FIELD: mining industry, determination of electric resistance of layer under rock surface via cased shaft of borehole. SUBSTANCE: resistivity logging system incorporates source of voltage and current, aid adjusting voltage and current, aid fixing electrodes and aid processing voltage and current. System has first pair of electrodes for feed of current designed for electric connection to casing tube at various heights inside borehole, near one of ends of borehole to feed electric current to casing tube and to maintain current of casing tube between mentioned electrodes via intermediate part of casing tube between these electrodes. It has second pair of electrodes to pick off voltage, to detect voltages created by leakage currents flowing from casing tube to rock. Second pair of electrodes is meant for placement above or beneath first pair of electrodes between intermediate part of casing tube and other end of borehole. One of electrodes of second pair is placed near first pair of electrodes feeding current and another electrode to pick off voltage is located at considerable distance form first electrode. Another electrode to pick off voltage can be arranged at bottom of borehole, near shoe of casing tube or at top of borehole, near ground surface. EFFECT: more accurate determination of leakage currents. 9 cl, 4 dwg
