Assessment and Improvement of Underground Coal Gasification Modelling

Abstract

Underground coal gasification (UCG) is a process to convert coal in-situ into combustible synthetic gas (syngas). Oxidant is brought downhole through an injector for coal combustion and gasification while resulting syngas is extracted from a producer. UCG offers a better way to exploit coal resources over conventional mining with smaller environmental footprint. It has gained considerable attention in emerging economies, e.g., China and India, which are coal-rich nations and have an ever-increasing energy demand. As a complex coal thermal recovery process involving multi-physics and kinetics, knowledge gaps remain before UCG reaches large-scale commercial implementation. To enhance knowledge, this work applies a modified simulation tool to model certain important aspects of UCG, i.e., assessing critically the use of a reservoir simulator to model UCG, exploring the theory of a prior linking method of reverse combustion, studying the role of coal cleats in governing fluid flow and heat transport with regard to aquifer contamination, and investigating the progressive changes in coal pores associated with UCG. Additional modelling efforts were made to explore an extended practical importance of UCG. The prospect of applying UCG to mobilize contiguous heavy oil is studied and the feasibility of linking UCG with carbon storage and sequestration is examined.