Rusted out 'pump-jacks' in the oil town of Luling, Texas.

Crude oil settled lower on Wednesday, wiping out most of their gains from the previous day, as a strong dollar, tumbling gasoline prices and rising U.S. crude inventories bore down on the market.

Adding to bearish sentiment was an internal OPEC document published by Reuters that showed weaker demand in the next few years for oil from the producer group, even as Saudi Arabia pumped near record levels to protect its market share.