On several occasions, the Soviet Union used nuclear weapons to plug oil leaks:
The USSR had a sad experience in containing oil-well flowing in Central Asia. Two breakdowns occurred almost simultaneously. One of them took place in Urtabulak, where a gas torch was burning. The other one took place in Pamuk – a breakdown at an oil well. The two giant flames were extinguished with the help of nuclear explosions. They drilled two wells to approach the emergency wells under the ground and lowered nuclear devices into the wells. The troubled wells were blocked as a result of the explosions.
The work was extremely hard, but it was worth it. I took direct participation in the experiment and was personally present there during the explosions. The experiment was a success. The exploitation of the Pamuk oil well was launched again and nothing could remind of the disaster which had been liquidated with the help of nucleal explosions.
It would probably work very well indeed, and only add a little bit to the radiation background. (The atolls in the Pacific where we detonated numerous bombs are now thriving natural environments.)