Traders said that the main WTI price driver had been American Petroleum Institute data showing a 7.5-million barrel draw to 507.2 million barrels in US crude inventories, the third weekly stock draw.

International benchmark Brent crude futures were trading at $46.46 per barrel, up 58 cents, or 1.26%, from their last close.

Traders said that Brent was being supported by firm import data from Japan.

Japan's customs-cleared crude imports rose 0.5% in August from the same month a year earlier, the Ministry of Finance said on Wednesday.

Japan, the world's fourth-biggest crude buyer, imported 3.38 million barrels per day of crude last month, the preliminary data showed.

Overall, however, oil markets remain over supplied as exporters around the world pump near record amounts, while demand stutters.

"Fundamentals suggest the oil market is likely to remain in surplus for longer than many expected," Dutch ING bank said, citing lower Chinese oil purchases and uncertainty around the global economy as factors weighing on markets.