Impressive resource figures.
The numbers on oil shale resources around the world are nothing short of staggering. Most of the following estimates are drawn from Duncan and Swanson (1965) unless otherwise cited. Oil shale deposits of Late Permian age in southern Brazil have been estimated to contain 800 billion barrels oil equivalent in shale that yields 10 to 25 gallons per ton, and 3.2 trillion barrels in possible extensions. Resources that yield 5 to 10 gallons of oil per ton were estimated to hold 4 trillion barrels of oil equivalent in possible extensions.
A 200 square-mile Middle Tertiary lake basin deposit in southwestern Montana has approximately 1000 feet of sediments which have not been appraised in detail but may contain tens of billion barrels of oil potential.
Weeks (1960) stated "possible potential resources" of higher grade oil shale in the U. S. are approximately 2 trillion barrels of oil equivalent, and 12 trillion barrels in the world. Duncan and Swanson (1965) estimated a world oil shale resource of 2.1 quadrillion barrels. Estimates of the volume of potential oil in the U. S. shale deposits have grown steadily since they were first studied in detail by the USGS in the early 1900’s. Duncan (1981) states "The oil shale deposits of the United States can be considered collectively as an enormous low-grade source of oil, hydrocarbon gas, or solid fuel. Deposits with an estimated yield of 10 gallons or more oil per ton of rock contain more than 2 trillion barrels; their possible extensions may contain an additional 3 trillion barrels; and, speculatively, other unappraised deposits may contain several times as much oil."
And then there are the actual normal oil finds and potential finds alluded to by ozbusdriver.
Do I need to quote the doomsayers as far back as the opening decade of the 20th century who have been predicting '13 years until no oil' over and over?
Certainly the oil shale, tar sands etc pose some issues still to be resolved before they become truly viable as an effective replacement for light sweet crude...but we have several hundred years before it becomes an issue...not 3-5
Think back over the technical advances in the last 100 yrs and then tell me you're prepared to bet
against mankind coming up with the goods before,
LONG before, all the light sweet and moderately heavier oils are even close to depleted.