瞬变电磁勘探中IP效应影响规律研究

The Research of IP Effect in Transient Electromagnetic Exploration

在瞬变电磁测量中,由于岩矿体的频散特性,会在结果中带入感应激发极化效应,使瞬变电磁晚期测道的数据发生倒转现象。笔者从Cole-Cole模型入手,深入分析了均匀半空间模型中各参数对瞬变电磁响应的影响,得出了充电率η和频率相关系数c对瞬变电磁响应的影响较大,而直流电阻率ρ0和时间常数τ对其影响较小的结论。对某矿区受激发极化(IP)效应影响的实测数据进行了分析,认为由于受IP效应的影响而造成了电阻率反演结果无法分辨出矿体位置,最终根据TEM数据发生的倒转现象,划定了矿体的位置;经过钻孔验证,吻合较好。在高极化地区应用该数据处理方法,可以有效地提高TEM的探测精度。

In measurements based on transient electromagnetic（TEM） methods, the TEM responses are often accompanied by induced polarization effects duo to the dispersion properties of rock and mineral body,which cause the TEM response appear sign reversal phenomenon. In this paper, we started from Cole-Cole model, analyzed the effects of homogeneous half-space model parameters on the transient electromagnetic response. We found that the parameters chargeability and frequency exponent c show a greater effect than DC resistivity and the time constant in TEM response. The measured TEM data subject to IP effect were analyzed for a mine. Because of the IP effect , the electrical resistivity inversion results could not distinguish ore body position, the reverse phenomenon of TEM data was used to locate the orebody. The result was verified by drilling. The detecting precision of the TEM data in high polarization region can be improved effec-tively with the data processing method.