The usual objective of thermal modelling is to identify the time and depth of hydrocarbon generation. Hydrocarbons are by-products of the metamorphism of organic material (kerogen) within sediments – a gradual process involving the expulsion of volatiles, gases, liquids and oils during the chemical alteration of buried organic matter. The thermal maturity of a rock is a measure of the degree to which this metamorphism has progressed.

Before we can make predictions about the timing of petroleum generation, we need to know two things. We need to understand the precise response of organic detritus to changes in thermal conditions, and we also need to know the thermal history of potential petroleum source beds. This chapter addresses those two requirements.

The Generation of Hydrocarbons from Organic Matter

The chemistry of converting organic matter into hydrocarbons is a whole separate field of expertise and is far too complex to investigate in great detail here. But a few words are necessary to illustrate the importance of temperature on the organic metamorphic process.