沙曲矿4煤层顺层抽采瓦斯运移规律数值模拟研究

发布时间：2018-02-24 21:13

本文关键词： 瓦斯运移数值模拟瓦斯抽采流固耦合瓦斯压力　出处：《辽宁工程技术大学》2013年硕士论文　论文类型：学位论文

【摘要】：近年来随着煤矿井下开采深度的增加和开采强度的增大,煤层瓦斯涌出强度也越来越大,严重制约着矿井生产,对于高瓦斯矿井这种问题表现的更为突出。矿井瓦斯抽采已成为瓦斯灾害防治的重要手段,同时瓦斯作为一种清洁高效的能源资源,如果能够最大限度的将煤层瓦斯采出并加以利用,可以变害为宝为人类造福。依据煤矿安全规程,对高瓦斯有煤与瓦斯突出危险的煤层在回采前,必须进行预抽,而如何确保瓦斯抽采效果,合理的布置钻孔,一直是个难题,目前多通过现场实测的办法,来估算抽采布置间距,该方法需要布置多组实验钻孔且需较长的抽采观测时间。本文基于本煤层瓦斯抽采方法选择及抽采钻孔布置问题,将煤岩体视为具有孔隙裂隙的双重介质结构,考虑由于瓦斯压力下降引起的孔隙结构的变形,从微观到宏观,逐步研究了煤层瓦斯的储存特征和渗流特征,在达西定律、菲克第一定律、连续性方程和辅助方程的基础上,以煤岩体体积应变为耦合媒介建立了考虑裂隙渗流、微孔隙扩散和煤岩体变形的耦合渗流场方程。借助于大型数值分析软件对建立的数值模型进行分析求解,并根据沙曲矿4煤层实际的瓦斯赋存条件,分别建立平面应变模型和三维几何模型,分析单孔和孔群抽采时煤层瓦斯压力、达西速度、渗透率等参数随抽采时间的变化规律,以及工作面倾向顺层钻孔抽采、工作面倾向倾斜顺层钻孔抽采和工作面扇形顺层钻孔抽采三种不同的顺层钻孔瓦斯抽采方法的抽采效果,研究了钻孔布置间距、夹角等参数对抽采效果的影响。研究结果表明：距离抽采钻孔较近位置瓦斯压降呈“L”型,较远位置呈反“S”型,随距离抽采位置增大,压降曲线逐渐由“L”型转为反“S”型；渗流速度随抽采时间变化呈三个阶段,抽采一周左右渗流速度达峰值,随后快速下降,抽采稳定后缓慢下降；工作面倾向顺层抽采与倾斜顺层抽采、扇形顺层三种抽采方法比较,相同时间倾向顺层抽采瓦斯压力降低较快,倾向倾斜抽采存在两个抽采区域瓦斯压力降低缓慢；扇形顺层抽采时,以施钻位置为中心,影响范围呈扇形辐射状发展,随距施钻中心位置增大,瓦斯压力下降速度减小；钻孔布置密度对扇形顺层钻孔瓦斯抽采的效果影响比较显著。
[Abstract]:In recent years, with the increase of mining depth and mining intensity, the intensity of coal seam gas emission is increasing, which seriously restricts the mine production. Gas drainage has become an important means of gas disaster prevention and control, and gas is a clean and efficient energy resource. If the coal seam gas can be extracted and utilized to the maximum extent, it can be turned into a treasure for the benefit of mankind. According to the coal mine safety regulations, the coal seam with high gas and dangerous gas outburst must be pre-drained before mining. However, how to ensure the gas drainage effect and how to arrange the boreholes reasonably is always a difficult problem. At present, the spacing of the drainage arrangement is estimated by the method of field measurement, which needs to arrange many experimental boreholes and take a long time to observe the drainage. Based on the selection of coal seam gas drainage method and the layout of drainage borehole, the coal and rock mass is regarded as a dual medium structure with pore fissure, and the deformation of pore structure caused by gas pressure drop is considered, from micro to macro. The storage and seepage characteristics of coal seam gas are studied step by step. On the basis of Darcy's law, Fick's first law, continuity equation and auxiliary equation, the fracture seepage is established with the volume strain of coal and rock mass as the coupling medium. The coupled seepage field equation of micro-pore diffusion and coal and rock mass deformation is analyzed and solved by means of large-scale numerical analysis software, and according to the actual gas storage conditions of No. 4 coal seam in Shaqu Coal Mine, the numerical model is analyzed and solved. The plane strain model and 3D geometric model are established respectively to analyze the variation of gas pressure, Darcy velocity, permeability and other parameters of coal seam during single hole and hole extraction. The effects of three different methods of gas extraction from inclined seam drilling and sector bedding drilling are studied. The influence of the parameters such as the spacing of borehole arrangement and the angle between the boreholes on the extraction effect is studied. The results show that the gas pressure drop is of "L" type near the borehole, and the "S" type is opposite in the distance. The pressure drop curve gradually changes from "L" type to "S" type with the increase of the distance extraction position, and the seepage velocity varies in three stages with the extraction time. The percolation velocity reaches the peak value in about a week of extraction, then decreases rapidly, and then decreases slowly after the stability of extraction. At the same time, the gas pressure decreases rapidly in the down-bed drainage, and the gas pressure decreases slowly in two drainage areas in inclined inclined drainage, and the influence range develops in the shape of fan-shaped radiation with the drilling position as the center, and the gas pressure decreases slowly in the two drainage areas in the inclined inclined drainage, and in the same time, the gas pressure decreases slowly in two drainage areas. With the increase of the location of the drilling center, the gas pressure decreases, and the borehole layout density has a significant effect on the effect of gas extraction.
【学位授予单位】：辽宁工程技术大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TD712

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