Abstract

In general, fluid porosity and permeability in a UCG process are potentially strong functions of solid content rather than geomechanics effect. In tight coal seams, modeling permeability as a function of fluid porosity is not sufficient and geomechanics coupling can enhance the permeability function. In tight coal seams, a pressure-dependent permeability model is crucial so that permeability can be increased before combustion and gasification take place. For precise prediction of the thermo-mechanical behavior of coal and char in a UCG process (roof spalling and collapsing, and sidewall scratching), a discrete element method is necessary.