Despite ongoing cuts, oil prices have not risen much beyond $50 per barrel. OPEC's success in drawing down inventories may hinge on output in the United States, which is not participating in the cuts. U.S. production has soared 10 percent since mid-2016 to more than 9.3 million bpd, close to top producer levels Russia and Saudi Arabia.
U.S. drillers have added rigs for 19 straight weeks, bringing the total 722, the highest number since April 2015 and the longest run of additions on record, according to energy services firm Baker Hughes Inc.
Almost all of the recent U.S. output increases have been onshore, from so-called shale oil fields.
Even if the rig count did not rise further, Goldman Sachs said it estimated U.S. output would increase by 785,000 bpd between the fourth quarter of 2016 and the fourth quarter of 2017 across the Permian, Eagle Ford, Bakken and Niobrara shale plays.
Analysts say that reducing bloated global stocks will be key to reining in oversupply.
"It's going to be all about inventories and whether they fall as much as OPEC thinks," said Greg McKenna, chief market strategist at futures brokerage AxiTrader.