A long-range view of the Oriental 1-1 natural gas field owned by CNOOC Ltd. The field has a daily output of 187 million cubic feet. Analysts say the company's two offshore gas platforms, shut down as a result of a pipeline leak, may remain closed for as long as two months. That, in turn, may lead to gas shortages in Guangdong province. [Photo/Xinhua]

BEIJING - China National Offshore Oil Corp Ltd (CNOOC) said it will finish on Wednesday the depressurization work needed to stop an underwater gas pipeline in the South China Sea from leaking.

With that task complete, CNOOC will focus on plugging the leak afterward, said the company, which shut down two offshore gas platforms in response to the accident.

At the same time, CNOOC neither said how much gas has been leaked nor when the platforms are likely to resume operating.

The pipeline leak is near the company's Zhuhai Hengqin gas processing terminal in Guangdong province. Most of the gas from there is distributed to local power stations, while a small portion goes for residential use, CNOOC said in a statement on Tuesday.

The leak, whose cause is still under investigation, led the company to suspend two offshore gas platforms in the Panyu 30-1 and the Huizhou 21-1 gas fields, both in the South China Sea.

The halt is expected to prevent the company from recovering 26,700 barrels of oil equivalent of gas a day. The company aims to recover 921,000 barrels of oil equivalent a day, a measurement based roughly on the amount of energy released by burning a barrel of crude oil.

The brokerage and investment group CLSA said in a report that the suspended gas fields may remain shut for as long as two months. That, in turn, may lead to gas shortages in Guangdong province, the country's industrial powerhouse.

Two sources from CNOOC, who took part in the company's response to the accident and requested anonymity, said the leaking pipeline is more than 200 kilometers in length and lies at points as deep as 100 meters underwater.

One of the sources said repairs to the pipe began to be made on Monday and that little gas has been released from the pipeline since the platforms were closed.

"The pressure is relatively high since part of the pipeline goes as deep as 100 meters."

If the repair goes smoothly and security concerns are laid to rest, the platforms will probably resume operation soon, said another source who also requested anonymity. He said it is difficult to know both what caused the leak and how much gas it has released.

Huang Zuoping, an official from a bureau in charge of the South China Sea fishery sector, said fishermen have been told not to fish near the leak area. The local environmental protection bureau said the water there shows no apparent signs of pollution and that the situation is under control.

If the halt in operations leads to a gas shortage, CNOOC Gas & Power Group plans to send gas from other places to meet the demand in the affected region, one source said.

The Penglai 19-3 oilfield in Bohai Bay, in which CNOOC holds a 51 percent stake, was forced to shut down in September after about 700 barrels of crude oil leaked from the field in June.

The company also reported detecting a small oil spill in Bohai Bay's Jinzhou 9-3 West oilfield in October.