The change in effective stress associated with swelling during carbon dioxide sequestration on natural gas recovery

The sequestration of CO2 by pumping it into deep coal seams is being investigated. It is therefore worthwhile to gather the information available on the interactions of CO2 with coals and the effects of CO2 on coals' properties in order to attempt a prediction of the long-term effects of sequestration. In the experiment, the volumetric changes of the coal matrix were monitored for a low-rank coal (Cdaf 84.14; Vdaf 33.4) for mixtures of CO2 and CH4 of different proportions and single gases. In the case of the sorption of a mixture of gases, the course of the kinetics of expansion of the coals studied indicates a lack of visible deformation of the coal structure. The observed phenomenon of a higher affinity to CO2 and displacement of CH4 by this sorbate may, provide one of the reasons for abrupt disturbances in the rock, by changes in the bed permeability, caused by competitive processes of sorption and desorption.