Collaborative Research: Hydrogeophysical Quantification of Hydraulic Conductivity from Electrical Measurements of the Effective Properties of Porous Media

合作研究：通过多孔介质有效特性的电测量对水力电导率进行水文地球物理量化

• 批准号: 0710949
• 负责人: Warren Barrash
• 金额: $ 12.7万
• 依托单位: Boise State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-08-15 至 2012-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0710949&HistoricalAwards=false
• 关键词: Collaborative; Research; Hydrogeophysical; Quantification; Hydraulic

We will conduct research on quantification of hydraulic conductivity (K) from complex conductivity (sigma*) measurements. We will study (1) coarse alluvial deposits of the Boise Hydrogeophysical Research Site (BHRS), and (2) finer glacial melt deposits. The (sigma*) contains information on (a) the interconnected pore volume, (b) the interconnected pore surface area, and (c) the pore throat size controlling flow. We will explore whether low frequency electrical parameters can provide proxies of these pore geometrical parameters used in K prediction based on percolation theory, as well as capillary tube models. Soils with a narrow grain size distribution exhibit a low-frequency peak in polarization theoretically related to a pore length scale. Models for K prediction based on percolation theory utilize a characteristic length scale. Our work will explore the effectiveness of K prediction based on percolation type theory using the pore length scale given by (sigma*) measurements. Soils that exhibit a broad grain size distribution are typically devoid of a polarization peak and instead exhibit a constant polarization over the frequency range of (sigma*) measurements. Models for K prediction based on capillary tube models rely on a proxy measure of the hydraulic radius of tubes, usually the measurable specific surface area per unit pore volume (Spor). Our research will explore whether the magnitude of the polarization can also be used to develop electrical models of K prediction.Laboratory studies will examine candidate petrophysical relationships linking (sigma*) to measures of the effective pore radius and (Spor). We will examine (1) the (r-) pore radius relation, where (r) is a relaxation time related to the peak in frequency (w) of the (sigma*(w)) polarization, and (2) the single frequency (sigma')-(Spor) relation. A theoretical framework for interpretation of (sigma*(w)) in terms of a complex surface conductivity ((sigma*)surf(w)), will be derived and its predictive capability evaluated by comparison with Darcy flow tests. Upscaling will be examined at the BHRS. Hydraulic conductivity estimates based on borehole (sigma*) profiles will be compared with K estimates from multi-level slug tests. Two strategies for inverting (sigma*) datasets for tomographic estimates of K are: (1) direct conversion of (sigma*) images to K images assuming a stationary K prediction equation, and (2) a structural inversion whereby the K zonation is estimated. These strategies will be assessed via comparison with spatial K distribution at the BHRS estimated from kriging of borehole-based K measurements, and available hydraulic tomography datasets.A Hydrogeophysics Workshop will be offered to Ph.D. students during Yr 3 of this project. We will also develop Honors student UnderGraduate (HUG) research experiences in Hydrogeophysics on the Rutgers-Newark (R-N) campus. This initiative, run in collaboration with the R-N Honors College, will provide 2-3 HUG stipends per semester. We will selectively target the unique minority population of the R-N campus. We will also accelerate ongoing efforts to make the BHRS a test bed for hydrogeophysics. Equipment purchased to conduct this research will be made available to the hydrological community via the Hydrologic Measurement Facility (HMF)-Geophysics module of the Consortium of Universities for the Advancement of Hydrologic Science (CUAHSI).

我们将通过复杂的电导率 (sigma*) 测量对水力电导率 (K) 进行量化研究。我们将研究 (1) 博伊西水文地球物理研究站 (BHRS) 的粗冲积沉积物，以及 (2) 较细的冰川融化沉积物。 (sigma*) 包含有关 (a) 互连孔隙体积、(b) 互连孔隙表面积和 (c) 控制流量的孔喉尺寸的信息。我们将探讨低频电参数是否可以提供这些孔隙几何参数的代理，用于基于渗流理论和毛细管模型的 K 预测。具有窄粒度分布的土壤在理论上与孔隙长度尺度相关的极化中表现出低频峰值。基于渗流理论的 K 预测模型利用特征长度尺度。我们的工作将利用 (sigma*) 测量给出的孔隙长度尺度，探索基于渗流类型理论的 K 预测的有效性。表现出宽粒度分布的土壤通常没有极化峰，而是在 (sigma*) 测量的频率范围内表现出恒定的极化。基于毛细管模型的 K 预测模型依赖于管的水力半径的替代测量，通常是每单位孔隙体积的可测量比表面积 (Spor)。我们的研究将探索极化的大小是否也可以用于开发 K 预测的电模型。实验室研究将检查将 (sigma*) 与有效孔隙半径和 (Spor) 的测量联系起来的候选岩石物理关系。我们将检查 (1) (r-) 孔隙半径关系，其中 (r) 是与 (sigma*(w)) 极化的频率 (w) 峰值相关的弛豫时间，以及 (2) 单频 (sigma')-(Spor) 关系。将导出根据复杂表面电导率 ((sigma*)surf(w)) 解释 (sigma*(w)) 的理论框架，并通过与达西流测试进行比较来评估其预测能力。 BHRS 将检查升级。基于钻孔 (sigma*) 剖面的水力传导率估计值将与多级段塞测试的 K 估计值进行比较。用于反演 (sigma*) 数据集以进行 K 层析估计的两种策略是：(1) 假设固定 K 预测方程，将 (sigma*) 图像直接转换为 K 图像，以及 (2) 估计 K 分区的结构反演。这些策略将通过与 BHRS 的空间 K 分布进行比较来评估，该分布是通过基于钻孔的 K 测量的克里格法估计的，以及可用的水力层析成像数据集。该项目第三年的学生。我们还将在罗格斯-纽瓦克 (R-N) 校园培养水文地球物理学荣誉学生本科 (HUG) 研究经验。该计划与 R-N 荣誉学院合作开展，每学期将提供 2-3 份 HUG 津贴。我们将有选择地针对 R-N 校园中独特的少数族裔群体。我们还将加快正在进行的努力，使 BHRS 成为水文地球物理学的试验台。为进行这项研究而购买的设备将通过水文科学促进大学联盟 (CUAHSI) 的水文测量设施 (HMF)-地球物理学模块提供给水文界。