Numerical simulation of a Deep Borehole Heat Exchanger in the Krafla geothermal system
Numerical simulation of a Deep Borehole Heat Exchanger in the Krafla geothermal system
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DOI：
10.1016/j.ijheatmasstransfer.2019.118496
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发表时间：
2019-11-01
影响因子：
5.2
通讯作者：
Falcone, Gioia
中科院分区：
文献类型：
--
作者：
Renaud, Theo;Verdin, Patrick;Falcone, Gioia
地热能源部门面临着与热回收效率和经济可行性有关的许多挑战。在冰岛深钻项目和意大利的DESCRAMBLE项目的推动下，欧洲对过热/超临界地热系统的研究正在取得进展。在冰岛，IDDP-1井到达了2100米深处的岩浆侵入体，为挖掘岩浆侵入体附近的地热潜力提供了新的机会。鉴于其高度腐蚀性，地热流体在常规地热生产期间削弱井筒完整性。闭环深钻孔热交换器（DBHE）不需要地下和威尔斯井之间的流体交换，是从这些非常规地热资源中回收热量的战略替代方案，同时最大限度地降低了原位储层损坏的风险。通过计算流体动力学（CFD）技术，模拟30年的生产，研究了与假设的DBHE钻进IDDP地质环境相关的热影响和热回收。根据IDDP-1井描述的简化地质特性，对两种井眼设计进行建模。结果表明，在生产的第一年，输出温度是工作流体速度的函数之前，达到伪稳态条件。井底附近的冷却扰动被证明是径向增长从10到40米之间的1和10年的生产，计算的输出功率达到1.2 MWth的单井。通过将内井延伸到地下更深处来增强底部井筒处的热传递。根据在油田规模上进行的全面经济分析，与开环增强型地热系统（EGS）的理论预期相比，闭环DBHE的技术风险显著降低，这可能超过每口井较低的热输出。(C)2019作者由爱思唯尔有限公司发布
The geothermal energy sector is facing numerous challenges related to heat recovery efficiency and economic feasibility. Research on superheated/supercritical geothermal systems is progressing in Europe, triggered by the Iceland Deep Drilling project (IDDP) and the DESCRAMBLE project in Italy. In Iceland, the IDDP-1 well, which reached a magma intrusion at a depth of 2100 m, raised new opportunities to untap the geothermal potential near magmatic intrusions. Given their highly corrosive nature, geothermal fluids weaken the wellbores integrity during conventional geothermal production. Closed-loop Deep Borehole Heat Exchangers (DBHE) that do not require fluid exchange between the subsurface and the wells represent a strategic alternative for recovering heat from these unconventional geothermal resources, while minimising the risk of in situ reservoir damage. The thermal influence and heat recovery associated with a hypothetical DBHE drilled into the IDDP geological settings are investigated via Computational Fluid Dynamics (CFD) techniques, simulating 30 years of production. Two wellbore designs are modelled, based on simplified geological properties from the IDDP-1 well description. The results show that, during the first year of production, the output temperature is function of the working fluid velocity before reaching pseudo-steady state conditions. The cooling perturbation near the bottom hole is shown to grow radially from 10 to 40 m between 1 and 10 years of production, and the calculated output power reaches up to 1.2 MWth for a single well. The heat transfer at the bottom well bore is enhanced by extending the inner well deeper into the ground. Subject to full economic analysis to be performed at field scale, the significantly lower technical risks of the closed-loop DBHE could outweigh the lower thermal output per well compared to theoretical expectations from open-loop Enhanced Geothermal Systems (EGS). (C) 2019 The Authors. Published by Elsevier Ltd.