The wettability of rocks and minerals critically impacts the efficiency and safety of energy-related subsurface operations, including geologic CO2 sequestration and CO2-enhanced oil recovery. In this study, we investigated the effects of salinity-induced chemical reactions on biotite wettability changes under relevant operation conditions. Pre-reacted biotite was prepared at 95 oC and 102 atm CO2 for 70 h in solutions with salinities of 0, 0.1, 0.5, and 1.0 M NaCl. Then high temperature and high pressure static and dynamic contact angles were measured for the pretreated biotite samples, using the captive drop method at 48 oC and 102 atm CO2 in 0.1 M NaCl solution. Biotite surfaces became rougher and more negatively charged from more significant dissolution with higher salinity. Rougher and more negatively charged surfaces supported thicker and more stable water films. Therefore, biotite basal surfaces became more hydrophilic after pretreatment with higher salinity. Additionally, CO2 adhesion was observed during the CO2 receding process. On samples reacted in 1.0 M NaCl solution, we observed CO2 adhesion (~50%) than samples reacted with lower salinities. Moreover, higher contact angle hysteresis was observed for samples with a higher incidence of CO2 adhesion, suggesting that CO2 adhesion could have contributed to the hysteresis. For the first time, we experimentally related chemical reactions and the consequent wettability alterations of minerals under GCS relevant conditions. These findings can be beneficial in understanding CO2 or other reactive fluids’ transport and their distribution in subsurface systems during energy-related operations.

Biotite wettability changes under geologic CO2 sequestration conditions: Influences of salinity-induced chemical reactions

251st National Meeting (2016)

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