This is a good point, but still, I'm sure a "properly sized" explosive that wasn't nuclear could do the trick too. I'm ignorant here: if a nuclear device were to be used wouldn't it irradiate the surrounding water? Wouldn't fallout plumes in the ocean would be more destructive than oil plumes? Or do you think it would be deep enough in the collapsed well to be insulated? Do I have any of this wrong?

Also, regardless of the explosive used, isn't there a chance it could ignite the reservoir?