Laboratory study of geological carbon sequestration using surrogate fluids: Dielectric measurement and scaling of capillary pressure-saturation relationships

Multiphase flow models are powerful tools to understand and predict the flow and trapping of supercritical-CO2 (scCO2) in deep saline geologic formations. The constitutive relationship between capillary pressure (Pc) and saturation (Sw) is the essential input parameter into these multiphase models. By selecting surrogate fluids that match the density and viscosity ratios between scCO2 and brine, the behavior of scCO2 and brine may be reproduced under ambient conditions, making it possible to overcome the difficulty of conducting laboratory-scale experiments with scCO2. This paper presents the Pc-Sw relationship for the surrogate fluids of scCO2 and brine measured using the dielectric sensor method. To explore the necessity and applicability of measuring the entire Pc-Sw relationship, we compared the dielectric sensor results with those from two scaling methods: classical Leverett scaling and a novel entry pressure scaling method. Additionally, the obtained surrogate fluid Pc-Sw values were compared with experimental data of scCO2 and brine under high pressure. The dielectric sensor method successfully obtained the Pc-Sw relationship and produced more accurate measurements of residual and irreducible saturations compared to scaling methods.