|USGS identified reserves||1.1||46||33|
|Enhanced recovery 34% to 50%||2.8||117||60|
|Unconventional oil resources||3.4||142||67|
|Oil shale and tar sands||17.4||725||137|
Current consumption rate of 0.024 trillion barrels per year.
Source: C.D. Masters, E.D. Attanasi, and D.H. Root. World Petroleum Assessment and Analysis, Proceedings of the 14th World Petroleum Congress (New York, NY: John Wiley and Sons, 1994).