Ergo Exergy - UCG

May 22, 2015

Effects of Rock Deformation and Groundwater Influx in Controlling Efficiency and Extraction rate in Underground Coal Gasification

Ergo Exergy Technologies Inc. presented at the 7th International Conference on Clean Coal Technologies, that was held in Krakow, Poland, on May 17-21, 2015.

The presentation summarizes many years of our research and practical experience in operating large-scale UCG reactors in various geologic and hydrogeological conditions.

In-situ reactors of a large-scale Underground Coal Gasification (UCG) plant operate under defining influence of both groundwater ingress and cave-in of surrounding rock.

Groundwater flow around and into UCG reactors is not indifferent to rock mechanics processes in the surrounding rock; in fact, for fully developed UCG reactors groundwater flow is controlled by induced permeability resulting from deformation of strata bordering the target coal seam.

Using numerical modeling and analysis of empirical data obtained from field operations of several large-scale UCG reactors, it is demonstrated that collapse and cave-in of inert overburden rock into an active UCG reactor, far from being detrimental to gasification process, is necessary for ensuring continuous efficient operation of the UCG reactor.

Effects of groundwater on gasification process efficiency and extraction rate are considered using analysis of empirical data from a number of large-scale UCG operations. It is shown that groundwater influx critically affects cold gas efficiency, heating value of the gas, gas leakage, and environmental performance of the UCG reactors.

We would like to gratefully acknowledge contribution made to this work by our colleagues from the School of Mechanical and Mining Engineering of University of Queensland, Australia.

© 2015 Ergo Exergy