Low-enthalpy geothermal systems in the Western Canadian Sedimentary Basin

加拿大西部沉积盆地的低焓地热系统

• 批准号: RGPIN-2022-04502
• 负责人: Hollaender, Hartmut
• 金额: $ 3.13万
• 依托单位: University of Manitoba
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=749357
• 关键词: Low; enthalpy; geothermal; systems; Western

Canada has enormous geothermal resources which could supply the country with a renewable and clean source of power. Traditionally, fluid temperatures >150°C are used to produce electricity, which require deep boreholes in sedimentary basins such as the Western Canadian Sedimentary Basin (WCSB). However, low-enthalpy, low-temperature (<150°C) resources can also be used in binary cycle power plants, which circulate a secondary fluid with a low boiling point. These geothermal power plants have great potential in sedimentary basins to provide base load electricity. However, its current use is limited worldwide because the geothermal use of sedimentary basins is new and barely tested. As such, substantial knowledge gaps remain related to thermal, hydraulic, geomechanical, and (geo)chemical (THMC) behavior of fluids and reservoirs. Geochemical and temperature data from boreholes are often scarce or contain high uncertainties. This has led to complications and failures when deep geothermal reservoirs have been targeted in the past (e.g. Hesshaus et al. 2013). Additionally, the systems require significant financial investment so that field testing is limited, and knowledge development is based on numerical modeling. Unfortunately, several of the numerical models cannot be verified against measurements because such benchmarks are unavailable. A novel attempt is to use evaporite formations such as Prairie Evaporite in the WCSB for geothermal systems since these formations have positive thermal anomalies. However, these formations are highly soluble and salt minerals can self-heal so that the permeability of the geothermal reservoir will change throughout its operation. My envisioned research program aims for a better, natural science-based approach to model the development of geothermal energy, including from highly saline environments. My current proposed research will focus on three areas: i) develop physically based benchmarks for groundwater flow near evaporite formations, ii) assess impact of mineral dissolution and precipitation on reservoir permeability, and iii) assess impact of geomechanical processes on reservoir permeability. I will use coupled THMC modeling to better understand flow and transport occurring in deep geothermal wells. The highly saline systems require careful consideration of fluid density, dispersivity, geochemical reactions, and changes in permeability. The permeability of these formations must be increased by hydraulic stimulation. Past work from my group characterized host rocks, the physics involved in the breakthrough technology, and the fluid flow and heat transport in single fractures and at reservoir scale. The proposed research will expand our findings to evaporite formations and develop the physics to integrate self-healing to allow for fully coupled THMC modeling. The results will contribute to wider acceptance and deployment of this technology due to be higher predictability of processes in deep geothermal reservoirs.

加拿大拥有巨大的地热资源，可以为该国提供可再生和清洁的能源。传统上，使用流体温度&150°C来发电，这需要在沉积盆地(如加拿大西部沉积盆地(WCSB))中钻深孔。然而，低热、低温(&lt；150°C)资源也可用于双循环发电厂，其循环的二次流体具有低沸点。这些地热发电厂在沉积盆地提供基本负荷电力的潜力很大。然而，目前它的使用在世界范围内是有限的，因为沉积盆地的地热利用是新的，几乎没有经过测试。因此，与流体和油藏的热、水力、地质力学和(地质)化学(THMC)行为相关的知识差距仍然很大。来自钻孔的地球化学和温度数据往往很稀少，或者含有很高的不确定性。这导致了过去针对深层地热储的复杂和失败(例如，Hesshaus等人)。2013年)。此外，这些系统需要大量的财政投资，因此实地测试是有限的，知识开发是基于数值建模的。不幸的是，有几个数值模型无法对照测量结果进行验证，因为这样的基准不可用。一种新的尝试是将WCSB中的草原蒸发岩等蒸发岩地层用于地热系统，因为这些地层具有正的热异常。然而，这些地层是高度可溶的，盐类矿物可以自我愈合，因此地热储的渗透率在其运行过程中会发生变化。我设想的研究计划旨在以一种更好的、以自然科学为基础的方法来模拟地热能源的发展，包括来自高度盐分环境的地热能源。我目前提议的研究将集中在三个领域：i)建立蒸发岩地层附近地下水流的物理基准，ii)评估矿物溶解和降水对储层渗透率的影响，以及iii)评估地质力学过程对储层渗透率的影响。我将使用耦合THMC模型来更好地了解深部地热井中发生的流动和传输。高含盐系统需要仔细考虑流体密度、分散性、地球化学反应和渗透率变化。这些地层的渗透率必须通过水力刺激来增加。我的团队过去的工作描述了主岩，突破性技术所涉及的物理，以及单裂缝和储集层规模的流体流动和热传输。这项拟议的研究将把我们的发现扩展到蒸发岩的形成，并发展物理学来整合自我修复，以允许完全耦合的THMC建模。这一结果将有助于更广泛地接受和部署这项技术，因为它对深层地热储层的过程具有更高的可预测性。