An oil sheen discovered last month in the Gulf of Mexico near the site of the Deepwater Horizon rig explosion matches samples from the 2010 BP Plc oil spill.
BP reported the sheen on Sept. 16 about 50 miles (80 kilometers) off the coast of Louisiana and the U.S. took samples 10 days later, the Coast Guard said in a statement on its website yesterday. The size of the sheen has varied depending on conditions, the Coast Guard said.
“The exact source of the sheen is uncertain at this time, but could be residual oil associated with wreckage and/or debris left on the seabed from the Deepwater Horizon incident,” according to the statement. “The sheen is not feasible to recover and does not pose a risk to the shoreline.”
An explosion aboard the drilling rig on April 20, 2010 caused 11 deaths and led to the biggest offshore spill in U.S. history, with an estimated 4.9 million barrels escaping into the Gulf.
The size of the sheen has varied, the Coast Guard said. It was 4 miles long about a week and a half ago, Petty Officer Ryan Tippets said today in a telephone interview. The width was not estimated, he said.
BP and Transocean Ltd., owner of the Deepwater Horizon, may be held “accountable” for costs associated with further assessments or operations related to the sheen, according to the Coast Guard’s statement yesterday.
“The most likely source is the bent riser pipe that once connected the rig to the well head, where a mix of oil, drilling mud and seawater were trapped after the top kill operation,” Brett Clanton, a spokesman for London-based BP, said in an e-mailed statement today.
Samples that BP analyzed from the sheen contain a compound found in the drilling mud and not in the source oil, the company said.
BP set a target for $30 billion of asset sales to shore up its balance sheet following the 2010 Macondo oil spill off the southern U.S. It later raised that goal to $38 billion by the end of 2013.
BP rose 0.6 percent to 438.75 pence at the close in London.