Drainage of Water from Sand in Developing Aquifer Storage

Abstract

Establishment of a usable gas storage reservoir in aquifer sands often requires that injected gas rise to displace water above it in the formation. Experimental work has been done on a simplified model of this process. Calculations with and without capillary forces were made in an attempt to simulate the experimental results. These consistently predicted quicker completion of the segregation than was observed. This leads to the conclusion that, without data on dynamic capillary forces, the types of calculation described give a reasonable lower bound on the length of time necessary for the segregation to occur. Calculations are shown for two fairly realistic cases and show the marked effect of a thin low permeability layer on the rate of segregation and gas bubble formation.

Non-monotonic Travelling Wave Fronts in a System of Fractional Flow Equations from Porous Media

“…B R. Hilfer hilfer@icp.uni-stuttgart.de 1 Much attention has recently been focussed on so-called saturation overshoot (see Hilfer and Steinle 2014;Xiong 2014 for recent reviews), a term that refers to the phenomenon of non-monotonic saturation profiles developing during wetting phase infiltration into a porous medium (Youngs 1958;Briggs and Katz 1966;Glass et al 1989;Shiozawa and Fujimaki 2004;DiCarlo 2004). A strong motivation for these studies were mathematical results excluding the existence of overshoot profiles for the traditional Richards equation from hydrology (Nieber 1996;Otto 1996Otto , 1997Geiger and Durnford 2000;Glass 2001, 2002;Egorov et al 2003;DiCarlo 2005DiCarlo , 2013Duijn et al 2007;Juanes 2008, 2009).…”

Permeability Hysteresis in Gravity Counterflow Segregation

“…To validate the proposed model we compare the numerical gas-water saturation profile with saturation profiles found in [7] and [20]. Following [7], we consider a sand pack with a permeability of 11.84 Darcys and porosity of 0.389.…”

“…Following [7], we consider a sand pack with a permeability of 11.84 Darcys and porosity of 0.389. The tube length is 86 cm.…”

“…The density of the wetting phase (water) is ρ w = 1 g/cm 3 and the density of the nonwetting phase (air) is considered negligible compared to ρ w . These values were taken from [7].…”

“…The model for hysteretic relative permeability of the nonwetting phase [2,12] follows experimental observations of drainage, imbibition, and scanning behavior of relative permeability [6,7,8,13,19]. Changes in the direction of the flow in drainage and imbibition are irreversible [6,18]; flow in the region between drainage and imbibition curves is in general almost reversible [8,19,17]; however, we will make the approximation that it is exactly reversible [6,13].…”