It depends on the barrels previous usage. Generally new oak isn't used on beer because of the cost and because it's too intense. Barley wines and stouts lend well to whiskey barrels dark sours, clean reds and browns to red wine barrels saisons and light Belgians to white wine barrels ect.. Big beers normally age better in barrels as well. Generally these beers are clean fermented then racked to barrels and aged. Potassium metabisulfate is added if you don't want sour beer. The sky's the limit though, I've had a juniper beer aged in gin barrels that was pretty tasty for example
On Tap - smoked porter on nitro
-Sour dubbel (15 months on oak)
- pliny the YOUNGER clone!
- dark english mild