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

全球能源需求正在稳步上升，预计未来15年将增长45%。从长远来看，可持续能源有望将经济增长与增加社会公平联系起来，同时根据联合国可持续发展目标保护自然资源。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年在欧盟各地安装了超过170万套。用于地热装置的通常应用的设计之一是开环系统，其包括安装在含水层系统/地下水体中的抽取和回注威尔斯井，以从含水层提取热量或将热量注入/储存到含水层中。该系统的效率取决于水井设施的生产力以及适当的含水层特性（包括含水层的含水量）。含水层渗透性和孔隙度）。与此同时，由于地表水资源受到气候变化影响的威胁，地下水体也越来越成为供水的目标。该研究项目将调查与地热装置有关的热羽流对含水层参数的影响（例如，孔隙度和渗透率）和水质。热羽流不仅可能通过促进无机沉淀和次生矿化作用来降低含水层的孔隙度和渗透率，而且还可能通过促进含水层内的微生物活动以及额外的生物量来降低含水层的孔隙度。这反过来又会影响地热设施的总体效率和可持续性，并减少地下水体供水的可持续产量。该项目将使用三叠纪舍伍德砂岩含水层（SSA）作为案例研究的例子。SSA是横跨英格兰中部和北方爱尔兰的一个重要区域含水层，可容纳深度大于100 m的饮用地下水。这项研究将结合联合收割机实验室规模的坦克实验与全面的实地实验，利用现有的钻孔装置在女王大学贝尔法斯特。这项研究将通过完成一系列主动钻孔地球物理测量、水力测试、水化学取样和微生物剖面分析，结合联合收割机对含水层系统的基线特征进行分析，并对实验性热注入测试进行长期监测。水化学和微生物取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地球物理监测。收集到的监测数据将被纳入数值热传输模型，以评估实地规模的含水层热特性，并更好地了解热羽流对含水层特性的影响。该项目将与英国地质调查局和北方爱尔兰地质调查局密切合作进行。

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).