Determination of Swelling Effect in CO2-Brine Systems Using Microfocus X-ray CT

Abstract

As one of the most viable technique, geological sequestration of CO2 has great potential for storing large amount of the injected CO2 into brine by dissolution. Understanding the mass transfer of CO2 into a brine sample is of great importance of CO2 sequestration. Swelling effect revealing the properties of dissolution play an important role. Other than oil swelling, it is difficult to observe directly using traditional methods due to the imperceptible extent of phase expansion in CO2-brine mixture. The combination of X-ray computed tomography and image processing techniques has made it possible to measure multiphase boundaries as well as swelling factors of CO2-brine systems at high pressures and elevated temperatures. In this work, a generalized methodology has been proposed and successfully applied. The experimental results show that both the mass transfer and the swelling factor increase with pressure. It is also found that the local contact angel significantly increases when gaseous CO2 turns into supercritical CO2.