Variable gain electromagnetic wave resistivity detection method and system while drilling

By extracting features from the induced current signal and adjusting the gain prediction value, the problems of gain adjustment lag and signal distortion in the drilling electromagnetic resistivity detection system when the formation properties change drastically are solved, and high-precision resistivity monitoring is achieved.

CN122169783APending Publication Date: 2026-06-09HUBEI HONGHUA LONG TECH MASCH & ELECTRICITY CO LTD
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
HUBEI HONGHUA LONG TECH MASCH & ELECTRICITY CO LTD
Filing Date
2026-02-06
Publication Date
2026-06-09

AI Technical Summary

Technical Problem

Existing electromagnetic resistivity detection systems used in drilling suffer from problems such as lag in receiving gain adjustment, signal saturation distortion, and environmental noise interference when faced with drastic changes in formation properties, leading to a decrease in monitoring accuracy.

Method used

By extracting features from the induced current signal, the basic gain prediction value is obtained using the antenna's time change rate of phase difference and the amplitude of the received signal. Combined with the gain correction coefficient and the circuit ambient temperature, the receiving gain of the receiving circuit is adjusted to achieve variable gain control.

Benefits of technology

It reduces signal saturation caused by abrupt geological interfaces, improves the linearity of signal processing and the robustness of the detection process, and ensures high-precision monitoring under complex working conditions.

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Abstract

This invention belongs to the field of geophysical logging technology, specifically relating to a variable gain electromagnetic resistivity detection method and system for drilling. The method includes: acquiring an induced current signal; extracting the real and imaginary parts of the magnetic field strength vector; calculating the antenna pair phase difference and the received signal amplitude; evaluating a basic gain prediction value based on the time rate of change of the antenna pair phase difference and the received signal amplitude fluctuation; evaluating the equivalent formation impedance matching residual by combining the antenna pair phase difference and the received signal amplitude, and obtaining a gain correction coefficient; obtaining a variable gain control voltage based on the basic gain prediction value, the gain correction coefficient, and the cumulative term of the circuit environment temperature deviation, and adjusting the receiving gain of the receiving circuit accordingly. This invention solves the technical problem of traditional gain control easily saturating at formation abrupt transition interfaces, ensuring that the signal is always in the optimal linear operating range, and improving the accuracy and robustness of full-range resistivity measurement.
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