Mine Roof Water Detection Based On Seismic-Constrained TEM in Ordos Basin, China

Mine roof water (water in the overlying aquifers of coal seam) seriously threatens the safe production of coal mines in the Ordos Basin in China. Transient electromagnetic (TEM) and seismic methods are the two key methods of mine roof water detection. To exploit the advantage of each method, the seismic-constrained TEM method is proposed. First, the seismic-constrained TEM inversion algorithm was constructed by adding a cross-gradient function to the pseudo-2D TEM inversion algorithm. The cross-gradient function makes the structures of the TEM and seismic models consistent in inversion. To match the seismic and TEM model grids, the interpolation of the seismic impedance model was proposed. Then, the proposed algorithm was successfully used in the Maiduoshan coal mine in the Ordos Basin. Data acquisition, seismic-constrained TEM inversion and interpretation were carried out. Seventeen boreholes were drilled to verify the interpretation results, and the drilling results are consistent with the detection results. Finally, the seismic-constrained and single TEM methods were compared. Results show that the seismic-constrained TEM method is superior to the single TEM method. The structural consistency of the resistivity and seismic impedance models increases in the seismic-constrained TEM inversion and decreases in the single TEM inversion. Seismic-constrained TEM inversion can add the stratigraphic structure information provided by the seismic method to the TEM inversion, thereby improving the inversion results.