Investing.com - Oil was lower Wednesday ahead of U.S. official stockpile data later in the session.
U.S. crude was off 35 cents, or 0.71%, at $49.21 at 08:00 ET. Brent crude shed 41 cents, or 0.78%, to $52.16.
The American Petroleum Institute (API) Tuesday reported a surprise build-up of 900,000 barrels in crude stocks in the latest week.
The API was expected to report a draw-down of 1.66 million barrels.
Official Energy Information Administration inventories are due out later Wednesday.
Higher U.S. output is offsetting the positive impact of production cuts of 1.8 million barrels a day by OPEC and non-OPEC producers.
Doubts are starting to emerge over whether the output cut accord will be extended beyond June as part of efforts to reduce inventories.