虚拟波动域三维海洋可控源电磁场正演模拟

Three-dimensional marine CSEM modeling in fictitious wave domain

本文基于对应原理将似稳态条件下频率域电磁场扩散方程转换成虚拟波动域电磁场波动方程,采用高阶时域有限差分进行求解,引入复频移完全匹配层吸收边界条件,降低了内存需求,提高了计算效率,并在虚拟波动域用伪δ函数离散电偶极源,实现了虚拟波动域任意取向电偶极源三维海洋可控源电磁场高阶时域有限差分正演算法.通过与拟解析解和频率域三维可控源电磁场数值模拟结果的对比,验证了本文算法的正确性和高效性,且探讨了网格参数和边界条件对不同频率电磁场模拟结果的影响.

In this paper,we transform quasi-state frequency domain diffusion equations to wave equations in the fictitious wave domain.A complex frequency shifted perfectly matched layer(CFS-PML)boundary condition is adopted to the high-order finite difference time domain(FDTD)algorithm for reducing storage requirements and improving computational efficiency.We divide the dipole source by the pseudo-delta function for simulating electromagnetic response of arbitrary orientation electric dipole.By comparing the numerical solution with 1D analytical solution and 3D frequency controlled source electromagnetic(CSEM)results,we verify the validity,the accuracy and the efficiency of the algorithm,and then investigate and analyze the influence of different grid parameters and boundary conditions on numerical result at different frequency.