Reversing losses from the previous two sessions, the BSE benchmark Sensex on Tuesday surged 147 points to a week's high of 18,653, led by gains in realty, IT and banking stocks.The 30-share index, which had shed 111 points in last two runs, had a jittery start and touched a low of 18,481. However, value buying in recently battered chips pushed it up by 146 points to 18,653.Broad-based National Stock Exchange index Nifty also rose by 46 points to 5,613.