CO2 Injection as a Non hydrocarbon Gas injection in a Sector Model of an Iranian Oil Reservoir

There is a consensus among specialists that Carbon dioxide (CO2) flooding is an effective method of enhanced oil recovery. CO2 injection causes oil swelling, reduction in the oil viscosity, oil vaporization and improving oil displacement by miscibility. Iranian oil reservoirs are expected to undergo serious pressure decline in upcoming years. Abundance of CO2, its availability and environmental issues regarding this gas, makes it a promising injection gas to overcome such challenges. Because of technological complexity and financial requirements to initiate a gas flooding project, a comprehensive evaluation is necessary before any other thing.The present work is concerned with investigation of CO2 injection process in a sector of a Southwest Iranian oil reservoir, giving a special attention to phase behavior and amount of recoverable oil. Thus we use real rock and fluid properties for simulation. The main focus is on equation of state (EOS), modeling of experimental PVT data, determining MMP (minimum miscibility pressure) for different gas compositions using a slim tube model. Other aspects such as the effect of different completion patterns, CO2 injection rate, and injection pressure on oil recovery are covered. Recovery values obtained from different flooding scenarios are also compared. Finally, we inspect recovery performance in different gas flooding scenarios and natural depletion.The simulation results indicate that CO2 injection to the studied sector of the reservoir causes a 12.9% increase in recovery factor in comparison with the natural depletion of this sector

Keywords:

Enhanced oil recovery , recovery factor , simulation , CO2 injection , regression