考虑激发极化效应的瞬变电磁一维Occam反演

发布时间：2018-03-30 15:55

本文选题：瞬变电磁法　切入点：激电效应　出处：《吉林大学学报(地球科学版)》2017年04期

【摘要】：大地的感应激发极化效应有时会在瞬变电磁晚期响应上产生负值变号现象。常规实电阻率瞬变电磁反演由于没有考虑激发极化效应,对于观测数据负值部分的解释一直存在问题,这影响了反演解释的真实性和可信度。对此,本文首先将Cole-Cole复电阻率模型加入正演计算,并验证了计算的准确性。然后在阻尼最小二乘法的基础上加入Occam平滑约束来构建反演方程,能够同时反演出零频电阻率、充电率、时间常数以及频率相关系数,实现了一维瞬变电磁复电阻率反演算法。最后,建立具有不同程度激发极化效应的典型层状理论模型进行反演试算与结果分析,结果表明,在激发极化效果明显的低阻高极化地层中,复电阻率反演效果更好。与实电阻率反演结果的对比说明,瞬变电磁复电阻率反演既可以达到实电阻率的常规反演效果,也能解决实电阻率无法实现的负值拟合问题。
[Abstract]:The inductive induced polarization effect of the earth sometimes produces a negative sign change phenomenon in the late transient electromagnetic response. The conventional real resistivity transient electromagnetic inversion does not consider the induced polarization effect. There are always problems in the interpretation of the negative part of the observed data, which affects the authenticity and reliability of the inversion interpretation. In this paper, the Cole-Cole complex resistivity model is first added to the forward calculation. The accuracy of the calculation is verified. Then the inversion equation is constructed by adding Occam smoothing constraints on the basis of the damped least square method, which can invert the zero frequency resistivity, charge rate, time constant and frequency correlation coefficient at the same time. The inversion algorithm of one-dimensional transient electromagnetic complex resistivity is realized. Finally, a typical layered theoretical model with different degree of induced polarization effect is established for inversion calculation and result analysis. The results show that, The inversion effect of complex resistivity is better than that of real resistivity inversion in the low resistivity and high polarization strata where the induced polarization effect is obvious. The comparison with the real resistivity inversion results shows that the transient electromagnetic complex resistivity inversion can achieve the conventional inversion effect of real resistivity. It can also solve the problem of negative fitting which can not be realized in real resistivity.
【作者单位】：吉林大学地球探测科学与技术学院;
【基金】：中国地质调查局项目(12120113098400) 吉林大学研究生创新基金资助项目(2016200)~~
【分类号】：P631.325

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