Depth correction technique of electrical marker based on electrical field component of CSAMT

Controlled Source audio-frequency Magnetotellurics(CSAMT) is an important geophysical method to detect water-rich areas and goafs in coal strata. However, the detection depth error is relatively large. Therefore, the electrical marker layer is used for depth correction to achieve the purpose of accurate interpretation of strata in this paper. A method for calculating all time apparent resistivity based on single component of electric field is proposed. The apparent resistivity can be obtained by translation algorithm, which is simple and fast without iteration. The relationship between the differential extremum of the apparent resistivity and the electrical marker layer is analyzed, and the electrical marker layer is identified by the well logging resistivity curve, then the depth correction coefficient is calculated by the ratio. Finally, the correction depth of any measuring point is obtained by interpolation in the whole region. Depth correction is carried out for the survey line R280 data of working face 31004, Xinyuan Coal Mine, and the results show that the corrected depth is in better agreement with the actual formation. Through comparison and verification of the known of known water-filled goaf boundary, water spraying point and borehole data, the desired goals are achieved. This method provides a new idea for fine data processing and interpretation by CSAMT in coal strata.