AFP/Getty Images Extraction work takes place in the Bakken shale formation in North Dakota.Crude futures edged lower again Thursday, following sharp declines in the prior session, but investor sentiment continued to be battered by data showing that the market remains awash in surplus oil. On Thursday, oil prices tanked by nearly 4% to their lowest level since November, following U.S. Energy Information Administration data that showed the decrease in crude stockpiles last week was smaller than anticipated. Compounding the woes was the unexpected increase in gasoline stocks, surprising many traders and analysts who expected much of the excess gasoline to be mopped up during the U.S. summer driving season. Data show gasoline demand has fallen for three weeks straight.via