Abstract

This work shows that UCG involves a very strong coupling of mass and heat transfer and chemical kinetics; Under-hydropressure injection can avoid or mitigate potential migration of species into overhead aquifer; Syngas production remains very robust with heterogeneity or variation in geological settings, e.g., cap sealing capability, coal thickness, and the degree of cleats development;  Injection pressure plays an overwhelming role in governing vertical mass transfer problem; Above-hydropressure injection pressure would promote migration of species upward into an aquifer, and thus should be avoided or one takes extreme caution.