Oil reversed gains in post-settlement trade Tuesday after API data showed a bigger than expected rise in inventory.
Crude inventories rose by 9.9 million barrels in the week to Feb. 26 to 517.1 million, compared with analysts' expectations for an increase of 3.6 million barrels.
Oil markets had risen as much 2 percent on Tuesday, maintaining their charge higher after a Wall Street rally helped turn around crude prices depressed initially by expectations that U.S. inventories had hit another record high.
Russian Energy Minister Alexander Novak's remarks that oil firms in the country support a proposal to maintain average production at January's levels also supported crude prices, traders said.
Russian President Vladimir Putin spoke of "more radical" measures to balance the global oil market, on top of a production freeze plan jointly pursued by Moscow with Saudi Arabia, Qatar and Venezuela.
Brent crude futures, the global benchmark for crude oil, traded up 7 cents at $36.64 a barrel after settling up 24 cents, or 0.6 percent, at $36.81 a barrel, above a session low at $35.95.