Maybe use a nuke to evaporate/burn the oil from the surface of the sea, if it's too hard to ignite otherwise. Might lead to some problems with pesky fallout, but hey, such is life.
That, or use white phosphorus. Lots of it. In other words firebomb the **** out of that oil stain. 
Nukes? firebombs? You're an American aren't you? 
Actually, no, I am Finnish citizen.
I was merely attempting to find a constructive use for all those tools of destruction.
If collecting the oil is unfeasible or not possible fast enough with given resources, let us get rid of the oil.
If igniting the oil is hard, let us firebomb it, aka use something as catalyst to maintain the fires so that the oil itself burns away along with the phosphorus. Negatives: incendiary chemical traces and combustion chemicals could be almost or just as bad for the environment.
If igniting the oil is impossible,
let us vaporize it with medium altitude nuclear warheads. Negatives: Fallout, collateral damage, only possible far enough out in the open ocean and logistically difficult to arrange...
