Abstract Hydraulic fracturing creates a complex fracture geometry in heterogeneous formations which are frequently simulated using Finite Element based fracture propagation modelling tools. Representing this geometry in Finite Difference based multiphase flow simulators poses some challenges. In this study, a Fracture Upscaling Method (FUM) is developed to represent complex fracture systems generated by the finite element method. It is demonstrated that this method can capture complex fracture geometries even when using coarse grids. This upscaling method can be used as a coupling tool between the output of any discrete fracture model and any finite difference-based reservoir simulator. FUM is tested against a field case and simulation results show a reasonable match with 120 days of production data. This method is then used to investigate the impact that natural fractures have on production from shale gas wells. The results show that the effect of orientation, spacing and length of natural fractures, on propagating hydraulic fractures can reduce the recovery factor by 30%. Furthermore, the ability of FUM to combine highly complex fracture networks with realistic multiple layer models with complex distributions of reservoir properties is demonstrated.

中文翻译：

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水力压裂油藏的裂缝放大方法 (FUM)：从离散裂缝建模到有限差分模拟

摘要 水力压裂在非均质地层中产生复杂的裂缝几何形状，经常使用基于有限元的裂缝扩展建模工具进行模拟。在基于有限差分的多相流模拟器中表示这种几何形状会带来一些挑战。在这项研究中，开发了一种裂缝放大方法 (FUM) 来表示由有限元方法生成的复杂裂缝系统。事实证明，即使使用粗网格，该方法也可以捕获复杂的裂缝几何形状。这种放大方法可以用作任何离散裂缝模型的输出和任何基于有限差分的储层模拟器之间的耦合工具。FUM 针对现场案例进行了测试，模拟结果显示与 120 天的生产数据合理匹配。然后使用该方法研究天然裂缝对页岩气井产量的影响。结果表明，天然裂缝方向、间距和长度对水力裂缝扩展的影响可使采收率降低30%。此外，还展示了 FUM 将高度复杂的裂缝网络与具有复杂储层特性分布的真实多层模型相结合的能力。