The pipe, which also sends crude oil to the north-east of the United States, could be subject to flooding or power outages if the hurricane hits pumping station. "The price range for Brent of $70-$80 per barrel in place since April could be tested", it said.
The American Petroleum Institute (API) on Tuesday reported a huge draw of 8.636 million barrels in the US crude oil inventories for the week ending September 7.
Still, traders said overall market sentiment was cautious because of concerns over the demand outlook amid the trade dispute between the United States and China.
"The Midwest accounted for the lion's share of the inventory drop, while lower crude imports, higher crude exports and higher refinery runs on the Gulf Coast also help explain away a good part of today's crude draw", he said.
The Paris-based energy agency said falling output in Iran and Venezuela could drive up prices if it is not offset by more production elsewhere.
In August, India imported about 5.23 lakh bpd of oil from Iran, its traditional market, down 32% over a month earlier.
Benchmark Brent crude LCOc1 futures rose 68 cents to settle at $79.74 a barrel. This news was being supported by the unknown, or the compliance with the USA sanctions on Iran.
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The previous sanctions cut 1.22 million bpd of Iranian crude oil exports which averaged 1.1 million bpd between 2012 and 2015, the Oxford Institute for Energy Studies data shows.
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.
Gasoline stocks rose by 1.3 million barrels, slightly below analysts' expectations. "The situation should be closely watched, the right decisions should be taken".
"Things are tightening up", the agency said in its monthly report, but added: "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".
"We see global oil demand growing by 1.4 million barrels per day in both 2018 and 2019", BNP Paribas said, implying that global markets are likely to remain sufficiently supplied.
Output from OPEC member Iran in August hit its lowest level since July 2016, the IEA said, "as more buyers distanced themselves from Tehran ahead of looming U.S. sanctions", the report said.
Oil traders were also watching the progress of category 4 Hurricane Florence that is expected to make landfall by Friday.