This study proposes a single-well enhanced geothermal system (SEGS) to mitigate the high-risk of traditional Enhanced Geothermal Systems (ESGs) with two or more wells and enhance the general applicability. A detailed thermodynamic model that couples the wellbore, reservoir, and organic Rankine cycle is built. For the reservoir, a three-dimensional flow and heat transfer model featuring a discrete fracture network is employed. The effects of injection flow rate, injection temperature, branch well length, and branch well spacing on net output work, pump power consumption, thermal efficiency, and exergy efficiency have been investigated. The results indicate that an increase in the injection flow rate improves the shaft power of the expander and the power consumption of the injection pump. An optimal flow rate of 30 kg/s is identified, which maximizes the annual net power output to 1221.2 kW. Additionally, an increase in the injection temperature is found to enhance the buoyancy effect, thereby improving both thermal and exergy efficiency, and reducing the power consumption of the injection pump. The maximum net output power is achieved at an injection temperature of 60 °C. The study also notes that the branch well length has a negligible effect on thermal and exergy efficiency and expander shaft work. However, a longer branch well length contributes to a decrease in the power consumption of the injection pump and an increase in the net power output. Finally, it is observed that increasing the lateral well spacing slows the rate decay of the production temperature. A spacing of 360 m is found to yield a maximum annual net output power of 1259.4 kW. In conclusion, this study offers significant insights and practical guidance for the development and utilization of SEGS, demonstrating its potential as an effective alternative to conventional EGS methodologies.

中文翻译：

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基于离散裂缝模型的单井强化地热发电系统数值模拟

本研究提出了一种单井增强型地热系统（SEGS），以减轻具有两口或更多井的传统增强型地热系统（ESG）的高风险并增强普遍适用性。建立了耦合井筒、储层和有机朗肯循环的详细热力学模型。对于储层，采用具有离散裂缝网络的三维流动和传热模型。研究了注入流量、注入温度、分支井长度和分支井间距对净输出功、泵功耗、热效率和火用效率的影响。结果表明，喷射流量的增加提高了膨胀机的轴功率和喷射泵的功耗。确定最佳流量为 30 kg/s，可使年净功率输出最大化至 1221.2 kW。此外，增加喷射温度可以增强浮力效应，从而提高热效率和火用效率，并降低喷射泵的功耗。最大净输出功率在注射温度为 60 °C 时实现。研究还指出，分支井长度对热效率、火用效率以及膨胀机轴功的影响可以忽略不计。然而，较长的分支井长度有助于减少注入泵的功耗和增加净功率输出。最后，观察到增加侧井间距减缓了生产温度的衰减速率。间距360 m，最大年净输出功率为1259.4 kW。总之，这项研究为 SEGS 的开发和利用提供了重要的见解和实践指导，证明了其作为传统 EGS 方法的有效替代方法的潜力。