The total computation domain (Figure 1) is comprised of wetting phase
(WP) and nonwetting phase (NWP) reservoirs denoted by [[OMEGA].sub.w,res] and [[OMEGA].sub.n,res], respectively, as well as the porous computational unit cell [[OMEGA].sub.cuc].
[S.sub.w,m]: Saturation of wetting phase
in matrix rock
Studies [38,43] indicated that observed rate dependency of wetting phase
experiment results at high IFT was reproduced by simulations with constant relative permeability (Kr) and capillary pressure (Pc), while observed rate effects of wetting phase
in experiments were at low IFT systems and were interpreted as a result of rate dependency in the Kr function.
The wetting phase
allows the clay to disperse and during the drying phase the surface tension forces the sand and clay into intimate contact, which results in lowering the water repellency by improving soil structure (Ward 1993).
Denote the wetting phase
by a subscript w and the nonwetting phase by n.
where [S.sub.e] is the effective saturation calculated with residual saturations, [lambda] and [p.sub.b] are constants realized from intercept and slope, [lambda] means pore size distribution, [p.sub.b] is interpreted as maximum capillary pressure, the [p.sub.c] is the capillary pressure which represents pressure difference between wetting phase
pressure and nonwetting phase pressure.
The capillary pressure [P.sub.C] has been assumed to depend only on the saturation of the wetting phase
(water); this capillary pressure can also depend on the surface tension, porosity, permeability, and the contact angle with the rock surface of the wetting phase
which in turn depends on the temperature and fluid composition; with such assumption on capillary pressure the parameters can also be included to study its effect in future.
(in water) The relationships between the percent weight change and time for coated specimens in water and 15% NaCl solution are shown in Figures 2, 3, 4 and 5 respectively.
The equation of continuity of the wetting phase
2 holds for identical viscosity ratios with increase in wetting phase
viscosity from 1 to 15 cp, but does not hold if the non-wetting phase is a gas.
Other parameters that were established for the water insertion procedure were the number of hours that water was to be inserted into the assemblies each day and the number of days for which wetting took place during the wetting phase
of the experiment.
In the displacement process, the [tau] value of the wetting phase
gradually decreased and that of the nonwetting phase gradually increased for both plugs, as presented in Table 2 and Figure 7.