is a term used in petroleum geology
to describe the cracking
process which results in the conversion of organic kerogens into hydrocarbons
This chemical reaction is believed to be a time, temperature and pressure dependent process which creates liquid and/or gaseous hydrocarbon Hc from primary kerogen X and can be summarised using the formula:
is the initial kerogen concentration
and X(t) is the kerogen concentration at time t.
It is generally held that the dependence on pressure is negligible, such that the process of catagenesis can be given as a first-order differential equation:
where X is the reactant (kerogen) and κ is the reaction-rate constant
which introduces the temperature-dependence via the Arrhenius equation
See also: diagenesis, fossil fuels.