Method for obtaining an acoustic logging axisymmetric model dispersion curve

By obtaining the dispersion curve of the axisymmetric model of sonic logging using the modified Bessel function and the local condition number peak method, the problems of low accuracy and non-convergence of iteration in the existing technology are solved, and higher accuracy cementing quality evaluation is achieved.

CN117634123BActive Publication Date: 2026-06-19UNIV OF ELECTRONICS SCI & TECH OF CHINA
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
UNIV OF ELECTRONICS SCI & TECH OF CHINA
Filing Date
2022-08-17
Publication Date
2026-06-19

AI Technical Summary

Technical Problem

In existing technologies, the calculation accuracy of dispersion curves of axisymmetric models in acoustic logging is low. Traditional methods are difficult to effectively obtain the dispersion poles of leakage modes, and the Gauss-Newton iteration method is cumbersome and does not converge, making it difficult to obtain dispersion curves.

Method used

The propagation mode dispersion poles are processed by the determinant method of the modified Bessel function, and the leakage mode poles are searched by the local condition number peak method. Combined with the global matrix form and boundary conditions, the propagation and leakage mode dispersion curves are separated to obtain the dispersion curve of the multipole sound source of the axisymmetric model.

Benefits of technology

It improves the calculation accuracy and reliability of dispersion curves, provides more accurate cementing quality evaluation data support, simplifies the iteration process, avoids the defects of traditional methods, and improves the practical application effect of sonic logging technology.

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Abstract

This invention discloses a method for obtaining dispersion curves of an axisymmetric model in acoustic logging. The method includes: determining the transmission mode between interlayer fluid-solid media based on the input parameter model; constructing a global matrix form of the entire model by combining the displacement and stress relationship equations of the coupling interface; using formation shear wave velocity as the dividing criterion; applying the determinant method of the modified Bessel function to the dispersion poles of the propagation mode; and applying the condition number peak method to the dispersion poles of the leakage mode to obtain the dispersion curve results of the entire model. This invention is applicable to obtaining dispersion curves of multi-layer axisymmetric models and various types of acoustic sources, including common open-hole wells, free casing, monopoles, and dipoles. It improves the research on dispersion curve acquisition methods for axisymmetric models, provides strong support for cementing quality evaluation, and provides support for the theory and foundation of acoustic logging.
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