OPEC said in its monthly market report for March that demand for its crude oil was down 100,000 barrels per day from February to 29.7 million bpd. Part of that decline was because of expanding production from North America, the cartel said.
OPEC's market report for April is due next week.
Charles Dewhurst, director of global markets at consulting firm BDO U.S.A., told Bloomberg News that OPEC shouldn't be pressured by North America's recent success.
"U.S. refineries are configured to process heavy and sour crude and that makes Canadian oil a perfect match for U.S. refiners and adds to North American energy independence," he said.
Saudi Oil Minister Ali al-Naimi said from Doha that his recent trip to China left him with a sense of optimism over the global oil markets.
"The expectations of energy demand and growth are still positive," he was quoted by the official Saudi Press Agency as saying.
Saudi output from March was static when compared to February at 9 million bpd, Bloomberg News estimates. OPEC as a whole provides around 40 percent of the world's crude oil.