不同机制条件下的煤层瓦斯流动方程研究  

Study on flow equation of coal seam gas under different mechanisms

作　　者：王洪磊[1,2] 王登科[1,2,3] 姚邦华[1,2] 

机构地区：[1]河南理工大学河南省瓦斯地质与瓦斯治理重点实验室-省部共建国家重点实验室培育基地,河南焦作454000 [2]河南理工大学安全科学与工程学院,河南焦作454000 [3]煤炭安全生产河南省协同创新中心,河南焦作454000

出　　处：《中国安全生产科学技术》2016年第4期20-24,共5页Journal of Safety Science and Technology

基　　金：教育部“创新团队发展计划”项目(IRT1235);国家自然科学基金项目(51574112,51304072,51404100);教育部科学技术研究重点项目(213022A);河南理工大学博士基金项目(B050201);河南理工大学“步步高”大学生科技攀登计划基金(SA-2016-072)

摘　　要：气体流动可分为连续流、滑流、过渡流、自由分子流,为研究不同流动机制下的煤层瓦斯流动规律,在充分考虑了不同扩散机制和滑移边界条件后,建立了适用于不同流动机制的煤层瓦斯流动方程,深入分析了视渗透率和达西渗透率的比值随Knudsen数的变化关系。研究结果表明:所提出的煤层瓦斯流动方程能准确描述包括达西流、滑流、自由分子流、过渡流在内的气体流动行为。瓦斯气体在煤层孔隙、裂隙中流动过程中浓度扩散和粘性流同时存在,当Kn<0.01时,粘性流起主导作用,瓦斯流动满足渗流方程;当Kn>10时,浓度扩散起主导作用,瓦斯流动符合扩散方程;在Kn的其他范围内,煤层孔隙裂隙中瓦斯流动以滑流、过渡流为主,在对之进行评价时应同时考虑扩散项和渗流项。研究结果可为揭示煤层瓦斯流动机理、提高煤层瓦斯抽采率和煤层气的产量预测准确度提供新方法和新途径。The gas flow can be divided into continuous flow,slip flow,transition flow and free molecular flow. In order to investigate the flow laws of coal seam gas under different flow mechanisms,a flow equation of coal seam gas being suitable for different flow mechanisms was established with fully considering different diffusion mechanisms and slip boundary conditions,and the change relationship between the ratio of apparent permeability to Darcy permeability and Knudsen number was analyzed deeply. The results showed that the proposed equation can accurately describe the gas flow behaviors including Darcy flow,slip flow,free molecular flow and transition flow. In the flow process of gas in pores and cracks of coal seam,the concentration diffusion and viscous flow exist simultaneously. If Knudsen number is less than 0. 01,the viscous flow plays a leading role,and the gas flow meets the seepage equation. If Knudsen number is larger than 10,the concentration diffusion plays a leading role,and the gas flow fits the diffusion equation. In other cases,the gas flow in pores and cracks of coal seam is mainly on slip flow and transition flow,and the diffusion term and seepage term should be taken into account simultaneously when conducting evaluation. It can provide new method and new way for uncovering the flow mechanism,improving the drainage rate and the prediction accuracy on output of coal seam gas.

关 键 词：煤层瓦斯 瓦斯扩散 瓦斯渗流 Knudsen数 流动机制 

分 类 号：X936[环境科学与工程—安全科学]