High-density electrical method for evaluating effectiveness of hydraulic fracturing of coal mine roofs

To address the problems of poor spatial continuity and difficulty in achieving real-time dynamic feedback in traditional evaluation methods for coal mine roof hydraulic fracturing—such as borehole observation, microseismic monitoring, acoustic emission, or roadway deformation detection—the high-density electrical method combined with electrical resistivity tomography is innovatively adopted to realize dynamic, quantitative, and three-dimensional visualization monitoring of fracture development and fracturing fluid migration during the fracturing process. Taking the 112205 working face of No. 1 Coal Mine of Shaanxi Xiaobaodang Mining Co., Ltd. as the engineering background, continuous apparent resistivity surveys were carried out before, during, and after the staged fracturing of the XBD-02L horizontal well. Based on resistivity variations, a quantitative evaluation index ρ_SL for fracturing effectiveness was proposed. The detection results showed that the effective influence range of fracturing reached up to 200 m in the horizontal direction and 57 m in the vertical direction, and the fracturing fluid exhibited a dynamic diffusion–loss process. Multi-source verification of the high-density electrical results was conducted by integrating geophysical and engineering data: audio-frequency electrical penetration imaging demonstrated that resistivity anomaly zones were highly consistent with water-rich structures, and mine pressure monitoring data indicated that the periodic weighting interval in the fractured area was reduced by 39.35%, showing a significant mine pressure mitigation effect. Based on high-density electrical detection, a dynamic visualization monitoring and quantitative evaluation system for the entire process of coal mine roof hydraulic fracturing is established, which provides key technical support for optimizing hydraulic fracturing design and ensuring safe and efficient coal mining.