scattering computation and migration by multi-directional parabolic approximation

What is it about?

In this work, in order to overcome the limitation of the classical parabolic approximation on the propagation angle, the idea of multi-axis approximation and the domain decomposition algorithm in computational electromagnetics are used to change the one-way approximation of the classic parabolic operator to achieve a multi-directional high-precision approximation of the parabolic equation; Based on this, the forward and backscatter information of the large azimuth target is calculated, and the full wavefield migration imaging of the structure target with steep dip angle is realized. The numerical results obtained indicate that the proposed multi-domain, multi-axial parabolic approximation operator accurately calculates the forward and back scattering field of the scater at large azimuths.Additionally, the green’s function expressed by the proposed approximation provided better imaging ability for steep inclination angles at a higher calculation efficiency. Furthermore, the proposed multi-domain, multi-axial parabolic approximation method is suitable for parallel computing, which can further improve the efficiency of the scattering field calculation and migration imaging.

Featured Image

Why is it important?

The fast and good calculation of the scattering field in a complex underground structure determines whether high-quality inversion and imaging can be performed on the complex underground structure. Currently, the scattering field and the migration of the full wavefield are calculated using numerical solutions of wave equations (Robein, 2012),Which can be divided into the geometric ray algorithms and wave equation algorithms.geometric rays can be calculated quickly, but pose disadvantages of an inability to describe complex fluctuations.The wave equation method can be further broken down into full wave field algorithm and one-way wave field algorithm; the full wave field method is based on the accurate solution of the wave equation, and the wave field information is rich and there is no angular limitation;However, it requires high computational cost and time, and some unhelpful wave field components generate a lot of noise during imaging (Ge Zhan, 2014).The one-way wave field algorithm is based on the parabolic approximate solution of the wave equation, which can describe complex wave phenomena and is calculated quickly.However, the one-way hypothesis of parabolic approximation leads to certain angular restrictions, Thus, it is difficult to cover the entire underground space effectively.

Perspectives