FRACTURED AQUIFER CHARACTERIZATION USING SMART NON-NEWTONIAN TRACERS

标题：使用智能非牛顿示踪剂表征断裂含水层研究者：John S.俄勒冈州塞尔克州立大学提案编号：1446915破碎岩石含水层是美国许多地区和世界其他大部分地区唯一的水源。了解这些沃茨，以及水运输的物质，对于提供和保护安全的饮用水是至关重要的。此外，水流裂隙岩在矿床的形成和深部地热系统的发育中也具有重要作用。这项研究也将有利于从裂缝储层中提取石油和天然气，包括那些由水力压裂产生的储层。 因此，这项研究是理论和潜在的非常实际的性质。能够识别裂缝中流体流动路径的方法非常有限。 这项研究将进行实验室实验，将使用独特的流体，可以更有效地采样的主要流动路径。 这些是非牛顿流体（例如，瓜尔胶和其它食品级流体）。 提出的新方法寻求一种切实可行的手段，深入了解流在裂隙岩石含水层和其他裂隙岩石系统。在实验室工作的同时，还将在法国普洛默观测站进行实地实验，在那里已经为这种实验建立了一个独特的对流场。此外，两名本科生将参与研究。识别裂缝岩石中的主导流动路径，其连通性及其水力学特性对于流体流动和溶质运移至关重要。示踪剂测试可以从实验室到现场规模描述这种含水层的特性。经典的示踪剂测试解释允许定义一个平均的“有效水力”孔径的基础上简化的运输模型。这项研究将：1）开发一种创新的示踪剂方法，使用非牛顿（“剪切变稀”）流体来识别天然裂缝网络中优先流动路径的孔径分布，以及2）研究这些“智能”示踪剂的流动行为，了解其流变性，以表征裂缝系统的水力特性。通过调整粘度，研究将能够选择允许流动的特定阈值或孔径大小，而较小的孔径将基本上“冻结”在凝胶填充的条件下。这将在实验室和装有仪器的现场进行测试，以证明其在描述含水层特性方面的实用性。剪切稀化流体在现实的岩石孔隙中的运动的实验观测将与流体输运的理论模型进行比较。此外，数值建模将探索由实验方法确定的假设（例如，稳定（非牛顿流体追逐水）与不稳定（水追逐非牛顿流体）流体驱替）。基于初步的结果，现场实验的方法将测试所提出的方法的有效性。在示踪剂试验期间，将使用时间推移探地雷达测量，以记录示踪剂的优先路径。该方法将在法国一个独特的、特征良好的断裂花岗岩地层中进行测试，其中完整的断裂几何形状和水力特性已经根据多种水文地球物理方法进行了定义。最后，数值模型将研究在这种情况下控制非牛顿流体流动传输的一阶参数的敏感性。与裂隙含水层水文地质学相关的理论概念将在实验室中提出和解决。

Title: Fractured Aquifer Characterization Using Smart Non-Newtonian TracersInvestigator: John S. Selker, Oregon State UniversityProposal Number: EAR 1446915Fractured rock aquifers are the only source of water in many parts of the United States and much of the rest of the world. Understanding these waters, and the materials that water transports, is critically needed for providing and protecting safe water drinking water. In addition, the role of water flow fractured rocks is important in the formation of mineral deposits and in the development of deep geothermal systems. This research will also benefit the extraction of oil and gas from fractured reservoirs, including those created by fracking. Thus, this study is both theoretical and potentially very practical in nature. Methods that can identify fluid flow paths in fractures have been very limited. This research will conduct lab experiments that will use unique fluids that can sample the major flow paths more effectively. These are the Non-Newtonian fluids (e.g., guar gum and other food grade fluids). The novel methods proposed seek a practical means of gaining insight into flow in fractured rock aquifers and other fractured rock systems. In parallel to the laboratory work, a field experiment will be performed at the observatory site of Ploemeur, France, where a unique fracture-flow field site has been established for just this kind of experiment. In addition, two undergraduate students will participate in the research.The identification of dominant flow paths, their connectivity, and their hydraulic properties in fractured rocks is critical for fluid flow and solute transport. Tracer testing can characterize such aquifer properties from laboratory to field scales. Classical tracer test interpretations allow defining a mean "effective hydraulic" aperture based on simplified transport models. This research will: 1) develop an innovative tracer approach using non-Newtonian ("shear-thinning") fluids to identify aperture distributions of preferential flow paths in natural fractured networks and 2) investigate flow behavior of these "smart" tracers, knowing their rheology, in order to characterize the hydraulic properties of fracture systems. By adjusting the viscosity, the research will be able to select for specific thresholds or aperture size that allow flow, while smaller apertures will be essentially "frozen" in a gel-filled condition. This will be tested in the laboratory and at the instrumented field site to demonstrate the utility in characterizing aquifer properties. The experimental observations of the movement of shear-thinning fluid in realistic rock apertures will be compared to theoretical models of fluid transport. Additionally, numerical modeling will explore the hypothesis identified by the experimental approach (e.g., stable (non-Newtonian chasing water) vs unstable (water chasing non-Newtonian) fluid displacement). Based on preliminary results, the field experimental approach will to test the validity of the proposed approach. Coupled time-lapse GPR measurement will be used during tracer tests in order to document the preferential paths taken by the tracer. The methodology will be tested in a unique, well-characterized fractured granitic formation in France where complete fracture geometry and hydraulic characteristic have already been defined based on multiple hydro-geophysical approaches. Finally, numerical models will investigate the sensitivity of first order parameters that control flow transport of non-Newtonian fluids in such context. Theoretical concepts related to fractured aquifer hydrogeology will be presented and addressed experimentally in the lab.