深部高瓦斯低透煤层水压致裂强化增透技术与应用

发布时间：2018-02-13 04:29

本文关键词： 穿层孔低透气性煤层水力压裂卸压增透数值模拟　出处：《安徽理工大学》2014年硕士论文　论文类型：学位论文

【摘要】：本文针对李嘴孜煤矿水力压裂卸压增透技术的研究,采用理论分析、数值模拟和现场试验相结合的方法,以A1煤层32321底板巷区域进行现场试验研究了水力压裂卸压增透效果。结果表明通过水力压裂措施能提高A1煤层的透气性系数、加强内部瓦斯气体的流动、湿润煤体降尘作用、提高抽采率降低煤层突出危险性的目的。对水力压裂的力学特性进行了分析,采用大直径的钻孔进行水力压裂时可增加钻孔四周的卸压区域,加大钻孔四周的煤体的暴露表面积,加强内部瓦斯气体的流动,起到增加煤层透气性的效果。分析了钻孔的起裂位置和起裂所需压力,得出：起裂压力的临界值在数值模拟实验中,模拟了不同埋深的起裂压力,得出煤岩体的起裂时的注水压力随着煤层埋深而增加,压裂钻孔起裂压力数据进行回归分析得到煤层埋深与起裂压力的关系式：y=10.351e0.0014x,R2=0.9837,计算得A1煤层处的起裂压力24.92Mpa。600m处的压裂半径在12.665-14.965m；500m处的13.683-16.876m；400m处压裂半径在16.011-18.846m；卸压区域的煤层渗透系数提高了2.5倍左右。现场试验中,通过对A1煤层的压裂试验,对压裂工艺流程和压裂前后的安全措施进行了详细设计,分走向和倾向方向上设计了考察方案。倾向上最大影响半径50m、走向上最大影响半径70m,水力压裂后对瓦斯抽采浓度和抽采量的提高十分明显,抽采浓度在36%～56%之间,平均抽采混合流量浓度0.3lm3/min,平均抽采纯流量则基本稳定在0.16m3/min,单孔纯流量约为0.013m3/min,压裂后干管抽采平均浓度为压裂前的1.7倍；压裂后单孔平均抽采纯量为压裂前的3.5倍,压裂影响区域煤层透气性系数达0.372m2/(MPa2·d)较原始0.062m2/(MPa2·d)提高了6倍。对李嘴孜煤矿A1煤层层内卸压增透技术的研究,结合现场实测,验证了力学分析结果和数值模拟计算结果的准确性。
[Abstract]:Aiming at the research of hydraulic fracturing and anti-permeability technology in Lizuizi Coal Mine, this paper adopts the method of combining theoretical analysis, numerical simulation and field test. In this paper, the anti-permeability effect of hydraulic fracturing is studied in 32321 floor roadway area of coal seam A1. The results show that hydraulic fracturing measures can improve the permeability coefficient of coal seam A1, strengthen the flow of gas gas in coal seam, and reduce dust of wet coal body. The purpose of increasing extraction rate and reducing coal seam outburst risk. The mechanical characteristics of hydraulic fracturing are analyzed. When hydraulic fracturing is carried out with large diameter borehole, the pressure relief area around the borehole can be increased, the exposed surface area of coal around the borehole can be increased, and the flow of gas gas inside the borehole can be strengthened. This paper analyzes the starting position of borehole and the pressure required for the initiation of the crack, and obtains the critical value of the initiation pressure of the coal seam with the effect of increasing the permeability of the coal seam. In the numerical simulation experiment, the initiation pressure of different burying depth is simulated, and the water injection pressure of coal and rock mass increases with the depth of coal seam burying. The regression analysis of fracture initiation pressure data obtained the relationship between coal seam burying depth and fracture initiation pressure, and calculated the fracture radius of A 1 coal seam at 24.92 Mpa.600m, 13.683-16.876m400m at 12.665-14.965mand 16.011-18.846m, respectively, and the fracturing radius was 16.011-18.846m, and the fracture radius was 24.92Mpa.600m at A1 coal seam, and the fracturing radius was 16.011-18.846m at 12.665-14.965mb.500m, and the fracture radius was 16.011-18.846m at the point of 12.665-14.965mb / 500m. The permeability coefficient increased about 2.5 times. In the field test, the fracturing process and safety measures before and after fracturing are designed in detail through the fracturing test of A1 coal seam. The investigation plan is designed in the direction of strike and inclination. The maximum influence radius on inclination is 50 m, and the maximum influence radius on strike is 70 m. After hydraulic fracturing, the concentration and quantity of gas extraction are obviously increased, and the extraction concentration is between 36% and 56%. The average pumping flow rate was 0.3lm 3 / min, the average pumping pure flow rate was 0.16m3 / min, the single hole pure flow rate was 0.013m3 / min, the average extraction concentration after fracturing was 1.7 times higher than that before fracturing, and the average extraction scalar amount after fracturing was 3.5 times higher than that before fracturing. The permeability coefficient of coal seam in the area affected by fracturing is 0.372m-2 / m-2 路d), which is six times higher than that of original 0.062m2 / m-1 / m-2 路d). Based on the research of pressure relief and antireflection technology in A1 coal seam of Lizuizi coal mine, the accuracy of mechanical analysis and numerical simulation results is verified by field measurement.
【学位授予单位】：安徽理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TD712

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