As Bloomberg reports:
“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 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.
Similarly, the Press-Register reported last year, in connection with a separate 10-mile oil slick linked to BP’s stricken well:
Scientific analysis has confirmed that oil bubbling up above BP’s sealed Deepwater Horizon well in recent days is a chemical match for the hundreds of millions of gallons of oil that spewed into the Gulf last summer.
The Press-Register collected samples of the oil about a mile from the well site on Tuesday and provided them to Ed Overton and Scott Miles, chemists with Louisiana State University.
The pair did much of the chemical work used by federal officials to fingerprint the BP oil, known as MC252.
“After examining the data, I think it’s a dead ringer for the MC252 oil, as good a match as I’ve seen,” Overton wrote in an email to the newspaper. “My guess is that it is probably coming from the broken riser pipe or sunken platform. … However, it should be confirmed, just to make sure there is no leak from the plugged well.”
But there is not that much oil in the riser. As the Washington Post reported Wednesday:
Marcia McNutt, director of the U.S. Geological Survey, said a rough calculation showed that the riser, if full of oil, could hold about 1,000 barrels of oil. Because it’s open on two ends it is unlikely to have that much oil, she said.
Indeed, Dr. Ian MacDonald – an expert in deep-ocean extreme communities including natural hydrocarbon seeps, gas hydrates, and mud volcano systems, a former long-time NOAA scientist, and a professor of Biological Oceanography at Florida State University- told us today:
The key statement in the BP discussion was the fact that oil recovered on the ocean surface was not biodegraded. This is not consistent with a pool of oil supposedly trapped in the wreckage of the riser, which would have been exposed to ambient bacterial activity for over two years.
In fact, top oil spill experts – such as UC Berkeley professor and government consultant Robert Bea and LSU professor Ed Overton (in an interview by phone yesterday) – have told us that oil blowups can create new pathways to the seafloor and enlarge natural oil seeps … so that leaks can continue for years.