Abstract: Methods and apparatuses for determining conductivity of a subterranean formation traversed by a well, particularly a cased well are provided. Variations in casing conductivity and/or electrode placement, arising from, e.g. thermal stress or expansion or corrosion, are compensated for. Compensation involves obtaining voltages developed in response to current flowing between relatively closely spaced current electrodes, and using these voltages to provide compensation for voltages developed in response to current flowing between more remotely positioned current electrodes. Modifications are described to permit conductivity measurements in partially cased or uncased wells, or wells being actively drilled.