I found a book at a yard sale that was written in 1968 and claims to predict what changes will have happened by 2018. It's a left leaning look through eyes of college professors and other experts.
They predict we will be well on our way to world government, scarce resources, end of conflict, and many other things that are laughable.
From 1945 to the first OPEC embargo in 1974, a barrel of oil cost around $20-$25 (inflation adjusted).
Over the last 40 years, we re-visit that price range from time to time, but it never lasts very long.
From 1974 to 2012, oil prices have been extremely volatile and have averaged more than $50 a barrel.