垂直磁偶源频率域电磁测深法一维正演及响应特征

One-dimensional Modeling and Response Characteristics of Vertical Magnetic Dipoles Frequency-domain Electromagnetic Sounding Method

为了探究磁偶源频率域电磁法的测深能力,以垂直磁偶源频率域电磁剖面装置为例,从垂直磁偶极子在一维层状介质的Z方向磁场公式出发,在低感应系数条件下推导了视电导率的表达式,最终实现了垂直磁偶源频率域电磁测深法的一维正演;然后通过对典型层状模型进行一维正演模拟,分析了磁偶源频率域电磁测深法的响应特征。结果表明:通过同时减小发射频率和增大收发距并保持频率与收发距平方的乘积不变能够实现电阻率测深,属于频率和几何测深联合方式,可见该方法能够准确地反映地下介质视电阻率的垂向变化信息。

To explore the magnetic dipole source frequency domain electromagnetic sounding ability,based on the vertical magnetic dipole source frequency domain electromagnetic profile device as an example,from a vertical magnetic dipole in the Z direction magne-tic field formula of one-dimensional layered media,under the condition of low induction number,the apparent conductivity of expression was deduced,finally achieving the vertical magnetic dipole source frequency domain electromagnetic sounding method,one dimensional forward.Then the response characteristics of the magnetic dipole source frequency domain electromagnetic sounding method were analyzed by a one-dimensional forward simulation of a typical layered model.The results show that the resistivity sounding can be realized by decreasing the transmitting frequency and increasing the transmitting distance while keeping the product of frequency and square of transmittance distance unchanged,which belongs to the combination of frequency and geometric sounding and can accurately reflect the vertical variation information of the apparent resistivity of underground media.