Federal officials investigating reports of small amounts of oil popping up on the Gulf of Mexico surface near where a BP well blew out last year said Friday they found no oil leaking from seafloor wells.
This week the Coast Guard and BP sent deep-sea robots down to the disaster site and no leaks were found at the well or at two other wells drilled during the months-long work to get the out-of-control well capped. They said no sheens were seen on the surface either.
"We saturated that area by both air and sea," said Coast Guard Chief Petty Officer John Edwards. "With no known origin, this sheen ranks up there among the thousands of other quote-unquote mystery sheens that happen every day in the Gulf."
Apparently there was a leak somewhere _ perhaps from a natural seep on the seafloor or some other source, even drilling equipment that sank to the seafloor after the Deepwater Horizon rig exploded on April 20, 2010, killing 11 workers and sparking the largest offshore oil spill in U.S. history. The BP well spewed about 200 million gallons of oil last year.
Ed Overton, a Louisiana State University chemist leading efforts to analyze the BP spill, said samples from sheens found earlier in the week near the site of the disaster matched the fingerprint of the crude that spewed from BP's well.
"It is essentially identical," Overton told The Associated Press when reached by telephone Friday. "It means that it is oil that came from that general area."
He said the amount of oil found was very small and that the sheen _ reported by the Press-Register newspaper in Mobile, Ala., this week._ may have amounted to as little as a gallon of oil. "This is a leak of a real small amount of oil," he said. "We're not looking at a repeat of last summer."
Because the sheen was so small, he said it might be coming from a leak that would be hard to find, perhaps from a "fissure in source rock or from somewhere else."
Overton said it was possible the oil could be from the mile-long pipe called a riser that extended between the Deepwater Horizon and the well when the blowout occurred. The riser, along with the Deepwater Horizon, sank to the bottom of the Gulf. He said oil may have been trapped in the riser and is only now dribbling out. He said the small sheens documented this week resembled leaks in the past found escaping from sunken damaged vessels.
But he added that the oil might have come from a natural seep from the same oil reservoir the BP well was tapping into. There are natural seeps in the area.
BP said it had not sent remotely operated vehicles to look for leaks along the riser, which it said belonged to Transocean Ltd., the drilling company that owned the Deepwater Horizon.
Brian Kennedy, a Transocean spokesman, said the company had not conducted a survey of the riser. He called it implausible for oil to be leaking from that structure.
Federal officials said they did not look at the riser during the recent deep-sea probes of BP's wells.