瞬变电磁视时间常数tau成像分析与应用研究

TEM image analysis and application of the apparent time constant tau

基于瞬变电磁二次场的衰减理论,分析了地质异常体岩性参数与瞬变电磁响应规律,即电导率与时间常数tau成正比,导电性越良好的矿体,其时间常数越大,且二次场曲线衰减越慢。将瞬变电磁数据分解成多时窗的含有tau参数的自然指数衰减规律,得出了晚期道基于时窗提取的视时间常数tau成像方法。通过物理模拟试算和实测数据的验证,视时间常数tau成像能很好地反映晚期道地质异常体在水平面上的空间分布特征。该方法计算速度快,克服了反演速度慢的问题,也为地质异常体的定位提供了重要依据,并为其他成像和反演方法提供约束条件有重大的指导意义。

Based on the attenuation theory of the transient electromagnetic secondary field,the relation of the lithology of the geological anomaly body and transient electromagnetic response,namely,the conductivity is proportional to the time constant tau,is analyzed in this paper,The better conductive of ore body,the larger its time constant,and the slow decay curve of secondary field.In the paper,the transient electromagnetic data are decomposed into many time window data which contains tau parameter exponential decay law of nature.And the time constant tau imaging method is based on the late time windows extraction.Thought the physical simulation test and validation of the measured data,the apparent time constant tau imaging method can well reflect the spatial distribution feature of geological anomalies on horizontal plane in the advanced road.The method calculation speed is fast,which overcomes the problems of slow inversion and provides an important evidence for location of geological anomalies.The apparent time constant have important significance for other imaging and inversion methods.