Study On The History Of Overpressure Evolution In West Lake Depression

The causes of overpressure in xihu depression are complicated.In this paper,the causes of overpressure in the middle of the xihu depression are analyzed by different methods.The overpressure of the west slope and the west sub-concave source rock in Xihu depression is the cause of the autogenous hydrocarbon supercharging,and the non-hydrocarbon source rock mudstone and reservoir overpressure are the causes of the adjacent source pressure conduction.The hydrocarbon source rock overpressure of the central inversion tectonic belt is the multiple causes of autogenous hydrocarbon supercharging and tectonic compression.In the basin simulation,In this paper,using the Petro Mod basin simulation software developed by Schlumberger in the xihu depression is restored to the central overpressure evolution history of xihu depression.Thermal maturity history simulation adopts the Easy% Ro chemical kinetic model proposed by Sweeney&burnham.In the simulation of hydrocarbon generation,a two-component model of kerogen oil and gas is provided by software.The characteristic is that with the change of kerogen type,In this paper,the paleo-pressure recovery in the study area is carried out by using fluid inclusion method and basin simulation method,and the history of abnormal pressure evolution is analyzed.The analysis shows that there are differences between the homogeneous temperature peaks of the west slope,the west subconcave and the central inversion structural belt: the homogeneous temperature peak value of the west slope and the west subconcave is 130-150 ?,the paleo-pressure coefficient is 1.1-1.8,and a large amount of hydrocarbon generation begins at 12 Ma or so.The homogenization temperature peak of the central inversion tectonic zone is 120-130 ?,and the paleo-pressure coefficient is the main factor.To concentrate on 0.9-1.2,a large number of hydrocarbon generation began around 14 Ma.The paleo overpressure is formed at the stage of paleo geothermal temperature > 120 ?,and the paleo pressure of the present atmospheric pressure formation is mainly from normal pressure to weak overpressure.Since the late stage of Longjing,Xihu sag has developed overpressure,which has undergone the evolution process of pressurization,depressurization and secondary pressurization.