A preliminary laboratory experiment on coalbed methane displacement with carbon dioxide injection

CH4/CO2 adsorption isotherm studies on coals samples give adsorption behavior, adsorption ratio, and other influential factors for enhanced coalbed methane recovery (ECBM) and CO2 sequestration by CO2 injection. Yet, they only provide static characteristics, and do not provide information on pressure-driven and concentration-driven during gas recovery and injection processes. The purpose of this study is to construct an experimental apparatus for CH4 displacement with CO2 injection and primarily study the basic procedure of coalbed methane (CBM), ECBM, and CO2 sequestration at driven-conditions.An experimental apparatus was built based on the configuration of one-injection well/one-production well under ideal conditions. The apparatus was used to model CBM with CH4 adsorption, investigate primary production of CBM and ECBM with gases desorption, and study CO2 sequestration with its breakthrough. The change of pressure and gases amount during gases injection and desorption, and residual quantity after gases desorption were employed to ECBM and CO2 sequestration with this equipment. The effect of CO2 injection on CH4 production was investigated on a small scale experimentally. The results indicate that the recovery procedure of ECBM and CO2 sequestration with CO2 injection can be studied with the apparatus and the gases adsorption/desorption characteristics obtained with the apparatus is obviously differ from that obtained with conventional volumetric measurement.