基于成像光谱的砂岩铀矿岩性分类深度学习方法

    Deep learning method for lithology classification of sandstone uranium deposits based on imaging spectroscopy

    • 摘要: 本文首先利用HySpex成像光谱仪对鄂尔多斯盆地西南部砂岩型铀矿钻孔ZKH3进行了扫描并开展了数据处理,获得了可反应岩石结构和成分信息的反射率图像数据。然后,依据砂岩铀矿岩性分类规则,分析HySpex成像光谱数据刻画岩石粒级和反映矿物成分的能力,认为本次图像数据的空间分辨率只能刻画粗砂级以上岩石颗粒特征,而图像光谱既能反演矿物成分,还包含岩石的结构信息,更适合用于岩性识别。其后,分析不同深度学习算法、模型和参数的特点,构建了包含7个一维卷积层、2个池化层、1个一维卷积注意力模块和3个全连接层卷积神经网络模型。并收集整理了7类岩石共26877条光谱样本,完成了模型优化和训练。最后,通过与支持向量机(SVM)的对比以及在整孔岩心中的应用,评价了模型性能。结果表明,其总体精度(OA)达到94.6%,其中泥岩、细砂岩、粉砂岩、中砂岩、粗砂岩、砂砾岩及背景的生产者精度(PA)分别为95.07%、72.02%、97.50%、97.37%、96.65%、97.33%、99.01%,Kappa系数为0.94,总体优于SVM,且取得了与地质编录相当的效果,表明基于成像光谱数据的深度学习模型具有良好的岩性分类性能,可为岩心数字化及自动化编录研究提供参考。

       

      Abstract: This article first used the HySpex imaging spectrometer to scan the rock of ZKH3 of sandstone uranium deposits in the southwestern Ordos Basin. After that, the data preprocessing was conducted and the reflectance data which can reflect rock structure and composition information was obtained. Then, based on the lithological classification rules of sandstone uranium deposits, the ability of HySpex imaging spectral data to depict rock particle size and reflect mineral composition was analyzed. It is believed that the spatial resolution of this image data can only depict the characteristics of rock particles above the coarse sandstone level, while the image spectrum can not only invert mineral compositions but also contain structural information of rocks, making it more suitable for lithology recognition. Subsequently, the characteristics of different deep learning algorithms, models, and parameters were analyzed, and a CNN model consisting of 7 one-dimensional convolutional layers, 2 pooling layers, 1 one-dimensional CBAM, and 3 fully connected layers was constructed. In addition, a total of 26877 spectral samples from 7 types of rocks were collected, and model optimization and training were completed. Finally, the performance of the model was evaluated through comparison with Support Vector Machine (SVM) and its application in the whole borehole.The results showed that its overall accuracy (OA) reached 94.6%, among which the producer’s accuracy (PA) of mudstone, fine sandstone, siltstone, medium sandstone, coarse sandstone, glutenite and background were 95.07%, 72.02%, 97.50%, 97.37%, 96.65%, 97.33%, and 99.01%, respectively. The Kappa coefficient was 0.94, which was better than SVM overall and achieved comparable results to geological logging. This indicates that the deep learning model based on imaging spectral data has good lithology classification performance, can provide reference for research on digitalization and automation of core logging.

       

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