METHOD OF ELECTRICAL LOGGING CASED WELLS Russian patent published in 2009 - IPC G01V3/22 

FIELD: physics; measurement.

SUBSTANCE: invention relates to well log survey and is meant for determining electrical resistivity of rocks in cased wells. The method of electrical logging cased wells employs a five-electrode probe, made in form of a series of three measuring electrodes equally spaced out along the axis of the well and two current electrodes, fitted beyond the borders of the measuring electrodes symmetrically about the middle measuring electrode. Bipolar rectangular pulses of direct current are alternately fed into the current electrodes of the probe. Measurement and digitisation of electric potential is done, as well as its first and second difference. All digitised signal quanta are respectively processed, filtered and resistivity of layers of rocks surrounding cased well is determined based on these signal quanta.

EFFECT: increased accuracy and reliability of the obtained information.

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