顺层瓦斯抽采钻孔合理封孔参数研究

发布时间：2018-08-13 19:47

【摘要】：顺层钻孔抽采是煤矿瓦斯灾害防治的主要手段,其中钻孔的封孔参数是决定瓦斯抽采效果的重要因素。为准确地确定顺层瓦斯抽采钻孔的合理封孔参数,本文基于王行庄煤矿12041工作面的地质条件,分析了巷道围岩的应力分布特征与渗透率演化规律。在此基础上,对顺层瓦斯抽采钻孔的合理封孔参数开展了模拟研究,并进行了现场试验验证。取得了以下研究成果:(1)通过对王行庄煤矿二_1煤层顶底板煤岩样进行了物理力学性能参数的测试,运用FLAC3D软件模拟了煤层巷道的开挖,结合现场钻屑量法确定了12041工作面巷道的围岩应力分布,并对巷道开挖扰动后围岩的煤体渗透率进行计算。结果表明,巷道围岩区域内煤体渗透率最大值为初始渗透率的2290倍,最小值为初始渗透率的0.36倍。(2)利用Comsol Multiphysics结合双重孔隙介质瓦斯运移过程中的气固耦合模型,对不同封孔深度与封孔长度的顺层钻孔抽采煤层瓦斯过程进行了数值模拟分析。结果表明,顺层瓦斯抽采钻孔的封孔深度不宜超过应力集中峰值点,超过应力集中峰值点时,在巷道应力集中峰值点处会形成一道屏障,阻隔峰值点两侧瓦斯的自由流动;顺层瓦斯抽采钻孔的合理封孔长度应穿过巷道卸压区,到达应力集中区,略小于巷帮到应力峰值点的距离。(3)使用Comsol Multiphysics软件,对浆液在封孔段煤体内的渗流扩散过程进行了模拟研究。结果表明,在相同的注浆时间内,增加注浆压力可以明显增加浆液渗透煤体的渗透率与浆液的扩散半径,浆液扩散半径的增加幅度随着注浆压力增加而慢慢变小;在相同的注浆压力条件下,通过延长注浆时间可以增加浆液的扩散半径,但其增加幅度逐渐变缓,存在一个极值;顺层瓦斯抽采钻孔的合理注浆参数应该是能够满足浆液完全封堵钻孔周边的煤体裂隙。(4)王行庄煤矿现场试验结果表明,合理的封孔参数将会使钻孔瓦斯的抽采浓度更高,衰减周期明显延长。
[Abstract]:Borehole drainage is the main method to prevent and cure coal mine gas disaster, and the hole sealing parameter is an important factor to determine the effect of gas drainage. In order to determine the reasonable hole sealing parameters of gas drainage borehole, this paper analyzes the stress distribution characteristics and permeability evolution law of roadway surrounding rock based on the geological conditions of No. 12041 face in Wangxingzhuang Coal Mine. On this basis, the reasonable hole sealing parameters of the gas drainage borehole are simulated and verified by field test. The following research results have been obtained: (1) through the testing of the physical and mechanical properties of the coal samples from the roof and floor of No. 1 coal seam in Wangxingzhuang Coal Mine, the excavation of the roadway in the coal seam has been simulated by using FLAC3D software. The stress distribution of surrounding rock of 12041 face roadway is determined by the method of drilling debris quantity in the field, and the permeability of surrounding rock after excavation disturbance is calculated. The results show that the maximum permeability of coal is 2290 times of the initial permeability and the minimum is 0.36 times of the initial permeability in the surrounding rock area of roadway. (2) the gas-solid coupling model is used in the process of gas migration in Comsol Multiphysics combined with dual porosity medium. The process of coal seam gas extraction with different hole sealing depth and hole sealing length is analyzed numerically. The results show that the sealing depth of gas drainage borehole should not exceed the peak point of stress concentration. When the peak value of stress concentration is exceeded, a barrier will be formed at the peak point of stress concentration in roadway, which will block the free flow of gas on both sides of the peak point. The reasonable length of sealing hole should pass through the pressure relief area of roadway and reach the stress concentration area, which is a little less than the distance from the side of roadway to the stress peak point. (3) using Comsol Multiphysics software, The seepage and diffusion process of slurry in the sealing section of coal was simulated. The results show that in the same grouting time, increasing grouting pressure can obviously increase the permeability of slurry permeable coal and the diffusion radius of slurry, and the increasing range of slurry diffusion radius decreases with the increase of grouting pressure. Under the same grouting pressure condition, the diffusion radius of the slurry can be increased by prolonging the grouting time, but the increase range is gradually slowed down, and there is an extreme value. The reasonable grouting parameters should be satisfied with the complete sealing of coal fissure around the borehole by slurry. (4) the field test results of Wangxingzhuang coal mine show that reasonable sealing parameters will make the gas extraction concentration of borehole higher. The attenuation period is obviously prolonged.
【学位授予单位】：华北科技学院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD712.6

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