Oil prices, which briefly dropped below $79 per barrel on Wednesday, jumped back up late in the afternoon to close over $80, as traders weighed a U.S. government report showing a surprise increase in the nation's crude inventories against concerns that a new storm could be brewing in the Gulf of Mexico, threatening production.
U.S. light, sweet crude for Novermber delivery dropped as low as $78.44 -- then jumped back up 77 cents to close at $80.30 per barrel.
In London, November delivery Brent crude fell $1.12 to $76.50 per barrel.
Oil prices had dropped sharply after the U.S. Energy Information Administrations said oil inventories in the world's biggest energy consumer rose by 1.8 million barrels last week, defying expectations for a decline.
"Everybody seems to have been caught by surprise by the crude stock build, but now people are watching a tropical depression that will be named Lorenzo when it becomes a tropical storm," said Phil Flynn of Alaron Trading in Chicago.
The increase in stockpiles came as imports notched higher and domestic refinery activity slumped to its lowest level since last March as companies shut plants for seasonal maintenance work.
Gasoline stocks, meanwhile, rose 600,000 barrels, while distillates inventories climbed 1.6 million barrels, the EIA said in the weekly report.