本项目拟开展耦合离子交换的scCO2-brine多相流体在纳米尺度岩石孔隙内流动特性的研究。地质封存中scCO2沿盖层岩石孔隙（直径小于50nm）的泄漏是伴随着流－固相间离子交换的多相流动过程。离子交换与CO2水合所引发的岩石表面溶解、矿化反应相关，其过程改变了孔隙表面形态和体系内受力，在纳米尺度流动中不可忽略。本项目拟采用分子模拟方法，对scCO2-brine-岩石系统界面特性、scCO2-brine与岩石表面间离子交换机理、耦合离子交换的多相流动过程及影响因素进行研究。从微观角度分析离子交换所引发的各相微观结构、相间作用力、流体粘性、流型、流速分布等流动特性变化；探究含离子交换的流动系统相间界面特性及相间作用力的变化规律及原因；确定调控流动的关键参数（温度、压强、盐浓度和CO2注入量等），以期对地质封存中CO2岩石孔隙渗流机理及相关界面现象进行阐述，为防止CO2泄漏的研究提供理论指导。

This project is planned to investigate the flow characteristics of scCO2-brine multiphase fluids in rock nanopores. The scCO2 leakage along the caprock pores (diameter less than 50 nm) in the geological sequestration is a typical multiphase flow process which accompanies with the ion exchange between the flow phase and solid phase. Due to the ion exchange, which happens in the process of dissolution and mineralization reactions after the CO2 hydration, has significant influence on the pore surface morphology and system internal force, these effects cannot be ignored in the nanoscale flow. Therefore, in this project, we plan to utilize molecular dynamics (MD) simulations to investigate the interfacial characteristics, the mechanisms of ion exchanging reactions on the rock surface and the multiphase flow process coupling with the ion exchange. Specifically, we plan to research the variations of microstructure, viscosity and flow characteristics (velocity distribution, and flow pattern) of the phases caused by the ion exchange. Meanwhile, the influence of the flow state on the ion migration is also planned to be analyzed in this project. Moreover, for the multiphase flow process with the ion exchange, we plan to observe the interfacial phenomena and system forces, and then probe the causes of their variations. Finally, the vital parameters (temperature, pressure, salt concentration and CO2 injection, etc.) of flow control will be determined in detail. This study is expected to explain and probe the flow mechanism and interfacial phenomena in the CO2 leaking process up through rock pores, which is a fundamental guideline to the relative research on CO2 leakage prevention methods.