基于BO-CNN-LSTM模型的冻土区水合物地层岩性识别方法

Research on the rock type identification method of gas hydrate reservoirs in permafrost regions based on the BO-CNN-LSTM Model

  • 摘要: 冻土区天然气水合物地层测井响应具有强非线性、时序相关性与多尺度特征,传统测井岩性解释方法存在人为干扰大、复杂岩性混淆严重、识别精度有限等问题,常规深度学习融合模型亦存在超参数依赖人工经验、泛化能力不足的缺陷。针对上述问题,提出一种基于贝叶斯优化融合CNN-LSTM的岩性识别方法(BO-CNN-LSTM),用于冻土区水合物地层精细岩性识别。该方法依托一维卷积神经网络(CNN)自动挖掘测井数据局部空间特征,结合长短期记忆网络(LSTM)精准捕捉地层深度序列演化规律,同时引入贝叶斯优化算法对模型卷积核数量、LSTM神经元数、学习率、dropout率等关键超参数进行全局自适应寻优,有效规避人工调参的主观性与局限性,大幅提升模型特征表征能力与训练稳定性。以祁连山木里冻土区水合物钻孔实测测井数据与岩心编录资料为基础,选取井径、岩石密度、自然伽马、视电阻率、声波时差五类核心测井参数构建数据集,完成8类地层岩性的分类识别实验,并通过五折交叉验证、多模型对比试验检验模型性能。试验结果表明:优化后的BO-CNN-LSTM模型岩性识别整体准确率达96.25%,实际钻孔应用预测准确率可达96.49%,精确率、召回率与F1分数均显著优于单一CNN、LSTM、传统CNN-LSTM及经贝叶斯优化的XGBoost、随机森林、SVM等机器学习模型。该模型可有效解决冻土区相似岩性误判混淆问题,能够精准刻画水合物储层地层岩性的纵向分布特征,为冻土区天然气水合物储层精细解释、储层评价与资源勘探提供高效可靠的智能识别技术支撑。

     

    Abstract: In response to the issues of low accuracy and significant lithological misidentification in traditional well-logging interpretation for gas hydrate exploration in permafrost regions, this paper proposes a fusion lithology identification method based on Bayesian Optimized Convolutional Neural Network–Long Short-Term Memory network (BO-CNN-LSTM). This method adaptively searches for the key hyperparameters of the CNN-LSTM model through Bayesian optimization, effectively integrating the strengths of CNN in extracting well-logging features with the capability of LSTM in modeling sequential information, thereby achieving high-precision lithology identification in gas hydrate-bearing formations in permafrost regions. Experimental results show that the overall identification accuracy of the BO-CNN-LSTM model reaches 96.25%, significantly outperforming traditional CNN-LSTM models and single deep learning models. This demonstrates the promising potential of the proposed method for lithology classification and reservoir evaluation in gas hydrate-bearing formations within permafrost regions.

     

/

返回文章
返回