"The Energy of Nations"

Most of us think that both below-and above-ground factors will define the peak, but the peak will be the peak: the most oil that can ever be produced in any one day. Perhaps production wobbles along on a plateau for a while before dropping, but it will never exceed that peak level. If we think of all the theoretically extractable oil under the ground as a tank, what we have to worry about is not so much the size of that tank, but the size of the taps: the actual global production capacity...

The risk debate is not about the oil ‘running out’. It will never run out. Oil reserves under the ground... are not the same as oil flows from production pipes at the surface.
— Jeremy Leggett, The Energy of Nations