激电和电磁效应对三维复电阻率正演结果的影响研究

Study on the influence of IP and EM effects of 3D resistivity modeling results

复电阻率法(CR)又称为频谱激电法(SIP),是一种重要的激电分支方法,在矿产勘查中应用非常广泛.然而,在实际的频谱激电野外观测资料中,总是会受到不同程度的电磁耦合效应的影响.因此,研究同时存在激发极化效应和电磁效应的复电阻率性质,对频谱激电法的实际数据处理具有一定的参考价值.本文首先在均匀半空间条件下,进行了复电阻率法的正演模拟.分析了频率、收发距的改变对视电阻率和视相位的影响.然后在有低阻异常体存在情况下,同时采用三维积分方程法和三维有限差分法,研究了不同条件下视电阻率和视相位的变化.最后,根据对正演模拟结果的分析,总结出不同程度的电磁耦合效应对视电阻率及视相位的影响规律,为准确分析异常提供了依据.

Complex resistivity method （CR） that is also called spectrum induced polarization method （SIP） is one of important IP methods been widely used in mineral exploration. Field observational data by the method of frequency spectrum induced polarization always includes electromagnetic coupling of varying degrees. Therefore, it is very significant to study the apparent resistivity method and electromagnetic coupling for the actual data processing of the SIP. This paper in first studied the complex resistivity forward modeling of the uniform half-space and analyzed the forward response of the different frequencies. We studied the effects of frequency and the different receiving distances. Then, we studied the changes of apparent resistivity and apparent phase under different conditions using the integral equation method and finite-difference method by the low-resistivity 3D model in half-space. Finally, basing on the analysis of the results of forward modeling, we deduced and summarized the influences of different degrees of electromagnetic coupling effect on apparent resistivity and apparent phase. The results will be useful for practical analysis of electromagnetic survey.