This study focuses on shale samples from the medium-deep lacustrine shale in the third member of the Shahejie Formation, Bohai Bay Basin. Thermal simulation experiments were conducted using gold tubes to study hydrocarbon generation. The results indicate that shale biomarkers vary at different thermal evolution stages and provide distinct geochemical indications. Compared with saturated hydrocarbons, aromatic hydrocarbon parameters can better indicate the maturity of high- to overmature crude oil. The correlation between the parameters of aromatic hydrocarbon -biomarkers and the maturity of crude oil is as follows: methylphenanthrene parameters (MPI1), 4-MDBT/1-MDBT, perene/benzo[e]pyrene, methylphenanthrene ratio (MPR), benzofluoranthene/benzo[e]pyrene, trimethylnaphthalene ratio (TMNr), and tetramethylnaphthalene ratio (TeMNr). The variation in several parameters indicates that 345â445 °C is thepeak oil generation window (the corresponding Ro is about 0.6â1.3%), during which hydrocarbon expulsion efficiency increased greatly, and residual hydrocarbons accumulate -massively. This research provides a basis for evaluating shale oil and gas resources. Shale with a vitrinite reflectance of 0.6â1.3% is the most beneficial for exploration and development.
