If it was that easy to cap they would. BP are losing billions over this. Set that against the cost of drilling a new well if this one was capped. here's no comparison.
>If they were really concerned about sealing it it off to protect the environment, they would have done that long ago. Their attempts appear to basically be to seal it while still allowing for oil to continue to flow into another rig or container ships so as not to lose too much $. Sad...
>
>
>>Russians suggest using an underground nuke to seal off the well:
http://trueslant.com/juliaioffe/2010/05/04/nuke-that-slick/>>
>>They used it 5 times to deal with what they call "petrocalamities". It's interesting that they've developed a rather apt term for the problem...
>>
>>It seems that hydrocarbon exploration in the Soviet Union/Russia is, ahem, "interesting":
http://www.youtube.com/watch?v=wF8tZjKTfEE