Primary Exploration of TEM Topographical correction in coal resource exploration

It is usually considered that TEM detection which uses the signal of secondary induction field is influenced little by the topography. In fact, with many years´ production practice, we find that the influence of topography should not be neglected. TEM exploration in the coal resources, with the coal seam shallow buried, is influenced more by the topography. In this paper, firstly, with the commonly used depth calculation formula in the coal field, we calculate the influence degrees of topography variation on induced electromotive force and attenuation time separately. Then, substitute the two influencing factors into the parameters and calculate new apparent resistivity. According to the new apparent resistivity calculation depth, a set of practical topographical correction methods about the coal measure strata will be obtained. The theoretical model and actual data have proved the effectiveness of this method and software.