RonsPics

I know this topic has been addressed before, but this question is in a different context. Is there any scientific reason that introducing either liquid oxygen or liquid nitrogen into the well-head of the oil leak in the Gulf of Mexico would not temporarily seal the leak? I would think that the temperature of either substance would be cold enough to almost instantaneously freeze the oil and make it into a temporary cap, but I am not sure if the pressure at the depth of the well-head would alter the freezing point of the crude enough to make this unviable.