Brooks-Corey parameters

Now that hcii is expressed solely in terms of the Brooks-Corey parameters for a given soil, Equation 6.4 becomes... 

In the above equations, Pc is the capillary pressure, /, is the Brooks-Corey pore-size distribution index, Sr is the residual saturation of the free product phase, a is the van Genutchen fluid/soil parameter, and the superscript n is the van Genutchen soil parameter. 

Although the approach is theoretically sound, both the proposed relationships between capillary pressure and saturation (Equations 6.23 and 6.24) are highly nonlinear and limited in practicality by the requirement of multiparameter identification. In addition, due to the inherent soil heterogeneities and difference in LNAPL composition, the identified parameters at one location cannot be automatically applied to another location at the same site, or less so at another site. For example, Farr et al. (1990) has reported the Brooks-Corey and van Genutchen parameters, X, ii, and o.a0, for seven different porous media based on least-square regression of laboratory data. The parameters are found to vary about one order of magnitude and do not show any specific correlation for a particular soil type. 

This section uses the Corey-type (Brooks and Corey, 1966) equation (Eq. 7.125) to describe relative permeabilities. We first use this type of equation to see the effect of IFT on the k, ratio in two-phase flow. Figure 7.37 compares the three k, ratios normal water/oil k miscible k and k between. Their parameters are presented in Table 7.10. The figure clearly shows that as the IFT is increased from the normal waterflooding high IFT to the intermediate IFT to the miscible flooding low IFT, the ratio of kj to k increases in the low Sw... 

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