ELECTRICAL CASED WELL LOGGING METHOD Russian patent published in 2010 - IPC G01V3/20 

FIELD: physics; geophysics.

SUBSTANCE: invention relates to well logging and can be used in determining electrical resistance of rock formations surrounding a well cased by a metal column. The method involves using a probe consisting of three equidistant measuring electrodes and two current electrodes placed outside the zone of the measuring electrodes. Inphase electrical currents are simultaneously transmitted into the column through both current electrodes in defined proportions. The proportion of the currents is changed and inphase electrical currents are simultaneously transmitted into both current electrodes in the altered proportion. During transmission, the currents themselves are measured, as well as the electric field potential at the contact point between the middle measuring electrode and the column, the first potential difference on the section of the column between contacts of the two outermost measuring electrodes and the second potential difference on the same section of the column. Resistivity is determined using a corresponding formula.

EFFECT: increased accuracy, wider range of measurements.

1 dwg