Experimental heating and kinetic models of source rocks: comparison of different methods

Closed system isothermal micro pyrolysis has been carried out for nine Upper Jurassic source rocks from the Norwegian Shelf, supplemented by hydrous pyrolysis experiments and open-system Pyromat kinetic determinations. In all investigated cases open-system kinetics is able to model the residual potential derived from S2 but not the respective low-temperature, closed-system isothermal experiments. The relatively detailed micro pyrolysis generation patterns obtained, allow us to differentiate between primary generation and secondary cracking of different carbon number classes of hydrocarbons. Formation of non-hydrocarbons or hydrocarbon “sinks” in residues can be inferred from these patterns. Comparison of results from low- and high-temperature experiments suggests that the “potential” of a source rock may vary according to heating history. Discrepancies between high- and low-temperature experiments may be explained in terms of competing reaction pathways. These may constitute a main source of uncertainty when extrapolating bulk kinetic models into geological conditions.