Method for estimating velocity of transverse waves based on inversion of equivalent elastic modulus for self-adapting matrix minerals

Abstract

The invention discloses a method for estimating the velocity of transverse waves based on the inversion of an equivalent elastic modulus for self-adapting matrix minerals, which belongs to the field of exploration geophysics, and used for solving the problem that in a conventional method for estimating the velocity of transverse waves based on a Xu-White model, an elastic modulus for matrix minerals is difficult to set accurately. The method comprises the following steps of: (1) setting the Poisson ratio of a dry core sample at a single logging depth point and the value selection range and initial value of an equivalent bulk modulus for matrix minerals; (2) carrying out inversion solution on a same fluid item from two different angles by using two different fluid item calculation methods so as to invert an optimal Poisson ratio of the dry core sample and an optimal equivalent bulk modulus and an optimal equivalent shear modulus for matrix minerals; and (3) estimating the velocity of transverse waves by using a simplified Xu-White model. In the method disclosed by the invention, the equivalent elastic modulus for matrix minerals is taken as an object of study, through reducing the number of target parameters, the precision and reliability of the method for estimating the velocity of transverse waves are effectively improved.

Description

technical field [0001] The present invention relates to the problem of shear wave velocity estimation in the field of exploration geophysics, which is a shear wave velocity estimation method based on the inversion of the equivalent elastic modulus of adaptive matrix minerals, and is used to solve the conventional shear wave velocity estimation method based on the Xu-White model It is difficult to accurately set the elastic modulus (bulk modulus and shear modulus) of matrix minerals, which effectively improves the accuracy and reliability of the shear wave velocity estimation method. Background technique [0002] In the logging data, there is usually a lack of shear wave logging data, which brings certain difficulties to the forward modeling of seismic waves and the parameter inversion of seismic attributes. Conventional shear wave velocity estimation methods mainly fall into the following four categories: (1) methods based on empirical relations, such as Han (1986), Greenber...

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Problems solved by technology

Conventional methods for setting the elastic modulus of matrix minerals mainly fall into the following five categories: (1) For single-matrix mineral rocks, refer to domestic and foreign petrophysical test values ​​for setting, and the defect is that the elastic modulus value of the same matrix mineral (2) For multi-matrix mineral rocks, use equivalent medium theory (such as V-R-H average) to calculate the equivalent elastic modulus (comprehensive influence value of various matrix minerals), and its defects It is difficult to accurately set the percentage content and elastic modulus value of each matrix mineral; (3) Based on the logging data, the statistical method is used to select the depth section with relatively uniform physical properties for statistical analysis (Zhang Jinqiang et al., 2010), and its defects are For rocks with complex structures or strata with strong heterogeneity, the error is relatively large; (4) the elastic parameters of rock matrix minerals are calculated based on laboratory test values ​​by taking cores and petrophysical tests, and the defect is that it is expensive; (5 ) adaptive matrix mineral bulk modulus inversion method (Lin Kai and Xiong Xiaojun et al., 2011), which is applicable to the situation where the shear wave velocity is known, and can only calculate the equivalent bulk modulus of matrix minerals, and cannot be directly applied to calculate matrix Shear Modulus of Minerals

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