The kinetics of thermal degradation of individual oil-generating macerals: calibration with microscopical fluorescence spectrometry and bulk flow pyrolysis

Kinetic models for petroleum generation describe petroleum formation as either a discrete set of reactions or a continuous distribution of reactions. The kinetic models are normally calibrated with data from laboratory experiments. This paper discusses theoretical, analytical and numerical problems encountered when results of laboratory experiments are extrapolated to geological conditions. An alternative approach based on geologically matured samples is presented, where quantitative petrological, micro-fluorometric and Hydrogen Index data are used in multiple regression analysis to estimate transformation ratios and genetic potentials of compositionally different oil-generating entities in source rocks. The data are further used in combination with reconstructed time-temperature histories to calculate consistent kinetic parameters for the thermal degradation of individual macerals. The results, both for the genetic potentials and transformation ratios, are within the expected range. The important aspect of the analysis is that the results were obtained by expressing the transformation ratio as a function of a fluorescence maturity parameter (Ω), and hence allow increased confidence in the application of fluorescence in maturity studies