So, all we need to do is dig a tunnel a couple of miles under the seabed, big enough to put a nuke in and get it properly positioned. How long will it take to drill the tunnel? Who is going to handle and place the nuke, oil-workers ?
How long will it take the government to modify a nuke that they can put under the water at such high pressures? How long will it take the administration to authorize such a procedure?
The russians used a nuke because the drilling techniques back then could only get them “close” to the bad well - maybe 100 feet? 500 feet? They used a nuke to scramble the rocks up (I wonder if they would also turn to one big glob of hardened glass?) to block off the bad well. Turn the whole cubic half mile (or whatever) into one big mass of cement/glass.
With today’s technology we can get right next to the bad casing, and even cut into the bad casing and inject the mud and cement to block it off. Just doing what had kept the oil and gas down in the hole while they were drilling, until the BP guy told them to pump out the heavy mud with light sea water.
The russkies used a nuke because it was the best technology at the time. We have better now.