径向强力膨胀法封孔提高抽采效果技术研究

On the boring hole sealing technology via the radial forceful expansion to improve the gas drainage effects

通过分析钻孔周围煤体在地应力作用下的变形与裂隙发育规律,结合鹤煤三矿原采用的瓦斯抽采钻孔封孔工艺,发现原采用的瓦斯抽采钻孔封孔工艺存在影响抽采瓦斯体积分数与效果的因素。确定合适的封孔材料需要满足4个主要的性质特征,提出了径向强力膨胀法封孔提高抽采效果技术。使用RFPA3D数值模拟软件研究了孔壁周围煤体裂隙发育范围,据此确定了封孔深度工艺参数,并在鹤煤三矿进行了现场对比试验。结果表明,与原封孔技术相比,应用径向强力膨胀法封孔技术封孔成功率高,抽采瓦斯体积分数和抽采纯量均有大幅度提高。

This paper aims to propose a method for improving the drainage effect by a new borehole sealing technology which was known as ＂the radial forceful expansion borehole sealing technology＂. This method is different from the traditional one in that it injects slurry into the fractures into the surrounding borehole, bore walls, the concave and convex surface of the coal seam at high pressures. When the slurry gets solidified, it will be mixed with the coal into the close association or combination and get closer to the passageway of the gas. It is known that the gas drainage is an important and useful method for preventing the gas accidents. However, low gas drainage concentration is always likely to lead to bad drainage effects. Our study indicates that the sealing quality of the gas drainage boreholes has a significant effect on the gas drainage concentration. So that in order to improve the drainage effect, first of all, it has to improve the borehole sealing quality. For this purpose, we have to analyze the factors which affect the borehole sealing quality, such as the regularity of the deformation and fracture development surrounding the boreholes, the properties of the sealing material and process. In addition, with the help of the numerical simulation software RFPA3D, we have also analyzed the fracture development of the hole and determined the proper layout parameters of the sealing process. Taking No.3 Hebi Mining Group into practice, firstly we analyzed the original sealing process of the gas drainage borehole, the law of deformation and fracture development surrounding the borehole under the ground stress as well as the factors affecting the gas drainage concentration and effects of the original sealing process of No.3 Hebi Mining Group. And, then, joining the results of the numerical simulation, we determined the appropriate sealing material needed to satisfy the four main demands and proposed the radial sealing technology to improve the gas drainage effects. The result of simulation shows that, in comparison with the original sealing process, this method can significantly increase the gas drainage concentration and heighten the borehole sealing quality and the drainage effect to a great extent.