3D marine controlled-source electromagnetic forward modeling with arbitrarily orientated dipole source
Yan Bo1,2, Li Yuguo3, Han Bo3, Mei Xiaoyong2, He Shaobo2, Xu Siwei2
1. Key Laboratory of Exploration Technologies for Oil and Gas Resources, Ministry of Education, Yangtze University, Wuhan, Hubei 430100, China;
2. International College, Hunan University of Arts and Science, Changde, Hunan 415000, China;
3. Key Laboratory of Submarine Geosciences and Prospecting Technology, Ministry of Education, Ocean University of China, Qingdao, Shandong 266100, China
Abstract：In practical marine controlled-source electromagnetic (CSEM) surveys,the electric dipole dragged in deep seawater is easily deviated from the preset position due to the influence of ocean currents,and impacts on electromagnetic data.Therefore we develop a numerical calculation method for arbitrarily orientated dipole source.First we calculate the primary electric field activated by arbitrarily orientated dipole source on the background model.Then taking this primary electric field as a new source for 3D target,we calculate the secondary electric field and achieve 3D CSEM forward modeling.This method can not only considerably improve the numerical solution accuracy in the vicinity of the source,but also improve calculation efficiency by reducing the grid number.The direct method used to solve the large linear equations formed by the finite-difference discrete is very appropriate for parallel processing for multi-dipole sources and avoids iteration errors.Comparing with analytical solutions of 1D model and conventional numerical solutions of 3D model,our tests prove the correctness of the proposed method.Furthermore we analyze dipole source position and length impacts on 3D marine CSEM numerical simulations.
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