into the pump room.
The rig, officially launched last May, was dedicated to exploring the South China Sea, in which China, Vietnam, the Philippines, Taiwan, Malaysia and Brunei have overlapping claims.
Before Husky chartered the rig it had drilled several deepwater wells for CNOOC Ltd, industry officials said.
The rig was built by China's Waigaoqiao shipyard and has a dual registration, with the China Classification Society (CCS) and the American Bureau of Shipping (ABS). It is owned by CNOOC and operated by China Oilfield Services (COSL).