A novel solution to the offshore oil well problem
The details of the BP accident in the Gulf of Mexico are finally trickling out. The latest rumor is that the well blew out while a tool was inserted into the blowout preventer. The tool is too strong for the shear rams to squeeze the well casing fully closed. The shear rams are designed with two opposed rams that act like a pair of pliers. When activated, the two faces pinch the casing closed. Not being fully closed is the bad news, being partially closed might be the "good" news.
Given the pressures due to the depth of water and the already cold temperature, the methane from the well is close to becoming methane hydrate naturally. The solution may be to help the process along.
I would suggest injecting liquid nitrogen into the soil around the casing as deep as possible using the remotely operated submersibles. The idea is to freeze the methane in the pipe. Once the well is frozen, you would cut off the blowout preventer and weld the casing shut. As long as there is a frozen plug far enough below the weld, there ought to be time to complete the welds before the plug melts.
It is a novel solution, but it is a weapon that already exists in the oil patch arsenal