Earlier today, Brent crude hit its highest since May at $80.62 per barrel, up $1.82 or 2.3 percent, by 0830 GMT.
U.S. West Texas Intermediate and international-benchmark Brent crude oil futures are trading sharply higher on Monday, shortly before the cash market opening after OPEC held its ground over the weekend and declined to agree to an immediate increase in output despite last week's pressure by President Trump to do so.
"Saudi Arabia and Russian Federation confirmed that they not raising output - and this is bad news for President Trump as he wants a lower oil price that is good for business", said CMC Markets David Madden.
But once the USA sanctions on Iran take full effect, it will become clearer whether the Saudis are correct that the market is well-supplied, or whether the traders have picked a victor in tipping higher prices. "I don't know of any refiner in the world who is looking for oil and is not able to get it", Falih told reporters after the meeting.
Commodity traders Trafigura and Mercuria said on Monday that Brent could rise to $90 per barrel by Christmas and pass $100 in early 2019, as markets tighten once U.S. sanctions against Iran are fully implemented from November.
The market has looked to softening demand from trade tensions between the US and China to offset the production cuts from Iran.
Iran will keep on selling oil in defiance of U.S. attempts to prevent Tehran from reaping profits from its major export earner, according to the head of the Iranian delegation at Sunday's meeting of oil producers in Algiers.
The meeting ended with no formal agreement on any additional supply boost. -China trade war and supply, especially from the USA, was seen sufficient in the next 12 months, said Janet Kong, BP Plc's head of trading in Asia.
Ben Luckock, co-head of oil trading at fellow merchant Trafigura said crude oil prices could rise to $90 per barrel by Christmas and to $100 by the New Year as markets tighten. "The reason Saudi Arabia didn't increase more is because all of our customers are receiving all of the barrels they want".
Concerns about production shortfalls are encouraging traders to place more long bets, boosting Brent prices, said Brian LaRose, a technical analyst at United-ICAP.
Crude oil futures have spiked in early Asian trade, gaining more than 1%. Citigroup Inc. sees crude at that level in the fourth quarter, but sees risks that it will go higher.
"Were they do so the oil market would be even more uncomfortably tight than we forecast for 2019 as spare capacity is eroded", Mr Bell added.