The 15-nation cartel's individuals agreed to originate up raising output starting in July this year to stabilize markets and offset losses in most important suppliers Iran and Venezuela, OPEC's third and sixth-greatest producers, respectively.
"In addition, there is a risk to growth from an escalation of trade disputes", the agency said.
In its monthly report, OPEC said world oil demand next year would rise by 1.41 million barrels per day (bpd), 20,000 bpd less than last month and the second consecutive reduction in the forecast.
Benchmark Brent crude futures were up $1.01 at $80.07 a barrel by 10:58 a.m. EDT (1458 GMT) after reaching $80.13 a barrel, its highest since May 22. The OECD also said that America's oil demand is set to post strong growth for 2018.
"Oil cut earlier losses and rose towards its highest level this year on Wednesday, after a drop in US crude inventories and as the prospect of the loss of Iranian supply added to concerns over the delicate balance between consumption and production".
Novak said global oil markets were "fragile" due to geopolitical risk and supply disruptions, but added his country could raise output if needed.
The increases extended a more than 2 percent climb in both crude benchmarks the previous session.
Nigerian crude oil differentials were largely unchanged yesterday, after a series of offers from Shell for October-loading cargoes drew no buyers, and even BP, which has been an active bidder this week, showed unwillingness to pay higher prices.
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Still, fears over a supply crunch remained, with Iran's output slumping by 150,000 barrels last month, according to Opec's monthly market report.
"Hence, world oil demand growth is now pegged at 1.62 Mmbpd for 2018, with total global consumption at 98.82 Mmbpd", it said. India, along with some other countries, has sought "waivers" from Washington that would allow them to continue to import Iranian oil and avoid retaliation from the USA for a certain period of time.
According to Oil Price, US Secretary of State Mike Pompeo has said that the US would consider waivers "where appropriate", but reiterated that the country expects to have Iranian oil exports to "zero".
U.S. Midwest crude oil inventories fell to 105.9 million barrels last week, the lowest weekly level since January 2015, EIA data showed.
Russian energy minister Alexander Novak on Wednesday warned of the impact of US sanctions against Iran.
"As we move into 2019, a possible risk to our forecast lies in some key emerging economies, partly due to currency depreciations versus the USA dollar, raising the cost of imported energy", the agency said.
That month Russian Federation produced 11.247 million bpd, a post-Soviet Union record-high.