煤层瓦斯钻孔抽采有效半径确定方法研究

发布时间：2018-05-24 11:07

本文选题：数值模拟 + 穿层钻孔　；参考：《煤炭科学研究总院》2017年硕士论文

【摘要】：作为煤矿安全开采当中的主要灾害之一,瓦斯灾害一直被人们所重视。目前,在防止瓦斯灾害方面,煤层瓦斯的预抽是防治煤和瓦斯突出以及井下瓦斯超标的关键手段。为保证质量,科学分配钻孔彼此距离和预抽时间较为关键,但设计钻孔彼此距离的关键是抽采半径值。抽采半径又受到种种影响因素的制约,所以,怎样迅速、合理、精准的评价钻孔半径对抽采规划阶段而言存在巨大价值,对保证煤矿的安全生产具有非常重要的意义。本文利用理论分析,数值模拟和现场测试的方法,对钻孔抽采有效半径与抽采时间等之间的规律进行了研究。结合实验室对邯郸峰峰羊东矿2#煤层测定的瓦斯基本参数,运用渗流力学等理论推导了瓦斯抽采有效半径与抽采时间之间相互影响的耦合数学模型,借助COMSOLMultiphysics软件,得出瓦斯抽采半径与时间彼此的几何曲线,最终明确瓦斯抽采半径的具体数值。以邯郸峰峰羊东矿2#煤层为试验点,根据《煤矿瓦斯抽采达标暂行规定》的要求,利用瓦斯压力降低法和SF6气体示踪法对该煤层Φ94mm、Φ113mm、Φ133mm穿层钻孔和顺层钻孔抽采半径进行实际考察,并对实测的数据进行了分析研究。研究表明:随着抽采时间的增加,钻孔周围的煤层瓦斯压力以钻孔为中心,从抽采压力开始逐渐上升,抽采时间越长,煤层中瓦斯压力影响的范围就越大;距钻孔距离越近,瓦斯压力梯度越大,相反距钻孔距离越大,瓦斯压力梯度就越小,逐渐接近零,瓦斯压力上升到原始瓦斯压力,最终形成一个抽采的"瓦斯压力漏斗";在抽采时间没有变化的基础上,距钻孔间距越近,其渗流速度越高;相反距钻孔越远,其渗流速度越小,伴随抽采工作时间的持续提升,其渗流速度也不断降低,最终逐渐接近静止;抽采半径伴随渗透率的不断提升而提升,伴随渗透率的提升,瓦斯的抽采有效半径随着抽采时间的延长而增大。对于邯郸峰峰羊东矿2#煤层穿层钻孔和顺层钻孔,在考察范围(Φ94mm-Φ133mm)内抽采半径与钻孔直径有一定的关系,钻孔直径越大,有效抽采半径随之增大,随着抽采时间的延长,钻孔直径对有效抽采半径影响变大。
[Abstract]:As one of the main disasters in the safe mining of coal mine, gas disaster has been paid attention by people all the time. At present, in the aspect of preventing gas disaster, the pre-drainage of coal seam gas is the key means to prevent coal and gas outburst and underground gas exceeding the standard. In order to ensure the quality, the scientific allocation of the distance between the boreholes and the pre-drawing time is more critical, but the key to design the distance between the boreholes is the extraction radius value. The extraction radius is restricted by various factors, so how to evaluate the drilling radius quickly, reasonably and accurately is of great value to the planning stage of extraction and mining, and it is of great significance to ensure the safety of coal mine production. By means of theoretical analysis, numerical simulation and field test, the law between effective radius and extraction time of borehole extraction is studied in this paper. Combined with the basic parameters of gas measured in coal seam of Fengfeng Yangdong Mine in Handan, the coupling mathematical model of the interaction between the effective radius of gas extraction and the extraction time is deduced by using the theory of seepage mechanics, and the coupling mathematical model is developed by means of COMSOLMultiphysics software. The geometric curves of gas extraction radius and time are obtained, and the specific value of gas drainage radius is finally determined. Taking coal seam of Fengfeng Yangdong Mine in Handan as the test point, according to the requirement of coal mine gas extraction reaching the standard, using gas pressure reduction method and SF6 gas tracer method, actual investigation is carried out on the drilling radius of 桅 94mm, 桅 113mm, 桅 133mm borehole and bedding borehole in Handan coal seam. The measured data are analyzed and studied. The study shows that with the increase of drainage time, the gas pressure around the borehole is centered on the borehole, and gradually rises from the drainage pressure. The longer the extraction time is, the larger the influence of gas pressure in coal seam is, and the closer the distance from the borehole to the borehole, the greater the influence of the gas pressure in the coal seam. The bigger the gas pressure gradient is, the greater the distance from borehole is, and the smaller the gas pressure gradient is, the closer the gas pressure gradient is to zero, and the gas pressure is rising to the original gas pressure. Finally, a "gas pressure funnel" is formed. On the basis of no change in extraction time, the closer the distance from the borehole, the higher the percolation velocity; on the contrary, the farther away from the borehole, the smaller the percolation velocity, which is accompanied by the continuous improvement of the extraction time. The percolation velocity is also decreasing and finally approaching to rest gradually; the extraction radius increases with the increase of permeability, and with the increase of permeability, the effective radius of gas extraction increases with the prolongation of extraction time. For the boreholes of coal seam passing through the seam and the boreholes in the shun bed of Fengfeng Yangdong Coal Mine in Handan, the extraction radius and the diameter of the borehole in the investigation range (桅 94mm- 桅 133mm) are related to the diameter of the borehole. The larger the diameter of the borehole is, the more the effective extraction radius increases, and with the prolongation of the extraction time, The influence of borehole diameter on effective extraction radius becomes larger.
【学位授予单位】：煤炭科学研究总院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD712.6

【相似文献】