Pitfalls in Three-Dimensional Numerical Modeling of Electrical Resistivity Method

Abstract

Three-dimensional electrical resistivity surveys have been regarded as one of the best techniques to eliminate subsurface shallow targets, although, the method suffers from ambiguity in the data interpretation. Therefore, numerical modeling has been involved for more comprehensive data interpretation. Several numerical modeling software packages have been developed, for example, RES3DMODx64. In addition, to perform a three-dimensional resistivity survey, a set of electrodes should be deployed as a grid on the ground surface which might be as a rectangular or a square grid. The optimum survey grid and electrode arrays, however, have to be tested. A three-dimensional subsurface resistive target has been numerically modeled before multiple three-dimensional resistivity data sets were generated using both of the rectangular and the square grids, and by utilizing the most popular electrode arrays; dipole-dipole, pole-pole, and, Wenner arrays. The data sets are then, inverted using a robust inversion algorithm, to generate three-dimensional resistivity models. Results were used in a quantitative comparison, and it showed that the dipole-dipole array was the optimum array in delineating the target’s shape, position, and resistivity value using the square grid. On the second rank, the rectangular grid uses the dipole-dipole array, then, followed by the Wenner array on the third rank. The pole-pole array was the poorest in the reconstruction of the subsurface target.