Collaborative Research: Permeability Enhancement by Fluid Pressure Oscillations

合作研究：通过流体压力振荡增强渗透性

• 批准号: 1045825
• 负责人: Chris Marone
• 金额: $ 36.39万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-07-01 至 2014-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1045825&HistoricalAwards=false
• 关键词: Collaborative; Research; Permeability; Enhancement; Fluid

This project will investigate fluid flow within rock masses in the shallow regions of Earth's crust, from the surface to ~10 km. Our work will focus on how dynamic stresses, for example caused by seismic waves, change flow properties of Earth's crust. Previous work shows that fluid permeability can change dramatically when rocks are shaken during earthquakes. The effects of strong shaking can be estimated, but the effects of weak shaking, for example due to a distant earthquake, are less well understood. We will perform laboratory experiments to investigate the processes and mechanisms that cause transient and permanent permeability changes due to dynamic stressing. The lab work will be coupled with theory and numerical methods to develop conceptual and quantitative models for permeability changes. Elastic waves produced during earthquakes can trigger a range of phenomena including seismicity, volcanic eruptions, and geyser activity. Dynamic stressing via the passage of seismic waves (or from other sources of transient loads) can also increase spring discharge, fluid flow in streams, and oil production, in some cases tripling the effective permeability of the natural system. These observations have been attributed to shaking-induced changes in permeability of shallow aquifers. However, the underlying mechanisms and the affect of dynamic stresses on poromechanical properties of rocks are poorly understood. Here we propose to investigate permeability enhancement by dynamic stressing using a multidisciplinary approach. Our preliminary work shows clear evidence of permeability enhancement in fractured rock subject to fluid pressure oscillations. The proposed work will expand the laboratory data while developing the theory and focusing on the underlying mechanisms. We will use knowledge of the processes and mechanisms operative in the laboratory to address the problem of upscaling our results to field conditions. We propose a series of experiments and models informed by observations of natural systems to (1) establish clear relationships between the controlling variables and the resulting changes in permeability, (2) analyze the physics of the enhancement and identify the underlying processes and (3) build appropriate numerical models of the results that can be applied at the laboratory and field scales. Results of the proposed experiments are expected to have significant impact on understanding fluid flow in the Earth's crust and seismic hazard. Understanding the physical basis for transient changes in permeability will lead to improved engineering approaches for oil reservoir and hydrological use.

这个项目将研究地壳浅层区域内的流体流动，从地表到大约10公里。我们的工作将集中在动应力，例如由地震波引起的动应力如何改变地壳的流动特性。以前的工作表明，当岩石在地震中摇晃时，流体的渗透率会发生巨大变化。强震动的影响是可以估计的，但弱震动的影响，例如由于遥远的地震，则不太清楚。我们将进行实验室实验，以研究由于动态应力引起的瞬时和永久性渗透率变化的过程和机制。实验室工作将与理论和数值方法相结合，以开发渗透率变化的概念和定量模型。地震期间产生的弹性波可以触发一系列现象，包括地震活动、火山喷发和间歇泉活动。通过地震波传播(或来自其他瞬时载荷来源)的动态应力还可以增加弹簧流量、水流和产油量，在某些情况下会使自然系统的有效渗透率增加两倍。这些观察结果被归因于震动引起的浅层含水层渗透率的变化。然而，动应力对岩石孔隙力学性质的影响及其内在机制还不是很清楚。在这里，我们建议使用多学科方法来研究动态应力增强渗透性。我们的初步工作表明，在流体压力振荡的情况下，裂隙岩石的渗透性增强是明显的证据。拟议的工作将扩展实验室数据，同时发展理论并专注于潜在的机制。我们将利用实验室中运行的过程和机制的知识来解决将我们的结果扩大到现场条件的问题。通过对自然系统的观测，我们提出了一系列实验和模型，以(1)在控制变量和由此导致的渗透率变化之间建立明确的关系，(2)分析增强的物理过程并确定潜在的过程，以及(3)建立可在实验室和现场尺度上应用的结果的适当的数值模型。拟议中的实验结果预计将对了解地壳中的流体流动和地震危险产生重大影响。了解渗透率瞬变的物理基础将有助于改进油藏和水文用途的工程方法。