电性源地-井瞬变电磁法全分量响应特性与探测能力分析

结合地面电性源瞬变电磁法（TEM）探测深度大和地-井TEM探测精度高的优点，本文提出对电性源地-井TEM进行研究.基于一维正演理论，本文对电性源在地下激发的六个电磁场分量的扩散、分布特性和探测能力进行分析研究.研究结果表明地下瞬变场各分量的分布特征与地面情况类似，但是对地层的探测能力与地面情况存在较大差别.各分量的探测能力与它们的扩散特性有关，其中受积累电荷作用，垂直电场E_z和水平磁场?_x分量对目标层的反映最为明显，E_x和?_y分量在地下扩散时受"返回电流"的影响会出现变号现象，使得异常体带来的影响被掩盖，不易被分辨.本文研究结果为发展电性源地-井TEM的施工技术、数据处理与解释，建立了相应的理论基础，获得了对该方法的初步认识.

Analysis on the full-component response and detectability of electric source surface-to-borehole TEM method

Considering the advantages of great detection depth of electric source transient electromagnetic method (TEM) and high detection precision of surface-to-borehole TEM, this paper proposed a study on the electric source surface-to-borehole TEM. Based on the one-dimensional forwarding algorithm, we analyzed the diffusion, distribution and detection capabilities of all the six electromagnetic field components excited by an electric source on the ground. The results show that the distributions of the underground EM fields are similar to those on the ground, but there is a big difference between their detection abilities. The detection ability of each component is related to their diffusion characteristics. The vertical electric field E_z and horizontal magnetic component dH_x/dt reflect the target layer most clearly when subjected to the accumulated charge. The value sign of underground E_x and dH_y/dt components will change affected by the ‘return current’, making the anomaly caused by the targets are blurred. The research results in this paper are to develop the construction technology, data processing and interpretation of the electrical source surface-to-borehole TEM, establish the corresponding theoretical basis, and obtain a preliminary understanding of the method.