WFEM 3D finite element numerical simulation based on vector potential and scalar potential
ZHOU Yinming1,2,3, WANG Jinhai4, HU Xiaoying3, HE Zhanxiang5, XIONG Bin6
1. School of Geosciences and Info-physciences, Central South University, Changsha, Hunan 410083, China; 2. Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring(Central South University), Ministry of Education, Changsha, Hunan 410083, China; 3. GME & Geochemical Surveys, BGP, CNPC, Zhuozhou, Hebei 072751, China; 4. Bureau of Geological Exploration & Deve-lopment of Qinghai Province, Xining, Qinghai 810029, China; 5. SUSTech Academy for Advanced Interdisciplinary Studies, Shenzheng, Guangdong 518055, China; 6. College of Earth Sciences, Guilin University of Technology, Guilin, Guangxi 541006, China
Abstract：The wide-field electromagnetic method (WFEM) puts forward a formula suitable for calculating apparent resistivity in the whole area. It fundamentally breaks through the shackles of the "far-field area" theory, effectively expands the observing range and depth of the artificial source electromagnetic method, and improves field observing accuracy and efficiency. Considering that the underground medium is a three-dimensional structure, a WFEM 3D finite element numerical simulation method was developed from the perspectives of vector potential and scalar potential based on Coulomb criterion. This method overcomes the problems of "pseudo solution" and discontinuity of model boundary in the calculation of electromagnetic field distribution directly based on Maxwell equations, and avoids more complex edge finite e-lement forward simulation. In addition, the background field is solved by a quasi analytical method, and the secondary field is solved by a finite element method, which overcomes the singularity of local shooting field. In a model example, a prism model was designed, and the analytical solution to the homogeneous layered medium was used to verify the correctness and accuracy of the method. Then the detection abilities of WFEM and CSAMT to typical 3D objects were compared and analyzed by using the forward algorithm. The results show that under the same conditions, WFEM can reflect the information of underground objects more accurately and has a higher resolution.
周印明, 王金海, 胡晓颖, 何展翔, 熊彬. 基于矢量位和标量位的广域电磁法三维有限元数值模拟[J]. 石油地球物理勘探, 2021, 56(1): 181-189.
ZHOU Yinming, WANG Jinhai, HU Xiaoying, HE Zhanxiang, XIONG Bin. WFEM 3D finite element numerical simulation based on vector potential and scalar potential. Oil Geophysical Prospecting, 2021, 56(1): 181-189.
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