Some oil can be made from shale and coal, but not as much as you think. Present rates of consumption far outstrip any possible rate of producing it from those sources. The petroleum fields of Saudi Arabia were truly massive, far larger than anything that has been found since. It was a one time windfall. No giant fields are still hiding anywhere, not even in Antarctica for which my company produced highly specialized petroleum exploration products for those geophysical surveys and expeditions. Antarctica may have a few medium sized petroleum fields but for the most part the continents moved away from there so no giant pinched (and geopressured) basins were formed like Saudi Arabia.
