Oil prices traded lower for the second day running on Wednesday after industry data showed U.S. crude oil, gasoline and distillate inventories unexpectedly rose last week.
Concerns over weaker demand due to rising COVID-19 cases globally also weighed on prices.
Benchmark Brent crude futures dropped 0.7 percent to $77.84 per barrel, while WTI crude futures were down 0.8 percent at $74.72.
Earlier this week, the price of oil per barrel had gone above $80 for the first time in around three years on expectations about tighter supplies because of rising demand in parts of the world.
Doubts re-emerged over demand, with China's industrial fuel consumption expected to take a hit in the near term amid growing power outages.
China is the world's top oil importer and second-biggest consumer of the fossil fuel after the United States.
Meanwhile, the American Petroleum Institute reported late Tuesday that U.S. crude oil, gasoline and distillate inventories rose last week.
Crude stocks rose by 4.1 million barrels for the week ended Sept. 24, defying expectations for a decline. Gasoline inventories rose by 3.6 million barrels and distillate stocks rose by 2.5 million barrels.
Traders expect Organization of the Petroleum Exporting Countries (OPEC) and allies, usually known as OPEC+, will decide to keep supplies tight when they meet next week.