Petroleum Maturation Processes Simulated by High-Pressure Pyrolysis and Kinetic Modeling of Low-Maturity Type I Kerogen

A low-maturity lacustrine Type I (oil prone) Lucaogou kerogen of deeper Permian source rocks in the Junggar Basin, northwestern China, was selected for the demonstration of high-pressure pyrolysis in a wider temperature range than that reported in the literature as well as the determination of the kinetic parameters in the generation and cracking of bitumen/heavy oil (C14+), light/condensate oil (C6–C14), wet gas (C2–C5), and dry gas (C1). The experiments were carried out in a gold-tube system at two heating rates of 20 and 2 °C/h under 50 MPa for kinetic parameter determination. The yields of C14+, C6–C14, and C1–C5 and calculated results of the generation and cracking kinetics as well as the plots of lnC2/C3–lnC1/C2 and (δ13C2–δ13C3)–lnC2/C3 followed widely accepted overall petroleum geothermal maturation processes, i.e., kerogen → C14+ → C6–C14 → C2–C5 → C1. According to the reconstructed burial thermal history, the yield prediction of the Changji Depression was found to be consistent with the actual petroleum accumulation that is mainly light oil rather than gases. This work would be useful to not only explain the widespread occurrence of light oil and condensate in the southern part of the Junggar Basin but also enhance confidence for further and deeper exploration in this area. Similar approaches of integrating high-pressure pyrolysis, kinetic modeling, and geothermal history should also be applicable to not only Type I but also other types of kerogens (Types II and III) with various degrees of maturation in other sedimentary basins.