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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.
It is urgent to perfect the theory and explanation system of this method in order to popularize and use it in production.In this paper, the characteristics of large amount of data of ground-based transient electromagnetic method are used in combination with differential Based on the principle of equivalent conductive plane, the fast approximation of transient field with higher accuracy is deduced from the electric dipole source This algorithm is extended to the fast approximate forward calculation of transient field at any point in space-to-space transient electromagnetic space of multi-radiation field source. The method is validated by four typical layered models Based on which the derivation of longitudinal conductivity and apparent depth as a function of ground-based transient electromagnetic method for multi-radiation field sources is further deduced.Using differential conductance, the sensitivity of the electrical interface and the associated superposition synthesis algorithm are outstanding anomalies, , And realizes the superposition and fast imaging of electromagnetic transient over the air in the multi-radiation field.The 3D model tests show that the fast imaging algorithm proposed in this paper is fast and effective System noise, and a better resolving power of the subsurface, help to improve the accuracy of interpretation multiple radiation source transient electromagnetic air.