In its monthly report, the OPEC said oil demand worldwide will be 1 million barrels per day, 60,000 barrels per day less than previously estimated.
The weaker outlook could persuade OPEC and its allies to reduce output.
OPEC’s report lowered its forecast for world economic growth in 2020 from 3.2% to 3.1% and said next year’s increase in oil demand will be outweighed by strong growth in supply from rival producers such as the US.