The Research About Mechanism Of Gas Adsorption In Nanoscale Pores Of Shale Clay

In the background of rich geological shale gas resources China has,it becomes the primary problem to mine shale gas in an efficient,low-cost and clean way at present.Currently,most of clay mineral adsorption experiments at demostic or abroad have been restricted with testing the real core,knowing clay mixed minerals,lacking of the experimental data of known clay mixed minerals.The relationship between minerals and isothermal adsorption capacity is unclear,while the prediction model doesn't take into account the effects of temperature and clay mineral content.The traditional adsorption model is a function of the isothermal adsorption amount V and the pressure P,and does not consider the influence of clay mineral content and mineral interaction.There are few studies on the microscopic mechanism of gas adsorption on nanopores of clay.Lacking of microscopic adsorption mechanism of clay minerals limited the research on shale gas occurrence mechanism.Based on macroscopic adsorption exprienment,this paper studies the influence mechanism of the interaction of single-component minerals on the adsorption capacity of mixed clay minerals.This paper which studies on mechanism of methane gas in clay minerals by Molecular Simulation,Quantitative study of the relationship between methane adsorption and intermolecular interaction energy,adsorption heat,adsorption phase density,adsorption site and other parameters under different temperature and pressure conditions,reveals the microscopic mechanism of shale gas adsorption,as well as laid the foundation of exploring the mechanism of shale gas generation and mining shale gas.The following understandings have been made through research:(1)The isothermal adsorption curves of montmorillonite,kaolinite,illite and chlorite were determined by gravimetric method at the same temperature.The results showed that the order of adsorption was:montmorillonite>kaolinite>chlorite>illite.(2)The isothermal adsorption curves of three-component mixed clay minerals of montmorillonite,kaolinite and chlorite were determined by gravimetric method.It is found that the curve morphology shows the adsorption characteristics of type I by comparing with the one-component isotherm adsorption experiment.The content of montmorillonite has the greatest influence on the isothermal adsorption of three-component mixed clay minerals.(3)An isothermal adsorption prediction model with considering mineral content and experimental temperature for three-component mixed clay minerals has been established.It is used to draw the isothermal adsorption prediction plate of the three-component mixed clay mineral.(4)The adsorption mechanism of methane in nanopores of montmorillonite,kaolinite and illite has been studied based on the Grand Regal Monte Carlo method.Parameters such as adsorption amount of methane and intermolecular action energy,adsorption heat,adsorption phase density and adsorption position have been quantitatively studied under different temperature and pressure conditions.This reserch has shown that the amount of methane adsorbed in clay minerals decreases with increasing temperature.As the aperture increases the isothermal adsorption of clay minerals,the increase of aperture and temperature will reduce the equivalent adsorption heat of methane in clay minerals,and the adsorption of methane in the pores of clay minerals is physical adsorption.