There is experimental evidence for that oil could be formed from the previously buried in the depths of the lithosphere of plant residues, but they first had to happen for a number of geochemical changes (hydrolysis of cellulose, the decomposition of protein, fat saponification, decarboxylation of fatty acids, etc.).

The form of the original burial of OM largely determines the subsequent mechanisms and processes for its conversion to hydrocarbons (HC) of the oil line.