Oil futures ended a strong week on a down note Friday, maintaining losses after data showed U.S. drillers added rigs.

Still, geopolitical worries and continued expectations that members of the Organization of the Petroleum Exporting Countries and other major producers will extend output curbs when they meet at the end of the month helped to lift crude futures to healthy weekly gains. Earlier in the week, oil futures hit levels last seen in June 2015.

On Friday, Brent crude the global oil benchmark, fell 41 cents, or 0.6%, to end at $63.52 a barrel on the ICE futures exchange. The contract saw a 2% rise for the week, according to WSJ Market Data Group On the New York Mercantile Exchange, West Texas Intermediate crude oil futures the U.S. benchmark, declined 43 cents, or 0.8% to $56.74 a barrel. For the week, WTI rose 2.3%. Both Brent and WTI logged their fifth straight weekly rise.

Oil was buoyed this week after Saudi Arabia detained 201 individuals including princes, businessmen and government officials after a three-year investigation, alleging that an estimated $100 billion of state funds have been embezzled. The actions helped to push oil prices to more than two-year highs this week. “Saudi Arabia is the second-largest crude producer after Russia, it’s the largest exporter and it’s the country with the largest spare capacity, so obviously if in such an important oil nation something happens which you didn’t expect at all, you start to price in a risk premium,” said Giovanni Staunovo, analyst at UBS Wealth Management.

This follows a recent escalation in geopolitical risks in other oil producers including Venezuela and Iraq, Staunovo said. Analysts said investors were already pricing in an extension to ongoing production cuts from major producers working in concert with OPEC. The group is due to meet on Nov. 30 when members are expected to discuss a potential nine-month extension to cuts implemented from January to help drain the global glut of oil supply. The current deal is due to expire in March 2018. Oil remained lower after oil-field services firm Baker Hughes said the number of U.S. oil rigs rose by 9 this week to a total of 738. Compared with the same time last year, the number of rigs is up by 286. While geopolitical turmoil has provided some lift to the market, “concerns surrounding increasing U.S. production, export levels, and drilling rates will likely provide resistance to rising oil prices in the coming months,” wrote analysts at Tradition, in a Friday note.

In other energy markets, Nymex December gasoline futures fell 0. 73 cent, or 0.4%, to $1.8124 a gallon, while logging a 1.1% weekly rise, with futures gaining for five consecutive weeks. December heating oil declined 1.2 cents, or 0.6%, to end at $1.9349 a gallon, marking a 2.6% weekly gain and booking its fifth weekly climb in a row.