Crude prices advanced on Wednesday as the U.S. Federal Reserve decided to continue its asset-buying program and extend the Operation Twist after a two- day meeting and the largest U.S. refinery caught fire due to a fractured pipe. However, the gains were limited as the weekly report showed U.S. crude oil inventory rose last week. Light, sweet crude for January delivery added 98 cents, or 1.14 percent, to settle at 86.77 dollars a barrel on the New York Mercantile Exchange. Brent crude for January delivery also gained and last traded around 109 dollars a barrel.