"Anybody who believes the US revolution has stalled should think again.
We have been very surprised at how resilient it is," said Neil Atkinson, head of oil markets at the International Energy Agency.
"It is easy for consumers to be lulled into complacency by ample stocks and low prices today, but they should heed the writing on the wall: the historic investment cuts raise the odds of unpleasant oil security surprises in the not too distant future," he said.
he warnings were echoed by Opec's secretary-general, Abdalla El-Badri, who said the current slump will lead to serious trouble when the cycle turns.
"It sows the seed for a very high price in the future," he said at the CERAWeek forum. The Opec chief admitted that the cartel has been caught badly off guard by crash, blaming the wild moves on speculative forces with control over 5m "paper barrels" on the derivatives markets.
"If there is any increase in price, shale will come back immediately," he said.
Mr Birol said investment in oil exploration and production across the world has been cut to the bone, falling 24pc last year and an estimated 17pc this year.
This is a drop from 0bn to 0bn a year, far below the minimum levels needed to keep up with future demand. Over the past 30 years we have never seen oil investment dropping two years in a row," he said.
he IEA said US frackers have been able to cut costs by 25pc-30pc and even more in the Permian Basin of West Texas.
"A year ago it was widely believed that this would happen by the end of 2015 but that view has proved to be very wide of the mark.
Contrary to widespread assumptions, the IEA report said Saudi Arabia and the Opec club will lose market share, treading water as North America and Brazil's "pre-salt" basin in the Atlantic account for most of the growth in global output by the early 2020s.