Cross dipole anisotropic rapid inversion method and system

Abstract

The invention relates to a cross dipole anisotropic rapid inversion method and system. The method comprises the steps that the data to be processed are preprocessed; the data to be processed include four-component data; the data to be processed are rotated so as to obtain the 45-degree azimuth angle phi with the fast transverse wave or slow transverse wave azimuth; the azimuth angle phi is utilized, and the theta is substituted in the rotation formula so as to obtain the fast transverse wave waveform and the slow transverse wave waveform when theta=phi+45 degrees is the fast transverse wave azimuth; the fast transverse wave waveform and the slow transverse wave waveform are used for fast and slow transverse wave slowness difference inversion, and the fast and slow transverse wave slownessdifference delta<s> is obtained through the principle of waveform matching; and the slow transverse wave waveform array is used for slow transverse wave slowness inversion, and the slow transverse wave slowness s2 is obtained through the linear prediction theory. Three-parameter joint inversion is converted into stepwise inversion of three single parameters so that calculation of the objective function can be simplified, the singularity of inversion can be reduced, the inversion stability can be enhanced and the inversion speed can be enhanced.

Description

technical field [0001] The invention relates to the technical field of applied geophysical well logging, in particular to a fast cross-dipole anisotropy inversion method and system. Background technique [0002] The detection of formation anisotropy plays an important role in the development of unconventional oil and gas. There are two types of causes of formation anisotropy: one is caused by directional fractures or inter-bedding in the formation itself, and the other is caused by biased in-situ stress. Therefore, identifying the anisotropy of the formation can detect formation fractures or the ground stress. At present, the four-component data measured by crossed dipoles are generally used in well logging to obtain formation anisotropy parameters through inversion: including fast and slow shear wave time difference and azimuth angle of fast or slow shear wave. The inversion method generally adopts the waveform matching method of Alford rotation or three-parameter simultan...

AI Technical Summary

Problems solved by technology

Although the waveform matching method can obtain relatively stable results, due to the joint inversion of three parameters, especially due to the need for global optimization of a relatively strong nonlinear function, the efficiency is generally low, and the results may also be unstable.

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