Oil futures continued lower after yesterday's higher-than-expected US inventory report.
Just before 11am, September-dated Brent futures contracts were down 77 cents at $55.88 a barrel.
US benchmark September-dated contracts were down 76 cents at $57.26, after yesterday's August-dated contract expiry.
The US Department of Energy (DoE) yesterday reported crude stocks had fallen by 900,000 barrels to 320 million barrels for the week ending July 15th.
Analysts were expecting to see falls of around 3.7 million barrels because of hurricane-related disruptions to production and crude imports.
The DoE also reported distillate stocks, which include heating oil, diesel and jet fuel, showed a larger-than-forecast rise.
Stocks rose for a ninth consecutive week by 2.3 million barrels to 123 million, against predictions of a rise of 1.7 million barrels.
Gasoline stocks fell by 1.3 million barrels, against predictions of a 900,000 barrel stock draw as the summer driving season continued to erode stocks for the third week.