A rift between Saudi Arabia and Iran over the Saudi execution of a Shi'ite cleric failed to boost prices this week, as it appeared to put an end to speculation that OPEC members could agree production cuts to lift prices.
U.S. crude for February delivery
Brent crude prices
"Geopolitical tension presents the greatest upside risk to the crude market, at least through the first half of the year," said Matt Smith, an analyst for energy database Clipper Data.
Still, a senior Iranian oil official said the country could moderate oil output and exports once Western sanctions are lifted to avoid putting prices under further pressure.
"We don't want to start a sort of a price war," Mohsen Qamsari, director general for international affairs of the National Iranian Oil Company (NIOC), told Reuters in an interview.
"We will be more subtle in our approach and may gradually increase output," Qamsari said. "I have to say that there is no room to push prices down any further, given the level where they are."
However, concerns over mounting stock levels added pressure to prices, with crude inventories in the United States rising by 439,000 barrels last week, according to a Reuters poll of eight analysts.
The U.S. Energy Information Administration (EIA) will publish its closely watched weekly data at 1530 GMT.
Data from American Petroleum Institute (API), an industry group, showed crude stocks fell last week by 5.6 million barrels, while stocks at the Cushing, Oklahoma, delivery hub rose by 1.4 million barrels.
"Demand growth and slowly declining non-OPEC crude production will stabilize (crude stock levels) in 2016 but not substantively reduce them until 2017," analysts at PIRA Energy said in a note.
The oil market also faced pressure from a strengthening dollar <.DXY> which hovered near a one-month high reached on Tuesday as traders sought safer havens.
(Reporting By Jacob Gronholt-Pedersen; Editing by Richard Pullin)
By Jacob Gronholt-Pedersen