The IEA study will try to answer one question that bedevils those trying to forecast future prices and the supply-demand balance: How rapidly are the world's top fields declining? The rates at which their production dwindles over time are a much-debated barometer of the health of the world's oil patch.
A study released earlier this year by the Cambridge Energy Research Associates, a consulting firm and unit of IHS, concluded that the depletion rate of the world's 811 biggest fields is around 4.5% a year. At that rate, oil companies have to make huge investments just to keep overall production steady. Others say the depletion rate could be higher.
"We are of the opinion that the public isn't aware of the role of the decline rate of existing fields in the energy supply balance, and that this rate will accelerate in the future," says the IEA's Mr. Birol.
Some analysts, however, contend that scarcity isn't the issue - only access to reserves and investment in tapping them. "We know there is plenty of oil and gas resource in the world," says Pete Stark, vice president for industry relations at IHS. He says the difficulties of supply aren't buried in oil fields, but are "above ground."
Mr. Morse at Lehman Brothers notes that there are plenty of questions about supply yet to be answered. "However confident the IEA may be about the data it has, they know nothing about the resources we've yet to discover in the deep waters or in the arctic," he says.