METHOD OF LATERAL ELECTRIC SOUNDING Russian patent published in 2002 - IPC

FIELD: geophysical examination of holes, determination of electric resistance of rock formations surrounding hole and of its change in radial direction with reference to axis of hole caused by penetration of drilling fluid into formation. SUBSTANCE: according to method of lateral electric sounding metal body of down-hole logging instrument is used as focusing member and functions also as stabilizer of value of axial resistance of hole. It is made of metal alloy with thermally stable resistance or of steel sections interconnected in one electric circuit by straps of metal alloy with thermally stable resistance in points of connection of measurement and current electrodes to this body. Body houses required set of sondes of second difference, each comprising measurement transducer of second difference and dipole source. Electric current is fed to body through every current dipole in turn. Second difference of potentials of electric field across section of down-hole logging instrument between three measurement electrodes of measurement transducer of second difference and potential of body in point of contact of body with center measurement electrode of measurement transducer are measured with each current supply to this or that current dipole. Specific electric resistance per each sonde is found by corresponding formula. EFFECT: increased precision of determination of specific resistance. 7 dwg