Preliminary modeling for module estimation on the underground coal gasification project

Abstract

Designing the module is one of the initial works of the underground coal gasification (UCG) feasibility study, consisting of the coal area to be gasified as panels and the coal to be left as pillars. Three models have been designed with each panel dimension 380 m in length, 150 m in width and 18 m thick. The finite element method is used in the study and the 2D and 3D geotechnical simulations have been carried out with variations of the pillars. As a result of 2D modeling, the critical strength reduction factor (SRF) is 0.25 with the highest deformation on the surface is 0.04 m (SMA-C) and 0.03 (SM-D) if the pillar is 50 m width. If SRF is increased to 0.37, the deformation on the surface is 0.36 (SMA-C) and is 13.5 (SM-D), respectively. From the 3D modeling results, if it is assumed that the velocity of the UCG reactor hole rate is 0.24 m/day until it reaches the final target length of the reactor hole 380 m, the maximum deformation of the soil surface at the SMA-C and SM-D locations is 0.074 m and 0.096 m, respectively. Determination of the module is important in the feasibility study and evaluation of the UCG site.