Permeability correction factors

For the Yucca Mountain site, incorporation of stress effects into hydraulic properties is based on a conceptual model of a highly fractured rock mass that contains three orthogonal fracture sets, as shown in Figure 2b. Porosity correction factor (F,) and permeability correction factors (Fu, Ft, FtJ calculated from the initial and current apertures (bii, b i, bsi and b , b , bj, respectively) in fracture sets 1, 2, and 3, according to ... 

Figure 8. Calculated and measured permeability correction factor Ft (see Equation 4 for definition of Ft)...

First of all, we used this mathematical model to correlate the in vitro and in situ permeabilities of grepafloxacin and ciprofloxacin [39], and the area correction factor Sf obtained was around 4, in accord with results obtained by other authors [52]. This difference is explained by the differences in absorptive surface in the in situ versus the in vitro model, as the latter presents microvilli but not villi or folds. Now we have expanded the number of element of the correlation to all the quinolones included in Table 4.2, and the area correction factor does not suffer any variation (see Fig. 4.8, p. 104). Even if this model has been constructed using very simplistic assumptions, the results are promising and demonstrate that a good modeling approach helps to identify the system critical parameters and how the system behavior changes from the in vitro to the in situ level [39]. It is important to notice that with this linear correlation we make the assumption that the main difference between both systems is the actual effective area for transport. Nevertheless, since the plot is far from being perfect, it is probable that there are more differences in both experimental systems, such as different paracellular resistance or different expression levels of the transporter, that account for the deviation. 

When the well does not completely penetrate the stratum to the impermeable bed, the permeability must be multiplied by a correction factor, 7. Values of this correction factor computed by Wyckoff et al (1934) are presented in Table 51. 

If appropriate dermal penetration data are available for rats in vivo and for rat and human skin in vitro, the in vivo dermal absorption in rats may be adjnsted in light of the relative absorption throngh rat and human skin in vitro. The latter adjustment may be carried out because the permeability of human skin is often lower than that of animal skin (McDougal et al., 1990 Sato et al., 1991 Barber et al., 1992 Howes et al., 1996). A generally applicable correction factor for extrapolation to man can, however, not be derived, because the extent of overestimation appears to be agent- and animal-specific (Bronaugh and Maibach, 1987 ECETOC, 1993). 

The first two factors are for a correction of the maximum value Z dfi to be expected if an oscillating redox ion in the outer Helmhotz plane, Z 10 s (infrared) at a distance dn (10 cm), the thickness of the Helmholtz layer, leads to an electron tunneling event for every oscillation. Thus Khet would become maximally 10 cm/s. The first correction factor is the permeability of the potential barrier at the electrode. 

Equations 17.51 and 17.52 define a sufficient number of criteria to allow the correct choice of the operating conditions in an SMB operating rmder linear conditions. This set of conditions is equivalent to the one derived by Storti et al. [16] (see later. Subsection 17.6.5), the so called Triangle Method. However, both sets of conditions are based on the assumption that all columns have identical characteristics and an infinite efficiency. In practice, the different columns of an SMB separator cannot be identical. Their individual average porosity, permeability, retention factors, and efficiency are more or less different, however slightly. The influence of the possible differences between the colunms of an SMB imit on its performance is discussed later (Subsection 17.7.1.5)... 

Foam with large and less stable bubbles is less likely to flow as a single fluid. Mast and Fried deduced that foam is propogated inside a porous medium by the breaking and reforming of foam bubbles. The gas flows as a discontinuous phase while toe liquid is transported as a free phase via toe film network. Nahid proposed that toe gas flow could be treated according to Darcy s law if a correction factor for the gas permeability is used. 

Standard conditions comprise a temperature of 273.15 K and a pressure of 10 Pa. Before introducing the SI units, the standard pressure was 1 atm. The correction factor is, however, negligible within the accuracy of measured permeability coefficients. 

Using a = 0.2 and b = 2.6 in Eq. (12.9) for both breakwater types, the correction factor 7/, initially intended to account for the surface roughness effect, is used to distinguish between the effect of permeability on the average overtopping rate q (Fig. 12.25) ... 

In the last expression, tortuosity t > 1 was added as a generalized factor to allow for a correction factor if the capillaries are not straight. Then, Th should be used instead of h [19]. Obviously, the other approach exploiting the permeability tensor offers better opportunity to account for the internal geometry of the porous medium because many theoretical predictions are... 

The membrane serves as a phase separator, which is made selectively permeable to those ions for which a concentration value (activity) is to be determined. Using the Nernst relation, with necessary correction factors for temperature and nonideality of the membrane, the potential between the known and unknown concentration can be measured and the unknown ionic concentration thus determined. 

If the polymer application is for viscosity control, then the simple model may be a 2-D areal or simple layered five-spot pattern the well locations will be known, and any faults that are known should be included using transmissibility modifiers. In this areal system, the key features in the calculation are that the oil viscosity is correct and reasonable estimates of the reservoir relative permeabilities are available. For a heterogeneity control flood, a multilayer cross-section similar to the eight-layer system described in Chapter 8 may be selected. Here, the most important factor is to get the layering structure and layer permeabilities correct, especially the permeability contrast between the high-permeability layer(s) and the position of this layer. The value of the kjk ratio may also be very important in this type of polymer flood, but it may be sufficient to know that it is > 0.05 for example (see Chapter 8). In such an application, the mobility ratio may be close to... 

The effective viscosity data from one of the six cores. Core A, are shown as a typical example (Fig. 15). When the polymer solution caused oil production, the water A/> determined at the original core saturation was no longer appropriate for calculating the effective viscosity. A correction step was used to adjust the water Ap to correspond to the new core saturation. The details of the correction method are discussed in the Appendix. The core saturation data, porosities, calculated water permeabilities, and pressure correction factors at each stage of the experiment are contained in Table 4. 

The Kozerty constarrt is essentially a correction factor that accormts for the tortuosity and orientation of the pore system. For high porosity values, the actual permeability, determined experimentally, is usirally lower than that predicted by... 

Average ratios and standard deviations of permeability coefficients reported by Peck et al. (1994) determined from 11 HEM samples. "Ratios based upon free aqueous diffusion coefficients corrected by diffusional hindrance factors that were calculated from Eq. 6 for each permeant based upon an Rp of 21 A. 

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