[autumnraine]

Anything they try to ‘plug the hole’ with will just push the oil and possibly dangerous methane gas out of the side of the pipe casing and make it nearly impossible to contain.

[Smokin' Joe]

Not exactly. The relief wells can be used to pump kill mud in at the bottom of the well, where it will put pressure on the producing formation even if the casing uphole is damaged. The wellbore can be cemented off, just not from the top, the kill mud and cement has to be pumped in at the bottom, which will actually put less pressure on the casing above it than trying to pump in kill mud from the top of the wellbore.

The relief well has been the most likely method to succeed from the start.