电性源瞬变电磁响应计算中的误差研究

摘要

Electric-dipole source TEM, having the character of high efficiency and resolution to geo-electric section, is more focused by the geophysicists. However, there will be some error that considering the long grounded line as the electric dipole, which affects the detecting precision. This paper analyzes the calculation error between approximation solution by line-filter method and accurate solution on homogeneous half-space. Traditional electric sounding uses the far-field calculation formula, which exists approximation of power series. This paper puts forward a new research thinking.%电偶源瞬变电磁测深具有工作效率高,对地电断面分辨能力强的特点,越来越受到地球物理学家的关注.但在电偶源测深时直接将具有一定长度的接地导线看作偶极子源会带来一定的计算偏差,影响了探测精度.偶极子响应近似解与精确解存在一定的误差,这里分析这些近似可能带来的计算误差.时域与频域的转换过程在目前的数值计算手段下还无法做到完全的无误差,通过均匀半空间下的场值响应解析解和采用目前常用的线性数字滤波方法计算的均匀半空间的场值响应进行对比,分析使用数值计算方法计算层状介质场值响应可能存在的计算误差.同时,在常规电偶源测深时,往往采用远区场计算公式,以满足偶极子近似的条件.远区场公式的推导过程中存在着幂级数展开的近似,通过对各展开项的分析,指出该近似过程可能得到的计算误差,最后,针对各种计算误差的存在,提出了新的研究方向和思路.