Research on controlled-source audio-frequency magnetotellurics three-dimensional numerical simulation with staggered-grid finite difference method in resistivity anisotropic media

摘要

Controlled-source audio-frequency magnetotellurics (CSAMT) has developed rapidly in recent years and arernwidely used in the area of mineral and oil resource exploration as well as other fields. The current theory,rnnumerical simulation, and inversion research are based on the assumption that the underground media havernresistivity isotropy. However a large number of rock and mineral physical property tests show the resistivityrnof underground media is generally anisotropic. With the increasing application of CSAMT, the demand forrnprobe accuracy of practical exploration to complex targets continues to increase. The question of how tornevaluate the influence of anisotropic resistivity to CSAMT response is becoming important. To meet therndemand for CSAMT response research of resistivity anisotropic media, this paper examines the CSAMTrnelectric equations, derives and realizes a three-dimensional (3D) staggered-grid finite difference numericalrnsimulation method of CSAMT resistivity axis anisotropy. Through simulating a 3D resistivity axis anisotropyrngeoelectric model, we compare and analyze the difference of CSAMT responses between different sourcernlocation and resistivity distribution of equator device and axis device. The result shows that the responserndifference between resistivity anisotropy and resistivity isotropy cannot be neglected.