Abstract:Shale gas is the hydrocarbon gas retained in black organic rich shale after hydrocarbon generation and evolution .In order to find out the variation law and influencing factors of products during hydrocarbon expulsion process, and reveal the hydrocarbon generation potential of marine organic rich shale, a black shale sample of Dalong Formation Shangsi section in Guangyuan area, Sichuan Basin were studied by pyrolysis simulated experiment. The results show as fellows. (1) Black shale has extremely high hydrocarbon generation potential, and the highest hydrocarbon yield is 452.43 mg/gTOC, of which the total yield of gaseous hydrocarbon is 195.45 mL /gTOC, and the highest yield of liquid hydrocarbon is 377.8 mg/gTOC. (2) With the increase of pyrolysis temperature, the oil yield shows the characteristics of rising first and then decreasing with the increase of temperature. The oil evolves into a sharp peak single peak characteristic, and the oil production peak is at 360 °C (eqvRo=0.96%). Methane and non-gaseous hydrocarbons have similar yield characteristics, and exhibit an increase trend with increasing maturity, while heavy hydrocarbon gas C2-5 exhibits the characteristics of first rise and then fall, which suggesting methane is mainly formed by oil cracking, and followed by heavy hydrocarbon gas cracking. (3) The δ13C of gaseous alkanes exhibits δ13C1<δ13C2<δ13C3<δ13C4, and the carbon isotope values of gaseous hydrocarbons are gradually enriched with 13C as the pyrolysis temperature increases, indicating that only kinetic fractionation of carbon isotopes occurred during the pyrolysis experiment. Based on the characteristics of thermal simulation product yield with increasing thermal maturity, the hydrocarbon generation model of black organic-rich shale is established, which is divided into two main stages: thermal catalytic oil and gas generation stage and thermal cracking moisture generation stage, In particular, simulated sample studied has not entered dry gas generation stage at an extremely high temperature during thermal pyrolysis experiment, illustrating that black shale still has a certain hydrocarbon generation potential at over-maturity stage, which is of great reference value for expanding the field of high- to over-mature shale gas exploration.