You have 5000 feet of water and then 18000 feet of pipe. I think the well is about 12 inches and narrows down to 6 inches at the bottom.
Do we have a nuke that small? How do we push it down the pipe against the pressure of the oil?
Are you gonna call Bruce Willis to stay behind and push the button? How else will you hold it in place against the thousands of pounds of pressure long enough to trigger it?
You don’t put the nuke into the bore hole of the well, you drill a well like the relief wells parallel to the leaking well a couple hundred feet apart and the explosion pinches off the leaking well, that is how the russians did it.
we had tactical nukes that went in an 8” gun, so the physics package could be sent down a drill pipe.