Critical Conditions for Wellbore Failure during CO2-ECBM Considering Sorption Stress

Significant stress changes caused by sorption-induced swelling raise the coal wellbore failure potential, which directly impacts safety and sustainability of CO2 enhanced coalbed methane (CO2-ECBM). Additionally, a mixture gas (CO2/N2) injection is recommended due to sharp decline permeability with pure injection. In this study, incorporating adsorption poroelastic effects, semi-analytical model stability during proposed. Model results indicate that field significantly influenced boundary condition sorption effect. addition, parametric studies are performed determine influence parameters, mechanical properties, composition on distribution then index. Furthermore, large proportion or N2 both cause instability. compressive hoop shear CO2. contrast, displacement CH4 weakly adsorptive will result in less even tensile stress, so may occur. Thus, (including CO2/N2) must be controlled failure, providing an accurate estimation in-situ seams’ storage capacity from perspective stability.