Reservoir shear wave velocity prediction method based on rock physics

Abstract

The invention relates to a reservoir shear wave velocity prediction method based on rock physics. The method comprises the steps that (1) supposing that the bulk modulus, the shear modulus and the density of a destination interval mineral are unknown constants, the error between a longitudinal wave velocity and a measured longitudinal wave velocity is acquired according to equation modeling, and the error between the acquired density and the measured density is calculated; (2) according to the minimum error criterion, the bulk modulus, the shear modulus and the density of a mineral component are inverted through a genetic algorithm; (3) and the shear wave velocity is calculated. According to the step (1), supposing that the elastic modulus of each rock component is an unknown constant in a reservoir logging curve section, the objective function of the inversion of the logging curve can be defined that a superscript M represents a simulation longitudinal wave velocity, O represents a logging observation longitudinal wave velocity, and w Rho and w rho represent normalized weighted coefficients; and the objective function is a nonlinear function of the bulk modulus, the shear modulus and the density of each mineral component. The method can be applied to a sand shale reservoir, and carbonate rock and other complex reservoirs.

Description

technical field [0001] The invention relates to the technical field of seismic exploration and development of oil and gas and coalbed methane, in particular to a method for predicting reservoir shear wave velocity based on rock physics. Background technique [0002] P-wave and shear-wave velocity intersection analysis, modulus intersection analysis and Poisson's ratio analysis are all important methods for analyzing reservoir oil and gas, and these analyzes need to know the logging data of compressional-wave and shear-wave velocity. But in reality, only a few wells in a work area have shear wave logging data, or even no shear wave logging data. Therefore, it is very important to predict the shear wave velocity from the compression wave velocity and the log evaluation of the compression wave velocity and the reservoir prediction. [0003] Petrophysicists Greenberg, K.L. and J.P.Castagna (1992) gave the empirical relational formula Vp=1.16Vs+1.36 for the velocity of water-bea...

AI Technical Summary

Problems solved by technology

The mineral modulus will vary in different regions and different reservoir characteristics (depth and temperature, etc.) (especially mudstone), so the modulus constant measured in the laboratory in different regions and different reservoir applications is not accurate

The shear wave velocity calculated using these moduli is also inaccurate

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