A fully absorbing PML method for staggered grid finite differences

Abstract

The invention relates to a total-absorption PML (perfectly matched layer) method applicable to staggered mesh finite differences. Factors including d / in PML, alpha and k in C-PML (convolutional perfectly matched layer) and m in M-PML (multiaxial perfectly matched layer) are integrated to obtain a numerical simulation result matched with a complex highly-deviated well sonic log; respectively fusing stretch factors of X-directional, Y-directional and Z-directional absorbing boundaries in the C-PML and stretch factors of X-directional, Y-directional and Z-directional absorbing boundaries in the M-PML into mixed stretch factors of X-directional, Y-directional and Z-directional absorbing boundaries. The total-absorption PML method applicable to staggered mesh finite differences has the advantages that advantages of C-PML and M-PML are taken by means of parameter optimization, and high efficiency of PML absorbing boundaries in solution of TTI (tilted transverse isotropy) media is realized; accuracy in calculation under the condition of incidence at extreme incidence angles is achieved, and excellent stability can be kept to extreme anisotropic media.

Description

technical field [0001] The invention belongs to geophysical (logging) exploration methods, in particular to the field of elastic wave numerical simulation. Background technique [0002] Oil is an important strategic resource. From the perspective of economy and technology, whether it is foreign cooperation, purchasing foreign oil fields through international bidding, or domestic exploration to find new oil and gas areas and re-evaluation of old oil fields, numerical simulation method is an important key technology, because it It can provide a theoretical basis for actual data, so it is of great significance to the development of the national economy and the reasonable determination of oil reserves. [0003] Acoustic reflection imaging logging has become a potential remote detection method, which plays an important role in both geosteering and shale gas exploitation in highly deviated wells and horizontal wells. Among the numerical simulation methods of various commonly use...

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Problems solved by technology

When we study the wellbore sound field produced by highly deviated wells passing through shale layers (often VTI (vertical transverse isotropic) media), a big problem we encounter is that the finite difference grid is a regular quadrilateral, Modeling in highly deviated wells produces jagged meshes, leading to unavoidable discretization errors

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