天然气全生命周期产量预测关键技术研究

Research on key technologies for production forecasting of natural gas throughout its life cycle

  • 摘要: 准确预测天然气井产量对开发决策优化具有重要意义。现有预测方法大多侧重整体建模,难以适应天然气井“增产-稳产-减产”的生命周期演变特征;且现有数据驱动模型大多忽略储层渗流场随时间演化的物理规律,难以准确反映物性的时序变化。本文从生命周期视角出发,提出气井产量预测方法(FGPM)。首先,通过断点检测算法划分气井生命周期,结合产量相对波动率判别气井生产阶段;随后,构建基于编码-解码结构的预测模型,针对生产阶段进行特征匹配训练,并集成为全生命周期模型;最后,从模型超参数优化和渗流规律融合两方面展开模型优化。实验证明:(1)全生命周期模型相较于单一周期模型预测精度更高。与TCN、LSTM、GRU等经典方法对比,FGPM的预测精度分别提升了42.10%、39.40%、36.16%。(2)面向FGPM设计的优化措施对模型性能提升起正向作用:(a)优化超参数后的模型,其MAPE、MAE和RMSE分别提升了9.9%、16.2%和19.4%;(b)融合渗流规律约束的FGPM,其MAPE仅为4.874479%,模型性能得到进一步提升。

     

    Abstract: Accurate prediction of natural gas well production is of great significance to optimize development decisions. Existing prediction methods mostly focus on overall modeling, which is difficult to adapt to the life cycle evolution of natural gas wells, which is characterized by “increasing production, stabilizing production, and decreasing production”; moreover, most of the existing data-driven models ignore the physical law of reservoir seepage field evolution over time, which is difficult to accurately reflect the temporal changes of physical properties. In this paper, a gas well production prediction method (FGPM) is proposed from the perspective of life cycle. Firstly, the life cycle of gas wells is divided by the breakpoint detection algorithm, and the relative fluctuation rate of production is combined to identify the production stage of gas wells; subsequently, a prediction model based on the coding-decoding structure is constructed, with feature matching training conducted for each production stage and integrated into the full-life-cycle model; finally, the model optimization is carried out from the optimization of the model hyper-parameters and the integration of seepage flow laws. The experiments proved that: (1) the prediction accuracy of the full life cycle model is higher compared with that of the single cycle model. Compared with the classical methods such as TCN, LSTM and GRU, the prediction accuracy of FGPM is improved by 42.10%, 39.40% and 36.16%, respectively. (2) Optimization measures for FGPM design play a positive role in model performance enhancement: (a) the model with optimized hyper-parameters has improved its MAPE, MAE and RMSE by 9.9%, 16.2% and 19.4%, respectively; (b) the FGPM incorporating the constraints of seepage law has a MAPE of only 4.874479%, and the model performance has been further improved.

     

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