They are also overlooking (or ignoring) the salt layers that may lay between sucessive layers of rock.
Shatter the salt and the expanse of leaking fisures may not even be able to be delt with.
http://en.wikipedia.org/wiki/Salt_dome
Not claiming any expertise, I use these threads to informally become a bit more knowledgeable about the topic.
This is the best resource that I have been able to come up with in casual searching on the effects that can be expected in setting off a nuclear explosion at depth...
The Effects of Nuclear Weapons
»
CHAPTER VI-Shock Effects of Surface and Subsurface Bursts. 231
Characteristics of Surface and Shallow Underground Bursts. 231
Deep Underground Bursts 238
Damage to Structures. 241
Characteristics of Underwater Bursts. 244
Technical Aspects of Surface and Underground Bursts. 253
Technical Aspects of Deep Underground Bursts. 260
Loading on Buried Structures. 263
Damage from Ground Shock 265
Technical Aspects of Underwater Bursts. 268
The question I have is related to the drill hole depth and angle.
If the drill is shallow (sideways) and goes through a salt dome to the deposit layer, then the nuke option is likely to carry a substantial risk.
If, however, the drill is deep/vertical (1+ kilometers), punches far beyond any surveyed salt dome or doesn't reach it, wouldn't a nuke's compression and/or heat effect collapse the drill hole and fuse the surrounding sediment to, in effect, place an obsidian cap on the drill hole and the immediate crater?
I am not advocating anything here, especially without an understanding of the particular sediment/rock layering of the drill site. I am just conjecturing about the feasibility of capping the oil flow at the cost of whatever collateral effects will occur, ie fish kill, shore damage from resultant waves, destabilization of local fault lines, etc. Radiation does not seem to be a worry based on the prior deep water testing.
If the capping efforts don't work, it would be reasonable to consider alternatives that can be more expeditiously applied than watching three or four months of oil gushing out, but always keeping in mind that there is no such thing as a free lunch.