Crude oil storage tanks are seen from above at the oil hub in Cushing, Oklahoma, March 24, 2016.
NYMEX WTI futures and options contract values for December 2018 delivery traded during the five-day period ending September 6, 2018, suggest a range of $56/Bbl to $85/Bbl with a 95% confidence level.
Benchmark Brent crude oil was down 65 cents a barrel at $79.09 by 1200 GMT.
Prices extended gains in post-settlement trade after industry data from the American Petroleum Institute showed USA crude inventories slumped 8.6 million barrels last week, versus analysts' forecasts of a 805,000-barrel decrease.
The American Petroleum Institute is scheduled to release its weekly count of stockpiles later Tuesday, followed by the US government's tally on Wednesday.
The United States is pushing all countries to halt oil imports from Iran after President Donald Trump in May withdrew from a 2015 deal between Iran and six world powers and ordered a re-imposition of sanctions on it.
Washington has asked buyers of Iranian oil to cut imports to zero in the run up to early November to force Tehran to negotiate a new nuclear agreement and to curb its influence in the Middle East.
"This is a huge uncertainty on the market - how countries, which buy nearly 2 million barrels per day of Iranian oil, will act. The situation should be closely watched, the right decisions should be taken". Accendo Markets analyst Artjom Hatsaturjants said Hurricane Florence is not expected to disrupt oil-drilling infrastructure, but could impact energy demand.
"It is related to the fact that not all the countries have managed to restore their market and production", he said, referring to outages and falling production in Mexico and Venezuela.
The IEA said tightening supply was putting increasing pressure on prices.
Iraq, OPEC's 2d-greatest producer which noticed method-file production in August at four.65 million bpd, is at the moment witnessing violent protests in and round Basra, which hosts the bulk of its oil production facilities and its greatest deepwater port. Demonstrators receive blocked roads and threatened to close down oil facilities in boom in opposition to failed speak products and providers, unemployment and political corruption.
US shipments to Japan will also rise to a record average of at least 134,000 bpd, the data showed.
Gasoline stocks rose 1.3 million barrels, while distillate stockpiles, which include diesel and heating oil, climbed by 6.2 million barrels, the EIA data showed.