A Finite Difference Calculation Method Based on Elastic Wave Equation in Pseudospace Domain

Abstract

The invention discloses a quasi-spatial domain elastic wave equation-based finite difference calculation method, belongs to the field of seismic exploration, and mainly mains at converting a conventional elastic wave equation into a quasi-spatial domain elastic wave equation so as to convert equally spaced distance grid step lengths of spatial domains into non-equally spaced propagation time steplengths so that people can accurately calculate propagation times at two sides of speed interfaces on the basis of strictly defining speed models. On the basis, the equation and a 2N (N is a positiveinteger)-order precision finite different expression of a completely matched layer boundary condition are given, so that finite difference wave field prolongation of seismic waves in a reverse time migration process can be realized. According to the method, the problem that a speed interface, in a reverse time migration section, of the conventional elastic wave equation is distorted can be well solved; and moreover, through carrying out wave field prolongation on the basis of a quasi-spatial domain elastic wave equation, interface false scattering and inter-layer reflection waves can be obviously weakened, so that the migration imaging quality is further improved.

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 an elastic wave equation in a 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 current...

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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 methods have limitations in solving interface distortion and suppressing interlayer reflection waves, and there is still little research in the field of elastic wave equations

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