EAR-PF: Dynamic flow channeling through complex fracture networks under multi-frequency oscillatory flow conditions: A fully-coupled hydromechanical approach

Jeremy R.博士帕特森已被授予美国国家科学基金会博士后奖学金，研究流动通道通过复杂的岩石裂缝网络在赖斯大学与乔纳森博士阿乔富兰克林博士合作。贝克尔在加州州立大学-长滩。深层地下代表了一种重要的和日益利用的资源，在那里可以提取热水作为能源，并可以封存碳。然而，这些策略需要对流体如何通过深层地下移动的透彻了解，这是由于裂缝的存在而复杂化的-裂缝是大多数深层岩石的共同特征-限制了我们预测这些深层岩层响应流体提取或注入的行为的能力。这些裂缝经常形成快速流动路径的互连网络，可以集中地下流体流动;然而，现有的测试方法限制了我们了解地下流体如何通过这些裂缝网络集中的能力。该项目的目的是进一步开发新的方法，旨在更好地了解复杂的，相互连接的岩石裂缝网络如何引导整个地下的流体流动。此外，该项目旨在让休斯顿独立学区（一个少数族裔占多数的学区）的学生了解地下水资源的重要性以及裂缝对地下水流的影响，双手-在教育工具和同伴视频制作，可以很容易地分发到整个学区的教室。天然岩石裂缝包括一个很小的一部分，深地下水系统，但他们主导地下流动集中在一个渠道化的方式，沿着高透射裂缝，通常被称为水力骨干流体。该提案将调查这个液压骨干的形成和演变与液压测试的时间尺度的变化，使用完全耦合，流体力学建模方法来分析以前收集的数据在镜湖断裂岩石实验场。这项研究的结果将提供一个时间分析，表明这个水力骨干不是一个静态的，而是一个动态的结构，随着水力测试的时间尺度的变化，导致显着的变化，地下流量和运输。结合动态裂缝位移测量，该提案中的工作代表了首次使用多频振荡流测试，以探索在完全耦合的水力力学框架下，通过复杂的裂缝网络沿着水力骨干的流量集中的动态性质。拟议研究的结果将提供一个框架，改善裂缝流动和运输建模模拟，减少在裂缝地下水系统中观察到的异常突破位置的风险。该奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

Dr. Jeremy R. Patterson has been awarded an NSF EAR Postdoctoral Fellowship to research flow channeling through complex rock fracture networks at Rice University with Dr. Jonathan Ajo-Franklin in collaboration with Dr. Matthew W. Becker at California State University – Long Beach. The deep subsurface represents an important and increasingly utilized resource where hot water can be extracted for energy and carbon can be sequestered. However, these strategies require a thorough knowledge of how fluids move through the deep subsurface, which is complicated by the presence of fractures – a common feature in most deep rocks –limiting our ability to predict the behavior of these deep rock formations in response to fluid extraction or injection. These fractures frequently form inter-connected networks of fast flow pathways that can focus subsurface fluid flows; however, existing testing methods limit our ability to understand how subsurface flows are concentrated through these networks of fractures. The purpose of this project is to further develop new methods aimed at better understanding how complex, inter-connected networks of rock fractures channelize fluid flow throughout the subsurface. Further, this project seeks to expose students in the Houston Independent School District, a majority-minority school district, to the importance of groundwater resources and the impact of fractures on groundwater flows through the building of a highly portable, hands-on educational tool and companion video production that can be easily distributed to classrooms throughout the school district.Natural rock fractures comprise a very small fraction of deep groundwater systems, yet they dominate subsurface flows by concentrating fluids in a channelized manner along highly transmissive fractures, commonly referred to as a hydraulic backbone. This proposal will investigate the formation and evolution of this hydraulic backbone with variations in the temporal scale of hydraulic testing using a fully-coupled, hydromechanical modeling approach to analyze previously collected data at Mirror Lake Fractured Rock Experimental Site. The results of this research will provide a temporal analysis that shows this hydraulic backbone is not a static, but rather a dynamic structure that changes with the timescale of hydraulic testing, resulting in significant changes to subsurface flow and transport. Combined with dynamic fracture displacement measurements, the work in this proposal represents the first use of multi-frequency oscillatory flow testing to explore the dynamic nature of flow concentration along a hydraulic backbone through complex fracture networks under a fully-coupled hydromechanical framework. The results of the proposed research will provide a framework that improves fracture flow and transport modeling simulations, reducing the risk of anomalous breakthrough locations observed in fractured groundwater systems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.