ConocoPhillips China has cleaned up 369 cubic meters of mineral oil-based drilling mud, or about 90 percent of the total volume released on June 17. The company expects to have the mud clean up complete by or before the end of August.
As previously reported to the SOA and to the public, ConocoPhillips China is also closely monitoring and sampling several small seeps which are appearing in a concentrated 15 meter diameter area on the sea floor approximately 15 meters north of the C Platform. While samples are still being analyzed, it is believed the source of these seeps is residual mineral oil-based mud associated with the June 17 release that is migrating up from shallow subsurface sand layers. The company is developing plans to stop the seeps. The C-20 well that was the source of the drilling mud release on June 17 was permanently sealed on June 19, and the company is confident the seal remains effective.
The total volume of material released from the seep area near the C Platform is estimated at approximately two liters per day. Any oil droplets released from the seep area are contained and cleaned up at the surface.
ConocoPhillips China first observed the seep on the night of August 14, and reported it to SOA on August 15. Subsequent reports were made to SOA on August 16, 18 and 20. The company also posted information about the seeps on its public website on August 16, and again in a news release issued to the news media and posted on the website on August 19.