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基于测井参数的页岩有机碳含量支持向量机预测

Prediction of shale organic carbon content support vector machinebased on logging parameters

  • 摘要: 为了解决传统的有机碳含量TOC测量方法成本高和无法获得TOC含量连续分布的问题,提出了一种TOC含量的统计预测方法。由于地层的岩性的不同,TOC含量的差异非常大,因此,首先对原始的测井数据聚类,通过聚类的方法将不同岩性的地层区分开,对不同的地层分别建立TOC含量的预测模型,再通过聚类的方法提高了各测井参数和TOC含量的相关性,这不仅提高了模型的准确性,而且使得模型更有说服力;然后通过粒子群算法优化SVM模型参数,避免了因人工选择参数带来的模型不稳定的问题,依此建立测井参数优选的SVM-RFE模型,对每一类分别进行测井参数筛选,有效的规避了各测井参数之间的信息冗余和不相关参数带来的模型性能降低和训练时间增加的问题;最后利用优选后的测井数据和SOM的分类结果,对不同的地层岩性分别建立SVR模型进行预测。结果表明:通过与其它TOC含量预测模型对比,SOM-SVR模型更加稳定,更有说服力,预测误差小,平均相对误差约6%,平均绝对误差不超过0.2。由此,可以通过SOM算法对不同岩性的地层进行聚类之后再建立TOC含量的预测模型,更有利于提高模型的精度。

     

    Abstract: In order to solve the problem that the traditional TOC (Total Organic Carbon )content measurement method is costly and unable to obtain continuous distribution of TOC content, a statistical prediction method of TOC content is proposed.Due to the difference in lithology of the stratum, the difference in TOC content is very large.Therefore, the original log data was first clustered, and the strata of different lithologies were separated by clustering, and predictive models of TOC content were established for different strata.The correlation between the logging parameters and the TOC content was improved by the clustering method, which not only improved the accuracy of the model, but also made the model more convincing.Then the particle swarm optimization algorithm optimized the SVM model parameters, avoiding the manual parameter selection.The model was unstable, and then the SVM-RFE model with well logging parameters was established.The logging parameters were screened for each type, effectively avoiding the information redundancy and irrelevant parameters between the logging parameters.The performance of the model was reduced and the training time was increased.Finally, the SVR model was established for different formation lithology by using the optimized logging data and SOM classification results.Compared with other TOC content prediction models, the results show that the SOM-SVR model is more stable, more convincing, and the prediction error is small, the average relative error is about 6%, and the average absolute error is less than 0.2.It can be concluded that the SOM algorithm is used to cluster the different lithology strata and then establish the TOC content prediction model, which is more conducive to improve the accuracy of the model.

     

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