Investigation of the Impact of Thermal Plumes on Aquifer Properties and Ground water quality

全球能源需求稳步上升，预计在未来15年内将增长45%。从长远来看，可持续能源有望将经济增长与社会公平联系起来，同时保护自然资源，符合联合国可持续发展目标。地热能是实现这一目标的关键支柱之一。在过去的几十年里，浅层地热能系统的应用一直在增加，2015年在欧盟安装了1770万台。地热设施的一种常用设计是开环系统，包括安装在含水层系统/地下水体中的抽水井和回注井，从含水层中提取热量或向含水层注入/储存热量。该系统的效率取决于井的产能以及合适的含水层特性（包括含水层渗透率和孔隙度）。与此同时，随着地表水资源受到气候变化影响的威胁，地下水体也日益成为供水的目标。该研究项目将调查与地热设施相关的热羽对含水层参数（例如孔隙度和渗透率）和水质的影响。热羽流不仅可能通过促进无机降水和二次矿化来降低含水层的孔隙度和渗透率，而且还可能通过增加生物量来促进含水层内的微生物活动，从而进一步降低含水层的孔隙度。这反过来又会影响地热装置的整体效率和可持续性，并减少地下水供应的可持续产量。该项目将以三叠纪Sherwood砂岩含水层（SSA）为例进行研究。SSA是横跨英格兰中部和北爱尔兰的一个重要的区域含水层，拥有100米深的饮用地下水。该研究将结合实验规模的水箱实验和利用贝尔法斯特女王大学现有钻孔装置的全面现场实验。该研究将通过完成一系列活跃的钻孔地球物理测量、水力测试、水化学采样和微生物分析，以及对实验性热注入测试的长期监测，将含水层系统的基线特征结合起来。水化学和微生物采样和分析将辅以使用光纤传感器的井下温度监测和微生物活动的生物地球物理监测。收集到的监测数据将整合到数值热输运模型中，以评估含水层的现场尺度热特性，并更好地了解热柱对含水层特性的影响。该项目将与英国地质调查局（BGS）和北爱尔兰地质调查局（GSNI）密切合作。

Global energy needs are steadily rising with a predicted increase of 45% within the next 15 years. In the long-term, sustainable energy is hoped to connect economic growth to increased social equity while preserving natural resources in line with the UN sustainable development goals. Geothermal energy presents one of the key pillars to achieve this goal. The application of shallow geothermal energy systems has been increasing over the past decades with >1.7 million units installed across the EU in 2015. One of the commonly applied designs for geothermal installations are open loop systems consisting of abstraction and re-injection wells installed in the aquifer system/groundwater body to extract heat from or to inject/store heat into the aquifer. The efficiency of the system relies on the productivity of the well installations as well as suitable aquifer properties (incl. aquifer permeability & porosity). At the same time, groundwater bodies are also increasingly targeted for water supply as surface water resources become threatened by the effects of climate change. The research project will investigate the impact of thermal plumes associated with geothermal installations on aquifer parameters (e.g., porosity & permeability) and water quality. Thermal plumes are not only likely to reduce aquifer porosities & permeabilities by facilitating inorganic precipitation and secondary mineralisation but also by promoting microbial activity within the aquifer with the additional biomass adding to the reduction of aquifer porosities. This in turn will affect the overall efficiency and sustainability of the geothermal installation and reduce the sustainable yield of the groundwater body for water supplies. The project will use the Triassic Sherwood Sandstone Aquifer (SSA) as a case study example. The SSA is an important regional aquifer across central England and Northern Ireland hosting potable groundwater to depth >100m. The study will combine bench-scale tank experiments with full-scale field experiments utilising existing borehole installations at Queen's University Belfast. The study will combine the baseline characterisation of the aquifer system by completing a series of active borehole geophysical measurements, hydraulic tests, hydrochemical sampling and microbial profiling with the long-term monitoring of experimental thermal injection tests. Hydrochemical and microbial sampling & analysis will be supplemented with downhole temperature monitoring using fibre optic sensors and biogeophysical monitoring of microbial activity. Collected monitoring data will be integrated into numerical heat transport models to evaluate field-scale thermal properties of the aquifer and to better understand the impact of thermal plumes on aquifer properties. The project will be run in close collaboration with the British Geological Survey (BGS) and the Geological Survey of Northern Ireland (GSNI).