Oil shale guesstimates for Australia are some 30 billion barrels (Stuart Fm. etc.). The oil shales would be mined, and then thermally treated (pyrolysis)to generate liquid hydrocarbons.
The Queensland and Australian governments have spent some Aus$380 billion on tests.
The projects are on hold. Not only cost is a factor, Greenpeace and others have raised strong objections. Much thermal energy (500 C) is required to convert the organic matter (kerogen) into hydrocarbons. Water also is a requirement.