We have no idea how much oil is still to be found. What we do know is that the more oil prices rise, the more oil will be produced. Furthermore, the more oil that is produced, the more likely it is that prices will fall.
A quick look around the world finds uneconomic oil in many places. Venezuela has more oil than Saudi Arabia, if you count its ultra heavy crude and tar sands. Canada has more than Saudi Arabia, if you count tar sands. The U.S. has more than Saudi Arabia many times over, if you count its oil shale and coal, which could be converted to gasoline and diesel fuel.
Price is the problem, not geology.
~ Thomas G. Donlan, A World of Wealth (2008), p. 14