OPEC published its monthly market report highlighting developments in August. It said world oil demand for the year was revised upward by 25,000 barrels per day because of improvements in the British, German and U.S. economies during the first half of the year.
The U.S. economy in particular is expected to grow by 2.5 percent next year.
"In 2014, world oil demand is projected to grow by 1 million bpd, in line with the previous forecast," the cartel's monthly market report said.
In terms of suppliers, OPEC said demand for its crude oil in August was down 124,000 bpd from the previous month. The United States, Canada, both Sudans, Russia, China and Colombia contributed to production gains from non-OPEC members.
The cartel said non-OPEC supply should increase by 1.1 million bpd this year. By next year, non-OPEC supply should grow by 1.2 million bpd.
OPEC said crude oil stocks should build as summer demand starts to wind down. The U.S. Energy Department last week said consumer demand for gasoline had decreased in part because of better fuel efficiency.
The Vienna-based OPEC said an increase in inventories should "provide a cushion" to oil markets, which complements the general expansion of crude oil production capacity.