Vitrinite reflectance as a measure of the range of influence of the temperature of a georeactor on rock mass during underground coal gasification

The mean reflectance of the vitrinite index determined for the collected samples and reflectograms, allowed the inference that when the georeactor was operating, the temperature in the UCG cavity reached approximately 1300 °C. Based on Ro, the point in a coal seam surrounding the georeactor corresponding to the temperature of approximately 700 °C was also identified, where there were signs of the initial stage of coal transformation. The point was located 1.94  m from the boundary of the UCG cavity. Then, at the distance of 1.73 m from the boundary of the UCG cavity the point with a temperature of approximately 1000 °C was identified. The tests confirmed that it is possible to use the method of determining the mean reflectance of vitrinite index to measure the distance of influence of georeactor temperature on the rock mass. This is particularly important for underground coal gasification conducted in active mines. In the future the results will be used to predict the time of heating needed for coal deposits to become gasified, based on laboratory tests and coal type.