Oil dropped towards $58 a barrel today as a Norwegian oilfield restarted after a brief outage and Opec prepared for an emergency meeting to finalise a cut in output.
US light crude for November delivery fell 14 cents a barrel to $58.42 by 1355 GMT. Brent crude fell 42 cents to $59.10.
Norwegian authorities said Royal Dutch Shell could restart its 80,000 barrels per day (bpd) Draugen oilfield earlier than expected today.
Prices had rallied on Friday as Shell and Statoil said they would shut down 280,000 barrels of oil equivalent per day output for a week or two to improve lifeboat safety as demanded by regulators.
Authorities have yet to grant Statoil permission to restart its larger field.
Ministers from the Organization of Petroleum Exporting Countries are due to meet on Thursday in Qatar to put an end to over two weeks of wrangling on how to cut a million bpd from the group's supply.
OPEC, which supplies a third of the world's oil, has faltered on whether to make the cut from its official output target of 28 million bpd or from actual production of around 27.5 million bpd.
The group's dithering has blunted the potential effect of the cut on prices. Oil has shed a quarter of its value since peaking at $78.40 a barrel in mid-July as inventories swell and supply concerns wane.