Baker Hughes on Friday reported that the number of active U.S. rigs drilling for oil rose by two to 678 this week. The total active U.S. rig count, meanwhile, was unchanged at 790, according to Baker Hughes. Oil prices continued to gain, with March West Texas Intermediate crude up 39 cents, or 0.8%, at $51.81 a barrel. It was trading at $51.72 before the rig data.Market Pulse Stories are Rapid-fire, short news bursts on stocks and markets as they move. Visit MarketWatch.com for more information on this news.