Underground coal gasification (UCG): An analysis of gas diffusion and sorption phenomena

Abstract

This article describes the results of measurements of the gas transport phenomena in coal and strata samples. The samples were taken from the surroundings of an underground georeactor in the “Barbara” Experimental Mine before and after an in situ underground coal gasification experiment. Measurements of the coal and strata samples indicate that the UCG process influences the porosity and structure of the coal seam and the strata surrounding the underground georeactor. Determining parameters such as the porosity, intrusion volume and diffusion velocity of the gases is crucial to assess the potential for environmental pollution during the UCG process. Moreover, measuring UCG gas transport in the strata and the post-process coal may provide useful information on how gas migrates into the surroundings of the georeactor.The analysis of the sample properties presented in this study included the total amount of desorbed product gases and the comparison of adsorption ability of the strata surroundings. The conducted analyses estimated the amount of the absorbed gases and defined the gases’ potential transport paths in the georeactor and the surroundings.