A methodology for velocity field measurement in multiphase high-pressure flow of CO₂ and water in micromodels

This paper presents a novel methodology for capturing instantaneous, temporally and spatially resolved velocity fields in an immiscible multiphase flow of liquid/supercritical CO₂ and water through a porous micromodel. Of interest is quantifying pore-scale flow processes relevant to geological CO₂ sequestration and enhanced oil recovery, and in particular, at thermodynamic conditions relevant to geological reservoirs. A previously developed two-color microscopic particle image velocimetry approach is combined with a high-pressure apparatus, facilitating flow quantification of water interacting with supercritical CO₂. This technique simultaneously resolves (in space and time) the aqueous phase velocity field as well as the dynamics of the menisci. The method and the experimental apparatus are detailed, and the results are presented to demonstrate its unique capabilities for studying pore-scale dynamics of CO₂-water interactions. Simultaneous identification of the boundary between the two fluid phases and quantification of the instantaneous velocity field in the aqueous phase provides a step change in capability for investigating multiphase flow physics at the pore scale at reservoir-relevant conditions.