A catastrophic April 2010 explosion at BP's Macondo well in the Gulf killed 11 men and led to the worst offshore oil spill in U.S. history, although BP's description of the site of the new sheen and a statement from a U.S. official seemed to indicate that the discovery wasn't near where the Macondo well blew up.
A sheen is a shiny coating that floats on the surface of the water, and could come from leaked or spilled oil. BP did not make clear what the source of the sheen was, but told The Associated Press it was not found near "any existing BP operations."
BP said in a statement the sheen was found near two abandoned exploration well sites in the Green Canyon Block in the Gulf of Mexico. According to a map published online by the U.S. Department of Energy, the Green Canyon Block — a large square-shaped area of water north of Louisiana — is adjacent the Mississippi Canyon Block where the Macondo well blew up.
"They are not investing any sheens in the vicinity of the BP well," Paul Barnard, Operations Controller for the New Orleans sector of the Coast Guard, told the AP on Thursday.
London-based BP spokeswoman Sheila Williams said the company had sent a "remote-operated vehicle" to examine the abandoned exploration wells, but declined to go into further detail.
Some oil naturally seeps from the floor of the Gulf and the AP has reported that at least 27,000 abandoned oil and gas wells in the Gulf are not routinely inspected when plugged or subsequently monitored for leaks.
BP's operations in the Gulf of Mexico have seen particular scrutiny following the disaster and it remains the area's largest leaseholder, but other energy companies have operations in the Gulf as well.
Williams said "there is a lot of sheen in the Gulf of Mexico area" and that the substance did not necessarily come from a BP operation.
"We're investigating potential sources of the sheen. We're not a position to say anything more," she said.