I was confused about why people keep harping on nukes when there are conventional weapons that are almost as powerful, and could do just as good a job of converting what might merely be a civilization-ender into a mass extinction event.
But, oh good, here it comes.
Seems a damn sight saner than, say, the US plan to use nukes to blast harbours in Alaska.
OK, so I'm setting a pretty low bar here.
There's always the chance that, instead of sealing the well, a nuke would simply blast a very large hole in the sea floor between the oil pocket and the water, leading directly to Maximum Fun.
The theory goes (as you see from the video): put a nuke down what would ordinarily be called a "relief well" and detonate it, crushing the well and pinching it off.
Nukes have a much better boom / size ratio than conventional weapons (duh) and therefore fit a little better into small holes in the ground.
MOAB doesn't seem like a starter, given that they're usually fucking huge and unlikely to fit. I see they want to put it on the sea floor as opposed to in a side well. All I can say to that is "Yikes."
gThis.
The GBU-43/B weighs 21,700 pounds, and carries 18,700 pounds of H6. It's not a small weapon.
The W54 nuclear warhead, the so-called backpack nuke, is only 11 inches wide, and weighs a mere 50 pounds. It's got a variable yield device all the way down from one kiloton to 10 tons.
Detonated underground, it's self sealing, with damn little fallout.
Adhering to the standard Nuclear Weapons Comparison Scale, this means the W54, at max yield, is one twentieth the power of the Hiroshima bomb.
The W54 (and the derivative SADM backpack nuke) is long obsolete and not available in inventory. The last of the SADMs were dismantled back in the 90s if I recall rightly. Smaller-diameter nukes were developed though -- nuclear artillery shells were developed that could be fired from a 152mm (6") gun. They too are all long-gone from inventory.
To use a nuke down a relief well it would have to be jacketed and armoured to withstand the pressure at about 15,000 feet below sea level (call it 6000 psi). The bottom of the relief wells being drilled in the Gulf at the moment will only have a bore of about 6 to 8 inches.
The relief wells will in fact be used to inject heavy drilling mud to stop the flow of oil and gas up the runaway bore followed by concrete to produce a solid seal. Afterwards more concrete will be put in from the top of the bore to permanently kill the well. One neat trick that's available in the drilling engineer's toolkit is that if the two relief wells are successfully completed it's possible to inject a two-part polymer adhesive instead of concrete as the final sealant -- one well pumps the resin and the other pumps the catalyst just like one of those Araldite glue-guns with the two syringes and the two chemicals react at the bottom of the bore.
Whoops. Guess I was wrong.
And how much movement would there be on the ocean floor? More than a foot, and New Orleans will be under 30 feet of water within 20 minutes, Houston within an hour.
Where are you getting your numbers?
It's even worse than that. Fuel-air bombs work by dispersing fuel in the air at approximately a stoichiometrically ideal ratio. Then they go boom.
Making this work in an anaerobic environment at 150 atmospheres of pressure is going to be somewhat interesting...
The BLU-82 "Daisy cutter" was a fuel-air bomb. The GBU-43/b is a conventional iron bomb with a guidance package bolted on it.
MOAB on wikipedia.
40 inches around, though. How much harder is it to drill a 40" well than an 8" well?
In any useful timescale, completely impossible.
captcha: one rescuer
He's proposing to use a fuel-air bomb at 150 ATM?
Yeah, that should work.
The soviets did shut off several natural gas fires with nukes - part of their "Nuclear Explosions for the national economy" program.
I can't speak to the effectiveness/economics of such a tactic compared to the non-nuclear relief well method described above by nojay, but setting off a conventional bomb at the ocean bottom probably won't work for the same reason as the problem shown in that Soviet video - if you don't cut it off down deep, the oil is going to start leaking through cracks in the bedrock as well as through the bore hole.
Why restrict ourselves to the real world at this point? A CTD imploder should do the job nicely. Then we can shift the oil out with runcible gates.