Marine controlled source electromagnetic method finite element forward method of anisotropic media

Abstract

The present invention is a marine controlled source electromagnetic method finite element forward method of anisotropic media. The method comprises: firstly, setting a reference electrical conductivity, wherein three non-zero diagonal elements of the reference electrical conductivity are electrical conductivities in the direction of three main axes: x, y, z; next, setting three Euler rotation angles, and after three times of Euler rotation, obtaining an electrical conductivity tensor model in any direction; then starting from Maxwell equations, obtaining a finite element equation that is satisfied by magnetic vector potential and scalar potential under Coulomb regulations on a condition that the electrical conductivity presents anisotropy; then, performing discrete segmentation on a research region by using a non-structural grid, so that a complicated geoelectric model can be constructed; combining an incomplete LU discomposition pre-condition factor with an IDR(s) algorithm, so as to realize efficient and precise solution of a large sparse linear equation; and finally, deriving vector potential and scalar potential of a secondary field by using weighted moving least squares solution, to obtain each component of an electromagnetic field. The method provided by the present invention has excellent universality and can be promoted for electromagnetic method numerical value simulation with complicated electrical conductivity distribution and high precision.

Description

technical field [0001] The present invention relates to the problem of arbitrary anisotropy of the electrical conductivity of the underground medium in the field of geophysical exploration, and proposes a three-dimensional unstructured finite element numerical simulation method of marine controllable source electromagnetic based on the secondary field vector position and scalar position, which is suitable for Numerical simulation research of geophysical exploration methods such as airborne electromagnetic, borehole electromagnetic and land surface electromagnetic with complex geometry and distribution of physical properties. Background technique [0002] The structure and properties of the Earth's interior are at the heart of the study of geophysics. The 21st century is an era in which earth science enters into an era of in-depth research on the anisotropy of media, tectonics, and deep dynamical processes. With the continuous improvement of modern observation technology and...

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Problems solved by technology

[0004] So far, for ocean controllable source electromagnetic numerical simulation of conductivity anisotropic media, most of them only consider the three-axis conductivity anisotropy, which certainly simplifies the problem. The induced conductivity anisotropy is often not limited to the three main axes, and may even be more complex, and in actual detection, the complex seabed topography and the influence of conductivity anisotropy on the interpretation of actual data may produce certain deviations

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