| 초록 |
Methane stays in coal seams as an adsorbed phase whose density is much higher than that of the gas phase. Conventional methods such as pressure depletion provide about 50 % CBM recovery whereas more than 90 % of methane gas can be recovered by enhanced CBM techniques with nitrogen or carbon dioxide injection, which is called N2- and CO2-ECBM, respectively. CO2 sequestration into unmineable coal seams, which is technically feasible, has two major advantages: storage of CO2 in coal seams as an adsorbed phase and recovery of residual CH4, based on the fact that CO2 usually adsorbs in coal more than twice than CH4, depending on coal rank and properties. This study will show the current status of CBM/CO2-CCBM development worldwide and discuss the research challenges to tackle to understand what is going on in coal seams during the development. |
