弹性各向同性介质一次散射波场高斯束Born正演

本文提出了一种弹性波一次散射波场的正演方法——弹性波高斯束Born正演.该方法以线性散射理论为基础,通过Born近似建立起地下散射点处不同波型的反射率同弹性波主分量波场之间的数据映射关系,利用高斯束所包含的走时、振幅和极性信息进行不同波型的局部平面波的合成,进而通过逆倾斜叠加将所合成的局部平面波转化为时空域的多分量地震记录.该方法不但保持了射线类方法高效的优点,还具备了处理多次走时波场的能力,从而保证了复杂构造的波场模拟的精度.文中两个数值模型的应用效果表明,本文所提出的弹性波高斯束Born正演算法具有近似于波动方程有限差分法的波场模拟精度以及高得多的计算效率.

Gaussian beam Born modeling method for single-scattering waves in elastic isotropic medium

We present in this paper a Gaussian beam Born modeling method for simulating single-scattering waves in elastic isotropic medium. Based on the linearized single scattering theory, we first construct the linear data mapping between multi-mode subsurface reflectivities and principal components of elastic waves, then compose multi-mode local plane-waves using the traveltimes, amplitudes and polarizations of Gaussian beams, and finally obtain the simulated multi-component data by transforming the composed local plane-waves to time-space domain. The proposed method not only keeps high efficiency of ray-based methods, but also is capable of dealing with multi-arrivals, and thus achieves accurate wavefield simulation in complex media. Trials on two synthetic models demonstrate that, compared with finite-difference modeling, this method can simulate the first order scattering waves in complex media with similar accuracy and much higher efficiency.