Last year in excess of 45,000 land wells were drilled and unconventional oil now represents a material part of the overall supply mix.

In the same book he predicted the development of unconventional oil and gas resources thanks to the advent of new technologies including hydraulic fracturing.

Also, there have been concerns about the uncertainty surrounding peak oil production and the higher cost of extracting unconventional oil.

Such mitigation could include energy conservation, fuel substitution, and the use of unconventional oil.

These oil sands resources are called unconventional oil to distinguish them from oil which can be extracted using traditional oil well methods.