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

Abstract

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 (°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.