Method for precisely inverting Young modulus and Poisson's ratio

Abstract

The invention discloses a method for precisely inverting Young modulus Poisson's ratio and belongs to the field of exploration and physical geography research. The method includes the following steps: conducting normal pre-processing on initial prestack seismic data, stacking at different angles the prestack seismic data which have been pre-processed; standardizing initial log data to make inversion parameters of Young modulus and Poisson's ratio, and conducting lowpass filtering on the result of the computing, constructing an inversion initial model; obtaining the difference between prestack seismic data reflection coefficient which have been subject to pre-processing and the reflection coefficient obtained by computing Young modulus Zeoppritz, constructing a right-side constant term of an inversion equation set; obtaining a first-order taylor expansion of each item of the Young modulus Zeoppritz equation set, based on the inversion initial model, obtaining each taylor expansion, constructing a right-side constant term of the inversion equation set. According to the invention, the method does not approximate the Zoeppritz equation, has stable process, and has reliable numerical values.

Description

technical field [0001] The invention belongs to the research field of exploration geophysics, relates to a method for measuring physical property constants of formation rocks, and in particular to a method for accurately inverting Young's modulus and Poisson's ratio. Background technique [0002] The physical constants of formation rocks, Young's modulus and Poisson's ratio, are important parameters for describing reservoir characteristics and fluid identification. Young's modulus is a dimension that characterizes the ratio of rock's positive stress to positive strain. Its size reflects the brittleness of rock and is related to rock lithology, porosity, and structure; The dimension of the ratio of tangential strains is a commonly used fluid factor. [0003] In recent years, with the increasing difficulty of exploration, the requirements for seismic exploration have become more and more stringent, and pre-stack inversion, as an effective means to accurately obtain the elasti...

AI Technical Summary

Problems solved by technology

Zhang Guangzhi et al.[Pre-stack joint inversion method of compressional and shear waves in shale gas reservoirs. Acta Geophysics, 2014,12:4141-4149.] proposed a method based on elastic impedance inversion for shale gas to directly obtain Young’s modulus and Density product and Poisson's ratio method, the above methods all use the approximate formula of the Zoeppritz equation for AVO inversion, so they will bring errors caused by the approximate formula

[0004] Elastic parameters are an important basis for judging reservoir characteristics and fluid identification. The traditional inversion method based on the precise Zoeppritz equation is to directly invert the velocity and density of P- and S-waves and then indirectly calculate various elastic parameters, which will inevitably lead to cumulative errors. The complexity of the Zoeppritz equation also makes it difficult to directly invert the elastic parameters.

Images