Application of the perfectly matched layer in 3-D marine controlled-source electromagnetic modelling
Application of the perfectly matched layer in 3-D marine controlled-source electromagnetic modelling
复制标题
完美匹配层在三维海洋受控源电磁建模中的应用
DOI：
10.1093/gji/ggx382
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Zhan Liu
中科院分区：
文献类型：
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作者：
Gang Li;Yuguo Li;Bo Han;Zhan Liu
本文将伸缩笛卡尔坐标系下的复频移完全匹配层（CFS-PML）方法成功地应用于三维频域海洋可控源电磁场（CSEM）数值模拟。通常在EM建模算法的传统框架内使用的狄利克雷边界假设边界处的电场或磁场值为零。这要求边界足够远离感兴趣区域中的源。为了减轻边界伪影，即使由于电磁波传播的扩散而允许单元尺寸朝向边界增长，也可能需要大的建模区域。与传统的Dirichlet边界相比，PML边界的优点是可以将感兴趣的模拟区域限制在目标区域内，并且周围只有少量的吸收层可以有效地抑制人工边界效应而不损失数值精度。此外，对于地震和海洋CSEM数据的联合反演，如果用PML代替传统的Dirichlet进行CSEM野外模拟，可以使同一测区采集的两种不同地球物理数据的建模区域相同，便于联合反演网格匹配。本文将CFS-PML边界应用于三维海洋CSEM数值模拟中，采用交错有限差分（SFD）离散。数值试验表明，与Dirichlet方法相比，CFS-PML方法也具有较好的精度。此外，使用CFS-PML的建模算法在计算时间和内存节省比使用Dirichlet边界的优势。对于本研究中的3D示例，与使用Dirichlet相比，使用PML的内存节省近42%，时间节省约48%。
In this study, the complex frequency-shifted perfectly matched layer (CFS-PML) in stretching Cartesian coordinates, is successfully applied to three-dimensional (3D) frequency-domain marine controlled-source electromagnetic (CSEM) field modelling. The Dirichlet boundary, which is usually used within the traditional framework of EM modeling algorithms, assumes the electric or magnetic field values are zero at the boundaries. This requires the boundaries be sufficiently far away from the sources in the area of interest. To mitigate the boundary artifacts, a large modelling area may be necessary even though cell sizes are allowed to grow toward the boundaries due to the diffusion of the electromagnetic wave propagation. Compared with the conventional Dirichlet boundary, the PML boundary is preferred as the modelling area of interest could be restricted to the target region and only a few absorbing layers surrounding can effectively depress the artificial boundary effect without losing the numerical accuracy. Furthermore, for joint inversion of seismic and marine CSEM data, if we used the PML for CSEM field simulation instead of the conventional Dirichlet, the modeling area for these two different geophysical data collected from the same survey area could the same, which is convenient for joint inversion grid matching. We apply the CFS-PML boundary to 3D marine CSEM modelling by using the staggered finite-difference (SFD) discretization. Numerical test indicates that the modeling algorithm using the CFS-PML also shows good accuracy compared to the Dirichlet. Furthermore, the modeling algorithm using the CFS-PML shows advantages in computational time and memory saving than that using the Dirichlet boundary. For the 3D example in this study, the memory saving using the PML is nearly 42 % and the time saving is around 48% compared to using the Dirichlet.