METHOD FOR DETERMINING ELECTRIC CONDUCTIVITY OF SOIL LAYER Russian patent published in 2000 - IPC

FIELD: borehole logging by geophysical method. SUBSTANCE: method involves dipping into borehole shaft an induction logging instrument incorporating magnetic-field source suited to inducing magnetic fields of various frequencies in soil layers and magnetic-field receiver suited to receive response magnetic fields at various distances from source and to produce signal typical of each response magnetic field. At least two of mentioned various frequencies and at least two of mentioned distances are chosen; source is controlled for each chosen frequency and distance so as to induce magnetic field of chosen frequency in mentioned soil layers that induces respective response magnetic field near instrument. Receiver is controlled at chosen distance from source so as to produce signal presenting response magnetic field. Signals are combined so as to produce integrated signal less dependent of electric conductivity in vicinity of borehole shaft and of electric conductivity of soil adjacent to chosen layer. EFFECT: improved accuracy due to eliminating impact of borehole environment and adjacent layers on logging results. 10 cl, 1 dwg