Kinetics of petroleum generation bulk and compositional

Rates of petroleum generation are dictated by the combined effects of exposure time of source rocks to temperature and kinetic parameters for thermal degradation. Kinetic models of bulk petroleum generation have been widely used for the last decades to predict the timing and rate of petroleum generation in basin modelling, and the newest developments in this field also incorporate information derived from the analysis of asphaltenes as well as kerogens (di Primio et al., 2000; Dieckmann et al., 2002), and have raised the question as to whether compositional predictions for humic coals are valid (Schenk & Horsfield, 1998).

Frequently overlooked, attention has to be paid to data acquisition because artefacts can result in temperatures for petroleum generation that are far too low (Schenk & Dieckmann, 2004). Also frequently overlooked is the enormously wide natural variability in kinetic parameters.

Kinetic parameters vary according to bond strength and heterogeneity, with the result that the onset of generation can differ by 40C or more for marine source rock kerogens.

We can help in having the kinetics measured correctly or selecting the closest kinetics from a database.

In the temperature history shown, generation varies between almost no charge to almost full charge, depending on the kinetics applied.

If 80% conversion is needed to fill a prospect, there is a: 60C difference, or a 2km depth difference, depending on the kinetics chosen.

Kinetics of petroleum generation bulk and compositional

Two kinetic parameters are routinely determined for determining the speed at which petroleum is generated in source rocks.

• Activation Energy: A distribution of activation energies is routinely calculated in the range 40-70 Kcal/mol.
• Frequency Factor: Most kinetic models calculate only a single frequency factor.

We use Dieckmanns (2005) extended kinetic model, in which each activation energy is paired by its own frequency factor. The result early gas and late gas charges are modelled accurately. Is the difference to single frequency factor models significant? In the Mackenzie Delta generation was 17 million years earlier!

The extended model is recommended, especially for terrigenous organic matter provinces.

We can reprocess your pyrolysis data to calculate extended kinetics. Ask us for details.