Dynamic Redistribution of Fluids in Porous Media

大多数地下活动扰乱土壤和岩石中流体的自然状态，因为流体经常通过地下注入、抽出或输送。所有这些技术引起局部压力场的变化，这些变化最初将多相系统扰动到非平衡状态，随着时间的推移，该非平衡状态松弛到稳态或准静态分布。松弛取决于孔隙尺度的过程，如动态接触角，空气-水界面的几何形状，润湿性的时间变化，以及在多孔介质中的局部非均匀性。本研究的重点是通过将内部微观扰动与外部宏观行为联系起来，对多孔介质中流体的动态再分布进行实验研究。该研究将评估润湿性，孔隙拓扑结构和膜的不混溶流体在多孔介质中的再分配的贡献，在从动态到稳态/准静态条件的过渡。将使用实验技术的组合，包括制造具有内置电动致动器的透明微模型，以在孔隙网络内部的孔隙尺度上操纵流体;使用新的颗粒沉积方法制造3D透明微模型;以及&使用荧光成像和激光共聚焦显微镜测量2D 3D流体分布，以确定吸收膜的作用，角流体和钉扎膜的静态和动态关系作为维数的函数。对实验数据集的分析将确定哪些静态和动态本构关系的竞争理论得到实验证据的支持，以及当前的理论是否足以描述多相流体松弛。理解孔隙连通性的标度和多孔网络的水力特性在今天特别重要，因为页岩气中的强烈活动依赖于裂缝网络来产生气体，也是因为试图将二氧化碳封存在地下。此外，污染物的修复工作，化学混合，和生物组织生长的合成多孔介质都取决于复杂的相互作用的几何形状与流体的动力学。这项研究将提供用于预测多孔介质中多种流体的流动和分布的理论方法的关键测试，并将使科学家和工程师能够将界面区域，不连续的流体相和膜几何形状与宏观水力特性联系起来。

Most subsurface activities perturb the natural state of fluids in soil and rock because fluids are often injected, withdrawn or transported through the subsurface. All of these techniques induce changes in the local pressure field that initially perturb a multiphase system into a nonequilibrium condition that, over time, relaxes to steady-state or quasi-static distributions. The relaxation depends on pore-scale processes such as dynamic contact angles, air-water interface geometry, temporal changes in wettability, and local heterogeneities in the porous media. This research focuses on an experimental investigation of the dynamic redistribution of fluids in porous media by connecting internal microscopic perturbations to external macroscopic behavior. The study will assess the contributions of wettability, pore topology and films to the redistribution of immiscible fluids in a porous medium in the transition from dynamic to steadystate/quasi-static conditions. A combination of experimental techniques will be used that include the fabrication of transparent micro-models with built-in electro-kinetic actuators tomanipulate fluids at the pore scale internal to the pore network; the fabrication of 3D transparent micro-models using a new grain deposition method; and the measurement of 2D & 3D fluid distributions using fluorescent imaging and laser confocal microscopy to determine the role of absorbed films, corner fluids and pinned films on static and dynamic relations as a function of dimensionality. Analysis of experimental datasets will determine which competing theories for static and dynamic constitutive relationships are supported by experimental evidence, and whether current theories are sufficient to describe multiphase fluid relaxation.Understanding the scaling of pore connectivity and the hydraulic properties of porous networks is of particular relevance today because of the intense activity in shale-gas which depends on networks of fractures to produce the gas, and because of attempts to sequester carbon dioxide in the subsurface. In addition, contaminant remediation efforts, chemical mixing, and biological tissue growth on synthetic porous media all depend on the complex interplay of geometry with the dynamics of fluids. This research will provide critical testing of theoretical methods used to predict flow and distributions of multiple fluids in porous media, and will enable scientists andengineers to connect interfacial areas, disconnected fluid phases and film geometry to macroscopic hydraulic properties.