The causes of oil spills from China's largest offshore oilfield remain unidentified six weeks after the first leak, oceanic authorities say. They warn that more spills are possible.
The series of spills has seen oil from the Penglai 19-3 oilfield operated by ConocoPhillips seep into Bohai Bay, off the coast of Shandong province, since early last month. There was public outrage over a delay by the American company and its joint-venture partner, the state-owned China National Offshore Oil Corporation, in reporting the spills and their true extent. Contradictory statements by the State Oceanic Administration and ConocoPhillips created more concerns.
Lin Zhongfang, deputy head of the northern sea branch of China Marine Surveillance, a paramilitary maritime-law enforcement agency of the oceanic administration, said on Friday the authorities had demanded ConocoPhillips conduct a thorough check of the sources of leaks, but it had not received any report from the company yet, Xinhua reported.
Xinhua said the measures taken to contain the oil were all up to date.
Seepage has been observed near platforms B and C of the oilfield since June 4. ConocoPhillips said on Thursday that it had stopped much of the seepage on the seabed near platform B, though small amounts of oil, estimated to be no more than a few litres per day, could still be traced.
At platform C, the company said, a cementing procedure successfully stopped the release within 48 hours of discovering oil and gas bubbles, and the well had been stabilised, plugged and abandoned.
Lin said there could be various causes for the oil bubbles observed near platform C. 'It's not certain whether the cementing procedure is really working, or if there is any other source of seepage on the seabed' near platform C, Xinhua quoted Lin as saying. 'Further investigation by ConocoPhillips is needed, as the State Oceanic Administration has asked it to do.'
The oceanic administration ordered a suspension of production on Wednesday at the two platforms.
The US firm said only 1,500 to 2,000 barrels leaked from the two platforms. Lin said the authorities would conduct their own assessment. Xinhua reported last week that 4,240 square kilometres of sea was polluted, much larger than the 840 square kilometres the administration reported early this month.
The leaks were not announced until almost a month after the first spill.