Oil markets were also underpinned by the ongoing Libya unrest as it became increasingly apparent that the North African country will take longer than expected to get its crude production facilities back to pre-crisis levels.
New York's main contract, West Texas Intermediate light sweet crude for October delivery rose 14 cents to USD 85.30 a barrel and Brent North Sea crude for October delivery was 21 cents up at USD 110.36.
"Over the coming week, crude markets will be looking for clearer information on the condition of the Libyan oil and gas infrastructure," said Sanjeev Gupta, who heads Ernst and Young's Asia-Pacific oil and gas practice.
Oil prices could drop temporarily if the crisis in the oil-rich North African nation eases, or if strongman Muammar Gaddafi is caught, said SEB Commodity Research analyst Filip Petersson.
"Bearish influences could come from Libya -- e.g. if Gaddafi is caught -- but these are likely to be short-lived as the market is starting to realise that Libya is highly unlikely to be back at pre-war capacity anytime soon," he said.
Meanwhile, investors are watching out for Friday's speech by Bernanke, which will be scrutinised for signs of whether he will support new stimulus measures to juice the sluggish economy. The US is the world's largest oil-consuming nation.