Dual laterolog equipment, electrode system of dual laterolog equipment and formation resistivity measuring method

Abstract

The invention relates to dual laterolog equipment, an electrode system of the dual laterolog equipment and a formation resistivity measuring method. The electrode system comprises an electrode system body and an insulation core rod, consists of a plurality of electrodes arranged on one insulation core rod, and is connected with a measuring circuit through a conducting wire; insulation materials are used for separating the plurality of electrodes; the center of the insulation core rod is a metal rod; a through hole is formed in the center of the metal rod; the metal rod is isolated from the electrode system; the electrode system comprises main electrodes A0 and A0', at least one pair of shielding electrodes A2, A2', A1 and A1', a plurality of pairs of voltage measuring electrodes A1*, A1*', M0 and M0' and at least one pair of voltage monitoring electrodes M2, M2', M1 and M1', wherein the main electrodes A0 and A0' are arranged in the middle of the electrode system; the shielding electrodes A2, A2', A1 and A1' are used for emitting shielding current for focusing main current; the voltage measuring electrodes A1*, A1*', M0 and M0' are used for measuring electrode voltage; the voltage monitoring electrodes M2, M2', M1 and M1' are used for voltage monitoring; the shielding electrodes A2 and A2 are in short-circuit connection; the main electrodes A0 and A0' are in short-circuit connection; and other electrodes are not in short-circuit connection. Therefore compared with a hard focusing mode, the electrode system has high measuring precision.

Description

technical field [0001] The invention relates to a well logging device used for petroleum exploration and development, in particular to a double lateral logging instrument, its electrode system, and a formation resistivity measurement method. Background technique [0002] Dual laterolog tool is the main instrument for measuring formation resistivity in open hole, studying formation invasion changes, and estimating oil saturation. The traditional dual laterolog tool mainly includes electrode system, electronic circuit, and insulating nipple. The resolution is about 0.6 meters. When the traditional dual laterolog tool performs deep lateral logging, the annular electrode emits current into the formation, and the cylindrical electrode emits shielding current to focus on the main current. A feedback loop is required in the electronic circuit to adjust the shielding current, and the control monitoring electrode is at Equipotential. For example, Chinese patent CN1712995A disclose...

AI Technical Summary

Problems solved by technology

Although the high-resolution azimuthal resistivity logging tool and logging method adopt digital focus mode and hard focus mode, compared with the original hard focus The method of short-circuiting the electrode ring with the same name still does not solve the influence of the vertical potential gradient formed in the center of the instrument, making it difficult to achieve higher measurement accuracy

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