The Gas Geological Characteristics Of Coal-bed No.13-1 In Panyi Coal Mining, Huainan Coal Feild

In recent years, with the lengthways development of mining depth on coal seam, the geological condition is more and more complexity, and the problem of mining gas is more serious. The No. 13-1 is a primary coal-bed from Panyi mining in Huainnan coal field, with its enlargement of mining depth, the range of coal and gas outburst is enlarger, which seriously threatens insuring safety in mining. Therefore, gas geological characteristics of coal-bed No. 13-1 is studied from two main aspects. One is the distributive characteristics of gas content, the other is the development of tectonically deformed coal.The coal-bed No. 13-1 is divided into three gas geological units, namely, the eastern, the mid and the western gas geological unit according to the circumscription of F4 fault and F5 fault, because the two faults control the flowing gas distribution of the coal-bed, consequently, the two faults affect the law of gas occurrence. Moreover, 109 gas testing samples are coordinated of coal-bed No. 13-1, on the basis of analyzing a good many factors which affect gas content, the relativity between gas content and the burial depth of coal-bed (the depth from coal-bed to bedrock surface) is established each gas geological unit by statistical regression. It is shown that the burial depth of coal-bed is a main controlling factor, which controls general trend of gas content in coal seam 13-1, the gas content increases with the increase of the burial depth of coal-bed.Lithological characteristics of the seam roof are one of factors, which lead gas content to change partially. 138 borehole sections and mining datum are analyzed and coordinated of coal-bed No. 13-1 in Panyi coal mining, and lithological characteristics of the roof are studied, the seam roof of coal-bed No. 13-1 is divided into 4 types, and the plane map of the roof types is plotted. The roof lithology and its combinatorial relation are mainly analyzed, on the top of coal-bed, the sandstone percentage is calculated in 20m, and each roof and its effect to underlying methane content of seam roof are discussed. It is shown that the sandstone of coal-bed No. 13-1 and its degree of diagenetic cementation is very fine, that is, the sandstone is rigid and its permeability is very poor, therefore, the seam roof of sandstone makes against dispersion of underlying methane content;The sandstone percentage in given range is not used to evaluative index, which effects to methane content of coal seam;The development of roof cranny is a key geological factor, which has influence on underlying methane content of seam roof.The development of tectonically deformed coal may qualitatively reflect hazard of gas outburst. Log curve of 120 boreholes are analyzed in coal seam 13-1, and the types of coal body texture are divided into primary coal, transitional coal and tectonically deformed coal, the distributive map of three coal body textures is plotted in coal seam 13-1. Furthermore, the percentage and thickness of tectonically deformed coal are calculated in the coal seam, and the layered characteristics of tectonically deformed coal are studied. Accordingly, the development of tectonically deformed coal is studied in the coal seam, and its relation with danger of coal and gas outburst is primarily discussed in coal seam 13-1.