Resistivity detection and its application in underground coal mine directional boreholes

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.