The sea is a big thing.
It does not want to be tamed.
For this the deep water rig does not sit on legs. It floats. It is a great steel island thing-It is held in place by nothing but fire and computers. It has thrusters on its belly. They fight the wind, the current, every second of every day, to stay over one spot on the dark seabed.
From there, a drill string, miles long, is sent down into the muck - The bit at its tip grinds through rock - There is a bigger pipe, the marine riser — This brings the broken earth back up but, the meanest thing sits on the seafloor - The blowout preventer. Basically a stack of steel valves a hundred tons heavy - Its only job is to wait for the deep pressure to surge, that's it.
Great hydraulic rams will slam shut if the preventer does its job.
The thing is mean enough to shear the drill pipe-in half and kill the well. If you want to pull fire from the deep, this is how they do it-With computers, and a very big knife, cheers.