The Occurrence Mechanism of Lacustrine Shale Oil in the Second Member of the Paleogene Kongdian Formation, Cangdong Sag, Bohai Bay Basin

The lacustrine shale in the second member of Kongdian Formation (Ek2) is most significant target oil exploration Cangdong Sag, Bohai Bay Basin, China. To investigate occurrence mechanisms and to reveal influencing factors mobility Ek2, a series analyses (X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), total organic carbon (TOC) analysis, Rock-Eval pyrolysis, low-temperature nitrogen physisorption (LNP), mercury intrusion porosimetry (MIP), multiple isothermal stage (MIS) pyrolysis) were conducted on samples collected from well cores Sag. results show that lithofacies can be categorized as laminated felsic shales, massive mixed carbonate shales. shales characterized by high matter abundance moderate thermal evolution with good excellent hydrocarbon generation potential contained Type I II1 kerogens. Laminated compared other lithofacies, had clear advantages amount free volatilized rock (S1), saturation index (OSI) value, movable content. LNP, MIP, MIS pyrolysis residual mainly occurred pores diameters smaller than 200 nm, pore diameter when some could reach 50 μm. lower limits where 7 30 respectively. controlled component, maturity, TOC content, volume. herein provide basis for evaluation optimal intervals.