基于时序自编码器的页岩气积液智能诊断方法

Intelligent Diagnosis Method for Shale Gas Liquid Loading Based on Temporal Autoencoder

  • 摘要: 页岩气现场井筒积液标记样本稀缺,现有积液诊断技术普遍存在预测精度偏低、预警滞后等工程痛点。为此,提出一种融合变分模态分解(VMD)与长短期记忆自编码器(LSTM-AE)的页岩气井筒积液智能诊断方法。以监控与数据采集(SCADA)系统采集的分钟级生产动态时序数据为基础,采用VMD算法对原始监测信号进行降噪与特征重构;依托页岩气井正常生产样本完成自编码器无监督训练,引入长短期记忆神经网络(LSTM)增强模型对生产数据时序演化特征的挖掘能力;依据模型输出的重构误差确定积液判别阈值,实现井筒积液工况的智能识别与早期预警。选取四川盆地威远区块平台井的积液历史监测数据,基于滑动窗口生成5 000组时序样本用于模型训练与测试。结果表明:模型在测试集上预警准确率达到97.8%,误报率仅为2.6%;实例井实时预警模拟结果显示,相较于人工坐岗判别,预警时间可提前31  min,具备优异的时效性,能够实现积液早期风险识别,验证了该方法在实际应用中的有效性。

     

    Abstract: Due to the scarcity of liquid loading samples in shale gas development field operations, resulting in low prediction accuracy and significant delay in early warning of existing liquid loading diagnostic methods, a novel early intelligent diagnostic method for shale gas wellbore liquid loading is proposed. This method combines Variational Mode Decomposition (VMD) and an improved Autoencoder (LSTM-AE). Based on minute-level production dynamic data collected by the Supervisory Control and Data Acquisition system (SCADA), VMD is applied to feature selection and reconstruction of the raw monitoring data. For model construction, an unsupervised training approach is used with normal production phase samples of shale gas wells to train the autoencoder model. Additionally, the Long Short-Term Memory (LSTM) network enhances the temporal feature extraction capability of the autoencoder for shale gas well production data samples. A discrimination threshold is set based on the reconstruction error output by the model, enabling intelligent recognition and early warning of liquid loading conditions. The experiment utilizes production dynamic monitoring data from a well with historical liquid loading records on a platform in the Weiyuan gas field of the Sichuan Basin. Using a sliding window, 5,000 normal production and liquid loading samples are generated for model training and testing. The results show that the model achieves an early warning accuracy of 97.8% on the test set, with a false alarm rate of only 2.6%. In real-time warning simulations for the test well, the model provides an early warning 31 minutes ahead of manual monitoring, demonstrating strong timeliness and the ability to provide early alerts during liquid loading events. This confirms the effectiveness of the proposed method in practical applications.

     

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