Influence of temperature and pressure on quartz-water-CO₂ contact angle and CO₂-water interfacial tension

We measured water-CO₂ contact angles on a smooth quartz surface (RMS surface roughness ~40nm) as a function of pressure and temperature. The advancing water contact angle θ was 0° at 0.1MPa CO₂ pressure and all temperatures tested (296-343K); θ increased significantly with increasing pressure and temperature (θ=35° at 296K and θ=56° at 343K at 20MPa). A larger θ implies less structural and residual trapping and thus lower CO₂ storage capacities at higher pressures and temperatures. Furthermore we did not identify any significant influence of CO₂-water equilibration on θ. Moreover, we measured the CO₂-water interfacial tension γ and found that γ strongly decreased with increasing pressure up to ~10MPa, and then decreased with a smaller slope with further increasing pressure. γ also increased with increasing temperature.