Gold tube pyrolysis study of source rock hydrocarbon generation in Bozhong area, offshore Bohai Bay Basin

Sealed gold tube pyrolysis was carried out for 3 source rock samples from the third (E₂s³) and first (E₃s¹) members of Shahejie Formation, and the third (E₃d³) member of Dongying Formation in the Shanan Sag, and 2 source rock samples from the E₂s³ in the Qinnan Sag in Bozhong area. These samples are lacustrine shale with a high organic matter content and low maturity, and contain type I kerogen. Minerals in the source rock samples are mainly clay minerals and contain a significant amount of calcite, quartz and feldspar. The gold tube pyrolysis experiments focus on liquid hydrocarbon generation. The mean hydrocarbon generation kinetics of E₂s³, E₃s¹ and E₃d³ source rock samples range between 219 and 222 kJ/mol, and the kinetics of all samples have a concentrated distribution. Samples from same sag but different intervals, and samples from different sags but same interval have no significant difference, but the samples with a relatively low content of clay minerals and a high content of calcite have a relatively higher mean hydrocarbon activation energy. Carbon isotopes of C_14⁺ liquid products during peak hydrocarbon generation can be 11.3% heavier than extracts from unpyrolyzed samples, and oil-source correlation with extracts from low maturity source rocks must consider this. TOC loss of residual solids can reach up to 48%. It is necessary to restore organic matter abundance and kerogen type when evaluating high maturity source rocks with a high organic abundance and favorable organic type.