Marine controlled-source electromagnetic (CSEM) method has proved to be a powerful tool and found its increasing applications for offshore resource exploration and tectonic studies. However, bathymetric variations and anisotropic structures encountered in practical measurements have posed challenges for reliable interpretation of marine CSEM data collected in increasingly complex geologic settings. In this study, we present a Finite element (FE) based forward algorithm for simulating 3-D marine CSEM responses in geologic settings characterized with rough bathymetry and electrical anisotropy. Unstructured tetrahedral meshes are employed to permit precise descriptions of arbitrary seafloor topography. After validating the accuracy of the algorithm, we investigate the effects of bathymetric variations and complicated electric anisotropy separately and jointly on marine CSEM responses. Numerical results have demonstrated that both the bathymetry and electrical anisotropy can cause significant distortions on marine CSEM responses, but to different extent. The effects of full electrical anisotropy and bathymetry have to be taken into consideration for reliable interpretations of marine CSEM data in practice.

中文翻译：

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具有非结构化四面体网格的各向异性介质中 3-D 海洋受控源电磁场的有限元模拟

海洋受控源电磁 (CSEM) 方法已被证明是一种强大的工具，并在近海资源勘探和构造研究中得到越来越多的应用。然而，实际测量中遇到的测深变化和各向异性结构对在日益复杂的地质环境中收集的海洋 CSEM 数据的可靠解释提出了挑战。在这项研究中，我们提出了一种基于有限元 (FE) 的前向算法，用于在以粗略测深和电各向异性为特征的地质环境中模拟 3-D 海洋 CSEM 响应。非结构化四面体网格用于精确描述任意海底地形。在验证了算法的准确性后，我们分别和共同研究了测深变化和复杂的电各向异性对海洋 CSEM 响应的影响。数值结果表明，水深测量和电各向异性都会导致海洋 CSEM 响应的显着失真，但程度不同。为了在实践中可靠地解释海洋 CSEM 数据，必须考虑全电各向异性和测深的影响。