Imbibition pressure

Magnitude of supplemental imbibition pressures Raimondi and Torcaso (10) showed that entrapment of nonwetting phase tends to occur as the invading wetting phase approaches high saturations. 

From capillary pressure measurements for sphere packings (11), the imbibition pressure at 70% wetting phase saturation is given by ... 

Thus, the ratio of the supplementary pressure to imbibition pressure can be expressed in terms of the Bond number as... 

Thus, if the imbibition pressure at the trailing edge of a potential blob is supplemented by 1/7 of the average imbibition pressure, entrapment is halved. 

Let us consider one more physical phenomenon, which can influence upon PT sensitivity and efficiency. There is a process of liquid s penetration inside a capillary, physical nature of that is not obvious up to present time. Let us consider one-side-closed conical capillary immersed in a liquid. If a liquid wets capillary wall, it flows towards cannel s top due to capillary pressure pc. This process is very fast and capillary imbibition stage is going on until the liquid fills the channel up to the depth l , which corresponds the equality pcm = (Pc + Pa), where pa - atmospheric pressure and pcm - the pressure of compressed air blocked in the channel. 

There are two approaches to explain physical mechanism of the phenomenon. The first model is based on the existence of the difference between the saturated vapor pressures above two menisci in dead-end capillary. It results in the evaporation of a liquid from the meniscus of smaller curvature ( classical capillary imbibition) and the condensation of its vapor upon the meniscus of larger curvature originally existed due to capillary condensation. 

At first we tried to explain the phenomenon on the base of the existence of the difference between the saturated vapor pressures above two menisci in dead-end capillary [12]. It results in the evaporation of a liquid from the meniscus of smaller curvature ( classical capillary imbibition) and the condensation of its vapor upon the meniscus of larger curvature originally existed due to capillary condensation. We worked out the mathematical description of both gas-vapor diffusion and evaporation-condensation processes in cone s channel. Solving the system of differential equations for evaporation-condensation processes, we ve derived the formula for the dependence of top s (or inner) liquid column growth on time. But the calculated curves for the kinetics of inner column s length are 1-2 orders of magnitude smaller than the experimental ones [12]. 

Interpretation for irreducible water saturation assumes that the rock is water-wet or mixed-wet (water-wet during drainage but the pore surfaces contacted by oil becomes oil-wet upon imbibition). If a porous medium is water-wet and a nonwetting fluid displaces the water (drainage), then the non-wetting fluid will first occupy the larger pores and will enter the smaller pores only as the capillary pressure is increased. This process is similar to the accumulation of oil or gas in the pore space of a reservoir. Thus it is of interest to estimate the irreducible water saturation that is retained by capillarity after the hydrocarbon accumulates in an oil or gas reservoir. The FFI is an estimate of the amount of potential hydrocarbon in... 

The capillary pressure PC(S) exhibits a marked hysteresis phenomenon when the liquid is alternately withdrawn (drainage) and introduced (imbibition) into the particulate bed. Consequently, capillary pressure changes as a result of variations in saturation do not follow a unique functional relationship. In fact, the suction is always higher on the drainage side of the imbibition-drainage cycle (M8). In Fig. 7 the suction curve starts at zero when S = 1. 

Nguyen et al. [205] designed a volume displacement technique that was used to measure the capillary pressures for both hydrophobic and hydrophilic materials. One requirement for this method is that the sample material must have enough pore volume to be able to measure the respective displaced volume. Basically, while the sample is filled wifh water and then drained, the volume of water displaced is recorded. In order for the water to be drained from fhe material, it is vital to keep the liquid pressure higher than the gas pressure (i.e., pressure difference is key). Once the sample is saturated, the liquid pressure can be reduced slightly in order for the water to drain. From these tests, plots of capillary pressure versus water saturation corresponding to both imbibitions and drainages can be determined. A similar method was presented by Koido, Furusawa, and Moriyama [206], except they studied only the liquid water imbibition with different diffusion layers. 

Of particular interest are exceedingly efficient imbibitions of acetone vapor into solid hosts at very low partial pressures (down to the detection limit), so that these reactions may be used for atmospheric detoxifications [5,28]. 

There is a relationship between yield of the extract and the saturation sorption or imbibition of solvent that is independent of the rank coal or the particular amine solvent (Dryden, 1951). An adsorption isotherm for ethylenediamine vapor on an 82% carbon coal exhibited three main features (1) chemisorption up to 3 to 6% adsorbed, (2) a fairly normal sorption isotherm from the completion of chemisorption up to a relative pressure of at least 0.8, and (3) a steeply rising indefinite region near saturation that corresponded to observable dissolution of the coal. 

Amott-Harvey Indices, in which spontaneous imbibition of, individually, water and oil compared with the maxima possible under forced (pressure) imbibition. These are used to calculate water (WI) and oil (OI) indices reflecting degrees of wettability between neutral and strongly wetting. 

Wettability Index (W), (based on the U.S. Bureau of Mines wettability test), in which the forced (pressure) imbibition of water is compared to forced imbibition of oil via capillary pressure curves. The wettability index varies from -oo for complete oil-wetting, to zero for neutral, to +°° for complete water-wetting. For practical purposes, W usually varies between about -1.5 and +1.0. 

The total specific volume, Vtoi, is determined pycnometrically by imbibition of the porous material in mercury at 0.1 MPa pressure. Note that most materials are not wetted by mercury. Hence, mercury will not penetrate into the pores at 0.1 MPa pressure. 

Figure 10. Axial pressure profiles observed at steady state for initial drainage experiment (no prior imbibition) and final drainage experiment (after a number of successive drainage and imbibition experiments).

Once such high gas saturations have been established, it is difficult to decrease these through liquid imbibition because of the breakup and trapping of the bubble trains once gas flow is stopped. If the gas flow is reinitiated, higher gas saturations can be realized however, the possible saturation changes in such dispersed flows are considerably smaller than those possible in non-dispersed flows. Further, the effects of flow rate or applied pressure drop on saturation are also small. 

Virtually all polymeric materials, not just those designed to function in an aqueous environment, will be exposed to environmental water at some stage of their service lives, and water imbibition can have adverse effects on their physical and mechanical properties.Although the polymer itself may be able to tolerate such degradation, if water is absorbed at the interfaces of high moduli materials, substantial swelling pressures and the generation of unwanted stresses can be anticipated. Combined STRAFI and MRM studies of some commercial thermoset adhesives used in the construction industry have... 

This is more than adequate to set news inks at commercial levels of ink application. Capillary imbibition is thus the predominant ink setting mechanism since spreading and bulk diffusion are much slower processes. However, two complications arise in this simplistic model. Implicit in the model is the assumption that the capillaries are connected to an inexhaustible supply of liquid. This is not the case, and it would be more reasonable to assume that as the larger capillaries drain the oil from the surface of the paper differential capillary pressures in the interconnected network drain the vehicle into progressively smaller capillaries emptying the larger ones (see Figure 1). These differential pressures can be expressed as ... 

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