Simulation Aspects of the CO2 Flooding, Sensitivity and Case Study

This paper combines the knowledge and experience accumulated in IRIS over past years from several case studies involving Tjelbergodden CO2 value chain, Ekofisk and Gullfaks CO2 injection compositional simulations. The paper discuss importance of representing physical effects in modelling miscible and immiscible CO2 injection in sandstone and carbonate reservoirs. The following effects are evaluated: • Transfer of CO2 from fracture into the matrix involving diffusion and gravity segregation; • Viscous effects and formation of low and high concentration hydrocarbon phases; • Compositional effects and oil swelling; The sensitivity and importance of these effects are studied on several simplified mechanistic models and later applied to actual field cases. The detailed overview of viscous fingering effect will be presented. Results from the mechanistic study of the CO2 matrix-fracture transfer will be presented. The paper also discusses aspects of Equation-Of-State (EOS) modelling and PVT studies necessary. Case studies of the CO2 and CO2-WAG IOR methods for the reservoirs on the Norwegian Continental Shelf (NCS) will be presented. Oil recovery potential of these IOR processes will be discussed.