CSAMT单分量数据解释方法

可控源音频大地电磁法(CSAMT)一直沿用大地电磁法(MT)的办法,通过计算电场分量与磁场分量的比值,求取卡尼亚视电阻率.而CSAMT场源已知,电场分量和磁场分量都与地下电阻率存在一定的关系,可以单独采用CSAMT电场分量或者磁场分量提取地下介质的视电阻率.本文通过分析电场分量与磁场分量的数据特性,提出利用CSAMT电场单分量数据进行视电阻率的计算,用改进的广义逆矩阵反演方法,使初始模型中的地电层数等于频道个数,克服了以往反演计算中层数较少的问题;实现全场区电场分量视电阻率曲线的拟合反演.同时对单分量视相位计算方法进行分析,结合山西大同地区积水采空区探测及数据解释结果,论证本文提出的单分量解释方法的有效性.

Interpretation of CSAMT single-component data

Following the Magnetotellurics method (MT), the apparent resistivity of the Controlled Source Audio-frequency Magnetotellurics (CSAMT) is usually derived from the ratio of electric field and magnetic field. For CSAMT, as the source power current density is known, both of the electric and magnetic field components are related to the resistivity of the earth. The apparent resistivity can be obtained from the single electric field or magnetic field. In this paper, we put forward the inversion and interpretation methods for single-component data of CSAMT after analysing the data features. During the curve fitting inversion, in order to increase the number of the inverted layers, the number of frequency of curves is regarded as the inversion earth layers number. The all-zone electric component apparent resisitivity inversion is developed. Then, the phase is introduced into the inversion process to omit the effect of static displacement. The field observation in water-filled mined-out space in Shanxi Province is used to verify the effectiveness of the new interpretation method.