Unless OPEC extends the curbs beyond June or makes bigger cuts, traders say oil prices are at risk of falling further.
Oil prices dipped on March 23, struggling to recover from four-month lows because of investor concerns that OPEC-led supply cuts were not yet reducing record U.S. crude inventories.
New production projects and a fresh shale boom could boost oil output by a million barrels per year and result in an oversupply in the next couple of years, according to Goldman Sachs.
That decline also came ahead of the release of weekly U.S. crude inventory data later March 21 and on March 22 that is expected to show a crude stock build of 2.6 million barrels.
OPEC oil producers increasingly favor extending beyond June a pact on reducing crude supply to balance the market, sources within the group said, although Russia and other non-members need to remain part of the initiative.
Benchmark Brent crude futures were down 55 cents at $51.21/bbl at 7:19 a.m. CT (12:19 GMT). U.S. West Texas Intermediate crude futures were trading 73 cents lower at $48.05/bbl.
Eleven non-OPEC oil producers that joined a global deal to reduce output to boost prices delivered 64% of promised cuts in February, an industry source said, still lagging the higher levels of OPEC itself.
Oil prices rose March 17, helped by a weaker dollar, as investors weighed the impact of OPEC production cuts against rising U.S. shale oil output and persistently high inventories.
Energy sector emissions of 32.1 gigatonnes were unchanged from 2015 and 2014 even though the global economy grew by 3.1%, the IEA estimated.
Gordon Birrell, who previously headed BP in Azerbaijan, will become COO for production, transformation and carbon in the BP upstream segment, reporting to Looney. Andy Krieger will become the new head of drilling. Krieger, previously vice president for drilling in the Gulf of Mexico, will report to Birrell.