Research progress and prospects for synergistic CO₂ enhanced oil recovery and sequestration technologies

Carbon Capture, Utilization, and Storage (CCUS) technology is a critical pathway for achieving deep decarbonization in the industrial sector. Among its applications, the synergistic technology of CO₂-enhanced oil recovery and geological sequestration (CCUS-EOR) has emerged as a prominent research focus due to its dual potential for large-scale emissions reduction and economic viability. Previous research has predominantly concentrated on either the mechanisms of enhanced oil recovery or those of geological sequestration in isolation. A systematic investigation into the synergistic mechanisms between these two processes has been relatively scarce, thereby constraining the advancement of this integrated technology. Moving beyond a conventional enumeration of technologies, this paper constructs a novel analytical framework based on the "dynamic evolution of sequestration states." Within this framework, the paper systematically elucidates the spatiotemporal evolution laws of sequestration states during continuous injection and identifies the "pore space competition effect" as the fundamental physical bottleneck limiting the sequestration potential of traditional water-based synergistic technologies. Through comparative analysis, this study demonstrates that water-free CO₂ thickening technology can fundamentally overcome this bottleneck, serving as the optimal transformation pathway to maximize both oil recovery efficiency and sequestration capacity simultaneously. Finally, the paper outlines future development trends for synergistic EOR and storage technologies, underscoring the dual drivers of technological innovation and policy support, with the aim of providing theoretical backing and technical references for enhancing the comprehensive benefits of CCUS-EOR projects. • Systematic review of CO 2 -EOR and sequestration synergistic mechanisms. • Clarifies transformation patterns of CO 2 sequestration states. • Analyzes key geological and operational parameters influencing synergy. • Comparative evaluation of mainstream EOR and storage synergy enhancement technologies. • Outline the future challenges and prospects of CCUS-EOR synergy development.