松软底板低透煤层穿层预抽瓦斯技术研究

发布时间：2018-09-08 10:33

【摘要】：本文针对松软底板低透煤层穿层钻孔抽采瓦斯困难的问题,从钻孔增透消突、围岩预注浆、钻孔密封和抽采参数优化等方面进行了理论研究和工程实践。研究了钻孔周围煤体的应力分布规律、渗透率变化规律和钻孔预抽煤层瓦斯消突机理。实测了鹤煤十矿二1煤层原始瓦斯基础参数,建立瓦斯抽采气固耦合模型,结合RFPA2D-Flow软件模拟了穿层钻孔抽采煤层瓦斯时,不同抽采时间、钻孔直径和抽采负压对钻孔周围煤体物理力学参数和瓦斯流动情况的影响,确定了合理的瓦斯抽采参数。研究了宾汉体浆液的柱形扩散理论,公式表明浆液扩散距离与岩土层渗透率、注浆压力、注浆时间及注浆管管径成正比,与浆液浓度成反比,结合二1煤层底板情况给出了水灰比为0.7和1.0的水泥基浆液柱形扩散时扩散半径与注浆压力、注浆时间的三维坐标图,为现场松软破碎底板围岩预注浆和钻孔带压注浆封孔提供理论依据。分析了钻孔漏气的形式和原因,建立了钻孔漏气模型,针对二1煤层底板松软破碎的情况,应采取围岩注浆减少岩体裂隙、降低抽采负压、增大钻孔封孔长度和使用小直径高强度瓦斯抽采管等措施改善封孔效果,确定钻孔封孔长度必须大于11m。现场实践中,对瓦斯抽采钻场周围岩体进行了带压预注浆封堵裂隙,实际注浆量比理论值高10.4%；采用PDC钻、扩单翼组合钻头对松软低透煤层进行掏穴扩孔增透；钻孔封孔时采用“两堵一注”式带压注浆全程封孔工艺,并使用小直径(1”)高强度PVC管用作孔内抽采管。考察了钻孔瓦斯抽采浓度、流量和抽采影响半径,多项技术措施的实施,达到了提高钻孔抽放瓦斯效果的目的。
[Abstract]:Aiming at the difficult problem of gas extraction by drilling holes in soft floor low permeable coal seam, this paper has carried out theoretical research and engineering practice from the aspects of antireflection and outburst suppression, surrounding rock pre-grouting, borehole sealing and optimization of extraction parameters. The stress distribution, permeability change and gas outburst suppression mechanism of coal body around borehole are studied. The original gas foundation parameters of No. 2 coal seam in No. 2 coal seam of Hewan No. 10 Coal Mine were measured, and the gas extraction coupling model was established. Combined with the RFPA2D-Flow software, the different extraction time of coal seam gas was simulated when the coal seam was extracted by drilling through the stratum. The influence of borehole diameter and suction negative pressure on the physical and mechanical parameters of coal body and gas flow around the borehole has been determined and the reasonable gas drainage parameters have been determined. The cylindrical diffusion theory of Bingham slurry is studied. The formula shows that the diffusion distance of slurry is proportional to the permeability of rock and soil layer, grouting pressure, grouting time and the diameter of grouting pipe, and is inversely proportional to the concentration of slurry. Combined with the case of the floor of No. 1 coal seam, the three-dimensional coordinate diagrams of the diffusion radius, grouting pressure and grouting time of cement-based slurry columnar diffusion with water-cement ratio of 0.7 and 1.0 are given. It provides theoretical basis for pre-grouting and hole-sealing with pressure grouting on site soft broken floor surrounding rock. This paper analyzes on the form and cause of gas leakage in borehole, establishes the model of gas leakage in borehole, aiming at the soft breakage of floor of No. 1 coal seam, it is necessary to adopt surrounding rock grouting to reduce the crack of rock mass and to reduce the negative pressure of mining. The length of hole sealing must be greater than 11m by increasing the length of hole sealing and using small diameter and high strength gas drainage pipe to improve the effect of hole sealing. In the field practice, the rock mass around the gas drainage drilling yard is plugged by pre-grouting with pressure, and the actual grouting quantity is 10.4% higher than the theoretical value, the PDC drill is used to expand the single wing combination bit to increase the permeability of the soft and low permeable coal seam. The "two plugging and one injection" process with pressure grouting was adopted in the hole sealing process, and the small diameter (1 ") high strength PVC pipe was used as the pumping pipe in the hole. The concentration, flow rate and influence radius of borehole gas drainage, as well as the implementation of several technical measures, have been investigated in order to improve the effect of borehole gas drainage.
【学位授予单位】：安徽理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TD712.6

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