| 增强型地热系统的多区域多物理场耦合三维数值模拟 |
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| 作者姓名： | 丁军锋 王世民 |
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| 作者单位： | 中国科学院大学地球与行星科学学院, 北京 100049;中国科学院计算地球动力学重点实验室, 北京 100049 |
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| 基金项目： | 国家自然科学基金（41374090，41674086）和中国科学院“百人计划”项目资助 |
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| 摘 要： | 增强型地热系统（EGS）研究对发展地热发电具有重要意义。由于EGS通常涉及多区域多物理场耦合，且井内流动处于湍流状态，在EGS数值模拟中需要正确处理区域耦合、合理模拟井内湍流，并达到足够的计算精度和效率。基于多区域多物理场耦合三维有限元模型，系统研究EGS渗流与传热过程。计算结果表明：1）通过施加正确的连接条件能够实现在EGS不同区域之间的压力场、速度场和温度场的自然耦合；2）多种湍流模型模拟井内流动给出基本一致的压力变化，并且预测井内湍流压降约为层流压降的4倍，但比注水井与生产井之间的总压降小3个量级，因而井内湍流对EGS采热过程总体影响不显著；3）在EGS结构和物性垂向变化、储层中自然对流、井内湍流效应均可忽略的条件下，EGS以水平方向渗流和水平方向对流传热占主导，从而可采用两维模型近似模拟。
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| 关 键 词： | 地热能 增强型地热系统(EGS) 有限元模型 区域耦合 井内湍流 |
| 收稿时间： | 2018-04-13 |
| 修稿时间： | 2018-04-27 |
Multi-region and multi-physics coupled 3D numerical simulation of enhanced geothermal system |
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| Authors: | DING Junfeng WANG Shimin |
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| Institution: | College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China;Key Laboratory of Computational Geodynamics of Chinese Academy of Sciences, Beijing 100049, China |
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| Abstract: | Studies on enhanced geothermal system (EGS) are important for developing geothermal power generation. As an EGS typically involves multi-regional and multi-physical coupling and the in-well flows are turbulent, it is necessary in EGS numerical simulation to handle regional coupling correctly, represent in-well turbulence reasonably, and achieve sufficient computational accuracy and efficiency. In this study, the processes of porous flow and heat transfer associated with EGS are systematically investigated based on a multi-region and multi-physics coupled 3D finite element model. The obtained results are given as follows. 1) The natural coupling of temperature, pressure, and velocity fields between different EGS regions can be successfully realized in terms of correctly posed connection conditions. 2) Different turbulence models for in-well flows predict essentially consistent in-well pressure variation. The turbulence pressure drop across the well depth is predicted to be about 4 times as large as the laminar pressure drop but 3 orders of magnitude smaller than the overall pressure drop from the injection well to the production well, resulting in insignificant influence of in-well turbulence on the EGS heat extraction process. 3) With the vertical variations of EGS structure and thermophysical properties, the natural convection inside the reservoir, and the effects of in-well turbulence all being negligible, an EGS is dominated by horizontal porous flow and horizontal convective heat transfer, and thus may be approximately simulated by 2D modeling. |
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| Keywords: | geothermal energy enhanced geothermal system(EGS) finite element model domain coupling in-well turbulence |
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