METHOD AND DEVICE FOR MEASUREMENT OF APPARENT ELECTRIC RESISTANCE OF ROCKS IN CASED WELL Russian patent published in 2014 - IPC G01V3/28 

FIELD: oil-and-gas industry.

SUBSTANCE: invention relates to geophysical analysis on cased well. electromagnetic field is excited by generator inductor coil supplied with bipolar current pulses 150 ms-long. Receipt of eddy current transient magnetic field is performed by coil inductor with ferrite core in time interval of 150-500 ms from solenoid coil supply current disconnection in continuous mode. Reception coil signal is pre-amplified by the use of high-Q-factor circuit of impact excitation including toroidal inductor coil. Electromagnetic field decay curves are analysed to calculate apparent electric resistance. Device comprises probing current source, generator and compensator coils arranged aligned and coaxially and connected in opposition via probing current source, reception coil, matching unit, registrator, extra toroidal inductor and switchgear. Extra toroidal inductor is connected with reception coil via switchgear elements in parallel with matching unit.

EFFECT: measurement of apparent resistance of rocks at sufficient accuracy.

2 cl, 5 dwg