METHOD OF LOGGING WELLS, CASED WITH METAL COLUMN Russian patent published in 2017 - IPC G01V3/20 

FIELD: mining engineering.

SUBSTANCE: invention is intended to determine specific electrical resistance (SER) of rock, surrounding a well, cased with the metal column. Substance: probe is used in the form of several measuring electrodes located along the well axis, and two current electrodes located on the opposite sides thereof. The measurement process consists of three cycles, in which bipolar pulses of electric current are alternately fed: 1) between the first and second current electrodes (the mode of monitoring the measurement conditions); 2) with respect to the electrode B in the first current electrode; 3) relative to the electrode B in the second current electrode. In each cycle, the fed currents and potential differences between each measuring electrode and the electrodes spaced from it by one and two intervals between the electrodes are measured; In the second and third cycles, the potential of one of the measuring electrodes is also measured. Based on the digitized measurement results of changes from the three cycles, the specific electrical resistance at the depths corresponding to the positions of the measuring probes is determined, except for the end ones, according to the appropriate formula, which also takes into account the diameter of the casing column. The mathematical formulas used in the method do not contain tuning factors.

EFFECT: increase the accuracy to detrmine the specific electric resistance due to influence of the diameter of the casing column, the position of the measuring interval relative to the face and wellhead, and more effective compensation of the unbalance effect of the electrode positions and the inconsistency of the casing column line resistance, and compensation of the guidance.

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