基于显微CT技术的低压瓦斯渗流特性模拟分析

Simulation analysis on seepage characteristics of low pressure gas based on micro CT Technology

针对尚未有基于真实煤样从微观角度进行分析研究瓦斯渗流规律的问题,通过采用渗流模拟建模方式,利用CT扫描构建具有真实孔隙结构的气肥煤模型,并通过Avizo软件截取其中的一部分,对入出口压差为0.74 MPa的低压瓦斯渗流进行了模拟分析研究。研究结果表明:沿渗流长度,瓦斯渗流压力逐步降低,在微米级范围内的泄压梯度较大;最大渗流速度出现在孔隙发育较好的出口附近,在孔隙孔径突然变小的区域,渗流速度也会突然增大;整体渗流过程中,由于煤体孔隙曲折迂回,瓦斯在煤体内部会发生积聚,部分瓦斯滞留在非联通孔隙,质量流量的变化存在一定的波动性,出口的瓦斯质量流量小于入口的瓦斯质量流量。

At present,from a view of a micro perspective,an analytical study based on a real coal sample,were not conducted on the issue of the gas seepage law. With a method of seepage simulation applied to establish a model,a CT scanning was applied to establish a gas fat coal model of normal porous structure. With the application of the Avizo Software to select a part of software,a simulation analysis was conducted on low pressure gas seepage with the inlet and outlet pressure difference of 0.74 MPa. The study results showed that along the length of the gas seepage and the has pressure was steadily decreased. The max seepage velocity was occurred near the outlet of the pore well developed,at the area with the porous diameter reduced suddenly,the seepage velocity also would be suddenly increased. In the completed seepage process,due to the bending and detour of the pores in coal seam,the gas would be accumulated in coal seam internal,a part of the gas would be delayed in the non-connected pores,the variation of the mass flow would be existed in a certain fluctuation,the gas quality and flow at the outlet would be less than the gas flow at the outlet.