U.S. crude climbed less than a dollar on Friday but finished down more than 2 percent for the week, marking the first time the benchmark has fallen for six straight weeks since December 1998. The Friday rally was driven in part by geopolitical tremors in Ukraine and the dollar backing off of its four-year high.
Brent crude futures settled up 53 cents at $83.39 per barrel on Friday but declined nearly 3 percent for the week, the seventh straight week down. The last time Brent fell for seven straight weeks ended in November 2002. The benchmark hit a four-year intraday low of $81.63 on Wednesday, down from a high above $115 in June. U.S. crude settled up 74 cents per barrel for the day at $78.65.
The dollar helped drive both the daily gains and the weekly losses, as Friday it retreated from its strongest level against a basket of foreign currencies in over four years. A strong dollar stunts the price of dollar-denominated oil benchmarks.
The Ukrainian military accused Russia of sending 32 tanks and truckloads of troops across the border, which if true would signal an end to the lull in violence between the two countries. Renewed fighting in the region could disrupt oil flows, throttle supply, and drive worldwide prices up.
However, some traders are skeptical that another flaring of violence in the region could affect supply and prices.
"There's not been a single supply disruption from the Ukraine situation in the past four, five months, though this time around it remains to be seen," said Tariq Zahir of Tyche Capital Advisors.
U.S. job growth increased at a brisk clip in October and unemployment fell to a six-year low of 5.8 percent, but missed analyst expectations for even stronger jobs growth.
Frigid forecasts for the U.S. Midwest driven by a polar vortex in the next two weeks boosted the market for heating oil, indirectly boosting demand for crude oil which can be refined to heat homes.
Increasing supplies of crude oil from North American shale formations have weighed heavily on prices this year, creating a glut in world markets and decreasing demand for oil from the Organization of the Petroleum Exporting Countries.
OPEC forecast on Thursday that its market share would be 5 percent smaller by 2018 as shale supplies continued to increase faster than demand.
But OPEC Secretary-General Abdullah al-Badri said the 12-member cartel, which pumps a third of the world's oil, was not panicking and thought prices would recover next year.
"I think the price will rebound by the second half of next year. But I don't know by how much. This situation of low prices cannot continue," Badri said after announcing the publication of the group's 2014 World Oil Outlook.
OPEC ministers will meet in Vienna on Nov. 27 to discuss how to react to falling oil prices and could decide to trim production.
Money managers cut their net long U.S. crude futures and options positions by 16,075 contracts to 158,182 in the week to Nov. 4, according to weekly data released by the U.S. Commodity Futures Trading Commission on Friday. (Additional reporting by Christopher Johnson in London and Keith Wallis in Singapore; Editing by Marguerita Choy and Lisa Shumaker)