The American Petroleum Institute on Wednesday reported an increase of 12.940 million barrels of crude oil in U.S. inventories for the week ending Oct. 6.
Analysts had expected an increase of 1.300 million barrels for the week.
The institute reported a decline of 4.210 million barrels in the previous week.
Oil prices fell on Wednesday. The West Texas Intermediate for November delivery decreased 2.48 U.S. dollars, or 2.88 percent, to settle at 83.49 dollars a barrel on the New York Mercantile Exchange.