Microscopic mechanisms of oil-water-rock interactions during CO2 enhanced oil recovery and storage: a comprehensive review

With the large-scale deployment of carbon capture, utilization, and storage (CCUS) technologies, CO 2 -enhanced oil recovery and storage (CO 2 -EOR & Storage) has emerged as a core technical approach that improves crude oil recovery efficiency and enables permanent carbon sequestration. The operational efficiency and long-term stability of this technology rely heavily on microscopic interactions occurring within reservoir oil-water-rock multiphase systems. This paper systematically investigates the physical interactions and chemical reaction mechanisms between injected CO 2 and reservoir crude oil, formation water, and rock media. After reservoir injection, CO 2 dissolves into crude oil and triggers oil swelling, viscosity decline, light component extraction, and miscible phase formation, which modifies crude oil fluidity at the molecular scale. CO 2 also dissolves in formation water to generate weak carbonic acid. The resultant acid reacts with rock minerals through dissolution, precipitation, and ion exchange and alters reservoir wettability, which dynamically reorganizes pore-throat geometries and subsurface flow environments. Competitive adsorption at oil–water–rock triple-phase interfaces, combined with the balance between capillary and viscous forces as well as multicomponent mass transfer and diffusion, governs the entire spectrum of microscopic interactions within the studied system. Existing research has transitioned from macroscopic characterization to nanoscale mechanistic investigations. Unresolved issues remain regarding reaction pathways under multiphase and multi-field coupling conditions, dynamic interfacial behaviors, and quantitative relationships between microscopic mechanisms and macroscopic engineering performances. This review elaborates the microscopic interaction mechanisms of CO 2 with oil-water-rock systems, delivering universal theoretical implications for reservoir research worldwide. It provides fundamental theoretical support for the optimization of global CO 2 -EOR and carbon sequestration projects and offers generalized theoretical guidance for international CCUS deployment.