This is interesting. Testimony from the U.S. Government Accountability Office before the U.S. House Subcommittee on Energy and Environment:
The Green River Formation *** contains the world’s largest deposits of oil shale. USGS estimates that the Green River Formation contains about 3 trillion barrels of oil, and about half of this may be recoverable, depending on available technology and economic conditions. The Rand Corporation, a nonprofit research organization, estimates that 30 to 60 percent of the oil shale in the Green River Formation can be recovered. At the midpoint of this estimate, almost half of the 3 trillion barrels of oil would be recoverable. This is an amount about equal to the entire world’s proven oil reserves. (Emphasis is ours.)
That seems to contradict the President's oft repeated statement that we have only 2% of the world's oil reserves ... and with only one shale formation!