Exploring multiple electrical layers overlying coal seams using the transient electromagnetic method.

The transient electromagnetic method (TEM) is widely applied in coal hydrogeological exploration owing to its sensitivity to low-resistivity bodies. However, when a coal seam is buried deep, particularly if there are multiple electrical layers in the vertical direction of the overlying stratum, the results of the calculation using the late-channel empirical formula of the TEM may no longer reflect the actual situation. In this study, we evaluated the principle of the one-dimensional (1D) Occam algorithm and the steps for performing an inversion.