U.S. West Texas Intermediate (WTI) crude futures rose to $63.67, the highest since December 9, 2014, before settling at $63.60 a barrel.
Brent crude futures also hit $69.37, the highest since May 2015 before closing at $69.33 a barrel.
OPEC, together with Russia and a group of other producers, last November extended an output-cutting deal to cover all of 2018.
The cuts were aimed at reducing a global supply overhang that had dogged oil markets since 2014.
OPEC is cutting output by even more than it promised and the restraint is reducing oil stocks globally, a trend most visible in the U.S., the world’s largest and most transparent oil market.
The cartel had at its November 30, 2017 meeting agreed to extend oil output cuts until the end of 2018 as part of the global efforts to eliminate excess oil supply in the international market. Sky more