煤矿井下定向钻孔中电阻率探测技术与应用

Resistivity detection and its application in underground coal mine directional boreholes

受高瓦斯/承压奥灰水威胁的工作面开采前,一般采取定向钻进技术在工作面底板开展压裂或注浆工程保障开采安全。利用底板定向钻孔开展孔中探测工作,可更加精细揭露工作面内隐伏构造,还可实现“一孔多用”。为解决定向钻孔内的探测问题,提出一种在水平定向钻孔中进行直流电阻率法探查的方法。定向钻孔施工完毕后,退出定向钻孔施工的通缆钻杆,送入内平钻杆,将孔中高密度电缆通过钻杆尾端特制水便送入钻孔,使孔中电缆平铺于钻孔中,在定向钻孔水平段,进行孔内直流电阻率法径向探测。在理论上通过数值模拟研究层状介质下单孔测量工作模式的接收信号衰减规律、视电阻率曲线变化特征、顶底板岩性对测量结果的影响等,并采用单孔测量数据对孔旁异常范围进行反演定位。数值模拟研究表明,孔中电阻率探测方法对隐伏的异常体有良好的探测效果。通过在陕西韩城某矿井下实际煤层底板探测试验,对研究区2个定向抽采钻孔孔中探测数据进行处理,反演结果异常区与工作面内隐伏小断层位置吻合,验证了定向钻孔中电缆布置的可行性和定向钻孔内通过孔内径向和孔间透视探测隐伏构造的可靠性。

The working face threatened by high gas or Ordovician limestone water pressure generally adopts directional drilling technology to carry out fracturing or grouting works at the bottom of the working face before mining to ensure the safety of mining.In-hole probing in directional boreholes in the bottom plate can reveal the hidden structures in the working face in a more detailed way,and can also realize“one hole for multiple uses”.In order to solve the detection problem in the directional drilling,a method of DC resistivity detection in the horizontal directional drilling is proposed.To solve the problem of detection in directional hole,a method of direct current detection in horizontal directional drilling is proposed.After the completion of directional drilling,exit the cable drill pipe of directional drilling and send it into the inner flat drill pipe.Sent the high-density cable of the hole into the drill hole through the special water supply device at the end of the drill pipe,so that the cable in the hole is laid flat in the drill hole.Through numerical simulation,the attenuation law of the received signal,the variation characteristics of the apparent resistivity curve,and the influence of roof and floor lithology on the measurement results of the working mode of single-hole measurement in layered media are studied,and the anomaly range near the hole is inverted by using the single-hole measurement data.In the horizontal section of the directional drilling,radial detection by direct current method in the hole is carried out.Numerical simulation results show that the resistivity detection method is effective in detecting concealed abnormal bodies.Through the actual coal seam floor detection test in a mine in Hancheng,Shaanxi Province,the data processing results of two directional extraction boreholes in the study area show that the anomaly area of inversion is consistent with the location of hidden small faults in the working face;the feasibility of cable arrangement in directional borehole and the reliability of radial/perspective detection of concealed structure in directional borehole are verified.