天然场源激电法的可行性

FEASIBILITY OF NATURAL SOURCE INDUCED POLARIZATION

基于对现有天然场源激电法观测方案的分析和对沿横向和垂向电性都不均匀的二维地电断面的数值模拟结果指出 ,天然 (大地 )电磁场由于地下导电性不均匀所引起的异常强度远大于激电效应引起的异常 ;提取被强大导电和电磁效应异常“淹没”的弱小激电异常的难度极大 ,现有方案都不具有普遍的可行性 .天然场源激电法的实际应用前景不容乐观 .人工源“长偏移距”的激电法本质上和天然场源激电法一样 ,都是在“远区场”中作激电观测 ,其前景同样不乐观 .

The existing observation schemes for natural source induced polarization (NSIP) and the numerical modeling results of 2-dimension geoelectrical sections with horizontal and vertical electrical non-uniformity are analyzed. It is pointed out that the MT anomalies caused by conductive and electromagnetic effects are overwhelming superiority to the IP anomalies produced by the induced polarization effects. Accordingly, it is very difficulty to pick up the week IP anomalies from the strong EM anomalies. The existing observation schemes for NSIP are not of universal feasibility. The practical application prospects of NSIP are not optimistic. The control source IP with long offset is intrinsically same as NSIP. They are both taking IP obsevation in the 'far zone of electromagnetic field'. So it's practical application prospects are not optimistic too.