China National Offshore Oil Corp. said it was told by the Chinese subsidiary of ConocoPhillips that less than 5 barrels of oil was released at the Penglai 19-3 oilfield.
CNOOC said the release occurred during an oil transfer but automatic isolation valves closed "immediately," preventing further release. The latest observation, as of Monday afternoon, indicated there was no oil sheen on the site, the company said.
Two leaks from Penglai 19-3, China's biggest offshore oilfield, released hundreds of barrels of crude oil into the water last year, resulting in marine pollution and environmental damage to a marine area of 2,400 square miles.
Conoco was ordered by Chinese authorities in September to stop production at the field, though it was restarted earlier this year.
Notable deaths of 2014 [PHOTOS]