Oil headed for its longest string of quarterly gains in more than a decade as impending supply disruptions threaten to fracture a global market with little margin for error.  Futures rose as much as 1.8 percent in New York on Friday while London-traded crude was on track for a fifth quarterly advance, a streak not seen since the first half of 2008. This historical echo comes as consumers once again eye supply disruptions and worry about the availability of backup supplies, just as they were a decade ago when the benchmark hit an all-time high above $147.  Fears are growing that the constriction of Iranian exports by U.S. sanctions and the collapse of Venezuela’s oil industry will leave a deep shortfall in the market.

Those worries have only been stoked this week as key producers from Saudi Arabia to Russia and the U.S. signaled their reserves are off limits.Some of the world’s largest oil producers and traders are warning that triple-digit prices could soon return, with negative consequences for the economy.  “There is concern in the market that the loss of barrels from Iran and Venezuela is not going to be made up for through extra supplies from particularly Saudi Arabia and Russia,” said Gene McGillian, manager of market research at Tradition Energy. “Worries about trade relations affecting economic growth have fallen away.”