BP, Coast Guard say 4-day inspection of Macondo well, Deepwater Horizon debris turns up no oil

A fourth underwater inspection of the BP Macondo well and the underwater debris field from the Deepwater Horizon explosion and fire found no signs of oil, news releases issued Tuesday by BP and the U.S. Coast Guard say. The four-day survey by remotely operated vehicles of the sea floor, triggered by repeated sightings of oil sheen on the surface at the well site 50 miles southeast of Venice, was conducted by contractors for BP and Transocean, the owner of the Deepwater Horizon drillship, under a plan approved by the Coast Guard.

"No conclusive evidence of hydrocarbons leaking was observed from any of the surveyed areas," said the news release. "However, a white, cloudy substance appeared to be emanating from several places on the overturned rig, and samples of the substance were collected. BP will review the results of the investigation with the Coast Guard."

“No apparent source of the surface sheen has been discovered by this effort,” said Coast Guard Capt. Duke Walker, Federal On-Scene Coordinator for Deepwater Horizon. “Next steps are being considered as we await the lab results of the surface and subsurface samples and more detailed analysis of the video shot during the mission."

The Coast Guard news release said satellite surveillance will continue to monitor the sheen while additional steps are considered. It asked members of the public to contact the National Response Center at 1.800.424.8802 to report pollution incidents, or the Coast Guard 8th District command center in New Orleans, at 504.589.6225, to report marine emergencies.

The survey was observed remotely by the Coast Guard, Bureau of Ocean Energy Management, Bureau of Safety and Environmental Enforcement, BP, Transocean, and on-scene coordinators from Louisiana, Mississippi and Florida. Coast Guard observers were also aboard the Olympic Triton, the mother ship for the ROVs.

Video of the inspections will be made available soon, and will be posted on www.restorethegulf.gov, the federal web site for oil spill response operations.

During the survey, the ROVs inspected the wellhead and sites of two relief wells drilled during the attempt to stop the flow of oil during the spill, the drilling rig that caught fire and sank to the Gulf's bottom, and segments of the riser pipe that once connected the rig to the well on the sea floor.

They also re-inspected the 86-ton, 40-foot-high concrete cofferdam that was abandoned about 1,500 feet from the wellhead after an unsuccessful attempt to use it to capture oil leaking from the well and funnel it to the surface. After an Oct. 17 report of an oil sheen at the well site, an ROV inspection found the cofferdam was leaking drops of oil. A few days after the discovery, ROVs plugged openings in the cofferdam.

The Deepwater Horizon caught fire on April 20, 2010, and sank two days later, leading to the collapse of the riser pipe and the uncontrolled release of oil from the well. The well was capped on July 15, 2010, and permanently sealed with cement on Sept. 19. The well was later "plugged and abandoned."
In August 2011, reports of an oil sheen at the surface near the wellhead resulted in BP conducting an underwater survey of the well and relief wells, which confirmed they were not leaking.

The latest survey followed reports by BP on Nov. 2 of satellite images of a sheen at the site and reports of oil sheens from "On Wings of Care" pilot Bonny Schumaker on Nov. 10. Schumaker reported that during several flights over the wellhead over two days, she was able to direct the Schmidt Ocean Institute’s Research Vessel Falkor to the sheen site, where it also conducted an inspection of the wellhead with an ROV and found no indication that the oil was coming from the wellhead or the debris field.