Abstract Tests of coal samples collected from a borehole drilled in the surrounding of an underground coal gasification georeactor were conducted. This experiment was conducted for the first time in an active coal mine in Poland. The aim of the tests was to determine the extent of heat penetration around the UCG cavity during a nearly two month gasification process. The method of measuring the mean reflectance of the vitrinite index (Ro), which is more generally used to measure the degree of the coalification of organic substances in coal (macerals) under the influence of temperature, was applied. The method is still used to evaluate the usefulness of coal for producing coke. 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.

中文翻译：

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镜质体反射率作为地下煤气化过程中地质反应器温度对岩体影响范围的量度

摘要 对地下煤气化地质反应器周围钻孔的煤样进行了试验。该实验首次在波兰的一个活跃煤矿中进行。测试的目的是确定在近两个月的气化过程中 UCG 腔周围的热渗透程度。镜质体指数（Ro）的平均反射率测量方法，更普遍地用于测量在温度影响下煤（微晶）中有机物的煤化程度。该方法仍用于评价煤炭生产焦炭的有用性。为收集的样品和反射图确定的镜质指数的平均反射率允许推断，当地球反应器运行时，UCG 腔内的温度达到约 1300 °C。根据 Ro，还确定了地球反应器周围煤层中与大约 700 °C 温度相对应的点，在那里有煤转变初始阶段的迹象。该点位于距 UCG 腔边界 1.94 m 处。然后，在距 UCG 腔边界 1.73 m 处，识别出温度约为 1000 °C 的点。试验证实，利用镜质体指数平均反射率的测定方法来衡量地质反应器温度对岩体的影响距离是可行的。这对于在活跃矿井中进行的地下煤炭气化尤其重要。