U.S. crude futures settled slightly lower on Friday after a Reuters survey found on Monday OPEC oil output rose in November from the previous month, led by a rebound in Iraqi exports after bad weather had temporarily halted supply growth from the group's second-largest producer.
The increase indicates the Organization of the Petroleum Exporting Countries is again pumping close to a record high as Saudi Arabia and other big producers focus on market share.
OPEC supply has risen in November to 31.77 million barrels per day (bpd) from 31.64 million in October, according to the survey, based on shipping data and information from sources at oil companies, OPEC and consultants.
Oil prices had risen more than 1 percent on Monday as speculators took bullish bets on the odd likelihood of a surprise outcome at this week's OPEC meeting and as refined oil products rallied.
Few traders and investors expect any material change to OPEC's production policy when the Organization of the Petroleum Exporting Countries convenes in Vienna on Friday. Still, some were hedging for the possibility of a surprise.