Yes, I have heard of this. It is not a fix, it is trying to commit suicide if you get too close to the fumes this can produce. If it does any good at all, it is temporary. People shoot down wells with shotguns etc. but I don't recommend that one either. Dry ice does nothing.
The thing to use is Nu-Well tablets. They are a slow dissolving tablet using sulphamic acid not muriatic or sulphuric. The last two violently react with sulphur. And they don't do a thing to iron encrustations on a well screen.
Here is a place you can call to buy the tablets. I don't stock them, because where I live all the wells are rock wells and don't need screens.
BJW Berghurst & Sons