Study and Field Application of Area-Apparent Porosity of Coal Seam Disturbance Based on Resistivity Imaging Technology

Electrical resistivity imaging technology provides an effective solution for geotransparency of underground roadways. In this paper, we use finite-element method simulations to obtain coupled equations for the resistivity of the representative elementary volume (REV) and propose a method for inversion of apparent porosity. The main conclusions are as follows: the resistivity of the REV is affected by the combined effect of resistivity and porosity. The porosity–resistivity change path is the basic path that characterizes the resistivity of the REV. A coupled equation for REV resistivity is established based on the differential effective medium approximation (DEMA), and the calculation equation of the apparent porosity of a coal rock body is derived. An inversion method of apparent porosity based on apparent resistivity data is proposed. The field results show that the apparent porosity varies significantly in the disturbed area and less in the undisturbed area. This study helps to improve the quantitative analysis for geotransparency of a deep coal rock state.