Oil prices closed at their highest level since December on Tuesday, driven by a weak dollar, and expectations that U.S. crude supplies could have fallen again last week for a fifth straight week.
The likelihood of high global supplies from OPEC's lack of will to cut output when it meets this week remained a factor for the market, but did not immediately impact prices.
Ministers from the Organization of the Petroleum Exporting Countries, responsible for more than a third of the world's crude output, meet in Vienna on Friday to decide on production policy for the next six months.
The group has been producing up to 2 million barrels per day more than needed this year, although analysts expect the market to eventually balance from higher demand.
While a decision by OPEC not to cut is principally bearish for oil, the market was propped up on Tuesday by a weaker dollar that made crude prices, denominated in the greenback, more affordable to holders of the euro and other currencies. The euro was up its most against the dollar since mid-March on bets that Greece would reach a deal with its creditors.