Experimental Investigation of Pressure Dependence of Contact Angle Measurement in CO2/Brine Systems

Abstract:

Wettability behavior in CO₂/brine systems is of great significance in ensuring carbon storage security and enhancing oil recovery because wettability drives multiphase flow dynamics and governs fluid distribution in porous media. Up until now, abundant experimental research has been done on studying the effects of pressure, temperature, brine salinity and other factors on wettability behavior by measuring contact angles using traditional methods. However, results regarding to the influence of pressure indicate discrepancies because of limitations of traditional measurement methods, complexities of rock samples, etc. Micro-CT imaging has also been used to measure in-situ contact angle in recent years, but insufficient data of this technique has been published in studies of pressure dependence. Thus, this research focused on investigating the impact of changes in pore pressure on in-situ contact angles at supercritical conditions in CO₂/brine systems by obtaining measurements at pore scale using micro-CT imaging technique. The experiment involves a series of drainage and imbibition cycles through a synthetic porous core to recreate various scCO₂ saturation conditions at different pressures. Fluid/fluid and solid/fluid interfaces are captured by micro-CT imaging, and then analyzed through digital image processing and an in-house contact angle measurement algorithm. Finally, the relationship between pore pressure and wettability in CO₂/brine systems can be analyzed via contact angle measurements. Findings from this research aim at advancing the understanding of wetting properties and modelling of multiphase flow in CO₂/brine systems at supercritical conditions, which can be implemented to future applications in carbon storage and enhanced oil recovery.