Abstract:

Underground coal gasification(UCG) is a method of in situ coal mining. In this paper, the technology process, reaction characteristics, influencing factors, together with the development and application prospect of UCG were introduced. In addition, site selection and groundwater pollution prevention regarding UCG were especially emphasized. Gas production during UCG is based on the reactions of the mixture of coal and rocks in the percolation channel, and involves the chemical reactions along both the axial direction and radial direction. With the expanding of gasification face, the period of gas emission on stable process control is formed. The UCG technology of retraction gasification by moving injection using coiled tubing along long distance directional drilling borehole provides the technical basis for UCG commercialization. UCG gas could not only be used for IGCC, but also be used as chemical raw gas for synthesis of methanol, ethylene, oil, aromatic hydrocarbons, etc. UCG must have broad application prospect with the remarkable safe and environmental advantages if groundwater pollution is properly carried out.

Key words: underground coal gasification, site selection, groundwater pollution, gas utilization