| 等效场源法的CSAMT三维无限元正演模拟 |
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| 引用本文： | 张林成,胡宏伶,汤井田,肖卫初,肖晓,原源.等效场源法的CSAMT三维无限元正演模拟[J].石油地球物理勘探,2021,56(3):622-630. |
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| 作者姓名： | 张林成 胡宏伶 汤井田 肖卫初 肖晓 原源 |
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| 作者单位： | 1. 湖南城市学院信息与电子工程学院, 湖南益阳 41300;2. 中南大学地球科学与信息物理学院湖南长沙 41008;3. 计算与随机数学教育部重点实验室(湖南师范大学数学与统计学院), 湖南长沙 410081;4. 核资源与环境国家重点实验室(东华理工大学), 江西南昌 330013 |
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| 基金项目： | 本项研究受湖南省教育厅优秀青年项目“基于非结构化有限元－无限元耦合的可控源电磁法三维正演研究”（20B111）、国家自然科学基金重点项目“基于物性约束的广域电磁法自适应三维反演与岩性识别方法研究”（41830107）、国家自然科学基金优秀青年项目“地球电磁学”（41922027）及国家自然科学基金青年项目“基于自适应加密的三维全电流RMT有限元－无限元耦合正演”（41904073）联合资助。 |
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| 摘 要： | 针对传统CSAMT三维正演场源奇异性及无穷边界处理等问题，提出了一种基于等效场源的CSAMT三维无限元快速高精度正演模拟算法。首先，通过精确计算场源附近一定范围内网格节点的电磁场，实现水平电偶极源的精确模拟；然后，采用无限元代替传统截断边界条件，通过有限元-无限元耦合法和并行直接求解方法，实现基于等效场源的CSAMT三维快速精确求解。均匀半空间模型测试结果验证了算法的正确性。同时，以趋肤深度公式为基础，开展了场源等效模拟的最佳范围研究，数值结果表明对于场源的等效加载范围最好不低于1.5倍趋肤深度。
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| 关 键 词： | 等效场源 无限元 并行直接求解 趋肤深度 |
| 收稿时间： | 2020-09-01 |
3D CSAMT infinite-element forward modeling based on equivalent source |
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| ZHANG Lincheng,HU Hongling,TANG Jingtian,XIAO Weichu,XIAO Xiao,YUAN Yuan.3D CSAMT infinite-element forward modeling based on equivalent source[J].Oil Geophysical Prospecting,2021,56(3):622-630. |
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| Authors: | ZHANG Lincheng HU Hongling TANG Jingtian XIAO Weichu XIAO Xiao YUAN Yuan |
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| Affiliation: | 1. College of Information and Electronic Engineering, Hunan City University, Yiyang, Hunan 413002, China;2. School of Geosciences and Info-Physics, Central South University, Changsha, Hunan 410083, China;3. Key Laboratory of Computing and Stochastic Mathe-matics(School of Mathematics and Statistics, Hunan Normal University), Changsha, Hunan 410081, China;4. State Key Laboratory of Nuclear Resources and Environment(East China University of Technology), Nanchang, Jiangxi 330013, China |
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| Abstract: | Traditional 3D CSAMT forward modeling has disadvantages such as source singularity and infinite boundaries. This paper proposes a 3D CSAMT forward modeling algorithm based on an equivalent source. It is fast and accurate for forward modeling of electric dipole sources. Firstly, accurately simulate the horizontal electric dipole source by calculating the electromagnetic field at the grid nodes in a certain range near the source. Secondly, replace the traditional cut-off boundaries with infinite elements, and implement finite element-infinite element coupling and paralleling to directly get fast and accurate 3D CSAMT solutions on an equivalent field source. The algorithm has been proved correct on a uniform half-space model. Finally, the optimal range of source equivalent simulation was studied based on the skin depth formula. Numerical results show that the best equivalent range of source shouldn't be less than 1.5 times of the skin depth. |
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| Keywords: | equivalent source infinite element direct solution by parallelling skin depth |
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