基于BP神经网络的时域激电谱Cole-Cole模型参数反演及应用

    Parameter inversion and application of the Cole-Cole model for time-domain induced polarization spectra based on the backpropagation neural network

    • 摘要: Cole-Cole模型的频谱参数可以提升时间域激电数据综合解释的分辨率,对于寻找金属矿有一定的潜力。利用BP神经网络模型预测反演频谱参数,不仅能够避免复杂的计算量提升反演速度,还可以充分挖掘时间域激电数据的使用效率来丰富地下矿体特征信息。基于此,本文利用数字滤波算法获得时间域视极化率衰减曲线表达式,以此表达式为正反演模型,对比探究训练集样本数、输入神经元个数、隐含层节点数和隐含层层数4种因素对BP神经网络模型训练及反演效果的影响,并筛选出最合适模型;进一步采用8个时间窗口的时间域激电数据,将训练好的BP神经网络模型应用在野外实测的时间域激电数据进行预测反演。研究结果表明,BP神经网络模型在理论数据集和实测数据集反演频谱参数均是可行的,反演效果具有精度高、误差小的特征,对于区分共生、伴生矿,减少误判有所帮助,具有一定的研究意义。

       

      Abstract: The spectral parameters of the Cole-Cole model can improve the resolution of comprehensive interpretation of time-domain induced polarization (IP) data, contributing somewhat to the exploration of metal deposits. Applying the backpropagation neural network (BPNN) model to the prediction and inversion of spectral parameters can avoid high computational complexity to improve the inversion speed. Moreover, the BPNN model can fully explore the utilization efficiency of time-domain IP data to enrich the characteristic information of subsurface ore bodies. Based on this, this study derived the mathematical expression of the time-domain apparent polarizability attenuation curve using the digital filtering algorithm. With the mathematical expression as the forward/inverse model, this study comparatively analyzed the impacts of four factors-the sample size of the training set, the number of neurons in the input layer, the node number of hidden layers, and the number of hidden layers-on the training and inversion effects of the BPNN model, determining the optimal model. Furthermore, this study trained the BPNN model using time-domain IP data from eight time windows. Finally, this study applied the trained BPNN model for prediction and inversion based on the measured time-domain IP data. The results indicate that the BPNN model is feasible in inverting spectral parameters based on both theoretical and measured datasets, manifesting high inversion accuracy and minor errors. Overall, the results of this study can assist in distinguishing paragenetic and associated minerals and reducing misinterpretation.

       

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