Oil prices edged higher on Friday, with Brent crude on track for its biggest weekly rally since 2009, following OPEC's decision to cut crude output in order to rein in a global glut.
The market's focus now shifts to the implementation and impact of OPEC's first production agreement since 2008, which will be joined by non-OPEC producers.
Crude prices on Friday were pressured by data showing oil output in Russia rose in November to a post-Soviet high and news that Moscow would use its record November oil production as its baseline when it cuts output.
U.S. West Texas Intermediate (WTI) futures settled up 62 cents, or 1.2 percent, at $51.68. The 5-day gain of 12.2 percent was the best weekly performance since February, 2011.
Front-month Brent crude futures were up 41 cents at $54.35 per barrel by 2:37 p.m. ET (1937 GMT). The contract was up about 15 percent this week.