CO2 Wettability Behavior During CO2 Sequestration in Saline Aquifer -An Experimental Study on Minerals Representing Sandstone and Carbonate

Abstract

Changes in wettability have been quantified by measuring the CO2 contact angle on some selected minerals typical for reservoir rocks quartz, calcite and feldspar, in the presence of brine at reservoir conditions by use of the captive-needle drop method. Also wettability alteration of the CO2 as a function of time was investigated. No significant change in contact angle was observed for any of the minerals as function of pressure and only small variation with change in temperature and salinity. All mineral surfaces remained strongly water-wet. A minimum in contact angle was observed at 36 °C near the critical pressure, which could be related to the near-critical behavior of the CO2-phase. Exposing the calcite mineral to CO2 for 50 days at fixed conditions did not cause any significant change in water wettability.