Utilization of zeolite as a potential multi-functional proppant for CO_2 enhanced shale gas recovery and CO_2 sequestration: A molecular simulation study of the impact of water on adsorption in zeolite and organic matter

摘要

We proposed to use zeolites as multi-functional proppants for enhanced shale gas recovery and CO2 sequestration in our previous paper and studied the competitive adsorption of CO2 and CH4 in silicalite-1 and kerogen organic matter. It is proved that CO2 released from proppants can be preferentially adsorbed by kerogen and replace the adsorbed CH4. In the present paper, we aim at studying the impact of water on the gas adsorption capacity and selectivity of CO2 over CH4 since water can significantly alter gas adsorption behaviors in zeolites and organic matter. We carry out grand canonical Monte Carlo simulations of water adsorption and the competitive adsorption of a CO2, CH4, and water mixture in silicalite-1 and in kerogen. It is found that water is less favored in both adsorbents but could suppress the adsorption of CO2 and CH4 when the water content is high, it can also enhance CO2/CH4 selectivity under some circumstances. Kerogen shows a stronger preference for adsorbing CO2 over CH4 under most conditions; thus, the replacement process of CO2 and CH4 with water present can still happen in the positive direction.