Effect of Hydrocarbon Expulsion on Light Oil/Condensate Generation During Artificial Maturation of Qingshankou Shale Kerogen from the Songliao Basin

As exploration expands into deep and unconventional petroleum systems, light oil and condensate have become key targets for reserve growth and production enhancement. This study employs the gold tube pyrolysis of kerogens from Cretaceous Qingshankou shale to investigate the role of hydrocarbon (HC) expulsion in light oil and condensate generation during thermal maturation. The results show that HC expulsion significantly reduces overall HC yields and alters their chemical composition. Specifically, compared with immature kerogen, n-hexane-extracted mature kerogen (EasyRo = 0.96%) exhibited reductions of 60%, 57%, and 50% in C15+ compounds, C6–14 HCs, and C1–5 gases, respectively. Moreover, the generation window of C6–14 HCs (a proxy for light oil) is narrowed and shifted toward lower maturity. Kinetic parameters were further used to establish two separate evolutionary models for methane, wet gas, light oil, and heavy oil. Based on these models, the shale oil resource potential of the first member of the Qingshankou Formation, the Qijia–Gulong Sag, is estimated to be (6.95–8.80) × 106 ton/km2 for the no-HC-expulsion scenario and (3.63–3.85) × 106 ton/km2 for the significant-HC-expulsion scenario (HEE = 84.35%). These results provide a valuable reference for assessing the light oil and condensate potential of high-maturity Qingshankou shale in the Songliao Basin.