Resistivity imaging using flexible electrode combinations for multihole- surface resistivity surveys

Abstract

This paper describes the use of flexible electrode combinations for multi-borehole-surface resistivity surveys. Traditionally resistivity imaging adopts standard electrode arrays, such as Schlumberger, Wenner or dipole-dipole. These arrays were originally designed for use in surface surveys. For cross-hole or boreholesurface resistivity surveys, no analogous standard array design exists. Therefore we introduce a new method to complete a multi-borehole-surface resistivity survey, which has significant application in civil engineering and environmental exploration. For the method, electrodes may be positioned in both surface and boreholes positions with almost no limitation on the amount of electrodes able to be used in the boreholes. Real cases are presented showing that the multi-borehole-surface resistivity method is capable of solving some very difficult civil engineering exploration problems. This method is based on advanced resistivity inversion techniques, flexible electrode combinations, along with a fast multi-channel data acquisition system. It can easily be used for 3D resistivity multi-borehole-surface surveys.