Investigation of the dynamic pressure surge effect in a fluid-filled fracture through numerical modeling and laboratory experiment

通过数值模拟和室内实验研究充液裂缝中的动态压力波动效应

• 批准号: 1833058
• 负责人: Yingcai Zheng
• 金额: $ 18.06万
• 依托单位: University of Houston
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-01 至 2021-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1833058&HistoricalAwards=false
• 关键词: Investigation; dynamic; pressure; surge; effect

It is well documented that naturally occurring earthquakes, even those located thousands of kilometers away, can dynamically trigger other earthquakes by the passage of a weak vibrating seismic wave. Furthermore, seismic waves can also induce liquefaction and volcanic eruptions. However, the physics of these triggered phenomena are unknown. This work will focus on understanding the physical conditions that can trigger earthquakes, either by passing seismic waves or by human activity, such as fluid injection at wells. Specifically, this study will investigate a pressure surge phenomenon, which could be the common underlying mechanism for all these triggered phenomena although in different geological settings. The investigator will use both numerical modeling and physical experiments to discriminate between competing physical mechanisms that lead to earthquake triggering. Elucidating the triggering mechanism has broad and fundamental societal impact in the mitigation of natural hazards. This work will support an early career faculty member and a graduate student. The passing of weak seismic waves not only can suddenly trigger earthquakes but can also change the fluid permeability of a hydrologic system, cause liquefaction and bring on volcanic eruptions. However, what mechanisms control all these different triggered occurrences are largely unknown because the stress perturbation due to the seismic wave is extremely small and it is on the order of a few thousand Pascal, equivalent to the weight of a few coins. Finding the underlying triggering mechanism has been a central problem in Geophysics. This 2-year study seeks to make a fundamental breakthrough in understanding these triggered phenomena. The investigator recently identified a dynamic pressure surge phenomenon where the fluid pressure in a fluid-filled fracture can increase 2-3 orders of magnitude relative to the incident wave pressure. The increase in fluid pressure can reduce the effective confining pressure to trigger earthquakes or to produce a pressure gradient to drive fluid flow. This newly discovered effect could be much more pronounced for a low-frequency incidence seismic wave than that for a high-frequency one, which agrees with observations. In addition to its frequency-dependence, the pressure surge phenomenon also depends on the fracture geometry and aperture. This project will investigate a scientifically testable hypothesis, which can fill the knowledge gap in understanding triggering of many phenomena, including earthquake dynamic triggering. To test this hypothesis, the investigator will use both high-performance computing on numerical models and laboratory experiments. The proposed idea and approaches are promising and may have far-reaching consequences in not only the earthquake but also the volcano hazards mitigation. In addition, the insights learned from this project can be used to create new subsurface sensing and imaging methods, useful in carbon sequestration, nuclear waste disposal, and unconventional/geothermal energy development.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.

有充分的证据表明，自然发生的地震，即使是那些位于数千公里之外的地震，也可以通过微弱的振动地震波来动态地触发其他地震。此外，地震波还会引起液化和火山喷发。然而，这些触发现象的物理机制尚不清楚。这项工作将侧重于了解可能引发地震的物理条件，无论是通过传递地震波还是通过人类活动，如向油井注入液体。具体地说，这项研究将调查一种压力波动现象，这可能是所有这些触发现象的共同潜在机制，尽管在不同的地质环境中。研究人员将使用数值模拟和物理实验来区分导致地震触发的相互竞争的物理机制。阐明触发机制在减轻自然灾害方面具有广泛和基本的社会影响。这项工作将支持一名早期职业教师和一名研究生。微弱地震波的传播不仅可以突然触发地震，还可以改变水文系统的流体渗透性，导致液化和火山喷发。然而，控制所有这些不同触发事件的机制在很大程度上是未知的，因为地震波造成的应力扰动非常小，大约是几千帕斯卡，相当于几个硬币的重量。寻找潜在的触发机制一直是地球物理学的中心问题。这项为期两年的研究试图在理解这些触发现象方面取得根本性突破。这位研究人员最近发现了一种动态压力波动现象，即充液裂缝中的流体压力相对于入射波压力可以增加2-3个数量级。流体压力的增加可能会降低触发地震的有效围压，或产生驱动流体流动的压力梯度。这一新发现对低频入射地震波的影响可能比对高频入射地震波明显得多，这与观测结果一致。压力波动现象除了与频率有关外，还与裂缝的几何形状和开度有关。这个项目将研究一种科学上可检验的假说，它可以填补在理解许多现象的触发方面的知识空白，包括地震动态触发。为了验证这一假设，研究人员将使用数值模型和实验室实验的高性能计算。提出的想法和方法是有希望的，不仅在地震方面，而且在减轻火山灾害方面可能会产生深远的影响。此外，从该项目中学到的见解可用于创建新的地下传感和成像方法，用于碳封存、核废料处理和非常规/地热能开发。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Laboratory Evidence of Transient Pressure Surge in a Fluid-Filled Fracture as a Potential Driver of Remote Dynamic Earthquake Triggering

充液裂缝中瞬态压力浪涌作为远程动态地震触发潜在驱动因素的实验室证据

• DOI: 10.1785/0320210015
• 发表时间: 2021
• 期刊: The Seismic Record
• 作者: Jin, Yuesu;Dyaur, Nikolay;Zheng, Yingcai
• 通讯作者: Zheng, Yingcai