oak barrel leaks

I have an oak barrel that has a slow leak and it drips wine out very slowly. I first have to fix the leak which I see might not be much of a problem, but my main concern now is the mold that formed on the spot where it leaked. I emptied the barrel from wine and filled it with water a couple weeks ago and I can see the white mold has floated to the top, so it has invaded the interior. My question is how to recover the barrel and put it back in operation. Does anyone know the best way. Any and all info is appreciated.