可控源音频大地电磁法方位非各向同性层状介质Occam反演

Occam inversion of CSAMT data in layered media with azimuthal anisotropy

目前,可控源音频大地电磁法测深资料反演主要基于各向同性介质,在复杂的地电体中,由于岩石裂隙或矿物形状等原因使得在各个方向的电阻率不同。本文主要探讨更为符合实际地质体情况的方位非各向同性层状介质在正交水平电偶源激发条件下的可控源音频大地电磁数据的反演。运用Occam反演方法,实现了可控源音频大地电磁法方位非各向同性层状介质反演。构建理论地电模型,通过理论模型合成数据的反演算例检验了所实现的可控源音频大地电磁法方位非各向同性层状介质反演算法的有效性和稳定性。同时,不同数据的反演结果表明:方位非各向同性介质的反演应同时使用视电阻率ρ_(sxy)、ρ_(syx)和相位φ_(xy)、φ_(yx)数据。

At present,the inversion of controlled source audio-frequency magnetotelluric data is mainly based on the isotropic media.Because of the rock fracture or the shape of mineral,the resistivity is different in each direction in the complicated geoelectric body. To fit actual geological conditions better,this paper mainly probes into the inversion of controlled source audio-frequency magnetotelluric data in layered media with azimuthal anisotropy induced by ground orthogonal horizontal electric dipoles. We develop an Occam inversion algorithm to invert controlled source audio-frequency magnetotelluric data for azimuthal anisotropy in layered media. Designing the theoretical geoeletric models,the synthetic examples demonstrate the validity and stability of the Occam inversion algorithm. At the same time,the inversion results of different data suggest that in order to get better inversion results of azimuthally anisotropic layered media the apparent resistivities ρ_（sxy）,ρ_（syx）,and phases φ_（xy）,φ_（yx）,should be used.