Faults as Conduit-Barrier Systems-Tracing Fluid Migration Along Faults in the Lower Rhine Embayment

作为管道屏障系统的断层——追踪莱茵河下游海湾沿断层的流体运移

• 批准号: 0609809
• 负责人: Mark Person
• 金额: --
• 依托单位: Indiana University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-07-01 至 2008-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0609809&HistoricalAwards=false
• 关键词: Faults; Conduit; Barrier; Systems; Tracing

Faults play a critical role in a wide variety of hydrogeological phenomena ranging from the role of faults in metalliferous ore-formation in sedimentary basins to the assessment of the risk of the spread of contaminated groundwater in faulted aquifer systems. This study focuses on fault zone permeability within poorly consolidated sediments using an exceptionally-rich field data set which includes high resolution geological data, and multi-decadal records of hydraulic head observations from a dense network of several hundred observation wells from the Lower Rhine Embayment that forms the southernmost Roer Valley Rift System (at the border area between Germany, the Netherlands and Belgium, Europe). As part of this study, thermal, isotopic, and geochemical data are collected from these wells, some of which cut through fault zones. A high resolution three-dimensional finite-element model of faults in the Lower Rhine Embayment will be developed to test new and existing conceptual models of fault permeability. One of the main questions is whether faults can act as conduit-barrier systems in which vertical fluid flow is enhanced while horizontal flow is impeded. Such a system could exist as a result of a strongly anisotropic permeability in the fault zone. We hypothesize that geochemical data along faults in the Roer Valley Rift System can serve as robust tracers which can document enhanced vertical fluid flow along faults. We will test a new algorithm that we developed to calculate fault permeability anisotropy in layered sedimentary sequences as a function of fault throw, effective stress and the clay-content of the lithologies flanking the fault zone. One of the main objectives of this study is to test this algorithm as well as the existing Fault Seal Analysis method developed in the petroleum industry.Results of the project will provide an improved understanding of factors controlling groundwater flow within faulted sedimentary aquifers. Many urban areas in the southwestern US are situated in extensional tectonic settings (e.g. Las Vegas, Albuquerque) and rely for their water supply upon siliciclastic aquifer systems cut by numerous faults. Given the increased demands on existing groundwater sources, the project will directly contribute to an improvement in the sustainable development of groundwater resources in extensional basins. The methods developed for fault seal prediction and fault property inclusion in groundwater flow models will improve the accuracy and efficiency of groundwater flow predictions and ultimately groundwater management. The risks of contaminant flow are becoming more acute given the increased usage of groundwater and associated commercial developments within urbanized areas. The knowledge and methods generated by this project will help improve risk assessment exercises associated with contaminant transport within aquifers containing faults (e.g. Yucca Mountain).

断层在各种各样的水文地质现象中起着关键作用，从断层在沉积盆地金属成矿中的作用到评估断层含水层系统中受污染地下水扩散的风险。本研究的重点是使用异常丰富的现场数据集，其中包括高分辨率的地质数据，并从下莱茵河Embayment，形成了最南端的鲁尔谷裂谷系（在德国，荷兰和比利时，欧洲之间的边界地区）的数百个观测威尔斯的密集网络的水头观测的几十年记录的断裂带渗透性差的沉积物。作为这项研究的一部分，从这些威尔斯井中收集了热、同位素和地球化学数据，其中一些井穿过断层带。将开发莱茵河下游湾断层的高分辨率三维有限元模型，以测试新的和现有的断层渗透率概念模型。其中一个主要问题是断层是否可以作为屏障系统，其中垂直流体流动被加强，而水平流动被阻碍。这种系统可能是由于断裂带中的渗透率具有强烈的各向异性而存在的。我们假设地球化学数据沿着断层在罗尔谷裂谷系统可以作为强大的示踪剂，可以记录增强垂直流体流动沿着断层。我们将测试一种新的算法，我们开发的计算断层渗透率各向异性分层沉积序列的断层落差，有效应力和断层两侧的岩性粘土含量的函数。本研究的主要目标之一是测试该算法以及现有的断层封闭性分析方法在石油industry.Results的项目将提供一个更好的理解的因素控制地下水流断层沉积含水层。美国西南部的许多城市地区位于伸展构造环境中（例如拉斯维加斯、阿尔伯克基），其供水依赖于被许多断层切断的硅质含水层系统。鉴于对现有地下水资源的需求增加，该项目将直接有助于改善伸展盆地地下水资源的可持续开发。断层封闭性预测和断层性质纳入地下水流模型的方法将提高地下水流预测的准确性和效率，并最终提高地下水管理。由于城市化地区地下水使用量的增加和相关的商业发展，污染物流动的风险变得更加严重。该项目产生的知识和方法将有助于改进与含有断层的含水层（如尤卡山）内污染物迁移有关的风险评估工作。