3D multinary inversion of controlled-source electromagnetic data based on the finite-element method with unstructured mesh
3D multinary inversion of controlled-source electromagnetic data based on the finite-element method with unstructured mesh
复制标题
基于非结构化网格有限元法的受控源电磁数据三维多元反演
DOI：
10.1190/geo2020-0164.1
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发表时间：
2021-01-01
期刊：
影响因子：
3.3
通讯作者：
Hu, Xiangyun
中科院分区：
文献类型：
--
作者：
Cai, Hongzhu;Long, Zhidan;Hu, Xiangyun
在常规正则化方法的可控源电磁(CSEM)反演中，重建的电导率图像通常是模糊的，分辨率有限。为了有效地获得更紧凑的电导率模型，我们将多元变换的概念应用到基于非结构四面体网格有限元方法的CSEM反演中。在多元反演的框架内，模型电导率只能在设计值范围内聚集，设计值通常是从其他先验信息或常规反演获得的。综合研究表明，与实际地电模型的最大光滑度反演和聚焦反演相比，多元反演产生的电导率图像具有更清晰的模型边界。我们进一步将该方法应用于陆地CSEM勘查找矿。与常规的最大光滑度反演法和聚焦反演法相比，多元反演法的结果更接近地面真实情况。该方法和数值算法为需要明确边界和聚类模型值的CSEM反演提供了一种新的方法和工作流程。在已知勘探目标的先验信息(如估计的电导值)的情况下，这种地电模型对于石油和矿产勘探中的地质解释非常有用。
In controlled-source electromagnetic (CSEM) inversion with conventional regularization, the reconstructed conductivity image is usually blurry and only has limited resolution. To effectively obtain more compact conductivity models, we apply the concept of multinary transformation to CSEM inversion based on the finite-element method with an unstructured tetrahedral mesh. Within the framework of multinary inversion, the model conductivities are allowed to be clustered only within the designed values, which are usually obtained from other a priori information or from conventional inversion. Synthetic studies show that multinary inversion produces conductivity images with clearer model boundaries compared to the maximum smoothness inversion and the focusing inversion for realistic geoelectric models. We further apply the developed method to a land CSEM survey for mineral exploration. The multinary inversion results are closer to the ground truth compared to the conventional maximum smoothness inversion and the focusing inversion. The developed method and the numerical algorithm provide a new approach and workflow for CSEM inversion when the models need to have clear boundaries and clustering model values. Such geoelectric models could be very useful for geologic interpretation in oil and mineral exploration when a priori information (such as the estimated conductivity values) of the exploration targets is known.