Prestack hybrid nonlinear inversion method and computer readable storage medium

Abstract

The invention discloses a prestack hybrid nonlinear inversion method and a computer readable storage medium. The method may include the following steps that: prestack linear inversion is performed onprestack seismic data so as to obtain the initial value of a transverse wave reflection coefficient and the initial value of a transverse wave velocity-to-longitudinal wave velocity ratio; a combinedelastic parameter is constructed based on the transverse wave reflection coefficient, the transverse wave velocity-to-longitudinal wave velocity ratio, and a density gradient; a prestack longitudinalwave reflection coefficient formula is expressed as a linear equation about the density gradient, a longitudinal wave reflection coefficient and the combined elastic parameter, linear solution is performed on the prestack longitudinal wave reflection coefficient formula, so that the density gradient, the longitudinal wave reflection coefficient and the combined elastic parameter are obtained; andan objective function about the transverse wave reflection coefficient and the transverse wave velocity-to-longitudinal wave velocity ratio is constructed, and linear solution is performed on the objective function, so that a final transverse wave reflection coefficient and a final transverse wave velocity-to-longitudinal wave velocity ratio are obtained. According to the prestack hybrid nonlinearinversion method and the computer readable storage medium of the invention adopted, a traditional four-parameter nonlinear problem is degraded into a two-parameter nonlinear problem, and therefore, various elastic parameters can be obtained with high efficiency and high precision.

Description

technical field [0001] The invention relates to the technical field of oil and gas geophysics, and more specifically, to a pre-stack hybrid nonlinear inversion method. Background technique [0002] Since the birth of the Zoeppritz equation describing the reflection and transmission coefficients of the isotropic medium interface in 1919, after the 1960s, many scholars calculated the compressional wave reflection (P-P) and shear wave reflection The (P-SV) formula is approximated into a variety of analytical forms, and there are about 30 kinds of inversions at present, forming three types of inversions: P-P wave inversion, P-SV wave inversion, and P-P and P-SV wave joint inversion. The method is widely used in actual reservoir and fluid prediction. [0003] Prestack inversion usually refers to AVO inversion, and its narrow theoretical basis is the P-P part of Zoeppritz equation or its approximate formula and convolution model. The basic point of view of the time-domain convol...

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Problems solved by technology

Thanks to the rapid progress of computers, nonlinear algorithms can be directly used to solve geophysical problems. However, the calculation amount of pre-stack nonlinear inversion methods is huge, and there are often multiple extreme values ​​of the objective function in actual geological problems, which leads to Trapped in local optimization (Zhang et al., 2013)

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