HR: 17:10h
AN: H34E-05    [Abstracts]
TI: The average equilibrium capillary pressure-saturation relationship in two-phase flow in porous media
AU: * Korteland, S
EM: S.Korteland@students.uu.nl
AF: Department of Earth Sciences, Utrecht University, P.O. Box 80021, Utrecht, 3508TA, Netherlands
AU: Bottero, S
EM: bottero@geo.uu.nl
AF: Department of Earth Sciences, Utrecht University, P.O. Box 80021, Utrecht, 3508TA, Netherlands
AU: Hassanizadeh, S
EM: hassanizadeh@geo.uu.nl
AF: Department of Earth Sciences, Utrecht University, P.O. Box 80021, Utrecht, 3508TA, Netherlands
AU: Helmig, R
EM: rainer.helmig@iws.uni-stuttgart.de
AF: Institute of Hydraulic Engineering, Stuttgart University, Pfaffenwaldring 61, Stuttgart, 70569, Germany
AU: Berentsen, C
EM: Berentsen@geo.uu.nl
AF: Department of Earth Sciences, Utrecht University, P.O. Box 80021, Utrecht, 3508TA, Netherlands
AB: We investigate the upscaling of capillary pressure-saturation form Darcy scale to larger scales. Often when simulations are performed to investigate flow processes in reservoirs and aquifers, the simulated domain has a size on the scale of tens of meters to kilometers. Oil reservoirs and aquifers usually have complex structures, consisting of heterogeneities on different length scales. In an ideal situation, a numerical flow simulator would include all these variations. However, often, the numerical gridsize is much larger than the scale of medium heterogeneities. Therefore, it is desirable to obtain an uspcaled capillary pressure-saturation relationship that can be used to represent the capillary pressure-saturation relationship at the scale of the numerical grid. We have investigated several different averaging methods that can be used to obtain an upscaled capillary pressure- saturation relationship. The average of saturation over a certain volume follows directly from its definition. However, for pressure it is not that obvious and several ways of obtaining an average pressure are investigated. We introduce a number of different averaging operators and performing numerical simulations of a static primary drainage experiment in a homogeneous domain with dimensions similar to a laboratory sample. Results show that a new definition of macroscale pressure, in which centroids of the two phases is taken into account, appears to be the most suitable. We have also shown that the way Pc-Sw relationship is measured results in a curve that is not an intrinsic property of the two-phase system, but is dependent on several factors, such as the applied boundary conditions.
DE: 1829 Groundwater hydrology
SC: Hydrology [H]
MN: 2007 Fall Meeting