Oil prices rose above $52 a barrel today as fears about inadequate refining capacity and strong demand later in the year countered the effect of ample supplies for now.
Brent crude oil in London gained 27 cents to $51.56.
"Seasonally firm demand, especially from the US, is expected in the fourth quarter in winter. Demand levels are expected to grow and the question remains whether the high Opec output can meet the increase," said Tony Nunan of Mitsubishi Corp in Tokyo.
Opec president Sheikh Ahmad al-Fahd al-Sabah said today the 11 members of the cartel will produce 30.3 million barrels per day this month, a rise of 600,000 bpd from April.
Opec has been seeking to boost stocks to prevent a supply crunch during the peak-demand northern hemisphere winter in the fourth quarter, and US inventories have swelled to the highest level for nearly six years.
The build-up would be the 12th in 13 weeks, but even an extended period of inventory increase might not be enough. Qatar Energy Minister Abdullah al-Attiyah said the global oil market was amply supplied for now, but he was concerned about supplies in the fourth quarter.