In an enhanced geothermal system (EGS), fractures and fracture networks are the predominant elements for fluid flow and heat transfer through the artificial reservoir. In this work, different conceptual discrete fracture networks were generated by characterizing the fracture number, fracture bifurcation and fracture connectivity of the fracturing area. A thermal–hydraulic (TH) coupled mathematical model was applied to evaluate the EGS thermal recovery process. Heat extraction capacity was appraised in terms of the temperature production, net power generation and thermal recovery rate. The results show that an interconnected fracture network with considerable bifurcation results in high heat production and power generation, however the energy efficiency is not optimized due to water loss. The effect of fracture connectivity is more significant than that of fracture spacing. The more fractures (bifurcations) the higher the overall and local heat recovery rates near the production well. For the case with connected fractures without bifurcation, the less characteristic length in the direction of flow results in a lower heat production and power generation.

中文翻译：

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裂隙网络模式对增强地热系统中双水平井吸热能力影响的数值研究

在增强的地热系统（EGS）中，裂缝和裂缝网络是通过人工储层进行流体流动和传热的主要因素。在这项工作中，通过描述压裂区的裂缝数，裂缝分叉和裂缝连通性，生成了不同的概念性离散裂缝网络。应用热-液压（TH）耦合数学模型来评估EGS热采过程。根据温度产生，净发电量和热回收率评估了排热能力。结果表明，具有明显分叉的相互连接的裂缝网络会导致高热量产生和发电，但是由于水分流失，能量效率并未得到优化。裂缝连通性的影响比裂缝间距的影响更大。裂缝（分叉）越多，生产井附近的整体和局部热量回收率就越高。对于连接的裂缝没有分叉的情况，沿流动方向的特征长度越小，发热和发电量就越低。