摘要
基于煤层瓦斯运移的多尺度扩散效应,根据变直径毛细管物理模型,通过压汞实验、低温液氮和二氧化碳吸附实验对贵州某矿7#煤层煤样的孔径分布进行测定,通过Knudsen方程得出不同扩散方式的临界直径,从而得出不同扩散方式所占比例,提出考虑多种扩散方式的有效扩散系数.建立了考虑多尺度扩散、Klinkenberg效应、基质收缩和有效应力的双孔隙介质耦合模型,利用多物理场耦合软件对煤层瓦斯钻孔抽采情况进行了数值模拟研究,分析了新模型条件下钻孔抽采煤基质和煤裂隙中的瓦斯压力分布以及瓦斯扩散速度和瓦斯渗流速度的差异,得出煤层瓦斯钻孔抽采情况下的运移规律.通过在井下打穿层钻孔进行瓦斯抽采,测量每天的瓦斯流速和流量,将现场测得的瓦斯流速和流量与数值模拟结果做对比,得出所建立的双孔隙介质模型符合工程实际的要求,为深煤层开采瓦斯防治提供参考.
Based on the multi-scale diffusion effect of coal seam gas migration,according to the variable diameter capillary physical model,through mercury injection experiment,low temperature liquid nitrogen adsorption and CO 2 adsorption experiment,the pore size distribution of coal samples in No.7 coal seam of a mine in Guizhou Province is measured.The critical diameter of different diffusion modes is obtained by Knudsen equation,and the proportion of different diffusion modes is obtained.The effective diffusion considering multiple diffusion modes is proposed coefficient.A dual porosity medium considering multi-scale diffusion,Klinkenberg effect,matrix shrinkage and effective stress is established.The numerical simulation of coal seam gas drainage by drilling is carried out by using multi-scale physical field coupling software.The gas pressure distribution in matrix and coal fissure,gas diffusion velocity and gas diffusion velocity are analyzed.According to the difference of gas seepage velocity,the migration law of coal seam gas under the condition of borehole drainage is obtained.The gas flow rate and flow rate of each day are measured by drilling through the layer under the mine for gas drainage.The gas flow rate and flow rate measured under the mine are compared with the numerical simulation results.It is concluded that the established double porosity medium model meets the actual requirements of the project,which provides a reference for gas prevention and control in deep coal seam mining.
作者
阴昊阳
许石青
郑连军
YIN Haoyang;XU Shiqing;ZHENG Lianjun(College of Mining,Guizhou University,Guiyang 550025,China;Guizhou Tianqian Quality Technology Testing Center Co.,Ltd,Guiyang 550000,China)
出处
《矿业工程研究》
2021年第1期62-70,共9页
Mineral Engineering Research
基金
贵州省科技支撑计划资助项目(黔科合支撑[2019]2887号)
国家自然科学基金资助项目(51864009)。
关键词
多尺度机理
瓦斯扩散
双孔隙介质模型
数值模拟
multi-scale mechanism
gas diffusion
dual porosity medium model
numerical simulation
