Molecular simulation study on the adsorption and storage behavior of CO2 in different matrix components of shale

Abstract

ABSTRACT This study investigates the adsorption and storage behaviour of CO2 in the different matrix components of shale based on a molecular simulation method. First, based on the Grand Canonical Monte Carlo (GCMC) method, we successfully established five pore models three fluid models to study the effects of temperature, pressure, pore diameter, water content, and CH4 on the adsorption of CO2. Then, based on the actual data from the shale of the Longmaxi Formation in Sichuan Basin, China, the storage capacity of CO2 in the shale is determined by calculating the density distribution of CO2 and the proportion of excess adsorbed gas. The results demonstrate that both high temperatures and water content are unfavourable for the adsorption of CO2 in the shale pores. The adsorption of CO2 increases with rising pressure while it decreases with increasing pore size. The magnitude and stability of CO2 adsorption in the pores of various matrix components is as follows: organic matter > montmorillonite > illite > kaolinite > quartz. Compared to the scenarios neglecting the adsorption of CO2, the storage capacity of CO2 decreases by 7.87%. The main finding of this study is expected to provide theoretical guidelines for CO2 adsorption storage in shale.