Hydrocarbon Generation Potential and Hydrocarbon Expulsion Process of Shahezi Formation Mudstone in Xujiaweizi Fault Depression in Songliao Basin

ABSTRACT The Shahezi Formation is another major set of source rocks in the Songliao Basin following the Qingshankou Formation. However, due to its deeper burial, its hydrocarbon generation and expulsion potential, as well as the processes involved, remain unclear. This study focuses on the Shahezi Formation source rocks in the Songliao Basin. Using the hydrocarbon generation potential method, and based on Rock‐Eval pyrolysis, TOC testing, R o testing, and basin modelling, it systematically evaluates the hydrocarbon generation and expulsion processes and potential of the Shahezi Formation source rocks in the Xujiaweizi fault depression. The results indicate that the hydrocarbon expulsion threshold of the Shahezi Formation source rocks is R o = 0.807%, with a maximum hydrocarbon generation potential of 498.71 mgHC/gTOC and a peak expulsion efficiency of 64.4%. The hydrocarbon generation centre is located in the central depression of the Xujiaweizi Fault Depression. The maximum hydrocarbon generation intensity and expulsion intensity reach 1000 × 10 4 and 500 × 10 4 t/km 2 , respectively. Based on these parameters, the total hydrocarbon generation and expulsion volumes of the Shahezi Formation source rocks are calculated to be 81.54 × 10 8 and 46.72 × 10 8 t. These findings suggest that the deep formations of the Xujiaweizi Fault Depression hold significant exploration potential for natural gas resources. The geological resource volume of petroleum in the Shahezi Formation is estimated at 0.13 × 10 12 m 3 , with the total volume of hydrocarbons retained within the source rocks estimated at 0.484 × 10 12 m 3 . The western Xujiaweizi and Anda–Songzhan areas exhibit considerable exploration potential.