Integration of Geochemical Processes and Fracture Flow for Design of Standing Column Wells

地球化学过程与裂缝流一体化在立柱井设计中的应用

• 批准号: RGPIN-2014-05877
• 负责人: Pasquier, Philippe
• 金额: $ 1.46万
• 依托单位: École Polytechnique de Montréal
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=567443
• 关键词: Integration; Geochemical; Processes; Fracture; Flow

In Canada, 30% of energy and 53% of electricity is used to heat or cool buildings. The use of geothermal heat pumps coupled with ground heat exchangers has experienced a growth of almost 150% in Canada between 2004 and 2008. Despite the significant energy savings it generates (up to 60%), the adoption of this green technology by building designers is no easy matter due to the high initial investment cost of ground heat exchangers. Standing column wells (SCW) are deep heat exchangers (up to 500 m) that use directly ground water. Although the construction costs of SCW systems can be 49% to 78% lower than closed-loop systems, SCWs are not used in Canada mainly due to an absence of validated design tools for fractured aquifers, a misunderstanding of the risks associated to the geochemical conditions of the groundwater (clogging, scaling, dissolution, algae growth) and a difficulty to assess the maintenance costs of these systems. Numerical simulation of fracture flow and of geochemical processes is widely used in hydrogeology. The novelty of this research program resides in its application to geoexchange and energy savings in a Canadian environment. Within the scope of the proposed research program, we intend to develop and validate experimentally numerical models to significantly increase our knowledge of the optimal construction and operation of SCW systems and, in turn, orient future design guidelines. To address this long-term objective, six projects are planned: A - INTEGRATE THE GEOCHEMICAL REACTIONS IN A THERMO-HYDROGEOLOGICAL SCW MODEL - Develop a three-dimensional numerical model that simulates the coupled thermal, hydraulic, hydrogeological and geochemical processes occurring in a standing column well. B - VALIDATE EXPERIMENTALLY A THERMO-HYDROGEOLOGICAL NUMERICAL MODEL - Validate, through in situ experimentations, the numerical model and the analytical solutions developed within the scope of projects A and C. C - INTEGRATE THE SPATIAL INTERACTIONS BETWEEN SCWs WITH A SPECTRAL APPROACH - Integrate, in a spectral framework, the thermal and hydraulic interactions occurring between the wells of a SCW system to predict the groundwater temperature arriving at a heat pump. D - EVALUATE THE IMPACT OF FRACTURE FLOW ON ENERGY SAVINGS AND DEVELOP GUIDELINES - Evaluate the impact of the fracture network on the entering water temperature and energy savings generated during the operation of a SCW, and suggest design guidelines. E - COMPARE THE LIFE-CYCLE OF SCW AND CONVENTIONAL SYSTEMS - Perform life-cycle financial analyses based on the economic, climatic and geological context prevailing in Canada and suggest design guidelines. F - MITIGATE THE IMPACT OF GEOCHEMICAL CONDITIONS ON THE OPERATION OF SCWs - Evaluate the impact of the hydrogeochemical conditions on the operation of SCW systems which use groundwater directly and identify and compare potential mitigation measures. The integration and study of some of the geochemical processes occurring during the operation of a SCW should lead to the development of mitigation measures and practical design guidelines and contribute to reduce the maintenance costs of SCW systems. The model developed in the scope of project C will be integrated to GeoAnalyser, a web-based application financed by the Canadian Geoexchange Coalition and intended to help designers worldwide to design geoexchange systems. Additionally, the guidelines developed in the scope of projects D, E and F will be integrated to the course “Training for Commercial System Designers” given by CGC in Canada. However, the most significant impact of the proposed research program will be the formation of highly trained hydrogeologists specialized in the design and operation of open geoexchange systems.

在加拿大，30%的能源和53%的电力用于加热或冷却建筑物。2004年至2008年间，加拿大地热热泵与地热交换器的使用增长了近150%。尽管它产生了显着的节能（高达60%），采用这种绿色技术的建筑设计师是不容易的事情，由于高初始投资成本的地热交换器。立柱威尔斯井（SCW）是直接使用地下水的深层热交换器（最高500米）。尽管SCW系统的建设成本比闭环系统低49%至78%，但加拿大没有使用SCW，主要原因是缺乏经过验证的裂隙含水层设计工具，对地下水地球化学条件（堵塞，结垢，溶解，藻类生长）相关风险的误解以及难以评估这些系统的维护成本。裂隙水和地球化学过程的数值模拟在水文地质学中有着广泛的应用。这项研究计划的新奇之处在于它在加拿大环境中的地球交换和节能应用。在拟议的研究计划的范围内，我们打算开发和验证实验数值模型，以显着增加我们的知识的SCW系统的最佳结构和操作，反过来，面向未来的设计指南。为实现这一长期目标，计划开展六个项目：A -将地球化学反应纳入热-水文地质SCW模型-开发一个三维数值模型，模拟在一个直立柱井中发生的热、水力、水文地质和地球化学耦合过程。B -通过现场实验验证热水文地质数值模型-通过在项目A和C范围内开发的数值模型和分析解决方案。C -用光谱方法整合SCW之间的空间相互作用-在光谱框架中整合SCW系统的威尔斯井之间发生的热和水力相互作用，以预测到达热泵的地下水温度。D -评估裂缝流量对节能和可再生能源指导原则的影响-评估裂缝网络对进入水温和SCW运行期间产生的节能的影响，并提出设计指导原则。E -比较SCW和常规系统的生命周期-根据加拿大普遍存在的经济、气候和地质背景进行生命周期财务分析，并提出设计准则。F -减轻地球化学条件对SCW运行的影响-评估水文地球化学条件对直接使用地下水的SCW系统运行的影响，并确定和比较潜在的缓解措施。对超临界水运行过程中发生的某些地球化学过程进行综合和研究，应有助于制定缓解措施和实用的设计准则，并有助于降低超临界水系统的维护成本。在项目C范围内开发的模型将被纳入GeoAnalyser，这是一个由加拿大地球交换联盟资助的网络应用程序，旨在帮助世界各地的设计人员设计地球交换系统。此外，在项目D、E和F范围内制定的准则将纳入加拿大总公司举办的“商业系统设计人员培训”课程。然而，拟议的研究计划最重要的影响将是形成训练有素的水文地质学家，专门从事开放式地球交换系统的设计和操作。