This report aims to provide a detailed theoretical review on the prediction of underground water flows, through a porous medium. In particular, Underground Coal Gasification (UCG) has been selected as the example to illustrate how to predict underground water flow with regards to its specific geological properties. There are many different types of porous mediums with their own individual densities; porosity, viscosity and permeability, to narrow the complexity of the properties, a sample application as UCG need to be been taken into
consideration to simulate its specific elements and factors that affect the underground water flow. UCG mining sites are suitable to simulate this approach, while during the UCG gasification process, underground coal reacts with the injected gas mostly with oxygen and further gasified by the oxidation products such as water. In most cases, ground water needs to be supplied from the surrounding aquifer for the gasification reaction, and thus the rate of water supply is very important to this process.
Using geological approach, the UCG mining site comprises of geological properties, example the porous medium, water recharge, water discharge, condition of underground water and boundary layer. The geological data collected been applied into numerical and analytical methods using finite element and computing coding. Assumptions and predictions have been made to demonstrate prediction of ground water flow through UCG mining site. Different UCG sites geological data been collected around the world as limited information are
available; some of the geological data need to be collect on-site. Examples of finite element modelling and coding process are shown in the Appendix to give an insight to the process flow on how to model and predict ground water flow. The prediction of water flow rate under fractured dominating most of the UCG site can be a critical issue to its surrounding environment and geological impact result in excessive groundwater usage withdrawal, addition review on the capabilities of the software in fracture analysis and on-site groundwater monitor.