Oil prices fell for a second day in volatile trade on Thursday, after hitting one-month lows following an unexpected surge in U.S. inventories and the return of more Nigerian crude to the market.
U.S. crude futures ended Thursday's session 8 cents lower at $45.64 a barrel. They earlier fell as low as $45.20, the weakest level since the contract crashed through a number of key technical levels to $43.76 on May 5.
Brent crude was down 15 cents at $47.91 a barrel by 2:36 p.m. ET (1836 GMT), after striking a session low of $47.56.
On Wednesday, U.S crude prices fell five percent after data showed big increases in U.S. inventories of crude oil and gasoline last week as refinery runs declined and exports fell.
"The inventory data was surprising to everyone, both in crude and in refined products," said Rob Haworth, senior investment strategist at U.S. Bank Wealth Management.