Repurposing a deep geothermal exploration well for borehole thermal energy storage: Implications from statistical modelling and sensitivity analysis
Repurposing a deep geothermal exploration well for borehole thermal energy storage: Implications from statistical modelling and sensitivity analysis
复制标题
重新利用深层地热勘探井进行钻孔热能储存：统计模型和敏感性分析的启示
DOI：
10.1016/j.applthermaleng.2022.119701
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发表时间：
2023
影响因子：
6.4
通讯作者：
Brown C
中科院分区：
文献类型：
--
作者：
Brown C
钻孔热能储存（BTES）是一项重要的技术，通过储存工业过程、空间冷却甚至是夏季多余的可再生风能或太阳能产生的余热，来最大限度地减少温室气体排放。本文通过纽卡斯尔的一口深地热探井考察了BTES的效率，该探井采用同轴深井热交换器（DBHE）完井进行了改造。以前，很少有研究调查1)使用单个DBHE进行热能储存或2)改造地热探井；因此，本研究通过在MATLAB上进行数值模拟，利用全局和局部灵敏度分析测试了10个设计参数对DBHE运行性能的影响，从而研究了深度BTES。在基本情况下，在920米深度运行的DBHE在6个月（冬季）产热阶段结束时，可以实现超过c.54 kW的热量提取率。当在提取前应用6个月（夏季）热充电阶段（在充电期结束时记录为250千瓦）时，在提取结束时记录的热产量增加到最低0.69千瓦。总的来说，在一个年周期内，向地层注入了1.23 GWh的热量，提取了0.46 GWh的热量。在所有局部灵敏度模拟中，经过6个月的充电后，平均热量提取率增加了9.5-55.6 kW。全局敏感性分析表明，未扰动地温梯度、流量、充注时进口温度和萃取时进口温度等参数对热采收率影响最大。其中大部分是操作参数，表明可以通过精心设计来优化深层BTES系统。该研究得出结论，单个dbh具有一定的存储余热的能力。然而，萃取过程中产生的额外热量只占充注阶段回注到地层的热量的一小部分（使用本研究提出的新储存效率指标计算为< 20%）。这种方法只有在存在大量剩余热量而替代价值不大的情况下才可能可行，并且存在适合改造的现有深井眼。如果这些条件不存在，那么更常规、更浅、更多井眼阵列可能更适合BTES。
Borehole thermal energy storage (BTES) is an important technology to minimise greenhouse gas emissions by storing surplus heat from industrial processes, space cooling or even excess summertime renewable wind or solar energy. This paper investigates the efficiency of BTES via a single deep ex-geothermal exploration well in Newcastle, retrofitted using a coaxial deep borehole heat exchanger (DBHE) completion. Previously, few studies have investigated 1) the use of a single DBHE for thermal energy storage or 2) the retrofitting of an ex-geothermal exploration well; therefore, this study investigates deep BTES through numerical modelling on MATLAB by testing the impacts of 10 design parameters on operational performance of a DBHE using both global and local sensitivity analyses.Under base-case conditions, a DBHE operating at a depth of 920 m could achieve a heat extraction rate in excess of c.54 kW recorded at the end of a 6 month (winter) heat production phase. When applying a 6 month (summer) thermal charge phase prior to extraction (recorded as 250 kW at the end of the charge period), the thermal yield recorded at the end of extraction was increased to a minimum of c.69 kW. In total, over an annual cycle, 1.23 GWh of heat was injected into the formation, and 0.46 GWh was extracted. Across all local sensitivity simulations, the average heat extraction rate was increased by 9.5–55.6 kW following a 6 month period of charge. The global sensitivity analysis demonstrated that thermal recovery was most influenced by parameters such as the undisturbed geothermal gradient, flow rate, inlet temperature during charge and inlet temperature during extraction. Most of these are operational parameters, indicating deep BTES systems can be optimised through careful engineering. The study concludes that single DBHEs have some capacity to store surplus heat. However, the additional heat yield during extraction is only a modest proportion of the heat reinjected to the formation during the charging phase (calculated as <20 % using the new storage efficiency metric proposed in this study). This approach is only likely to be viable where there is a large source of surplus heat with little alternative value, and where there is an existing deep borehole suitable for retrofitting. If these conditions do not exists, more conventional, shallower, multi-borehole arrays are likely to be more suitable for BTES.