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: 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=566209
• 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 (FLUTe™); 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 Krásný, 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.

基岩含水层破裂被广泛用于加拿大和国际上的国内和文化供水。了解基岩地层的破裂对于评估深层地质存储库和石油开发也至关重要。如果只有薄（或没有）冰川沉积物覆盖岩层，则浅层晶体基岩含水层可能容易受到人类活动污染的影响。断裂的基岩含水层是污染物运输的主要导管。结晶裂开的基岩含水层是加拿大中部和东部的许多基础（例如加拿大盾牌）以及美国东北部，美国西北部。这些含水层的岩石基质孔隙率低，因此污染物扩散的能力较低。水和污染物主要通过岩石骨折通常以高地下水速度传播，因此有可能快速运输速率。为了帮助保护这些含水层的供水，需要使用强大的方法来改善晶体含水层的水解表征和理解。 G360应用地下水研究中心的研究人员广泛使用了系统的离散断裂网络（DFN）方法（Parker，2007年），以表征用于流量和污染物运输应用的沉积基岩含水层。拟议的研究计划的目的是应用这种DFN方法的几种新颖支柱，以：1）在加拿大盾牌的晶体基岩中首次使用这些方法，而不是沉积基岩（例如，多洛斯通）； 2）将新的结果与使用不同方法（即跨包装器的slug测试，泵送测试和下孔视频仪）进行的先前水解表征研究和在现场地点进行的污染物传输研究进行了比较。结果将用于改善用于浅层裂缝晶体基岩含水层的流量和污染物传输的概念模型。这项研究将具体包括：1）使用专门的柔性且不可渗透的钻孔线性（Flute™）的深度 - 渗透率测量渗透率和流量； 2）高分辨率温度分析，用于识别水解活性分数； 3）使用压力，热和染料作为示踪剂与线性的新型跨孔测试，并通过数值建模来解释； 4）使用原位问题和衬里进行水解后水质（硝酸盐和浊度）监测。这种研究经济是使用在Tay River Field地点（Levison等，2012）和肯尼迪野战站（Elmhirst和Novakowski，2012年）的现有广泛的井基础设施（Levison等，2012）和肯尼迪野战站（2012）。大约20％的土地表面包括结晶盾岩（Gustafson和Krásný，1994年）。使用多种证据，对所有流量，污染物运输和补救工作都需要彻底理解，包括孔径，传输，间距和连通性，以及水资源工程，水文地质学和自然资源的利用，都需要进行彻底的理解。 G360 DFN方法的新方法将在研究环境中应用，并有机会将结果与以前的表征工作和现场实验进行比较。同样，将用衬里的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（包括来源保护）的重要应用，并为顾问和研究人员提供有效的，具有成本效益的工具，以快速表征结晶含水层。这项研究将由博士，硕士和本科生进行，他们将获得适用于行业或继续研究的有价值的培训。