The adsorption capacity of shale gas is mainly influenced by the factors such as burial depth

mineral composition

temperature and pressure.The shale gas in South Sichuan has the characteristics of large buried depth

high temperature and high pressure.It has great significance to determine the adsorption and desorption characteristics of this kind of shale reservoir in supercritical state for the implementation of gas reservoir production.By the combination of indoor physical simulation experiments and molecular dynamics simulation

the composite characterization model of Illite and Kerogen is constructed and optimized

the multiple prediction model of "whole area adsorption capacity of the deep shale gas in South Sichuan is developed

and the adsorption and desorption characteristics of the gas reservoir are clarified.The experimental results show that:with the increase of formation pressure

the adsorption capacity increases gradually

and when the pressure is higher than 15 MPa

the increase of adsorption capacity gradually slows down.Under the original conditions of gas reservoir

the adsorbed gas volume accounts for 20%～25% of the total gas volume.When the formation pressure drops to 20 MPa

the recovery degree of free gas is about 70%～90%

and the recovery degree of adsorbed gas is about 25%～40%.