Feasibility of enhanced coalbed methane recovery by CO2 sequestration into deep coalbed of Qinshui Basin

Feasibility analysis of enhanced coalbed methane recovery by CO2 sequestration is important for the develop- ment of abundant deep coalbed methane resource in China. In this study,the relationships between reservoir parame- ters and burial depth were analyzed,and the simulation on CO2 sequestration into coal were carried out. The results show that reservoir parameters vary nonlinearly with the increase of burial depth and their transition burial depths are close. The coalbed in Qinshui Basin are divided into shallow,transition and deep part according to two key proposed transition burial depth of 500-600 m and 950-1 150 m. Strongly heterogeneous of reservoir parameters in shallow coal seams transform into homogeneous in deep coal seams. Through the contrasting simulations of CO2 sequestration into different burial depth coal seams,the coalbed methane recoveries are enhanced in all the cases,and the increments of coalbed methane recovery comparing with none injection decrease in the order of transition,shallow and deep coal seams. More early and longer injection time have higher improvement on coalbed methane recovery. To achieve an ob- vious coalbed methane recovery,a certain amount of CO2 should be sequestrated into coal seams. Deep coalbed has higher CO2 storage capacity than shallow and transition part coal seams.