The U.S. sits on 46 billion barrels of proved crude oil reserves, with 60% of that locked in dense underground rock.
That rock makes it increasingly expensive to extract, and most of the best places have already been developed. The rest will be tough to 'crack'.
Natural gas is another thing altogether. Gas flows much easier through that dense rock, so there are magnitudes more to extract than we have of oil.
Means as a country we will pay more for it, but will effectively never run out of hydrocarbons to use for energy.
