基于代理模型的缝内支撑剂铺置形态高效预测方法

AN EFFICIENT METHOD FOR PREDICTING THE MORPHOLOGY OF PROPPANT PACK BASED ON SURROGATE MODEL

  • 摘要: 非常规油气储层体积压裂中,大量支撑剂颗粒随压裂液注入地层裂缝,其在缝内的铺置形态将决定裂缝支撑效果和导流能力。准确预测缝内支撑剂铺置形态有助于优化压裂设计、提升改造效率。实验和数值方法是当前模拟缝内支撑剂堆积过程和铺置形态的主要手段,但仍存在模拟尺度小、模拟耗时长和操作成本高等局限。本论文以支撑剂输送数值模拟结果为数据集,提取了表征支撑剂铺置堆积的特征参数,基于级联神经网络,建立了支撑剂铺置形态预测的智能代理模型。结果表明,代理模型预测结果与数值模拟结果高度吻合,预测时间仅为模拟时间的1.3‰。本论文提出的模型和方法已经实现支撑剂输送仿真加速,极大地缩短了支撑剂铺置形态的预测时间,其进一步完善后将在压裂实践中具有广泛的应用前景。

     

    Abstract: In the volume fracturing of unconventional oil and gas reservoirs, a large number of proppant particles are injected into underground along with the fracturing fluid, and their placement patterns will determine the propping effect and conductivity of fractures. Accurate prediction of in-fracture proppant placement patterns contributes to the optimization of fracturing design and the improvement of fracturing efficiency. At present, experimental and numerical methods are the main approaches to reproduce the proppant accumulation process and placement patterns in fractures, which are still confined by limited simulation scale, time-consuming computation and high-cost operation. In this paper, the numerical simulation results of proppant transport were adopted as data sets for input, training and testing. The characteristic parameters reflecting the process of proppant accumulation and packing were extracted, and an intelligent proxy model for the prediction of proppant placement pattern was established based on the cascade neural network. The results show that the predictions of proppant placement patterns are highly consistent with those presented by numerical simulations, while the time consumed by prediction in only 1.4‰ of that consumed by simulation. The model and approach proposed in this study have accelerated the speed of proppant transport simulation and greatly shortened the prediction time of proppant placement pattern, which will be widely applied in fracturing at field after further improvement.

     

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