Title : Molecular simulation of competitive adsorption of CO2-shale oil in kerogen with different moisture content
Abstract:
The competitive adsorption between shale oil and CO2 in kerogen is of great significance for CO2 enhanced oil recovery (CO2-EOR) and CO2 storage. In this paper, molecular dynamics (MD) method is used to construct dry kerogen model, and grand canonical Monte Carlo (GCMC) method is used to construct kerogen model of shale reservoir with different moisture content. Considering the influence of moisture content and alkane composition of shale oil, the competitive adsorption behavior of shale oil and CO2 in kerogen is simulated, and the influence of moisture content on the adsorption capacity, adsorption heat, density distribution and adsorption selectivity of CO2 and shale oil was analyzed, and the feasibility of CO2 storage was evaluated. The results show that the presence of moisture content inhibits the adsorption of shale oil and CO2, and significantly reduces the ability of CO2 to replace shale oil. With the increase of moisture content, the adsorption capacity of shale oil decreases, and the effect of CO2 replacement of shale oil is improved. The adsorption capacity of long chain alkanes in shale oil decreases under moisture condition, and the competitive adsorption effect between short chain alkanes and CO2 is more obvious. The adsorption selection of CO2 and shale oil under the optimal moisture content is more conducive to CO2 storage. Based on the real kerogen model of shale reservoir, this study provides an effective guide to quantitatively reveal the competitive adsorption between CO2 and shale oil from the microscopic perspective.
