摘要
渭北煤田多变形运动期和多组构造叠加孕育出的煤系断层带对煤层瓦斯赋存产生重要影响。采用地质分析、COMSOL Multiphysics多物理场数值模拟和现场数据监测相结合的方法,分析煤系正断层带的应力分布特征及断层之间相互作用关系,研究煤系正断层带影响下的煤层渗透率变化特征,模拟正断层带形成后的瓦斯运移状态和浓度分布情况,基于瓦斯含量和瓦斯涌出量监测结果进一步分析得到煤层瓦斯赋存规律。研究结果表明:煤系断层带的应力集中主要分布在煤层断层面上,应力降产生在岩层、煤层及各断层面交汇点处;煤系断层带影响区域的煤层渗透率由大到小依次为:断层面、区域平均值、断层上盘、断层下盘;随模拟时间增加,煤层瓦斯浓度逐渐减小,煤系正断层带内部地堑、地垒、阶梯状断层瓦斯浓度降低速率略大于两侧边界断块,瓦斯在断层断块内部及正断层带外侧边界表现出明显的积聚特性;煤系正断层带内部瓦斯含量和回采期间回风流瓦斯体积分数平均值分别为2.5921 m3/t、0.2240%,断层带外部边界两侧平均值分别为4.4802 m3/t、0.4549%,表明煤系正断层带两侧形成新的瓦斯富集区域。
The coal measure fault zone generated by the superimposition of the polytropic movement and multiple struc-ture has important effects on the coal seam gas occurrence.The method of combining the geologic analysis,COMSOL Multiphysics numerical simulation and field data monitoring was adopted to analyze the interaction relations between the stress distribution characteristics and faults of the normal fault zone in the coal measure,study the coal seam per-meability variation characteristics influenced by the normal fault zone in the coal measure,and simulate the gas migra-tion status and concentration distribution condition after the formation of the normal fault zone.The coal seam gas oc-currence law was further analyzed and obtained based on the monitoring results of the gas content and the gas outflow.As indicated by the study result,the stress concentration of the coal measure fault zone was mainly distributed on the fault plane of the coal seam.The stress drop occurred at the intersections of rock strata,coal seams and fault planes.The coal seam permeability in the affected area of the coal measure fault zone was in the order of large to small:the fault plane、average value in the area、upper wall of the fault、lower wall of the fault.The coal seam gas concentration was decreased gradually with the simulation time.The gas concentration decrease rates of the internal graben,horst and step fault in the normal fault zone of the coal seam were slightly higher than those of the boundary fault blocks at the both sides,and the gas showed obvious accumulation characteristics in the faults and fault blocks and the boundary outside the normal fault zone.The gas content in the normal fault zone of the coal measure and the average volume fraction of the return gas during stoping were 2.5921 m3/t and 0.2240%.The average values at the both sides of the boundary out-side the fault zone were 4.4802 m3/t and 0.4549%.Accordingly,the new gas-concentrated areas were formed at the both sides of the normal fault zone in the coal m
作者
肖鹏
吴铭川
双海清
韩凯
高振
程玥颖
XIAO Peng;WU Mingchuan;SHUANG Haiqing;HAN Kai;GAO Zhen;CHENG Yueying(College of Safety Science and Engineering,Xi’an University of Science and Technology,Xi’an 710054,China;Key Laboratory of Western Mine Exploitation and Hazard Prevention Ministry of Education,Xi’an University of Science and Technology,Xi’an 710054,China;Western Engineering Research Center of Mine Gas Intelligent Extraction,Xi’an University of Science and Technology,Xi’an 710054,China)
出处
《煤田地质与勘探》
CAS
CSCD
北大核心
2022年第10期16-25,共10页
Coal Geology & Exploration
基金
国家自然科学基金项目(51774235,52074216)。
关键词
正断层
瓦斯地质
煤层瓦斯
数值模拟
瓦斯赋存
normal fault
gas geology
coal seam gas
numerical simulation
gas occurrence
