This experimental study was aimed to estimate interfacial tension of brine-
CO2 by using a pendant bubble method and image analysis. Measurements were performed for wide ranges of temperatures, pressures, and salinities covering reservoir conditions in Pohang basin, a possible candidate for
CO2 storage operation in Korea. The profiles of
CO2 bubbles in brine obtained from image analysis with the densities of brine and
CO2 from previous studies were applied to Laplace-Young equation for calculating interfacial twnsion in brine-
CO2 system. The experimental results reveals that the interfacial tension is significantly affected by reservoir conditions such as pressure, temperature and water salinity. For conditions of constant temperature and water salinity, the interfacial tension decreases as pressure increases for low pressures (P <
Pc), and approaches to a constant value for high pressures. For conditions of constant pressure and water salinity, the interfacial tension increases as temperature increases for T <
Tc, with an asymptotic trend towards a constant value for high temperatures. For conditions of constant pressure and temperature, the interfacial tension increases with increasing water salinity. The trends in changes of interfacial tension can be explained by the effects of the reservoir conditions on the density difference of brine and
CO2, and the solubility of
CO2 in brine. The information on interfacial tensions obtained from this research can be applied in predicting the migration and distribution of injecting and residual fluids in brine-
CO2-rock systems in deep geological environments during geological
CO2 sequestrations.
Keywords: CO2;Brine;Interfacial tension;Pendant bubble method;Geological CO2 sequestration;