Oil prices edged up Thursday amid bargain-hunting after the prior day's sell-off on concerns about the US "fiscal cliff" and the European public debt crisis.
New York's main contract, West Texas Intermediate crude for December, rose 65 cents from Wednesday to settle at $85.09 a barrel.
Brent North Sea crude for delivery in December gained 43 cents to $107.25 a barrel in London trade.
On Wednesday the WTI contract had plunged more than $4 to a four-month low in the wake of US President Barack Obama's re-election Tuesday that defeated Republican challenger and Wall Street favorite Mitt Romney.
Persistent fears concerning the eurozone's sovereign debt crisis kept a cap on price rebound, said John Kilduff at Again Capital.
And traders also continued to worry that US political gridlock will prevent a compromise to avoid the "fiscal cliff" of automatic tax cuts and spending hikes at the end of the year, which could tip the US back into recession.
Oil prices Wednesday were hammered after the European Union lowered its economic forecasts for the eurozone, to a contraction of 0.4 percent this year and miniscule 0.1 percent growth in 2013.
On Thursday, OPEC cut its medium-term forecast for global oil demand, citing "growing concern" about economic growth especially in the eurozone.
By 2016, demand was expected to reach 91.8 million barrels per day, the Organization of Petroleum Exporting Countries said in its annual World Oil Outlook report.
Last year, it had forecast average daily demand at 92.9 million barrels within four years.
OPEC said that in its last two reports it had taken a more positive view on demand based on the monetary and fiscal stimulus measures were put in place in many countries.
"This year, however, there is growing concern about immediate prospects for economic growth, particularly in the eurozone," it said.