中文摘要：

多辐射场源地空瞬变电磁法目前仍处于研究阶段,迫切需要完善该法的理论和解释体系,以便在生产中推广使用.本文利用地空瞬变电磁法数据量大的特点,结合微分电导与相关叠加合成算法,实现了多辐射场源地空瞬变电磁法快速成像解释.首先基于等效导电平面原理,从电偶极子源出发推导了较高精度的瞬变场快速近似正演计算公式,采用剖分叠加的思想,将其推广到多辐射场源地空瞬变电磁法空间任意一点瞬变场的快速近似正演计算,并用四种典型的层状模型验证了该法的计算精度.以此为基础,进一步推导了多辐射场源地空瞬变电磁法的视纵向电导和视深度计算公式.利用微分电导对电性界面敏感和相关叠加合成算法突出异常、压制干扰的特点,实现了多辐射场源地空瞬变电磁相关叠加快速成像.三维模型试验表明,本文提出的快速成像算法计算速度快,能有效压制噪声,且对地下界面有较好的分辨能力,有助于提高多辐射场源地空瞬变电磁法的解释精度。

英文摘要：

Multi-source transient electromagnetic method is still in a research stage at present. It is urgently needed to complete its theory and interpretation system to spread this method in practice.This paper takes advantage of large data volume of this method and realizes fast imaging on the basis of differential conductance and correlation stack method. Fast approximate forward formula with higher precision of an electric dipole is firstly deduced based on the floating plate theory. With the subdivision method,this formula can be promoted for fast forward modeling of any point in space of multisource transient electromagnetic method. Four typical layered models are used to test its calculation accuracy. With the above-mentioned work,apparent longitudinal conductance and apparent depth formula with higher precision of multi-source transient electromagnetic method can be got. Differential conductance has such advantage as high sensitivity to electrical layer boundary, while correlation stack algorithm can effectively highlight anomaly and suppress random disturbance. With these two characteristics, fast imaging on correlation stack of multi-source transient electromagnetic method is then achieved. The results of three dimensional model show that the fast imaging technique proposed in this paper has fast calculation speed and good resolution of subsurface electrical layer,which can help improve the interpretation precision of multi-source transient electromagnetic method.