Improving crystalline bedrock aquifer conceptual models using novel discrete fracture network methods

使用新颖的离散裂缝网络方法改进结晶基岩含水层概念模型

• 批准号: RGPIN-2014-03973
• 负责人: Levison, Jana
• 金额: $ 1.82万
• 依托单位: University of Guelph
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=680781
• 关键词: Improving; crystalline; bedrock; aquifer; conceptual

Fractured bedrock aquifers are widely used for domestic and municipal water supply in Canada and internationally. Understanding fracturing in bedrock formations is also critical to assessing deep geological repositories and petroleum exploitation. Where only thin (or no) glacial deposits cover rock formations, shallow crystalline bedrock aquifers can be vulnerable to contamination from human activities. Fractures are primary conduits for contaminant transport. Crystalline fractured bedrock aquifers underlie much of central and eastern Canada (e.g., the Canadian Shield) and eastern, north-central and northwestern United States. These aquifers have low rock matrix porosity and thus low capacity for contaminant diffusion. Water and contaminants travel predominantly through rock fractures at often high groundwater velocities and thus there is potential for rapid transport rates. In order to help protect these aquifers for water supply, robust methods are required to improve the hydraulic characterization and understanding of crystalline aquifers. **The systematic Discrete Fracture Network (DFN) Approach (Parker, 2007) has been widely used by researchers in the G360 Centre for Applied Groundwater Research group to characterize sedimentary bedrock aquifers for flow and contaminant transport applications. The objective of the proposed research program is to apply several novel pillars of this DFN Approach in order to: 1) use the methods for the first time in the crystalline bedrock of the Canadian Shield as opposed to sedimentary bedrock (e.g., dolostone); and 2) compare new results to previous hydraulic characterization research conducted using different methods (i.e., straddle packer slug tests, pumping tests and down hole video-logging) and to contaminant transport studies conducted at the field sites. The results will be applied to improve conceptual models for flow and contaminant transport for shallow fractured crystalline bedrock aquifers. This research will include specifically: 1) depth-discrete measurements of permeability and flow using specialized flexible and impermeable borehole liners (FLUTeT); 2) high resolution temperature profiling for identifying hydraulically active fractures; 3) novel cross-hole tests using pressure, heat and dye as tracers coupled with the liners, interpreted via numerical modeling; and 4) post hydraulic characterization water quality (nitrate and turbidity) monitoring using in situ probes and liners. This research economizes by using existing extensive well infrastructure drilled into the Canadian Shield at the Tay River Field Site (Levison et al., 2012) and Kennedy Field Station (Elmhirst and Novakowski, 2012). **About 20% of the land surface comprises crystalline shield rock (Gustafson and Krásny, 1994). A thorough understanding, using multiple lines of evidence, of fracture parameters including apertures, transmissivity, spacing, and connectivity are required for all flow, contaminant transport and remediation efforts, with applications in water resources engineering, hydrogeology and natural resource exploitation. Novel methods of the G360 DFN Approach will be applied in a research environment with the opportunity to compare results to previous characterization efforts and field experiments. Also, a unique in situ nitrate probe and fluorometer will be tested with lined boreholes. This research will contribute to important applications for water supply and contaminant migration, including source protection, and provide consultants and researchers effective, cost efficient tools for rapidly characterizing crystalline aquifers. The research will be carried out by doctoral, Master's and undergraduate students who will gain valuable training applicable to work in industry or continued research.

破裂的基岩含水层广泛用于加拿大和国际上的家庭和市政供水，了解基岩地层的破裂对于评估深层地质储库和石油开采也至关重要，其中只有薄层（或没有）冰川沉积物覆盖岩层、浅层结晶基岩。含水层很容易受到人类活动的污染 裂缝是大部分中央含水层下方污染物输送的主要渠道。加拿大东部（例如加拿大地盾）以及美国东部、中北部和西北部的含水层岩石基质孔隙度较低，因此污染物扩散能力较低，地下水流速通常较高。因此，为了帮助保护这些含水层的供水，需要强有力的方法来改善结晶含水层的水力特征和理解。离散裂缝网络 (DFN) 方法（Parker，2007）已被 G360 应用地下水研究组中心的研究人员广泛使用，以表征沉积基岩含水层的流量和污染物传输应用。拟议研究计划的目标是应用多种方法。该 DFN 方法的新颖支柱是为了： 1) 首次在加拿大地盾的结晶基岩而不是沉积基岩中使用这些方法（例如，白云石）；2）将新结果与之前使用不同方法（即跨式封隔器段塞测试、泵送测试和井下视频记录）进行的水力特性研究以及在现场进行的污染物迁移研究进行比较。用于改进浅层裂隙结晶基岩含水层的流量和污染物迁移的概念模型，该研究将具体包括：1）使用专门的柔性和流量进行渗透率和流量的深度离散测量。不渗透钻孔衬管（FLUTeT）；2）用于识别水力活动裂缝的高分辨率温度剖面；3）使用压力、热量和染料作为示踪剂与衬管结合的新型跨孔测试，并通过数值模拟进行解释；使用原位探头和衬管进行水质（硝酸盐和浊度）监测 这项研究通过使用在泰河现场的加拿大地盾中钻探的现有广泛的井基础设施来实现经济节约（Levison 等人，2017）。 al.，2012）和肯尼迪现场站（Elmhirst 和 Novakowski，2012）**约 20% 的陆地表面由结晶盾岩组成（Gustafson 和 Krásny，1994）。所有流量、污染物传输和修复工作都需要参数，包括孔径、透射率、间距和连通性，并应用于水资源工程、 G360 DFN 方法的新方法将应用于研究环境，并有机会将结果与之前的表征工作和现场实验进行比较。此外，还将使用衬里钻孔测试独特的原位硝酸盐探针和荧光计。这项研究将有助于供水和污染物迁移的重要应用，包括水源保护，并为顾问和研究人员提供有效、经济高效的工具来快速表征结晶含水层。博士生、硕士生和本科生将获得适用于工业工作或继续研究的宝贵培训。