Crude oil prices eased back Thursday morning, slipping to less than $91 per barrel after stockpiles rose in the week ending Friday. Crude oil inventory rose by 2.9 million barrels in the week, the U.S. Energy Information Administration said. Stocks reached 369.2 million barrels and are higher than the upper limit of the average range for this time of year. The gain in supply put pressure on prices. November delivery West Texas Intermediate crude oil dropped $1.33 overnight to $90.79 on the New York Mercantile Exchange. Natural gas prices shed 1.4 cents to $3.4656 per million British thermal units. Home heating oil lost 2.65 cents to $3.1629 per gallon. Reformulated blendstock gasoline dropped 5.5 cents to $2.7092 per gallon. At the pump, the average price for a gallon of regular unleaded gasoline was $3.737 per gallon, down from Wednesday\'s $3.756, AAA reported.