Crude prices rose in Asian trade on Wednesday on stronger energy demand fuelled by the need for heating fuel during the northern hemisphere winter.
New York's main futures contract, light sweet crude for delivery in February, turned higher in afternoon trade, rising 23 cents to 79.10 US dollars a barrel.
Brent North Sea crude for February delivery was up 36 cents to 78.00 dollars.
A rising US dollar had capped gains during morning trade as a stronger greenback makes dollar-priced oil more expensive.
Analysts said the oil market was expected to take a further lead from the weekly US Department of Energy report on the country's stockpiles due for release later Wednesday.
The market is expecting a drop in inventories because of higher demand for heating fuel during the northern hemisphere's winter and a rebound in the US economy, a key engine for global growth