Relative permeability factors affecting

A comprehensive review of the important factors that affect the flow of emulsions in porous media is presented with particular emphasis on petroleum emulsions. The nature, characteristics, and properties of porous media are discussed. Darcy s law for the flow of a single fluid through a homogeneous porous medium is introduced and then extended for multiphase flow. The concepts of relative permeability and wettability and their influence on fluid flow are discussed. The flow of oil-in-water (OfW) and water-in-oil (W/O) emulsions in porous media and the mechanisms involved are presented. The effects of emulsion characteristics, porous medium characteristics, and the flow velocity are examined. Finally, the mathematical models of emulsion flow in porous media are also reviewed. 

Lefebvre du Prey, E.J., 1973. Factors Affecting Liquid-Liquid Relative Permeabilities of a Consolidated Porous Media. SPEJ 13 (1), 39-47. 

Three factors play key roles in determining the relative permeabilities of different polymers to a given penetrant molecule permeating by the solution-diffusion mechanism. The "free volume" available for molecule to traverse the polymer plays a major role, especially in the diffusivity. The cohesive forces between the polymer chains (i.e., how tightly the chains are held together) are also crucial. Finally, the solubility can be affected very significantly by the strength of the interactions between the penetrant molecule and the structural units in the polymer chains, i.e., by the "compatibility" of the polymer and the penetrant with each other. 

The microscopic displacement efficiency is affected by the following factors interfadal and surface tension forces, wetlabihty, capillary pressure, and relative permeability. 

Another factor affecting the microscopic displacement efficiency is the fact that two or more fluids are usually flowing in an EOR process. When two or more fluid phases are present, the saturation of one phase affects the permeability of the other(s), and relative permeabilities have to be considered. Figure 1 is an example of a set of relative permeability curves plotted against the wetting phase saturation (water in this case). 

The distribution of the oil, gas and water in the porous medium was better understood when Botset and Wyckoff (9) carried out the first experiments on relative permeability. They showed that either oil or gas would flow only if a specific minimum saturation of the phase in question existed in the flow region of the porous material. Some of the early workers also recognized that either the oil or gas droplets could be discontinuous, and in this condition, would be hard to displace by flowing water because of the Jamin effect. In 1927, Uren and Fahmy (10) investigated a number of "factors which affect the recovery of petroleum from unconsolidated sands by waterflooding. Table 1 lists these factors and the general results observed by Uren and Fahmy. With one exception (rate), the results observed by Uren and Fahmy are similar to generalizations which most experts in this field claim today after work of more than 50 years. 

The above factors are also applicable when geotextiles are used for filtration. However, with filtration the intention is to form a natural filter cake at the fabric/soil interface that will retain the fines consequently the pore-size requirement is different than that for the separation function. For filtration, the AOS of the textile must be smaller than the larger sizes of soil particles, but of sufficient dimension for the small soil particles to pass through, otherwise the geotextile will become clogged or blind and its permeability adversely affected. The fabric must have a pore-size distribution with a large number of larger size pores, so that a relatively unhindered water flow is maintained where some of the smaller size pores become blocked. 

The significance of numerous mediators varies according to the nature of inflammatory response involved, whether it is an acute, immediate-immune or delayed hypersensitivity type. The lymph node permeability factor (OUT) appears to have a major role in delayed hypersensitivity. It is affected by relatively high doses of indomethacin, (I) salicylate and pyridinol carbamate.(II)... 

PLA (poly(lactic acid)), or PHEE (poly(hydroxy ester ether)) [3-5]. These commercially available polyesters show some interesting and reproducible properties, such as more hydrophobic characters, lower water permeabilities, and some improved mechanical properties, relative to PLS. The preparation of the blends is the main factor affecting their properties and their behavior during processing. The solid-state properties of the blends depend on the nature of the polyester phase. At ambient temperature, polyesters can be rigid (e.g., PLA) or soft (e.g., PCL, PBSA, PBAT), so the corresponding mechanical properties are tunable. Research results... 

The physical state of the skin is considerable affected by external factors such as relative humidity, temperature, and air movement at the skin surface. If this contact is broken (for example, by external applications of ointments or creams), it is reasonable to assume that the new skin will change in some way, sometimes to an extent that creates new conditions of permeability for the test material. This would be the case, for example, if the stratum comeum becomes more hydrated than normal due to the topical delivery form. Temperature might also have an effect, as is the case when any constituents of the vehicle affect the inner structure of the skin through interactions with endogenous skin substances. Often several of these processes occur together. 

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