高斯射线束正演与偏移

Gaussian beams forward simulation and migration.

本文在介绍高斯射线束原理和正演的基础上,从叠后偏移开始分析了高斯射线束偏移的基本原理,并给出了优化的思路和具体的算法流程。高斯射线束是波动方程集中于射线附近的高频近似解,高斯射线束法将射线理论和波动方程方法紧密结合在一起,利用高斯束替代普通射线方法中的射线进行波场正演和延拓,既保持了射线方法的高效性和灵活性,又保留了波场的动力学特征,不仅克服了普通射线方法的一些缺点,而且由于无需两点试射,因而效率非常高。将高斯射线束法引入偏移,利用高斯射线束的性质,可以解决基尔霍夫方法的多值走时问题。模型试算表明,本文介绍的高斯射线束偏移方法能够充分利用高斯射线束的优势,既具有较高的效率又能够获得较好的成像效果。

On the basis of introducing Gaussian beams principle and forward simulation, the paper analyzed the basic principle of Gaussian beams migration starting from poststack migration and gave optimized idea and concrete algorithm flow. The Gauss beam is high-frequency approximate solution that wave equation centralized around the ray, which closely combines the ray theory with wave equation. Replacing the ray in common ray method, using Gaussian beams to carry out wave forward simulation and continuation both keeps the high-efficiency and flexibility of ray method and retains the dynamic feature of wavefield; not only overcomes some shortcomings of conventional ray method, but also is high efficiency because without two-point trial-ray shooting. Introducing Gaussian beams into migration and using the property of Gaussian beams are able to solve the issue of multi-value travel-time in Kirchhoff method. The model test showed the Gaussian beams migration introduced in the paper is able to fully use the superiority of Gaussian beams, both having high efficiency and getting better imaging results.