TY - JOUR
T1 - Dynamic effects in capillary pressure relationships for two-phase flow in porous media
T2 - Insights from bundle-of-tubes models and their implications
AU - Celia, Michael Anthony
AU - Dahle, Helge K.
AU - Majid Hassanizadeh, S.
N1 - Funding Information:
This work was supported in part by the U.S. National Science Foundation through Grant EAR-0309607, by Norsk Hydro and The Norwegian Science Foundation under Grant 151400/210, and by the Dutch Scientific Foundation through the 'upscaling' project under Grant 809.62.010.
PY - 2004
Y1 - 2004
N2 - Traditional multi-phase flow models use an algebraic relationship between capillary pressure and saturation. This relationship is based on measurements made under static conditions. However, this static relationship is then used to model dynamic conditions, and evidence suggests that the assumption of equilibrium between capillary pressure and saturation may not be justified. Extended capillary pressure-saturation relationships have been proposed that include an additional term accounting for dynamic effects. In the present work, we study the underlying pore-scale physical mechanisms that give rise to this so-called dynamic effect. The study is carried out with the aid of a simple bundle-of-tubes model wherein the pore space of a porous medium is represented by a set of parallel tubes. We perform virtual two-phase flow experiments in which a wetting fluid is displaced by a non-wetting fluid. The dynamics of fluid-fluid interfaces are taken into account, and we consider systems in which viscosity differences influence the displacement process. From these experiments, we extract information about overall system dynamics, determine coefficients that are relevant to the dynamic capillary pressure description, and determine large-scale effects that are associated with viscosity differences between the two fluids. Based on these results, we then speculate about possible scale effects and the significance of the dynamic term.
AB - Traditional multi-phase flow models use an algebraic relationship between capillary pressure and saturation. This relationship is based on measurements made under static conditions. However, this static relationship is then used to model dynamic conditions, and evidence suggests that the assumption of equilibrium between capillary pressure and saturation may not be justified. Extended capillary pressure-saturation relationships have been proposed that include an additional term accounting for dynamic effects. In the present work, we study the underlying pore-scale physical mechanisms that give rise to this so-called dynamic effect. The study is carried out with the aid of a simple bundle-of-tubes model wherein the pore space of a porous medium is represented by a set of parallel tubes. We perform virtual two-phase flow experiments in which a wetting fluid is displaced by a non-wetting fluid. The dynamics of fluid-fluid interfaces are taken into account, and we consider systems in which viscosity differences influence the displacement process. From these experiments, we extract information about overall system dynamics, determine coefficients that are relevant to the dynamic capillary pressure description, and determine large-scale effects that are associated with viscosity differences between the two fluids. Based on these results, we then speculate about possible scale effects and the significance of the dynamic term.
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U2 - 10.1016/S0167-5648(04)80043-1
DO - 10.1016/S0167-5648(04)80043-1
M3 - Article
AN - SCOPUS:80051584753
SN - 0167-5648
VL - 55
SP - 127
EP - 138
JO - Developments in Water Science
JF - Developments in Water Science
IS - PART 1
ER -