On Interplay of Capillary, Gravity, and Viscous Forces on Brine/CO2 Relative Permeability in a Compositional and Parallel Simulation Framework

摘要

The effectiveness of CO2 storage in saline aquifers is governed by interplay of capillary, viscous, and buoyancy forces. Recent experimental data reveals the impact of pressure, temperature, and salinity on interfacial tension (IFT) between CO2 and brine. The dependence of CO2-brine relative permeability and capillary pressure on IFT is also clearly evident in published experimental results. Improved understanding of the mechanisms that control the migration and trapping of CO2 in subsurface is crucial to design future storage projects that warrant long term and safe containment. Simulation studies ignoring the variation in interfacial tension and its effect on petrophysical properties of trapped CO2 saturations, relative permeability and capillary pressure have a poor chance of making accurate predictions of CO2 injectivity and its migration. We have developed and implemented a general relative permeability model that combines effects of pressure gradient, buoyancy, and IFT in an Equation of State (EOS) compositional and parallel simulator. The significance of IFT variations on CO2 migration and trapping is assessed.