基于多测点多频点的大地电磁一维区域阻抗恢复  

Multi-frequency and Multi-site Impedance Recovery of One-dimensional Region Structure

作　　者：王琪琪 马涛[1] 王红兵 谭鑫 高鑫 汪强强 Wang Qiqi;Ma Tao;Wang Hongbing;Tan Xin;Gao Xin;Wang Qiangqiang(Shaanxi Railway Engineering Survey Co.,Ltd.,China Railway First Survey and Design Institute Group Co.,Ltd.,Shaanxi Xi’an 710000,China)

机构地区：[1]中铁第一勘察设计院集团有限公司陕西铁道工程勘察有限公司,陕西西安710000

出　　处：《工程地球物理学报》2022年第4期566-573,共8页Chinese Journal of Engineering Geophysics

基　　金：西藏自治区科技厅重点研发计划项目(编号:XZ202001ZY0011G)。

摘　　要：在实际勘探中,浅部三维电性不均匀体的存在会导致大地电磁响应发生畸变,使阻抗张量偏离真实区域阻抗,影响后续反演和解释工作。本文主要利用1D(One-dimensional)区域构造中静态因子的统计学性质对多测点多频点畸变校正方法进行了改进。首先通过粒子群全局优化算法得到GB(Groom-Bailey,GB)分解参数中确定参数的全局最优解空间,将其作为高斯牛顿法的初值来进行局部优化,然后通过ssq(the Sum of the Squared Elements,SSQ)旋转不变量的统计特性得到不确定参数,最后利用正演模型验证了该算法的有效性。结果表明:该方法结合了粒子群算法和高斯牛顿法,避免结果陷入局部最优,通过正演模型发现不确定参数随测点位置呈“正态分布”,在异常体中心位置取最大,并且不确定参数可以指示静态效应的影响频段。同时静态校正后视电阻率和相位曲线与未受畸变影响的数据具有较高的重合度,说明该方法很好地消除了1D区域构造中多个浅部异常体的影响,恢复了原始区域阻抗信息。In actual exploration,the occurence of three-dimensional shallow electrical inhomogeneity affects the subsequent inversion and interpretation because of the distortion of the magnetotelluric response,which makes the impedance tensor deviate from the real regional impedance.In this paper,integration of the statistical properties of the static factor in the 1D(one-dimensional)area structure greatly improves the multi-frequency and multi-site distortion correction method in the following way.First,the global optimal solution space of the determined parameters in the GB(groom-bailey)decomposition parameters is obtained by the particle swarm global optimization algorithm,then it is used as the initial value of the Gauss-Newton method for local optimization through ssq(the sum of the squared elements)of the rotational invariant to obtain uncertain parameters,and finally the validity of the algorithm is verified by the use of the forward model.The results show that,being“normally distributed”with the position of the measurement point,the uncertain parameters take the maximum value at the center of the abnormal body.Through the forward model,after combining particle swarm optimization with Gauss-Newton method to avoid the result falling into local optimum,uncertain parameters can indicate the frequency band of influence of static effects.At the same time,the apparent resistivity and phase curves after static correction are liable to coincide with the data not affected by distortion,indicating that this method can eliminate the influence of multiple shallow anomalies in the 1D area structure and restore the original area impedance information.

关 键 词：大地电磁测深法 1D区域构造 GB分解 SSQ旋转不变量 静态效应 

分 类 号：P631.3[天文地球—地质矿产勘探]