Underground Coal Gasification (UCG) refers to the in-situ gasification of coal. It is accomplished by first establishing two vertical boreholes – the injection well and the production well. Next, the two wells are horizontally linked within the coal seam using specialized techniques such as directional drilling. Reactant gas mixtures (steam & oxygen) are sent through the injection well and suitable conditions for the ignition or start-up of the coal reactions is provided.