f Nonlinear 3D Inversion of Crosswell Electrode Loggind Data

Electrode logging as known in the oil industry is a method for determining the electrical conductivity distribution around a borehole or between two boreholes from the electrostatic field (dc) measurements in the borehole. In this paper we discus the reconstruction of the conductivity in a three-dimensional Romain between two boreholes. The electric current density integral equation will be taken as point of departure. This vector integral equation leads to substantially better results than inversion based on the scalar integral equation for the electric potential. We will use a nonlinear inversion scheme based on a new method, the so-called Contrast Source Inversion method (CSI), recently introduced by Van den Berg and Kleinman (1997).