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    多级分解驱动−融合地面井瓦斯抽采短期预测

    Multi-level decomposition-driven fusion for short-term prediction of ground well gas extraction

    • 摘要: 针对地面井煤层瓦斯抽采预测过程中的非线性、多尺度和噪声干扰问题,提出了基于多级分解与多模型协同机制的短期瓦斯抽采预测模型。利用ICEEMDAN和EWT算法对原始信号进行双层模态分解,以样本熵值2、1分别划分高、中、低频分量,并对高频分量进一步应用VMD分解细化。分别采用ELM、BO-BiLSTM和TCN对高、中、低频段信号开展预测,最后通过BP神经网络对三路模型输出结果进行融合预测,构建多级分解驱动−融合模型(ELM/BO-BiLSTM/TCN-BP)。通过与ELM、BO-BiLSTM、TCN和BP 4个单一预测模型预测精度开展对比实验,定量表征多级分解驱动−融合地面井瓦斯抽采短期预测模型精度。实验结果表明,该模型的预测精度显著优于传统单一模型,对短期波动、中期趋势和长期平稳成分的预测优势显著,实现了对短期、中期和长期动态的精确预测。其中ELM、TCN模型对高、低频分量测试集R2均接近1,具有较强的稳定性与精度。BO-BiLSTM模型在中频分量上泛化能力略有下降,但其R2仍有0.792 4。基于预测模型误差对比指标,多级分解驱动−融合短期预测模型测试集RMSEMAEMSEMAPE分别为4.195 4、3.255 4、17.601 1、1.045 2,较单一模型分别降低了71.06%、68.96%、92.10%、69.64%,融合模型R2为0.936 6,显著高于ELM、BO-BiLSTM、TCN和BP模型,分别提高了162.50%、285.91%、375.91%和305.45%,展现出更高的预测精度和泛化能力。多级分解驱动−融合模型相较于传统单一模型,显著提升了预测精度与稳定性,为地面井瓦斯抽采现场提供了多层次的准确预报。

       

      Abstract: To address the nonlinearity, multiscale characteristics, and noise interference involved in predicting coalbed methane extraction from surface wells, a short-term methane extraction prediction model based on multi-level decomposition and a multi-model collaborative mechanism was proposed. The original signal was subjected to two-stage modal decomposition using improved complete ensemble empirical mode decomposition with adaptive noise (ICEEMDAN) and empirical wavelet transform (EWT). The decomposed components were classified into high-, medium-, and low-frequency groups using sample entropy thresholds of 2 and 1, and the high-frequency components were further refined through variational mode decomposition (VMD). An extreme learning machine (ELM), a Bayesian optimization-based bidirectional long short-term memory network (BO-BiLSTM), and a temporal convolutional network (TCN) were employed to predict the high-, medium-, and low-frequency components, respectively. Subsequently, a backpropagation neural network (BPNN) was used to integrate the outputs of the three models for ensemble prediction, thereby constructing a multi-level decomposition-driven fusion model, denoted as ELM/BO-BiLSTM/TCN-BPNN. Comparative experiments were conducted against four individual prediction models, namely ELM, BO-BiLSTM, TCN, and BPNN, to quantitatively evaluate the prediction accuracy of the proposed model. The experimental results showed that the proposed model significantly outperformed the conventional individual models in predicting short-term fluctuations, medium-term trends, and long-term stable components, thereby achieving accurate prediction across multiple temporal scales. The ELM and TCN models achieved R² values close to 1 for the high- and low-frequency components in the test set, respectively, indicating high prediction stability and accuracy. Although the BO-BiLSTM model exhibited slightly weaker generalization capability for the medium-frequency components, its R² value remained at 0.7924. Based on the comparison of prediction error metrics, the proposed multi-level decomposition-driven fusion model achieved RMSE, MAE, MSE, and MAPE values of 4.1954, 3.2554, 17.6011, and 1.0452, respectively, on the test set. Compared with the individual models, the four error metrics were reduced by up to 71.06%, 68.96%, 92.10%, and 69.64%, respectively. The proposed model achieved an R² value of 0.9366, which was significantly higher than those of the ELM, BO-BiLSTM, TCN, and BPNN models, corresponding to relative increases of 162.50%, 285.91%, 375.91%, and 305.45%, respectively. These results demonstrate that the proposed model provides superior prediction accuracy, stability, and generalization capability compared with conventional individual models, thereby supporting accurate multi-timescale forecasting for field coalbed methane extraction through surface wells.

       

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