多孔介质内互溶流体界面不稳定性现象强化传热传质机理研究

Heat and mass transfer enhancements due to interfacial instabilities of miscible fluids in porous media are the key problems that affect the efficiencies of CO2 sequestration in saline aquifers and CO2 miscible flooding. Due to the complexity of pore structures, the developments of interfacial instabilities, the interaction among different fluid components, and the interaction between fluid and solid wall, the coupling between flow and mass transfer, the mechanism of mass transfer enhancement due to interfacial instabilities of miscible fluids in porous media is very complicated. The traditional methods are not suitable for studying this problem own to their limits. The lattice Boltzmann method based on mesoscopic kinetic theory is a promising approach for the study of such a complicated problem. In this project, we will adopt the coupled lattice Boltzmann model with a boundary condition that can accurately describe the chemical reactions between fluid and solid wall, to analyze the effects of geological characteristics and dimensionless parameters on the fluid flow, heat and mass transfer during the developments of interfacial instabilities. The mechanism of the heat and mass transfer enhancements due to interfacial instabilities will be revealed by scaling analysis. The research achievements of this project provide detailed data and theoretical basis for CO2 sequestration in saline aquifers and CO2 miscible flooding, and have important theoretical and practical significances for reducing CO2 emissions and enhanced oil recovery.

多孔介质内互溶流体界面不稳定性强化传热传质问题是影响CO2咸水层封存和CO2混相驱油工程效果的关键问题。由于涉及复杂孔隙结构、界面不稳定性发展、流固间相互作用和流体间热质传递，互溶流体界面不稳定性强化传热传质机理极为复杂。传统数值方法在研究此类问题时受到很大限制，基于介观动理学理论的格子Boltzmann方法是研究该类问题的有效方法。本项目从孔隙尺度出发，采用格子Boltzmann模拟与理论分析相结合的方法，针对CO2咸水层封存中密度指进和CO2混相驱油中粘性指进这两种典型界面不稳定性现象的特点，研究不同因素(储层特征、流体性质、注采条件)对界面不稳定性过程中流体传热传质的影响，总结影响传热传质的主控因素，揭示界面不稳定性强化传热传质的机理，为改善CO2咸水层封存和CO2混相驱油效果提供数据支撑和理论依据，发展和完善CO2埋存和高效利用中的复杂渗流理论。

多孔介质内互溶流体界面不稳定性现象中的强化传热传质问题涉及复杂孔隙结构、界面不稳定性发展、流固相互作用和流体间热质传递，是一个多物理过程、多场耦合的问题，该问题的复杂性极大限制了人们对其内部规律和传热传质机理的认识。本项目从孔隙尺度出发，采用格子Boltzmann模拟与理论分析相结合的方法，对界面不稳定性强化传热传质的机理进行研究。本项目基本按照计划执行，首先构建了能够正确描述孔隙尺度下多孔介质内流体流动及传热传质现象的格子Boltzmann模型；然后，基于构建的LB模型，对多孔介质内互溶流体粘性指进和密度指进两种典型的界面不稳定性现象进行数值模拟研究，系统研究不同多孔介质结构特性以及不同工况下互溶流体界面不稳定性的发展规律以及流体流动与传热传质的规律；最后，采用理论分析方法，解析出粘性指进和密度指进发展不同阶段下主导传热传质的因素，揭示了强化传热传质的机理，为发展石油开采增产增效技术和二氧化碳埋存安全评估机制奠定理论基础。