GEOCHEMICAL CHARACTERIZATION OF SEDIMENTARY ORGANIC-MATTER BY MEANS OF PYROLYSIS KINETIC-PARAMETERS

A new means to classify organic matter in rock samples using kinetic parameters is described. Kinetic parameters are computed for Rock-Eval comparative pyrolysis curves, using a single heating rate experiment. The kinetic parameters are computed by an improved Freeman-Carroll method, assuming an overall nth-order reaction. Kinetic parameters are used for characterizing the type and maturity of sedimentary organic matter. For kerogens, the kinetic parameters are obtained on extracted-rock samples. They provide a complementary determination of organic matter type, by using the S2 peak shape which is not described by the classical Rock-Eval parameters. For resins + asphaltenes, the kinetic parameters are computed on the S2' pyrolysis curve obtained by comparative pyrolysis. They allow the determination of the type of kerogen from which they were derived and also their maturity level. The kinetic characterization can be applied directly to current Rock-Eval analysis and used in routine analysis, without changing the standard procedures but care should be taken for bitumen rich samples.