What you DON'T do is drop nuke right into oil/gas and detonate.
What you do is dig smaller hole (definitely not going down to where actual oil is), put nuke inside, and calculate payload so that it shifts ground nearby and breaks oil pipe (we're talking about moving kilotons of ground just a bit further then width of the pipe, not blowing a crater). Once that is done you should have leakage stopped completely, or at least reduced enough to stop it with other methods.Actual radiaton is buried many meters under ground by the same blast, so there shouldn' t be any contamination.
That's optimistic scenario, but still, it has almost no risks mentioned by others (blast NEVER touches actual oil and cannot make another hole).
Russia profits either way.
They got lots of carbon credits when they signed Kyoto treaty to reduce carbon emission levels, and then had their industry production drastically drop from collapse of Soviet Union. Estimated worth of those carbon credits is about 20-60 billion $.
Look at it from a simple example - a sattelite flying above the Earth that sends some file. As long as it covers large area, you can propagate this file faster then it'd took sending it through wires. Yes, it'll require "preparation" (you need to upload file to satellite first), but you'll get faster file distribution in the end. Each recipient gets his file at a speed of light, but group bandwidth increases immersely.