Thermal Performance, Design, and Sustainability of Borehole Heat Exchangers within Challenging Hydrogeological Environments

总体目标是在具有挑战性的水文地质环境中推进低温地热能（钻孔热交换器[BHEs]）的使用和性能。考虑了两种环境：进入深层中温异常的系统和不连续永久冻土中的浅层系统。本质上，这些代表了地理交换系统的两个端元问题区域。***原位油砂热采方案向地下100米的沥青储层注入大量能量，将蒸汽室边缘的温度从7 - 11摄氏度提高到200摄氏度，沿着储层边缘提高到50摄氏度。从本质上讲，这些操作无意中充当了地下热能储存系统。该项目将设计高效、可持续的闭环BHEs，在水库内工作，并进行全面的能源和碳平衡评估。经济分析将支持商业和监管案例，考虑将再生能源作为沥青提取操作的负碳（即二氧化碳）成分。提出了温室工业作为消耗所提取热量的模型案例。***低温地热应用通常限于平均地面温度在5至10摄氏度或更高的地区。然而，在不连续的永久冻土带，利用BHEs提取热量的潜力是存在的。抽热可以有效地逆转冻土退化，稳定地基。虽然在寒冷的气候条件下，使用BHEs满足空间供暖需求通常不经济，但在偏远地区远离柴油燃料来源的好处，同时稳定永久冻土是缓解因素。将使用FEFLOW的BHE模拟能力，但现在使用新的pifrefreeze插件来模拟冻结的地面条件。***由于对温室气体排放、可持续性和高能源价格的担忧，地源地热系统正受到越来越多的关注。然而，设计方面的考虑和监管框架并没有以同样的速度发展。具有挑战性的环境很少受到业界的关注，因为研究基地不支持实践。”油砂储层是目前加拿大最大的能源资产之一。然而，对开发水库所需的温室气体排放的担忧仍然存在。一个新颖的想法是在生产结束时回收储层中剩余的热量。通过利用这种能源来支持温室产业，关闭后，现有的基础设施将得到利用，并将为当地居民提供就业机会。在不连续的永久冻土地区，使用BHEs作为建筑热源可以稳定地基，并允许清洁能源取代柴油。*****

The overall objectives are to advance the use and performance of low temperature geothermal energy (borehole heat exchangers [BHEs]) in challenging hydrogeologic environments. Two environments are considered: systems accessing deep medium-temperature anomalies, and shallow systems in discontinuous permafrost. In essence, these represent two end-member' problematic zones for geoexchange systems. ***In-situ oil sands thermal recovery schemes inject a tremendous amount of energy into bitumen reservoirs 100's of metres underground, raising the temperatures from 7 - 11C to as high as 200C at the steam chamber edge, and 50C along the reservoir edge. In essence, these operations have unintentionally acted as underground thermal energy storage systems. This project will design efficient and sustainable closed loop BHEs that work within the reservoirs and perform comprehensive energy and carbon balance assessments. Economic analysis will support the business and regulatory case for considering the recycled energy to be a negative carbon (i.e. CO2) component of the bitumen extraction operations. A greenhouse industry is proposed as the model case for consumption of the extracted heat. ***Low temperature geothermal applications are normally limited to areas whose average ground temperatures are 5 to 10C or warmer. However, the potential exists to use BHEs to extract heat in zones of discontinuous permafrost. Heat extraction can effectively reverse permafrost degradation and stabilize foundations. While it would not normally be economical to use BHEs for space heating needs in cold climates, the benefits of moving away from diesel fuel sources in remote areas, while stabilizing permafrost are mitigating factors. FEFLOW's BHE simulation ability will be used but now with the new piFreeze plug-in to simulate freezing ground conditions. ***Ground source geothermal systems are drawing increased attention due to concern about greenhouse gas emissions, sustainability, and high energy prices. However, design considerations and the regulatory framework have not advanced at the same pace. Challenging environments receive little industry attention because the research base is not there to support the practice'. Oil sands reservoirs are currently one of Canada's largest energy assets. However, concerns about greenhouse gas based emissions required to produce the reservoirs remain. A novel idea is to recover the heat remaining in the reservoir at the end of production. By utilizing this energy to support a greenhouse industry, post closure, existing infrastructure will be utilized and employment opportunities will be maintained for the local population. Using BHEs as a source of building heat in regions of discontinuous permafrost could stabilize foundations and allow for a clean energy source to replace diesel.*****