Characters of coal classification and coal rank distribution in third member of Shahejie Formation in eastern depression of Liaohe basin

Under general geological study of exploratory development of coalbed gas and underground gasification of coal bed in eastern depression of Liaohe basin,authors apply the basic principle of coal geology and the data of vitrinite reflectance and technical analysis of coal to ascertain that coal classification are dominantely the lignite,long-flame coal and gas coal of coal-bearing upper section of third member of Shahejie Formation.And then dissertate the variational regularity between coal rank and buried depth in vertical and otherness of vertical limit of coal rank in different coal-rich regions.The results show that the long-flame coal distributs in the six coal-rich regions,the lignite distributs in southwest and north central region and gas coal distributs in south central of eastern depression on plane.At last it is pointed out that the regional geothermal field and volcanic activity control the spatial distribution of coal rank.