Abstract We propose a novel multilateral-well coaxial closed-loop geothermal system (CCGS) to help realize the commercial exploitation of hot dry rock. Compared with the enhanced geothermal system, it avoids the high-cost fracturing and environmental problems by closed-loop circulation. Also, the multilateral-well CCGS can significantly increase heat production than traditional vertical-well or horizontal-well CCGSs via lateral wellbores. Then, we establish a new 3D transient model and validate it with experimental data. The temperature field is studied. The Influences of injection flow rate, number of lateral wellbores, wellbore size, thermal conductivity of insulation pipe, and reservoir temperature are analyzed. Results show that the lateral wellbores are vital to improving heat extraction, and a viable lateral-wellbore spacing is determined. The total energy output rises linearly with time, while the extracted heat in the initial stage is limited though the thermal power is high. There is an appropriate injection flow rate by comparing the total energy output and dissipation. A smaller wellbore size is preferred due to the minor effect. A reasonable thermal conductivity exists for the insulation pipe. Particularly, the high-temperature geothermal resources at various depths can be efficiently developed through the multilateral-well CCGS given the effect of reservoir temperature.

中文翻译：

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新型多井同轴闭环地热系统的排热分析

摘要 我们提出了一种新型的多井同轴闭环地热系统（CCGS），以帮助实现干热岩的商业开发。与强化地热系统相比，它通过闭环循环避免了高成本的压裂和环境问题。此外，与传统的垂直井或水平井 CCGS 相比，通过侧井眼，多边井 CCGS 可以显着增加热产量。然后，我们建立一个新的 3D 瞬态模型并用实验数据对其进行验证。研究温度场。分析了注入流量、侧井眼数、井眼尺寸、保温管导热系数、储层温度等因素的影响。结果表明，侧井眼对于提高热量提取至关重要，并且确定了可行的侧井眼间距。总能量输出随时间线性上升，而初始阶段提取的热量有限，但热功率很高。通过比较总能量输出和耗散，有一个合适的注入流量。由于较小的影响，较小的井筒尺寸是优选的。保温管存在合理的热导率。特别是在储层温度的影响下，多井CCGS可以有效开发不同深度的高温地热资源。保温管存在合理的热导率。特别是在储层温度的影响下，多井CCGS可以有效开发不同深度的高温地热资源。保温管存在合理的热导率。特别是在储层温度的影响下，多井CCGS可以有效开发不同深度的高温地热资源。