REGIONAL VARIATION OF COAL RESERVOIR HETEROGENEITY AND DISTRIBUTION OF FAVORABLE RESERVOIR IN QINSHUI BASIN

摘要

Qinshui Basin lies in southern Shanxi Province, China, between 35°-38°N, 112°00'-113°50'E. Its long axis extends overally in NNE direction, with a width of 120km from east to west, a length of 330km from south to north and a total area of more than 30,000km~2 (Zhang et al., 2000). It is the biggest and most distinctive high rank coal-bearing basin in China. The reserve of high rank coal is as high as 190 billion tons. The basin has a huge reserve of coalbed methane. As investigated, the coalbed methane in the reservoir above 2000m in depth, lower than weathering belt and with a gas content of more than 4m~3/t is as much as 3280 billion m~3, which is 22.87 percent of the total resources in China (Zhang et al., 2001; Ye et al., 1998). As a result of complex structural systems and Mesozoic-Cenozoic magmatic activities, the coal evolution in Qinshui Basin is characterized by multi-stage and multi-thermo-source superimposed metamorphism (Yang et al., 1996) and the heterogeneity of coal reservoir increased. In this paper, the regional variation of coal reservoir heterogeneity and its controlling factors were explained with the heterogeneity of composition characteristics and physical properties of coal reservoir. The favorable coal reservoir was evaluated by applying Analytic Hierarchy Process and fuzzy mathematics.