Research on Comprehensive Geophysical Exploration Technique Experimental for Permeability Enhanced Effect of Hydraulic Fracturing

In order to test the influence range of hydraulic fracturing in gas control, three geophysical methods, namely electromagnetic wave CT method, mine transient electromagnetic method and mine high-density electric method, were used to detect through-hole drilling and fracturing area of the working face before and after hydraulic fracturing, the geophysical response characteristics of each geophysical method to hydraulic fracturing were studied and verified its validity. The results show that the electrical parameters of the coal and rock layers around the fractured borehole have changed significantly after water injection and fracturing. The electromagnetic wave CT method shows that the surrounding rock field intensity attenuation in the range of 5 m to 15 m of the fracturing borehole location increases, transient electromagnetic method shows that the apparent resistivity decreases by about 1.5 times to 2.0 times in the range of about 20 m near the fracturing borehole, and the mine high- density electric method is characterized by the extension of the relatively low-resistance zone from the lateral direction of the fracture hole to the detection of the laneway. The gas extraction and recovery exposure are basically consistent with the test results.