Integrated Structural and Hydrologic Charactrization of Fault Zone Permeability at Well Field to Regional Scales

区域尺度井场断裂带渗透性的综合结构和水文表征

• 批准号: 0610027
• 负责人: Shemin Ge
• 金额: --
• 依托单位: University of Colorado at Boulder
• 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: 2006-08-01 至 2010-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0610027&HistoricalAwards=false
• 关键词: Integrated; Structural; Hydrologic; Charactrization; Fault

0610027GECurrent understanding of fault-zone permeability at regional scales is limited. Particularly,permeability measurements across faults are scarce. Yet, there are clear indications that faultshave large hydrogeologic impacts on various geologic processes at this scale, as evidenced byvariable hydraulic head gradients, geochemical and geothermal anomalies across faults. Thereremain questions that are scientifically fundamental and practically significant regarding largescalepermeability of fault zones and their impact on aquifers. For example, how geologic andhydrologic information can be best integrated to effectively constrain regional-scale faultpermeability? While existing knowledge on fault permeability at small scales is indispensablescientifically, ultimately, it is the regional-scale permeability that is needed in conceptual andnumerical models for solving problems related to water resource management and transport offluid, solute, and energy in the Earth's crust.The scientific objective of this research is to characterize fault-zone permeability at the wellfieldto regional scale with constraints from field-based structural observations, hydrogeologictesting, and interpretation from conceptual and numerical modeling. The basis hypotheses arethat distinctive hydrogeologic responses around a fault could be observed from cross-faultaquifer tests and that fault-zone permeability features could be established from a comprehensiveunderstanding of the outcrop structural characteristics, borehole data of host rocks, andhydrogeologic tests conducted at multiple scales. Using the Elkhorn thrust fault in Colorado as afield site, the research plan consists of the following: (1) to characterize the geology and internalstructure of the fault zone to better understand the influence of juxtaposition of differentlithologies on fault-zone hydrogeologic properties, (2) to drill and core new boreholes throughthe fault zone to obtain direct field observations for fault-zone permeability, (3) to conduct crossfaultpumping tests in the new and preexisting holes to provide the much need directmeasurements on fault-zone permeability, and (4) to develop a fault-zone permeability model,through numerical modeling that integrates geologic, hydrogeologic, and geophysical field data.Three aspects of the intellectual merit are recognized. First, the study takes a new directionin characterizing fault-zone permeability by closely linking geologic observations andhydrogeologic testing data. Second, this proposed research offers the opportunity to gainhydrogeologic insight into a particular type of fault that is common but highly understudied - a thrust fault with a crystalline hanging wall and sedimentary footwall at regional basin scales. Finally, the cross-fault permeability tests coupled with geologic characterization planned in this research will be a significant advance in characterizing fault-related permeability by providing much-needed field measurement data.The major aspect of the broader impact of this proposed research is on enhancingundergraduate students experience in hydrogeology, in addition to training graduate students and contributing to better groundwater resource management in the western US. This research will benefit a large group of undergraduate students. Undergraduate students will be involved in all stages of this project. Specific approaches to implement this commitment include: (1) Recruit top undergraduates to conduct honor theses, (2) Field exercise related to an upper-division hydrogeology class. Groundwater level mapping and aquifer tests can be incorporated into class related activities, and (3) Drilling new boreholes will be coordinated so that students can observethe operation. Finally, the PIs plan to co-teach a two-credit two-week summer undergraduate field hydrogeology class. The research will provide an excellent venue for many different projects for this field class and help to realization of this plan.

0610027 GE目前对区域尺度上的断层带渗透率的理解是有限的。特别是，跨断层的渗透率测量很少。然而，有明确的迹象表明，断层对各种地质过程有很大的水文地质影响，在这种规模，证明了可变的水头梯度，地球化学和地热异常断层。关于断层带的大规模渗透性及其对含水层的影响，仍然存在一些具有科学基础和实践意义的问题。例如，如何最好地整合地质和水文信息，以有效地约束区域尺度的断层渗透性？虽然小尺度断层渗透率的现有知识是不可或缺的科学，但最终，在解决与水资源管理和流体，溶质，本研究的科学目标是在区域尺度上描述井场断层带渗透率的特征，基于结构观测、水文地质测试以及概念和数值模拟的解释。其基本假设是，通过跨断层含水层测试可以观察到断层周围独特的水文地质响应，通过对露头结构特征、围岩钻孔数据和多尺度水文地质测试的全面了解，可以建立断层带渗透性特征。使用科罗拉多的埃尔克霍恩逆冲断层作为野外场地，研究计划包括以下内容：（1）确定断层带的地质和内部结构特征，以更好地了解不同岩性的并列对断层带水文地质特性的影响，（2）在断层带钻取新的钻孔并取芯，以获得断层带渗透性的直接现场观测结果，（3）在新井和既有井中进行跨断层抽水试验，提供急需的断层带渗透率的直接测量数据;（4）通过综合地质、水文地质和地球物理资料的数值模拟，建立断层带渗透率模型。首先，将地质观测与水文地质测试资料紧密结合起来，在断层带渗透性表征方面开辟了新的研究方向。其次，这项研究提供了一个机会，以获得水文地质洞察到一个特殊类型的故障，是常见的，但高度欠研究-逆冲断层与结晶上盘和沉积下盘在区域盆地规模。最后，跨断层渗透率测试加上地质表征计划在这项研究中将是一个显着的进步，通过提供急需的现场测量data. the更广泛的影响，这项拟议的研究的主要方面是在enhancingbudget学生的经验，在水文地质学，除了培养研究生和促进更好的地下水资源管理在美国西部的断层相关的渗透率。这项研究将使一大群本科生受益。本科生将参与该项目的各个阶段。具体做法包括：（1）招收优秀本科生撰写荣誉论文;（2）开展水文地质学高年级实习。地下水位测绘和含水层测试可以纳入课堂相关活动，（3）钻探新的钻孔将协调，使学生能够掌握操作。最后，PI计划共同教授一个为期两周的两学分的夏季本科野外水文地质学课程。本课题的研究将为这门课程的多个不同项目提供一个很好的平台，并有助于这一计划的实现。