A Theoretical Study on the Governing Laws for Fluid Transport in Rough Fractures

粗糙裂缝中流体输运规律的理论研究

• 批准号: 9804789
• 负责人: Shemin Ge
• 金额: $ 15.05万
• 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: 1998
• 资助国家: 美国
• 起止时间: 1998-07-15 至 2002-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9804789&HistoricalAwards=false
• 关键词: Theoretical; Study; Governing; Laws; Fluid

9804789GeNatural rock fractures exist at all scales in the earth's upper crust. They play a major role in groundwater movement, solute transport, and waste isolation in geologic media. Characterizing fluid flow and mass transport in fractured rocks depends on our knowledge of how fluid transports through individual fractures. Yet fluid flow in fractures bounded by two rough surfaces is complex. Important questions on the validity of the cubic law and the Reynolds equation for rough fractures have been studied by many. The general conclusions are that the cubic law can only provide a qualitative description of flow rate, the Reynolds equation is not valid for rough fractures and effects of aperture and tortuosity need to be included in better governing flow laws. The primary goals of this research are (1) to systematically explore and quantify the effects of fracture roughness, tortuosity, and the formation of flow channeling on governing flow laws, and (2) to develop a better governing flow law for rough fractures by understanding the fluid transport mechanisms. Specifically, I will attempt to achieve the following objectives: (1) develop a rational method to characterize fracture geometry of natural rocks, (2) investigate the formation of channelized flow paths in generated and profiled fractures, (3) examine the conditions under which the modified Reynolds equation is valid, (4) identify the transitional flow regime from Darcian to non-Darcian flow, and (5) construct a better governing law that captures the dominant features of fluid transport in rough fractures. I will employ an array of theoretical approaches and utilize the existing lab experimental data to achieve these objectives. The Reynolds equation, the modified Reynolds equation including geometric variables of local aperture and tortuosity, and the Navier-Stokes equations will be solved numerically to simulate fluid flow in rough fractures. The Lattice Boltzmann method will be used for simulating both linear and non-linear fluid transport in fractures with complex geometries. The proposed research represents a comprehensive theoretical attempt to examine the governing laws for fluid transport in rough rock fractures.

[804789]天然岩石裂缝存在于地球上地壳的各个尺度上。它们在地下水运动、溶质运输和地质介质中的废物隔离中起着重要作用。描述裂隙岩石中的流体流动和物质输运取决于我们对流体如何通过单个裂隙进行输运的认识。然而，由两个粗糙表面包围的裂缝中的流体流动是复杂的。关于粗糙裂缝的三次定律和雷诺方程的有效性的重要问题已经得到了许多人的研究。总的结论是，三次定律只能提供流量的定性描述，雷诺方程对粗糙裂缝不适用，孔径和弯曲度的影响需要纳入更好的控制流动规律。本研究的主要目标是：(1)系统探索和量化裂缝粗糙度、弯曲度和流道形成对控制流动规律的影响；(2)通过了解流体输运机制，建立更好的粗糙裂缝控制流动规律。具体而言，我将努力实现以下目标：(1)建立一种合理的方法来表征天然岩石的裂缝几何形状；(2)研究生成裂缝和剖面裂缝中渠化流道的形成；(3)检验修正雷诺方程有效的条件；(4)确定从达西流到非达西流的过渡流态；(5)构建一个更好的控制规律，捕捉粗糙裂缝中流体输送的主要特征。我将采用一系列理论方法并利用现有的实验室实验数据来实现这些目标。采用数值求解的方法对粗糙裂缝中的流体流动进行模拟，并对包含局部孔径和弯曲度几何变量的修正Reynolds方程和Navier-Stokes方程进行数值求解。晶格玻尔兹曼方法将用于模拟具有复杂几何形状的裂缝中的线性和非线性流体输送。提出的研究代表了一个全面的理论尝试，以检查流体在粗糙岩石裂缝中运移的控制规律。