A Finite Difference Calculation Method Based on Pseudospace Domain Acoustic Wave Equation

Abstract

The invention relates to a finite difference calculation method based on the quasi-spatial domain acoustic wave equation and belongs to the field of seismic exploration. The main idea of the method isto transform a conventional acoustic wave equation into a quasi-spatial domain acoustic wave equation so that the equally spaced 'distance' grid length steps in the spatial domain is transformed intonon-equally spaced 'propagation time' length steps. Thus, a user can accurately calculate the 'propagation time' on both sides of a velocity interface based on a strictly defined velocity model. Then, the equation of a 2N-order (N is a positive integer) precision finite difference expression for its perfectly matched layer boundary condition is given based on this. Accordingly, the finite difference wavefield extension of seismic waves in the process of reverse time migration can be realized. The method can well solve the problem of the shape distortion of the velocity interface in the reverse-time migration profile of a conventional acoustic wave equation. In addition, the wave field extension based on the quasi-spatial domain acoustic wave equation can significantly weaken the interfacepseudo-scattering and the inter-layer reflection wave so as to further improves the quality of offset imaging.

Description

technical field [0001] The invention belongs to the field of seismic exploration, and in particular relates to a finite difference calculation method based on the acoustic wave equation in the quasi-space domain. Background technique [0002] Seismic exploration is currently the most effective geophysical method for proving underground geological structures, and it mainly includes three links: seismic information acquisition, data processing, and result interpretation. Seismic data processing is an important bridge connecting information acquisition and result interpretation. For a long time, precise subsurface structural migration imaging has been a research hotspot in seismic data processing. [0003] In the field of migration imaging, reverse time migration imaging based on the two-way wave equation theory is recognized as an accurate method. This technical method is generally applied to an important numerical calculation method - the finite difference method in the cur...

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Problems solved by technology

In order to reduce the influence of interlayer reflection waves, Baysal et al. derived the non-reflection acoustic wave equation under the assumption that the wave impedance of the underground medium is constant, and the effect of suppressing interlayer reflection is only good at vertical incidence; He Bingshou et al. Arbitrary wide-angle acoustic wave equation reverse time migration technology, but the imaging effect of this method is poor in shallow layers; Yoon et al. In the application of the structural area, the calculation error of the Poynting vector is relatively large

[0005] It can be seen that the current method has limitations in solving the interface distortion and suppressing the reflected waves between layers.

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