Relative permeability

The permeability relative to a pure liquid, usually water, may be determined with the help of different devices that operate on the principle of measurement of filtrate volume obtained over a definite time interval at known pressure drop and filtration area. The permeability is usually expressed in terms of the hydraulic resistance of the filter medium. This value is found from ... 

High-permeability passive perimeter gas control systems entail the installation of highly permeable (relative to the surrounding soil) trenches or wells between the hazardous waste site and the area to be protected (Figure 16.6). The permeable material offers conditions more conductive to gas flow than the surrounding soil, and provides paths of flow to the points of release. High-permeability systems usually take the form of trenches or wells excavated outside the site, then backfilled with a highly permeable medium such as coarse crushed stone. 

Atactic polypropylene exhibits a greater vapor permeability relative to either syndiotactic or isotactic polypropylene of the same molecular weight distribution. Why is this so ... 

Relative permeability is the reduction of mobility between more than one fluid flowing through a porous media, and is the ratio of the effective permeability of a fluid at a fixed saturation to the intrinsic permeability. Relative permeability varies from zero to 1 and can be represented as a function of saturation (Figure 5.8). Neither water nor oil is effectively mobile until the ST is in the range of 20 to 30% or 5 to 10%, respectively, and, even then, the relative permeability of the lesser component is approximately 2%. Oil accumulation below this range is for all practical purposes immobile (and thus not recoverable). Where the curves cross (i.e., at an Sm of 56% and 1 - Sm of 44%), the relative permeability is the same for both fluids. With increasing saturation, water flows more easily relative to oil. As 1 - SI0 approaches 10%, the oil becomes immobile, allowing only water to flow. 

Formation permeability Relative permeability NAPL viscosity Actual NAPL thickness... 

Figure 12.4 Solute permeability relative to the permeability of a film of water for various solutes in a regenerated cellulose membrane (Cuprophan 150). This type of membrane is still widely used in hemodialysis devices...

Many of these formations consist of layers of porous media with varying permeability. If a zone is very permeable relative to the rest of the formation, most of the injected fluids will enter it. Extremely viscous CO2 could be used as a diverting agent which would tend to minimize flow through a highly permeable layer. In this application a gel or very viscous liquid would be formed near the wellbore in this layer and remain immobile. Subsequently injected fluids would then flow into the other layers. 

Fig. 8. Matrix porosity versus permeability reduction in faults. The upper trend describes the range of permeabilities observed within actively deforming cataclastic deformation bands. Permeabilities ate enhanced at low porosities, and slightly reduced at high porosities. The lower trend describes how inactive faults after burial show highly reduced permeability relative to the matrix. This permeability reduction gets more significant with increasing matrix porosity.

When this method is used for permeation studies, suitability of the methodology should be demonstrated, including determination of permeability relative to that of a reference compound whose fraction of dose absorbed has been documented to be at least 85%, as well as use of a negative control. Supportive data can be provided by the following additional test methods ... 

Also evident In these data Is a decrease (nom. 16%) In permeability relative to the control values after ensonlflcatlon. Apparently the latter caused some change In the Neoprene. 

The calcium permeability of ganglion-type nicotinic receptors is reported to be similar to that of adult muscle in experiments on superior cervical ganglion, intracardiac ganglia, and chromaffin cells, with values for calcium permeability (relative to sodium or cesium) between 0.5 and 1 and fractional current mea-... 

On the right of equation 4, the generation and coalescence rates, rg and rc, are expressed on a per volume of gas basis. These two terms are fundamental, for they control bubble texture. At steady state, far from any sources or sinks, and where rock properties are constant (e.g., absolute permeability, relative permeability, and capillary-pressure functions), bubble size is set by rg = rc. That is, the rate of bubble generation by snap-off balances the rate of bubble coalescence by capillary-pressure suction (20). To proceed, kinetic expressions are needed for rg and rc. 

Figure 13. Effect of couplings on permeability relative change, after excavation (base case, SKI)...

The temperature rising in the vicinity of the heaters causes an evaporation of liquid. Due to thermal and pressure gradients it comes to a vapour diffusion, which can lead to a strong modification of the humidity distribution in the barrier system. Modifications in the humidity distribution on the other hand directly affect the hydraulic characteristics, since the permeability depends strongly and nonlinearly on the saturation. By cooling it comes to a condensation of water vapour and thus to the increase of water saturation. For the permeation of water from the adjacent rock into the barrier system the characteristics of the multiphase flow are crucial in the contact area of both materials - the contrast in permeability, relative permeability and capillary pressure. For the water flow into the barrier, the subsequent delivery of water is further important due to regional hydraulic gradients. 

Morreale et al. find that 80 wt%> Pd-20 wt% Cu alloys exhibit higher resistance to H2S (at very high partial pressures of hydrogen) relative to the 60 wt% Pd-40 wt% Cu composition [77]. However, the 80-20 composition has a lower initial (unpoisoned) permeability relative to the 60—40 composition. The 80-20 Pd-Cu composition has the face centered cubic crystal structure as do unalloyed elemental palladium and copper [77]. 

Figure 2.14 (a) Dimensional swelling of 2-SPAES-xx, 4-SPAES-xx, and Nation 117 at 80°C. (b) Tradeoff plot of proton conductivity as a function of methanol permeability, relative to Nation 117. Reproduced with permission from Ref. [164]. 

Gas Parmaability. The oxygen, carbon dioxide, and water vapor permeability of polyesters depend not only on composition but also on degree of crystallinity, orientation, and temperature. Regardless of the variable, PEN always exhibits significantly reduced gas permeability relative to PET. Some examples are illustrated in Table 6. 

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