Experimental Study of CO2 Injection Into Saline Formations

We present laboratory experiments to investigate the influence of gravitational, viscous, and capillary effects on the CO2 injection process. Quasi 2D experiments are performed in a vertical glass-bead pack in the parameter range of: interest for CO2 sequestration in deep aquifers (i.e., with Bond numbers of approximately 10(-3) and capillary numbers on the order of 10(-4)). The objective is to investigate the type of flow regimes that Occur under favorable as well as unfavorable conditions of density and viscosity. The experiments demonstrate the existence of pore-scale instability in the presence of unfavorable gradients of viscosity and density. Consequently, conventional mathematical models may not be able to represent these unstable flows appropriately. A comparison with estimates from percolation theory shows reasonably good agreement with experimental observations.