We have about 60 cubic miles of oil to draw from. 25 cubic miles have been recovered. The last 10 cubic miles wll be very difficult. Look at present daily oil consumption worldwide plus its upward trend and, given the 25 cubic miles of petroleum remaining, set a date for Ragnarok.

Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz3.pdf