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    基于堆叠集成学习的致密砂岩储层束缚水饱和度预测与渗透率计算

    Prediction of Bound Water Saturation and Permeability Logging Evaluation in Tight Sandstone Reservoirs Based on Stacked Ensemble Learning

    • 摘要: 致密砂岩气藏是目前重要的油气勘探领域,其储层孔隙结构复杂、渗透率低、束缚水含量高,测井评价技术面临挑战。核磁共振测井能够准确地识别储层束缚水和可动水,但无法覆盖所有探井,常规测井资料的束缚水饱和度预测与渗透率计算具有局限性,迫切需要深入研究新方法。本文提出了一种基于堆叠集成学习的致密砂岩储层束缚水饱和度预测与渗透率计算方法,以核磁共振测井计算的束缚水饱和度为标签,引入常规测井数据及岩石物理模型计算的储层特征参数为输入,融合物理模型与数据驱动,构建多个基学习器(随机森林、极端梯度提升和梯度提升)与元学习器(随机森林)组合的集成学习框架。通过训练多个基学习器生成初始预测结果,将其作为特征输入至元学习器中,利用交叉验证方式训练,实现常规测井的束缚水饱和度预测。根据岩石物理实验结果,回归Timur公式,结合预测的束缚水饱和度,实现致密砂岩含气储层渗透率计算。该方法在东海陆架盆地XH凹陷C区块HG组致密砂岩储层进行应用,预测的束缚水饱和度平均绝对误差小于5%,渗透率平均对数误差小于0.2,该方法显著提高了致密砂岩储层束缚水饱和度预测与渗透率评价精度,具有良好的适应性和推广价值。

       

      Abstract: Tight sandstone gas reservoirs are currently a key focus in oil and gas exploration. However, their complex pore structures, low permeability, and high bound water content pose significant challenges for well logging evaluation. While Nuclear Magnetic Resonance (NMR) logging can accurately distinguish between bound and movable water in the reservoir, it is not available for all exploration wells. Therefore, predicting bound water saturation and calculating permeability from conventional logging data remains limited and requires further study. This paper proposes a stacked ensemble learning method for predicting bound water saturation and evaluating permeability in tight sandstone reservoirs. Bound water saturation calculated from NMR logging is used as the prediction label, while conventional logging data and reservoir characteristic parameters derived from rock physics models are used as input features. A stacked ensemble learning framework is constructed, integrating physical models with data-driven approaches , consisting of multiple base learners (Random Forest, Extreme Gradient Boosting, and Gradient Boosting) and a meta-learner (Random Forest). Initial predictions from the base learners are input into the meta-learner, which is trained using cross-validation to predict bound water saturation from conventional logs. Permeability is then calculated based on the predicted bound water saturation using a regressed Timur equation, combined with rock physics experimental results, to realize permeability estimation of tight sandstone gas-bearing reservoirs. This method was applied to the tight sandstone reservoirs of the HG Member in the XH Depression, located in the C Block of the East China Sea Shelf Basin. The mean absolute error of the predicted bound water saturation was less than 5%, and the logarithmic error in permeability was below 0.2. The proposed method significantly improves the accuracy of bound water saturation prediction and permeability evaluation in tight sandstone reservoirs and demonstrates strong adaptability and applicability for broader use.

       

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