A month ago, it seemed inevitable: a massive global oversupply of crude oil production would overwhelm storage tanks in Oklahoma and fill supertankers off Singapore. Now, there are growing signs that the U.S. oil market can avoid the doomsday scenario in which it runs out of room to stockpile surplus crude, a development that oil traders worried would send crude prices into another tailspin. One reason is that refiners, spurred by high profit margins, are rushing to buy crude and churn out more fuel in response to an unexpectedly swift rise in U.S.