There is a “Cold Welding” product [i.e. not conventional heat welding] used to glue on the Space Shuttle tiles by NASA, that if pumped into the gusher holes HUNDREDS OF GALLONS AT A TIME, would seal them completely. It can be used very easily UNDERWATER for repairs of any kind with boats, pool cracks, tank cracks, radiator leaks, anywhere wet or dry. It works under 2500psi, the oil well holes are pumping out at 2000psi, so there is an extra 500psi in the product's favor. 
It is called Velodur, or Durmetal.

http://www.durmetal.com/