ISSN:
1573-1634
Keywords:
Unsteady-state relative permeabilities
;
displacement
;
local volume averaging
;
interfacial tension
;
interfacial viscosities
Source:
Springer Online Journal Archives 1860-2000
Topics:
Geosciences
,
Technology
Notes:
Abstract In constructing simulations, it is commonly assumed that steady-state relative permeabilities can be used to describe displacements, which are unsteady-state flows. In order to test this assumption, a statistical structural model is used in the context of local volume averaging to examine the effects of interfacial tension, the interfacial viscosities, wetting and the viscosity ratio upon the capillary pressure and relative permeability functions in a displacement. The statistical structural model is a highly simplified idealization of the local pore structure, in which pores are randomly oriented in space, but no pore interconnections are recognized. While the statistical structural model is too simplified to give accurate descriptions of the relative permeabilities, it should be sufficient to determine whether significant qualitative differences between steady-state and unsteady-state relative permeabilities might be expected. Our results suggest that, whether we are concerned with an imbibition or a drainage, it is not important to distinguish between steady-state and upsteady-state relative permeabilities, when the local (not macroscopic) capillary number N ca≪10-2. Unless the interfacial tension is very small everywhere or the overall pressure gradient very large, it may be satisfactory to use steady-state representations for the relative permeabilities. This means that, for a waterflood in a petroleum reservoir, the difference between steady-state and unsteady-state relative permeabilities is almost certainly negligible. For an optimum surfactant flood in a petroleum reservoir, at least within the immediate neighborhood of the displacement front, it may be important to make the distinction.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00179531
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