We present three-dimensional(3-D)modeling method of marine controlled-source electromagnetic(CSEM)fields in general anisotropic media using an adaptive finite element approach based on the vector-scalar potential.The ...We present three-dimensional(3-D)modeling method of marine controlled-source electromagnetic(CSEM)fields in general anisotropic media using an adaptive finite element approach based on the vector-scalar potential.The modeling is based on the governing Helmholtz equations in the vector-scalar potential system.Unstructured tetrahedral grids are employed,which can exactly simulate the terrain relief and complex electrical structures.Moreover,based on the gradient recovery technology,the adaptive finite element approach is used to drive the mesh refinement,and make the finite element solutions converge gradually to the exact solutions.The primary-secondary field approach is used to improve the numerical accuracy of CSEM fields near the source point,where the primary field is calculated by using the quasi-analytical formula.The accuracy of this approach is verified by a one-dimensional model.Two 3-D models are used to demonstrate the effectiveness of the adaptive mesh refinement and the influences of dipping anisotropy layer on the marine CSEM responses for both inline and broadside geometries.The complex synthetic model is simulated to show the capability and flexibility of the approach for geometrically complex situations.展开更多
基金support from the Natural Science Foundation of Jiangxi Province,China(Nos.20202ACBL211006,20202BAB213017)the National Natural Science Foundation of China(Nos.41774078,41904075).
文摘We present three-dimensional(3-D)modeling method of marine controlled-source electromagnetic(CSEM)fields in general anisotropic media using an adaptive finite element approach based on the vector-scalar potential.The modeling is based on the governing Helmholtz equations in the vector-scalar potential system.Unstructured tetrahedral grids are employed,which can exactly simulate the terrain relief and complex electrical structures.Moreover,based on the gradient recovery technology,the adaptive finite element approach is used to drive the mesh refinement,and make the finite element solutions converge gradually to the exact solutions.The primary-secondary field approach is used to improve the numerical accuracy of CSEM fields near the source point,where the primary field is calculated by using the quasi-analytical formula.The accuracy of this approach is verified by a one-dimensional model.Two 3-D models are used to demonstrate the effectiveness of the adaptive mesh refinement and the influences of dipping anisotropy layer on the marine CSEM responses for both inline and broadside geometries.The complex synthetic model is simulated to show the capability and flexibility of the approach for geometrically complex situations.
