Carbon dioxide sequestration in saline formations: Part 2—Review of multiphase flow modeling

• Recent work on multiphase flow modelling and data required for engineering design.
• Conventional mode of multiphase flow does not deal with physical complications.
• More data for CO2–brine fluid properties than for multiphase flow properties.
• Lack of robust modelling and data leads to large uncertainty in studies.

This part of the review presents published work on the related aspects of multiphase flow modeling and the laboratory data required for reservoir engineering studies of injectivity and storage capacity, trapping mechanisms and seal integrity. The current capability of multiphase flow models to characterize the immiscible flow of CO2 and brine is examined. Our review indicates that the conventional mode of multiphase flow is not equipped to deal with complications that appear during CO2 sequestration such as non-equilibrium pore scale flow, multiscale hydrodynamic instability and viscous coupling. The review of fluid and multiphase flow properties of CO2–brine mixtures under sequestration conditions reveals that there is more published data for CO2–brine fluid properties than their multiphase flow properties. This is mainly because CO2–brine fluid properties have long been investigated by different industries whereas studies on CO2–brine–rock systems have begun only recently driven by CO2 sequestration. CO2 differs from other gases such as N2 or CH4 in interaction with formation brine and the impact of this interaction on multiphase flow of CO2 and brine in saline formations is yet to be understood. This leads to a large uncertainty in current modeling studies.