Percolation of Supercritical CO₂ in a Porous Medium Saturated with Water

Abstract

We experimentally investigated the effect of capillarity and buoyancy on non-wetting phase saturation after the drainage. Distributions of the NWP in porous media have been visualized by mean of microtomograhy at a pore-scale for a supercritical CO 2 and water system. In the case of the upward injection, gas saturation is low compared with the upward case, because the capillary fingering is enhanced by buoyancy. Gas saturation increases with the capillary number because of the pressure gradient along the porous medium. In the case of the downward injection, the fingering is suppressed by buoyancy. As a result, the high gas saturation is achieved over the wide range of capillary number. The gas saturation decrease slightly with the capillary number because of the instability associated with the injection flow rate. The combined dimensionless group of Bond number and capillary number is introduced to correlate with the gas saturation obtained for the nitrogen and water system.

Non-wetting phase saturation after drainage from the wetting-phase-filled porous medium

“…Under these conditions, CO 2 was in a supercritical state. Four fluid pairs were selected such that the dimensionless Bond number, capillary number, and viscosity ratio covered those of the CO 2 and water system in the aquifers (Cinar et al, 2009;Suekane and Okada, 2013). The packed bed of glass spheres with a well sorted diameter was used as a porous medium because its homogeneity eliminated the unacceptable capillary effect due to the inhomogeneity of the porous medium (Mikami et al, 2014).…”

“…The solid line denotes Equations 9 (a) and 11 (b) and the dash lines denote the deviation of 0.1 in the non-wetting phase saturation from the empirical equation. Experimental results were plotted for a supercritical CO 2 and water system *1 Suekane and Okada (2013) and *3 Akbarabadi and Piri (2013) and for liquid CO 2 and water system *2 Uemura et al (2013) pressure dispersed the displacement front and had a stabilizing effect on viscous fingering. The permeability of the packed bed decreased in proportion to the square of the glass bead diameter.…”

“…The experimental results obtained for the supercritical CO 2 and water system are plotted in Figure 8. Suekane and Okada (2013) measured the supercritical CO 2 saturations with a packed bed of glass beads having a diameter of 200 μm at a capillary number ranging from 4.8 × 10 −9 to 4.8 × 10 −7 at the upward and downward injection. Uemura et al (2013) visualized the migration of liquid CO 2 in a packed bed of sand resulting from buoyancy.…”