METHOD OF LATERAL ELECTRIC PROBING Russian patent published in 2016 - IPC G01V3/20 

FIELD: electricity; mining.

SUBSTANCE: invention relates to geophysics and can be used to determine electric resistance of rock formations surrounding well and its change in radial direction relative to well axis. Summary: method employs probe consisting of set of multiple-electrode probes second difference, each of which is in form of three equidistant measuring electrodes, and located outside housing of downhole instrument and supply electrode electrically isolated from it. Current supply in feed electrode is fed in turns above and below multiple-electrode probes of second difference arranged along length of radiating electrode. At each of current feed from one pole of source of electric supply electrode field potential is measured at point of it contact with middle measuring electrode of each triplets of measuring electrodes, first difference of potentials is on section of supply electrode between contacts of two extreme measuring electrodes of each triplets of measuring electrodes and second difference of potentials at same section of supply electrode between contacts of all three measuring electrodes of each triplets of measuring electrodes. Electrical resistivity of rock formations surrounding well is defined by appropriate formulae.

EFFECT: high accuracy of determining true specific resistance of surrounding well formations and its change in radial direction due to higher level of useful signal of second potential difference and minimising effect of changes in resistance of supply electrode on measurement result, high rate of logging due to simultaneous measurement of all probes of downhole instrument.

6 cl, 4 dwg