Monitoring CO2 invasion processes at the pore scale using geological labs on chip

In order to investigate at the pore scale the mechanisms involved during CO2 injection in a water saturated pore network, a series of displacement experiments is reported using high pressure micromodels (geological labs on chip-GLoCs) working under real geological conditions (25 < T (degrees C) < 75 and 4.5 < p (MPa) < 8). The experiments were focused on the influence of three experimental parameters: (i) the p, T conditions, (ii) the injection flow rates and (iii) the pore network characteristics. By using on-chip optical characterization and imaging approaches, the CO2 saturation curves as a function of either time or the number of pore volume injected were determined. Three main mechanisms were observed during CO2 injection, namely, invasion, percolation and drying, which are discussed in this paper. Interestingly, besides conventional mechanisms, two counterintuitive situations were observed during the invasion and drying processes.