Noncontacting electrical conductivity sensor for remote, hostile environments

Abstract

A device for measuring the electrical conductivity at the surface of a large or semi-infinite body at centimeter scale has been developed. The right frequency contacting measurement uses single turn transmitter and receiver loops to generate and detect eddy currents in the material to be probed. Response is linear in conductivity over the four decades of interest in geophysical investigations. The mechanical design of the sensor makes it insensitive to temperature and pressure changes, and to accelerations, impact, and abrasion. Therefore, it is operable in remote, hostile environments such as deep boreholes.