New Delhi, March 28 -- It could be months before we know the total cost of the unprecedented disruption to global energy supplies from the Iran war. That was the message executives from oil majors imparted at CERAWeek, S&P Global's annual energy conference in Houston this week.

Several CEOs of the world's biggest oil-and-gas companies told the conference that forward oil futures are underpricing the potential impacts of the loss of supply. WTI crude hit $100 a barrel Friday for the first time since the war began. December futures were priced at $77 a barrel and in the mid $70s early next year, though futures prices have been rising.

"The physical market isn't being reflected in the price," said Carlos Pascual, a former energy envoy at t...