Oil prices steadied around $50 a barrel on Thursday, close to the week's lows, on doubts proposed OPEC production cuts would be sufficient to balance the market, although a weaker dollar supported sentiment.
North Sea Brent crude was up 25 cents at $53.25 a barrel by 0908 GMT. U.S. light crude was up 20 cents at $49.97 a barrel.
Both benchmarks have fallen more than $2 a barrel from highs reached on Monday when investors bought heavily in the wake of an agreement by the Organization of the Petroleum Exporting Countries and Russia to cut production to reduce a supply glut.
OPEC members and oil producers outside the group will meet again this weekend in Vienna to discuss details of last week's deal, which aims at an overall reduction in output of around 1.5 million barrels a day.
Some analysts have suggested promised output cuts may be insufficient to dent global oversupply and rebalance markets.
"Momentum continues to wane in crude," said Jeffrey Halley, senior market analyst at OANDA brokerage in Singapore.
Stocks data on Wednesday provided little guidance on the state of the U.S. oil market.
U.S. crude oil inventories dropped 2.4 million barrels in the week to Dec. 2, compared with analyst expectations for a draw of 1 million barrels.
But stocks at the Cushing, Oklahoma delivery hub for U.S. crude futures increased by 3.8 million barrels, the most since 2009, according to the U.S. Energy Information Administration (EIA).
The U.S. dollar index fell as Treasury bond yields eased and investors eyed next week's Federal Reserve meeting.
"A slightly weaker U.S. dollar is supportive of oil prices," Michael McCarthy, chief market strategist at CMC Markets, said.
A weak dollar makes dollar-denominated oil less expensive for importing countries.
(Additional reporting by Jane Chung in Seoul and Keith Wallis in Singapore; Editing by Dale Hudson)