Enhancement the VES models based on the TEM measurements and the application of static shift corrections.: case study from Egypt

Abstract

ABSTRACT Variations in conductivity in the near-surface, such as the presence of small and localized three-dimensional (3D) bodies, cause a galvanic distortion in direct current (DC), so the measured apparent resistivity is affected by a constant shift on a log scale called Static Shift. In this study, We used electromagnetic sounding techniques to correct for the static shift affecting the electric resistivity data only. The term “static shift” is used because apparent resistivity is distorted by a constant, shifting value (S) on a log scale, which lead to misleading interpretation. It was noticed that the two data sets' sounding curves at the same location have a concordant pattern. The problem was noticed in the 1D inversion models for VES and TEM were not matched together before removal of VES data shift. The TEM and VES measurements are represented on the same graph, then the shifting factor (S) is calculated for the VES curves to directly overlap the TEM curve. The 1D inversion model for VES curves after removing the shifting factor shows matched data with the TEM 1D model.