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.

9804789Ge 地球上地壳中存在各种尺度的天然岩石裂缝。 它们在地质介质中的地下水运动、溶质运输和废物隔离中发挥着重要作用。 表征裂隙岩石中的流体流动和质量传输取决于我们对流体如何通过单个裂缝传输的了解。 然而，由两个粗糙表面界定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被许多人研究过。 一般结论是三次定律只能提供流量的定性描述，雷诺方程对于粗糙裂缝无效，并且需要将孔径和弯曲度的影响纳入更好的控制流动定律中。 这项研究的主要目标是（1）系统地探索和量化裂缝粗糙度、曲折度和流道形成对控制流动规律的影响，以及（2）通过理解来开发更好的粗糙裂缝控制流动规律流体输送机制。具体来说，我将尝试实现以下目标：（1）开发一种合理的方法来表征天然岩石的裂缝几何形状，（2）研究生成裂缝和异形裂缝中通道化流动路径的形成，（3）检查形成裂缝的条件修正的雷诺方程是有效的，(4) 识别从达西流到非达西流的过渡流态，(5) 构建一个更好的控制定律，捕捉粗糙裂缝中流体传输的主要特征。 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。 对雷诺方程、包含局部孔径和弯曲度几何变量的修正雷诺方程以及纳维-斯托克斯方程进行数值求解，以模拟粗糙裂缝中的流体流动。 格子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。 这项研究代表了一项全面的理论尝试，旨在研究粗糙岩石裂缝中流体传输的控制规律。