Acoustic logging dipole sound source automatic adjusting method based on piecewise linear frequency modulation

Abstract

The invention discloses an acoustic logging dipole sound source automatic adjusting method based on piecewise linear frequency modulation, wherein the method comprises the following steps: transmitting an excitation signal to a logging stratum, receiving a corresponding echo signal, and extracting a bending wave signal in the echo signal; processing the bending wave signal to obtain a corresponding frequency spectrum curve; acquiring three amplitudes under different frequency bands in the frequency spectrum curve; acquiring duration time corresponding to three amplitudes respectively; increasing the duration corresponding to the maximum amplitude value, and reducing the duration corresponding to the minimum amplitude value; and determining a new excitation signal according to the adjusted three durations. Starting from actual requirements during underground operation, self-adaptive parameter adjustment can be carried out according to underground environment changes, so that it is ensured that signals adapt to changing underground geological environments.

Description

technical field [0001] The invention relates to the field of geophysical well logging, in particular to an automatic adjustment method of a dipole sound source for acoustic logging based on segmented linear frequency modulation. Background technique [0002] In dipole acoustic logging, the low frequency phase velocity of the dipole is close to the formation shear wave velocity, while the high frequency can reflect the shear wave velocity near the borehole wall. Therefore, obtaining signals in a wider frequency band and then extracting broadband dispersion curves can better perform dispersion correction and near-borehole imaging. The excitation intensity of the bending wave excited by the dipole in the wellbore varies with the frequency. Generally speaking, the excitation intensity of the bending wave is relatively high near the Airy phase frequency point, while in the low frequency band (near 2kHz) and high frequency band (8kHz Nearby) is relatively low, especially in the c...

AI Technical Summary

Problems solved by technology

However, in the current research and application, the parameters of the segmental chirp signal are fixed and cannot be adjusted

In the actual logging process, the formation environment changes in real time, and with the change of downhole temperature and pressure, the frequency response of the transducer and other performances will also change accordingly. correct compensation for varying flexural wave excitation intensity curves, which affect log quality

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