Numerical simulation of CO2 injection, and dissolved gas injection for enhanced oil recovery in complex reservoirs with transmissible and non-transmissible faults

To promote the utilisation of CO2, steps to limit global warming to a global average temperature below 2 degrees C and net-zero emission future by 2050 this study investigated the effectiveness of CO2 and dissolved gas injection for enhanced oil recovery from a reservoir with transmissible and non-transmissible faults. Unlike previous studies focusing on either miscible or immiscible gas injection, this study investigated both and adopted an advanced hybrid modelling combination of solvent, Todd-Longstaff and miscibility models to reveal CO2, oil and rock interactions in complex reservoirs with transmissible and non-transmissible faults. The findings suggest oil recovery of up to 42% during miscible injection and 32% for dissolved gas injection. This study reveals the nuanced understanding of how structural complexities may influence EOR and carbon sequestration. While miscible CO2 injection appeared to be more efficient for early oil recovery and maintaining reservoir pressure, immiscible gas may hold a greater potential for sequestration. This study further identified the complexity of reservoir structures and addressed well placement, fluid dynamics and pressure maintenance as contributing factors to improved oil recovery or CO2 sequestration.