Immiscible Displacements and Capillary Trapping in CO2 Storage

Fundamental study of CO2-H2O-mineral interactions for carbon sequestration, with emphasis on the nature of the supercritical fluid-mineral interface.

“…The actual distribution may follow a truncated power law. The capacity of a geologic medium for capillary trapping can then be related to the key controlling factors by This relationship is qualitatively consistent with the measurements of residual saturation for scCO 2 and n-decane in brine-saturated Berea sandstone [114]. The measurements show a systematically higher residual saturation for n-decane than that for scCO 2 .…”

“…Based on a simple cubic lattice calculation, the threshold is estimated to be 0.341 for ganglia with a uniform size [110]. This is consistent with a recent column experiment, which shows that the maximum residual supercritical CO 2 phase in Berea sandstone is about 35% [114] This seems reasonable, considering that the core sample used in this experiment is small (~ 4 cm in diameter and 8 cm in length) and, as a result, the size distribution of ganglia is limited to a relatively narrow range. In an actual reservoir, however, the size of ganglia is expected to distribute over a much broader range, and the actual capacity could be higher.…”

“…With increasing the contact angle, the trapping efficiency decreases, especially when the angle approaches 90º. The contact angle on a porous aluminum silicate substrate in scCO 2 was measured to be 10º to 40º, depending on the confining pressure [114]. Chiquet et al [115] measured the contact angle for quartz and mica under various ionic strengths and confining pressure.…”

The role of capillary trapping during geologic CO2 sequestration

“…For geologic carbon sequestration, two diff erent displacement regimes, namely drainage and imbibition, are observed [7][8][9][10][11]. Drainage refers to the decreasing saturation of a wetting phase.…”

“…After completion of the injection the gas is displaced by brine and forming a vertical path migrates towards the top of formation due to the buoyant force and the density diff erence -imbibition phase. System wettability determines fl uid distribution on the pore scale [6][7]. Typically brine is a wetting phase for the rock matrix and during displacement gas bubbles (non-wetting phase) are trapped in small clusters of pores as an immobile phase (Fig.…”