Series Expansion Based 2.5D CGI Inversion Method

This paper presents a new inversion method used for the determination of 3D geological structures. The horizontal alterations of the layer parameters (i.e. thicknesses and resistivities) are discretized in series expansion form. The unknowns of the inversion are determined by an iterative linearized inversion method weighted by Steiner’s Method (Most Frequent Value Method). The result of the inversion is defined from the data of the bi-directional Schlumberger arrayed VES (Vertical Electric Sounding) measurements in each profile and in multiple profiles. A 3D Finite Difference method was applied for forward modelling. The structure is approximated with a 2D model discretized by single-variable series expansion. The 3D forward modelling procedure gives the opportunity to calculate data measured in two or multiple directions. The suggested interpretation method gives an approximate solution. Proceeding more accurate 3D inversion will be provided by the binary series expansion.