大同煤田同忻矿瓦斯地质特征及突出危险性预测

Coal Mine Gas Geological Characteristics and Outburst Risk Prediction of Tongxin Mine in Datong Coalfield

以大同煤田同忻矿为研究对象,以矿井基础地质资料为基础,共采集62口钻井共214个瓦斯气样,以实验测试为手段,以理论分析为方法,得出了瓦斯气样成分特征;划分了各个煤层的瓦斯带类型;分析了断裂、褶皱、陷落柱、埋深、岩浆侵入、煤化程度等因素对瓦斯赋存的影响;探究了各因素的影响机理;并预测了瓦斯突出危险性。结果显示:瓦斯成分以N 2、CH 4和CO 2为主,山4#煤为N 2-CH 4带和N 2带,2#煤层中包括N 2-CH 4带和N 2带,3-5#煤层中包括N 2-CH 4带、N 2带和CO 2-N 2带,8#煤层中包括N 2-CH 4带和N 2带,9#煤层中包括N 2-CH 4带和N 2带,将矿井鉴定为高瓦斯矿井;研究区断裂性质多为正断层,利于瓦斯气体的垂向运移和散失;向斜轴部、背斜鞍部、鼻状构造的倾斜端及“S”型背斜转折端等构造部位易于瓦斯的富集保存;封闭性陷落柱为瓦斯赋存提供储集空间,而与导水裂隙带联通的陷落柱则有助于瓦斯气体的散失;瓦斯含量与煤层埋深呈正相关关系,与岩浆侵入区煤样挥发分呈明显负相关关系,而无岩浆岩区,挥发分与瓦斯含量无明显相关性,煤层埋深越大,突出危险性越高;瓦斯突出危险性预测结果显示研究区突出危险性较小。

In this study,Tongxin coal mine in Datong coalfield is taken as the research object,based on the basic geological data of the mine,214 gas samples are collected from 62 wells.The types of gas zones in each coal seam are divided by means of experimental test and theoretical analysis,the composition characteristics of gas samples are obtained,the influence of fracture,fold,collapse column,burial depth,magma intrusion and coalification degree on the occurrence of gas are analyzed,and the influence mechanism of each factor and the risk of gas outburst are discussed.The results show that,The gas is mainly composed of N 2,CH 4 and CO 2.Shan 4#coal is composed of N 2-CH 4 belt and N 2 belt.The 2#coal seam includes N 2-CH 4 belt and N 2 belt.The 3-5#coal seam includes N 2-CH 4 belt,N 2 belt and CO 2-N 2 belt.The 8#coal seam includes N 2-CH 4 belt and N 2 belt.The 9#coal seam includes N 2-CH 4 belt and N 2 belt.The mine is identified as high gas mine;the faults are mostly normal faults,which are conducive to the vertical migration and loss of gas;the syncline axis,the saddle of anticline,the inclined end of nose-like structure and the turning end of"S"type anticline are easy to accumulate and preserve gas;the closed collapse column provides the storage space for gas occurrence,while the collapse column connected with the water conducting fracture zone is conducive to the loss of gas;there is a positive correlation between the gas content and the depth of coal seam,and a significant negative correlation between the gas content and the volatile content of the coal sample in the magmatic intrusion area,while there is no obvious correlation in magmatic rock area,the deeper the coal seam is buried,the higher the risk of outburst;the prediction results of the gas outburst risk show a low hazard.