In morning trade, New York's primary contract, West Texas Intermediate (WTI) light sweet raw for October delivery eased 10 cents to $85. 20 the barrel and Brent North Sea crude for Oct delivery rose 19 cents to $110. 81.
Bernanke is placed to speak later in the day at the central bankers' conference in Jackson Hole, Wyoming, where his speech is going to be under heavy scrutiny for clues on whether he'll push for further measures to bolster the loose US economy.
The US is the world's greatest oil-consuming nation.
"We are waiting to see what the Fed needs to say, " said Bart Melek, head of commodity technique for TD Securities.
The unrest in Libya, where pockets of resistance from forces loyal to strongman Muammar Gaddafi remained in areas of the capital Tripoli, was a factor in supporting Brent crude prices.
Brent is more affected than WTI by the problem in Libya as oil from the North Sea in addition to from Libya serve the European markets.
Around 85% of Libyan oil output was exported to Europe before revolt disrupted the country's production six months back.
Meanwhile, new weather forecasts that Hurricane Irene was no longer bearing down on the US Gulf coast— home to many refineries and offshore oil rigs— and was instead at risk of the US east coast brought relief to the actual markets.