Examination of adsorption behaviors of carbon dioxide and methane in oxidized coal seams

Abstract

The injection of CO2 to enhance coalbed methane recovery is a promising way for carbon dioxide sequestration and exploitation of coal-bed methane. In this work, molecular simulation is conduced to investigate the adsorption and diffusion behaviors of carbon dioxide and methane in coal seams. The effect of coal oxidation is further evaluated. The adsorption amount and isosteric heat of CH4 and CO2 in mono-component and binary mixture are compared. The results reveal that the partial oxidation of coal will weaken the carbon dioxide adsorption capacity and isosteric heat. In contrast to the mono-component, the CH4 adsorption in a binary mixture is greatly reduced owing to the presence of CO2. Meanwhile, the effect of coal oxidation on gas diffusion is also examined. The results demonstrate that the coal oxidation will promote the gas diffusion.