Dynamic Evolution of Minimum Miscibility Pressure in CO2–Crude Oil Systems: A Review

In the context of the rapid advancement of carbon capture, utilization and storage (CCUS) technologies, CO2 flooding has garnered considerable attention owing to its dual benefits in boosting oil recovery and enabling geological carbon sequestration. Maximum oil displacement efficiency can be achieved when CO2 achieves miscibility with crude oil. Minimum miscibility pressure (MMP) is a pivotal criterion for determining oil-gas miscibility. Field operations demonstrate that the miscibility state between CO2 and crude oil varies spatially and temporally within reservoirs during flooding processes, which manifests the dynamic evolution of MMP. Precise determination of MMP has remained a key research focus. This paper reviews experimental protocols and theoretical prediction models for MMP, and clarifies the potential of various approaches for studying MMP evolutionary behavior. The underlying mechanisms and evolutionary rules of MMP are elaborated in terms of component interaction, reservoir conditions and displacement parameters. Meanwhile, practical MMP applications are analyzed based on two representative CO2 flooding pilot projects. Finally, current research outcomes are concluded and prospective research trends are proposed. This Review systematically demonstrates that MMP dynamic evolution arises from the coupling effect of multiple factors, providing essential theoretical insights and technical guidance for optimizing project design and managing pressure dynamics in CO2 miscible flooding development.