An automatic adjustment method of dipole sound source for acoustic logging based on segmented linear frequency modulation

Abstract

The invention discloses a method for automatically adjusting a dipole sound source in acoustic logging based on segmental linear frequency modulation. The method includes the following steps: sending an excitation signal to the logging formation, receiving a corresponding echo signal, and extracting the echo signal from the echo signal. The bending wave signal; process the bending wave signal to obtain the corresponding spectrum curve; obtain the three amplitudes under different frequency bands in the spectrum curve; obtain the duration corresponding to the three amplitudes respectively; increase the duration corresponding to the maximum amplitude value, and decrease The duration corresponding to the minimum amplitude value; according to the adjusted three durations, a new excitation signal is determined. Starting from the actual needs of downhole operations, adaptive parameters can be adjusted according to changes in the downhole environment, so as to ensure that the signal adapts to the changing downhole geological environment.

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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