A Unified Approach to Characterizing Fracture-Flow Systems: Coupling Radar Tomography, Tracer Experiments, and Hydraulic Data

在水文地质学中最紧迫的问题之一是描述裂隙岩石系统的非均质性。为了建立水头变化和溶质运移的预测模型，需要精确的控制裂缝流动的水力特性的三维表征。这个问题一直很困难，因为通常使用单一类型的数据（例如水力试验）来推断裂缝流动路径和流动障碍的复杂模式。对数据集的单独分析可能会导致裂缝岩石几何形状和水力特性的“图”彼此不一致。我们建议同时反演多种类型的信息，从地球物理数据（本地和井间雷达）到水力测试，再到示踪剂测试，提供了一种可以识别裂缝含水层非均质性的方法，包括裂缝带几何形状、连通性和透射性。每种类型的数据都使用适当的物理模拟模型进行分析，包括波浪传播、水头变化和溶质迁移模型。我们提出了一种基于非常灵活的优化过程的耦合反演过程，称为模拟退火。该方法将生成与所有类型的数据（例如，水头、浓度、雷达）一致的图像，并显示裂缝带几何形状、水力导率估计和空间可变不确定性估计。它将被开发并应用于综合数据和现场数据。我们过去对沉积矿床的经验表明，综合数据分析练习可以促进“耦合”反演方法的快速开发和测试。一旦了解了所提出方法的优点和局限性，将其应用于复杂的现场数据，就可以对该方法进行真正的测试。现场数据将来自新罕布什尔州镜湖的岩缝实验场地。迄今为止，USGS已经收集了雷达层析成像、地震层析成像、钻孔地球物理测井、水力测试数据和示踪剂测试数据。他们愿意把这些新收集的数据提供给我们，我们认为这是一个难得的机会。该项目将深入了解从不同类型的数据中可以提取的信息、数据的相对价值，以及如何使用不同类型数据的联合分析来推断裂缝带结构。

9705812 Gorelick Among the most pressing problems in hydrogeology is describing heterogeneity in fractured-rock systems. Accurate 3D characterization of the hydraulic properties controlling fracture flow is required for predictive models of hydraulic head changes and solute migration. The problem has been difficult because typically a single type of data (e.g., hydraulic tests) has been used to deduce the complex pattern of fracture flow paths and flow barriers. Individual analysis of data set may lead to "maps" of fractured rock geometry and hydraulic properties that are inconsistent with each other. We suggest that simultaneous inversion of multiple types of information ranging from geophysical data (local and cross well radar) to hydraulic tests to tracer tests provides an approach that can identify fractured-rock aquifer heterogeneities including fracture zone geometry, connectivity, and transmissive properties. Each type of data is analyzed with the appropriate physical simulation models, including ones for wave propagation, hydraulic head changes, and solute migration. We propose a coupled-inversion process based on a very flexible optimization procedure known as simulated annealing. The method will yield images that are consistent with all the types of data (e.g., heads, concentrations, radar) and indicate fracture-zone geometry, hydraulic conductivity estimates, and spatially variable uncertainty estimates. It will be developed and applied to both synthetic and field data. Our past experience for sedimentary deposits has shown that synthetic data analysis exercises can promotes rapid development and testing of the "coupled" inversion approach. Once the benefits and limitations of the proposed method are understood, application to complex field data provides a true test of the method. The field data will be from the fractured-rock experimental site at Mirror Lake, New Hampshire. To date, the USGS has collected radar tomography, seismic tomography, borehole geophysical log s, hydraulic test data and tracer test data. In what we consider to be a unique opportunity, they are willing to make these newly collected data available to us. The project will provide insight into the information that can be extracted from different types of data, the relative worth of data, and how joint analysis of different types of data can be used to deduce fracture-zone architecture.