激发极化介质的瞬变电磁一维正演

摘要

To study the IP effect ("induced polarization effect") generated by IP media according to the rule of TEM response, the authors firstly solve the electromagnetic responses which have the same K⁃factor, introduce the Dias model describing IP effect in the frequency domain, and then use the sinusoidal transform to get TEM response with the IP information. As the chargeability increases, the amplitude of the electric filed is changed in the homogeneous half⁃space. With the increase of the relaxation time, the IP anomaly appears in the late time. And the IP anomaly appears in the early time when the polarization resistance coefficient is increased. Among different resistivity models with the same chargeability in the middle layer, it can be summarized that the H⁃type model can easily show the polarization layer, while the K⁃type is the worst model to manifest the induced polarization effect, with the performance of the A and Q⁃type lying between H and K type.%为了研究激发极化介质所产生的激电效应对瞬变电磁的响应规律，先求解相同装置的频率域电磁法响应，将表征介质激电效应的Dias模型在频率域中引入，然后采用正弦变换得到带有激电信息的瞬变电磁响应；重点讨论均匀半空间和层状可极化大地下的瞬变电磁响应特征。通过正演模拟分析得到：在均匀半空间情况下，极化率越大极化效应越强；激电时间常数越大，出现激电异常的时间越晚；极化电阻系数越大，出现激电异常时间越早。对于中间层极化率相同的不同电阻率的三层模型呈现如下规律：H型地电断面反映极化层能力最强，K型反映极化层能力最差，A型和Q型介于两者之间。