CO2-Plume Geothermal (CPG) after enhanced oil recovery (EOR)

The global energy transition requires novel carbon utilization methods to enable integrated and optimized low-carbon energy production. Coupling CO 2 -based geothermal energy extraction with CO 2 -enhanced oil recovery (EOR) represents a promising yet largely unexplored approach for improving resource efficiency and carbon sequestration. This study investigates the integration of CO 2 -Plume Geothermal (CPG) energy production with CO 2 -EOR in mature oil reservoirs using numerical simulations of conceptual heterogeneous reservoir models. The interplay between EOR and CPG performance in terms of energy production and CO 2 storage is evaluated and compared to understand the geotechnical implications of this integration. The analysis highlights that initiating CPG operations after EOR significantly benefits from the established CO 2 plume, facilitating immediate and efficient geothermal energy extraction. Results show that integrating CPG with EOR increases total energy recovery by 20%–50% relative to the energy produced by EOR alone, yielding CPG thermal power outputs ranging from 13 to 23 MW th /km 2 . Continued CO 2 injection during CPG operations further increases total CO 2 storage by 80%–280%, driven primarily by improved volumetric sweep of previously unswept reservoir volumes and enhanced CO 2 density resulting from reservoir cooling. While reservoir heterogeneity strongly influences oil recovery during EOR, its effect on CPG thermal output is less pronounced, since native reservoir fluids (oil and brine) have already been largely displaced during the EOR stage, and the CO 2 plume gradually stabilizes over time. These findings demonstrate the viability and advantages of integrated CO 2 -EOR and CPG systems, offering insights into novel methods essential for sustainable subsurface resource management and climate-change mitigation. • Coupling CO 2 -EOR with CPG yields noticeably higher total energy production compared to EOR alone. • Ongoing CO 2 injection during CPG significantly increases storage capacity, aided by cooling-induced density increase. • Reservoir heterogeneity strongly influences oil recovery in EOR but has a more modest effect on CPG thermal output. • This hybrid approach offers a pathway to large-scale CCUS by repurposing mature oil fields for geothermal power and enhanced geologic CO 2 storage.