Shallow Water Three-Dimensional Transient Electromagnetic Modelling by Using Fictitious Wave Field Methods
Keywords:Air layer, complex terrain, fictitious wave field, shallow water, three-dimensional modeling
The marine transient electromagnetic method is a valuable means for locating mineral resources because of its higher detection resolution as well as other advantages. However, this method is easily affected by the air layer and complex terrain, which significantly increase its calculation times. We addressed this problem by developing a three-dimensional finite-difference method based on the principle of correspondence between the diffusive and fictitious wave fields. Using a fast-iteration formula appropriate for a large time step, solving the Maxwell equations in a fictitious wave field, and the effects of air and seawater parameters on the electromagnetic response in shallow water are discussed. Choosing the first derivative of a Gaussian as a source, the 3D numerical simulation of transient electromagnetics in a shallow water area is realized. Comparing to the existing methods, the effectiveness of the proposed method is verified. The results show that this method enables fast and high-precision numerical calculations for 3D models and provides theoretical guidance for detecting seabed mineral resources in complex geological environments in shallow water.
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