Experiment on swelling strain of confined coal mass with CO2 sequestration

In order to investigate the coal volumetric swelling during CO2 storage, the self-developed MCQ-Ⅱ CO2-ECBM experimental equipment was used to perform coal deformation through injecting CO2 to meager coal, meager lean coal and weakly caking coal samples (100 mm×100 mm×200 mm) with constant injection pressure under 31 MPa bulk stress at 25℃. At the same time, the micro-pores were investigated with nine small coal samples (6 mm×6 mm×6 mm) through a micro-CT system. The results show that: At minimum 4.5 μm observation of CT section structure, the meager coal porosity (4.67%) is less than that of meager lean coal (5.39%) and weakly caking coal (12.10%); During 12 hours of CO2 injection, coal volumetric strain is influenced by pore pressure and CO2 adsorption swelling, which is linearly proportional to the amount of gaseousness CO2 storage under 31 MPa confinement pressure; With the same CO2 storage, the volumetric swelling strain of the meager coal is more than that of the weakly caking coal and meager lean coal; Due to the anisotropy of modulus of elasticity, the radial strain increases faster than the axial strain and both of them are linearly proportional to the amount of gaseousness CO2 storage. © 2016, China Coal Society. All right reserved.