ViT-KAN模型驱动下的砂岩热储地热潜力智能评估与可解释归因分析

Intelligent evaluation and interpretable attribution analysis of geothermal potential of sandstone thermal storage driven by ViT-KAN model

  • 摘要: 砂岩热储地热资源具有清洁、稳定及可再生优势,在“双碳”目标下对区域能源结构转型意义重大,但地质条件复杂、热储非均质性强及勘探不确定性等因素使区域地热潜力精准评估仍面临挑战。本文以鲁西北平原为研究区,综合10项地热地质指标,采用皮尔逊相关系数与方差膨胀因子开展特征筛选;融合KAN(Kolmogorov-Arnold Networks)与ViT(Vision Transformer)构建ViT-KAN砂岩热储地热资源潜力评估模型,从分类判别能力与概率预测精度两个维度选取受试者工作特征曲线下面积、准确率、召回率等8个指标对模型性能进行评价;结合SHAP(Shapley Additive Explanations)与反事实分析方法,揭示地热潜力的关键影响因素。结果表明:底板埋深与热储厚度存在多重共线性,经特征筛选后予以剔除,以降低输入特征冗余;ViT-KAN模型测试集的受试者工作特征曲线下面积、准确率和召回率分别为0.936、0.840和0.907,均优于ViT模型,且预测误差更低;高地热潜力区主要分布于研究区北部德城区、陵城区与平原县,模型预测结果与地热井点分布较为一致,ViT-KAN模型在低潜力区识别和勘探风险控制方面具有一定优势;SHAP与反事实分析揭示,热储温度、孔隙度和热储厚度是影响地热潜力预测的关键因素。研究成果可为区域地热资源评价与靶区优选提供技术支撑。

     

    Abstract: Sandstone thermal storage geothermal resources are clean, stable and renewable, which is of great significance to the transformation of regional energy structure under the goal of "double carbon". However, the complex geological conditions, strong heterogeneity of thermal storage and exploration uncertainty still make the accurate assessment of regional geothermal potential face challenges. In this paper, Beiping, western Shandong Province was taken as the research area, and the geological structure conditions and thermal storage characteristics were comprehensively considered. Ten evaluation indexes, such as elevation, slope and water depth, were selected, and Pearson correlation coefficient and variance expansion factor were used to carry out feature screening. Combining KAN(Kolmogorov-Arnold Networks) and ViT(Vision Transformer), a ViT-KAN model for evaluating the potential of geothermal resources in sandstone thermal storage is constructed, and eight indicators, such as receiver operating characteristic curve area, accuracy and recall rate, are selected from two dimensions of classification discrimination ability and probability prediction accuracy to evaluate the performance of the model. Combining SHAP (Shapley Additional Explanations) and counterfactual analysis method, the key controlling factors of geothermal resources potential are revealed. The results show that there are multiple collinearities between the buried depth of floor and the thickness of thermal storage, which are eliminated after feature screening to reduce the redundancy of input features. By comparing the changing trends of Loss and AUC in the training process, the Loss of the test set of ViT-KAN decreased to 0.334, and the AUC reached 0.936, both of which were better than those of ViT's 0.365 and 0.914, and the convergence was more stable, indicating that the introduction of KAN can effectively optimize the training process and improve the prediction accuracy. Compared with ViT, ViT-KAN has higher AUC, ACC and Recall in training set and test set, lower MSE, RMSE and MAE, and the overall ROC curve is dominant (AUC in test set is 0.936, RMSE is 0.401), and its classification discrimination ability and prediction error control are better than Vit. The classification of geothermal potential based on natural discontinuity method shows that the overall spatial pattern predicted by the two models is consistent, and the high-potential areas are concentrated in Decheng District, Lingcheng District and Pingyuan County in the north, but ViT-KAN describes the high-potential areas more finely, with the extremely low and low potential areas accounting for 49.2% in total, while ViT has raised this ratio to 60.9%, with the high and extremely high potential areas accounting for 12.2% and 8.8% respectively. The high geothermal potential areas are mainly distributed in Decheng District, Lingcheng District and Pingyuan County in the north of the study area. Compared with the known well point distribution, the classification results of the two models are highly consistent, and the proportion of geothermal wells increases with the increase of potential grade, in which ViT-KAN accounts for 87.61% of geothermal wells in extremely high potential area, and the proportion of non-geothermal wells in medium and high potential area is significantly reduced. Thermal storage temperature, porosity and thermal storage thickness are the key factors affecting geothermal potential prediction, all of which are positive contributions. The research results can provide technical support for regional geothermal resources evaluation and target area optimization.

     

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