There are 42 gallons of oil in each barrel of oil. If the price of crude oil is $75 a barrel, the cost of the raw material required to produce a gallon of gasoline is $1.78. This figure does not include costs incurred to transport crude oil to a refinery, refine the oil into gasoline, transport the gasoline to distribution hubs or wholesalers, deliver the gasoline to retail locations or operate service stations.
The question then becomes, "why the difference?" Proved (that's the word EIA uses) world oil reserves are about 1.2 trillion barrels (this does not appear to include the Bakken Reserve).
This is an interesting paper that appears to show that "recoverable and unconventional sources" petroleum is much, much greater than "proven (their term) reserves". It also appears to debunk the claim that the Middle East holds 2/3 of all available petroleum. "Recoverable and unconventional sources" are not necessarily economically or technologically feasible to exploit...for now. I found the conclusion to be most illuminating.
I'm not sure I fully endorse this from CATO. But it's a worthwhile read as well.
From what I am seeing in these few articles, the price of oil is driven more by speculation and politics than by supply and demand.