1. School of Safety Engineering,China University of Mining and Technology,Xuzhou　 221116,China; 2. National Engineering Research Center for Coal Gas Control,China University of Mining and Technology,Xuzhou　 221116,China

由于对负压在瓦斯抽采过程中作用机制认识不清,煤矿往往采用恒定的抽采负压,导致抽采的瓦斯浓度低、利用难度大,不利于瓦斯的资源化抽采与利用。建立了考虑基质瓦斯拟稳态扩散、裂隙瓦斯渗流、渗透率演化及煤体变形的瓦斯运移气固耦合模型,并采用Comsol Multiphysics对模型进行数值解算。分析了扩散及渗流过程对瓦斯运移的影响,研究了负压在瓦斯抽采过程中的作用机制。考虑抽采负压作用的变化,结合抽采瓦斯及漏风并联关系,获得了不同抽采负压下瓦斯浓度变化。结果表明随抽采时间增加,负压的作用逐渐减弱,降低抽采负压能够有效提高抽采瓦斯浓度。针对当前煤矿抽采瓦斯浓度低的现状,提出了抽采钻孔"分组并联"降低抽采负压、提高瓦斯资源化利用的技术措施。

A constant negative pressure is used in the coal mines owing to a lack of research on the effect of negative pressure on methane extraction,resulting in the low methane concentration and difficult utilization,which is not condu- cive to the extraction and utilization of methane resource. In this study,a gas-solid coupling model of coalbed methane migration considering the pseudo-steady diffusion in coal matrix,seepage in fractures,permeability evolution and coal deformation is proposed. Comsol Multiphysics is used to conduct a numerical solution of the proposed model. The effects of the diffusion and seepage processes on the methane migration are analyzed,and the role of the negative pres- sure on methane extraction is studied. The methane concentrations of different negative pressures are calculated consid- ering the changing effect of negative pressure combined with the parallel relation between the methane migration and the air leak. The research results reveal that the negative pressure effect weakens gradually with the increasing methane extraction time and the reduction of the negative pressure can effectively increase the methane concentration. To change the present situation of the low methane concentration and utilization rate in coal mines,a new technical measure of methane extraction through parallel boreholes in groups is proposed to adjust the extraction negative pressure and increase the methane utilization rate.

国家自然科学基金资助项目(51574229；51374204)；

Cheng Yuanping,Dong Jun,Li Wei,et al. Effect of negative pressure on coalbed methane extraction and application in the utilization of methane resource[J]. Journal of China Coal Society,2017,42(6):1466-1474.