基于有限元的二维各向异性地层中大地电磁响应

地球介质的电各向异性现象是普遍存在的,而传统上电磁法的理论研究与实际应用多是基于各向同性理论的假设,因此研究基于各向异性理论下电磁场的响应特征就显得非常迫切。从Maxwell方程出发,推导了二维倾斜各向异性下大地电磁场的偏微分方程,并采用有限元法对设计的一系列二维各向异性模型进行数值计算。结果表明,不论改变各向异性系数还是改变倾角,均能引起视电阻率和相位曲线的显著变化;由于倾角的影响,导致了视电阻率曲线在空间上的不对称。研究结果为大地电磁资料的处理和解释提供理论基础和技术指导。

Magnetotelluric response of 2D anisotropic stratum based on finite element method

The electrical anisotropy of the earth is universal, and the theoretical research and practical application of electromagnetic method are mostly based on the assumption of isotropic theory. Therefore, it is very necessary to study the response characteristics of electromagnetic field based on anisotropic theory. Starting from Maxwell′s equation, this paper derives the partial differential equations of the magnetotelluric field under two-dimensional tilt anisotropy, and uses the finite element method to perform numerical calculations on a series of designed two-dimensional anisotropy models. The results show that whether changing the anisotropy coefficient or changing the dip angle can cause significant changes in the apparent resistivity and phase curves. And due to the influence of dip angle, the apparent resistivity curves are asymmetric in space. The results provide theoretical basis and technical guidance for the processing and interpretation of magnetotelluric data.