Oil prices fell in early Asian trading on Tuesday after Goldman Sachs (NYSE:GS) said that prices needed to remain low in coming months to achieve a slowdown in U.S. production growth. Brent May crude had dropped almost half a dollar to $57.65 a barrel by 0017 GMT. U.S. May crude was down 39 cents at $51.76. The fall came after prices jumped more than 5 percent on Monday as traders reassessed how quickly Iran might increase exports after a preliminary nuclear deal and anticipated that a months-long rise in U.S. crude inventories may be slowing.