The world is consuming oil at a rate that will result in oil production peaking in 15 to 25 years, a group of geoscientists told the American Association of Petroleum Geologists’ annual convention in Long Beach, Calif.
When world oil production reaches the peak by 2020-40, the rate will be 90-100 million b/d, only 10-20% higher than it was in 2005. Depending on the level of world oil resources, which is highly uncertain, that peak is likely to last 20-30 years before production begins its ultimate decline.
The estimates are released for the first time following an AAPG Hedberg Research Conference on Understanding World Oil Resources held in November 2006 in Colorado Springs.
Richard Nehring, chairman of that conference, said present estimates of conventional and unconventional world oil resources range from 3.4 to 5 trillion bbl. “These estimates of technologically and economically feasible world oil potential fall in the optimistic range of published estimates of world oil resources,” Nehring said.
The world took more than 140 years to consume the first trillion barrels produced since the Drake well in Pennsylvania in 1859. Consumption of the second trillion barrels will occur within only 30 years.
Additions to world oil resources will come from three sources: recovery growth, undiscovered, and unconventional.
Recovery growth from existing fields, not discoveries, has been the major contributor to world oil production in the last 25 years. Growth in recovery from existing fields is also likely to be the largest source of future additions to world oil supply.
Worldwide, about 300 billion bbl of known oil, or about a 10-year supply, is either being developed or planned for future development.
About 50% of the world’s oil has characteristics acceptable for enhanced oil recovery application, but EOR is currently applied to about 11%. More intensive development, either through tighter well spacing or the extensive use of horizontal and multilateral wells, also promises to increase recovery.
Extrapolating past trends of recovery growth from existing fields adds about 1 trillion bbl to the overall ultimate production expectation, about 200 billion bbl of which would come from EOR.
Undiscovered resources are the best understood source of future additions. They are the most thoroughly studied, a study that increasingly has strong theoretical support.
Worldwide estimates of undiscovered oil resources presented at the AAPG Convention, drawn from an augmented version of the USGS Worldwide Assessment, range from 480 to 1,550 billion bbl.
Nine geologic provinces (each with a mean estimate of 25 billion bbl or more) account for 65% of the mean world estimate.
Given the locations of the undiscovered potential, most is 15-40 years away from initial production.
Unconventional resources-tar sands and extra-heavy oil, oil shale, and oil from mature source rocks-provide a massive in-place resource. Each is known to have at least 3-4 trillion bbl.
The problem with these unconventional resources is recoverability. Each faces a major challenge, whether poor quality oil (extra-heavy oil), poor quality reservoirs (oil from source rocks), or both (oil shale).
Production of extra heavy oils and oil shale also requires substantial energy, enough so that oil shale production may be severely constrained by being mostly uneconomic due to a low net energy gain.
The 75 Hedberg conference participants came from 18 countries on all six populated continents.