After the deal was announced on Wednesday, the market focused on the implementation and impact of OPEC`s first output cuts since 2008, to be joined by Russia and possibly other non-OPEC producers.

Crude prices were pressured by data showing oil output in Russia rose in November to a post-Soviet high and Moscow`s plan to use its record November oil production as its baseline when it cuts output.

With cuts being implemented next year only against end-2016 levels, analysts said there was still a possibility that oversupply, which has halved oil prices since 2014, remains a factor next year.

"Global, and especially U.S., crude oil inventories are currently at extremely high levels after two years of massive oversupply," Societe Generale analysts said.

"While the OPEC agreement is very significant and will result in some moderate global stockdraws next year, it is likely to take more than one year for crude inventory levels to return to more normal levels."

Front-month Brent crude futures LCOc1 ended the session up at $54.46 a barrel, up 52 cents, 0.96 percent. The contract rose more than 15 percent for the week, its biggest gain since early 2009.

U.S. crude CLc1 settled at $51.68 per barrel, up 62 cents or 1.21 percent and notched its biggest weekly gain since early 2011, with a rise of 12 percent.

Oil drew support from a weak dollar, which slipped against a basket of currencies .DXY. Still, traders said profit-taking ahead of the weekend limited crude`s price gains.

Prices rose to session highs after the White House said it expects U.S. President Barack Obama to sign U.S. legislation extending sanctions against Iran for 10 years into law.

Iran is also seen as a wild card in the execution of the OPEC deal.

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