Where’s the Oil Coming From?

For more than a month, a persistent oil sheen has been seen in the Gulf of Mexico near the site of the 2010 Deepwater Horizon disaster. After positively linking the oil to BP’s Macondo well, federal officials have suggested the oil is escaping from drilling wreckage on the gulf’s floor, but a Florida State University oceanographer cautions the rush to such an assumption.

“I would hesitate in sort of writing this thing off and saying, ‘oh, it’s just leftover oil in the riser,’” said FSU Oceanographer Ian MacDonald.

An active post-spill researcher, the oceanographer first noticed the sheen that authorities and BP are currently investigating during an Oct. 5 flyover of the area. It was substantially larger than ones he’d seen before.

“Something changed,” MacDonald said. “And it changed abruptly in September.”

BP reported the sheen to the United States Coast Guard Sept. 16. The oil company had noticed it on satellite images of the Mississippi Canyon during the previous week.

Samples of the oil were sent to the USCG’s Marine Safety Lab in Connecticut, where it was positively identified as Macondo oil.

“The exact source of the sheen is uncertain at this time,” the Coast Guard said in a statement last week, “but could be residual oil associated with wreckage and/or debris left on the seabed from the Deepwater Horizon incident in 2010.”

This week, an undersea remotely operated vehicle (ROV) is being used in an attempt to identify the specific source of the oil sheen at the Macondo site.

“The source is what they’re trying to figure out,” said Petty Officer Jonathan Wally, with public affairs at the USCG’s 8th District in New Orleans.

MacDonald, who will be making a research trip to the Macondo site next month, said that oil trapped in the wreckage and debris would present a finite threat, as only oil already trapped could be released. The persistence of this current sheen has him questioning the wreckage-theory.

He also doesn’t feel the presence of drilling mud—used during attempts to stop the leak in 2010—in the recent sheen samples is evidence that the oil originated from the wreckage.

“The problem is, there’s drilling mud everywhere around that well,” MacDonald said.

The FSU oceanographer said that if the oil stemmed from the Deepwater Horizon wreckage, it should be weathered after two years of being trapped.

“The big question is, how fresh is this oil?” MacDonald said, venturing that fresh oil would likely be originating from somewhere other than the wreckage.

The Coast Guard did not immediately know the condition of the oil samples collected at the Macondo well site. In its release last week, the agency noted that the sheen size has varied over the weeks depending on conditions.