BEIJING - Oil prices inched up on Friday, with investors trying to gauge the potential impact on supply from looming sanctions by the United States on Iran's crude exports.
The most-active Brent crude futures contract, for December, was up 9 cents, or 0.11 percent, at $81.47 per barrel at 0637 GMT.
The front-month November contract will expire later on Friday and is at $81.78 a barrel. The contract rose to four-year high of $82.55 on Tuesday. Brent is set to rise 5.6 percent in September, on track for the biggest monthly gain since April.
U.S West Texas Intermediate (WTI) futures were up 15 cents, or 0.21 percent, at $72.27 per barrel. It is set to gain rose 3.5 percent this month, the biggest increase since June.
"The market has been focusing on trading headlines on the Iran sanctions for a whole week. But views on how much OPEC and Russia can make up for the losses vary," said Chen Kai, head of commodity research at Shengda Futures.
The sanctions on Iran, the Organization of the Petroleum Exporting Countries (OPEC) third-largest producer, start on Nov. 4, with Washington asking buyers of Iranian oil to cut imports to zero to force Tehran to negotiate a new nuclear agreement and to curb its influence in the Middle East.
Concerns around the sanctions also led to a widening difference between WTI and Brent prices as it created positive conditions for U.S. oil exports. The spread between the two futures contracts rose to $9.51 per barrel, as Brent hovers around its biggest premium to WTI in three months.
"Oil exporters will take advantage of the looming discount with heightened buying activities on the WTI benchmark", Benjamin Lu from Philip Futures said in note.
Saudi Arabia is expected to quietly add extra oil to the market over the next couple of months to offset the drop in Iranian production, but is worried it might need to limit output next year to balance global supply and demand as the United States pumps more crude.
Two sources familiar with OPEC policy said Saudi Arabia and other producers discussed a possible production increase of about 500,000 barrels per day (bpd) among OPEC and non-OPEC producers.
However, ANZ said in a note on Friday that major suppliers were unlikely to offset losses due to the sanctions estimated at 1.5 million bpd.
At its 2018 peak in May, Iran exported 2.71 million bpd,nearly 3 percent of daily global crude consumption.