Multiple Cold Trap Pyrolysis Gas Chromatography: a new technique for modeling hydrocarbon generation

The newly developed Multiple Cold Trap Pyrolysis Gas Chromatography (MCTP-GC) technique allows us to calculate activation energies for the generation of individual hydrocarbons from source rocks. This improves our ability to predict the timing of oil generation and the compositional changes of oil at the different stages of kerogen conversion. The activation energies for n-C12 and n-C24 for a Type II kerogen (Toarcian Shale) are 57.5 ± 0.8 kcal/mol and 51.2 ± 2.2 kcal/mol with frequency factors of 8.71 × 1016/min and 1.15 × 1015/min, respectively. The relative rates of alkane generation are n-C24 >n-C18 >n-C12 >n-C2−C5. By comparing the rates of generation from kerogen and asphaltenes for Monterey source rocks, we conclude that normal alkanes can be generated directly without going through an asphaltene intermediate.