Wettability recovery

Resilient Diners. Resilient liners reduce the impact of the hard denture bases on soft oral tissues. They are designed to absorb some of the energy produced by masticatory forces that would otherwise be transmitted through the denture to the soft basal tissue. The liners should adhere to but not impair the denture base. Other critical properties include total recovery from deformation, retention of mechanical properties, good wettability, minimal absorption of... 

Albertsson (Paiiition of Cell Paiiicle.s and Macromolecules, 3d ed., Wiley, New York, 1986) has extensively used particle distribution to fractionate mixtures of biological products. In order to demonstrate the versatility of particle distribution, he has cited the example shown in Table 22-14. The feed mixture consisted of polystyrene particles, red blood cells, starch, and cellulose. Liquid-liquid particle distribution has also been studied by using mineral-matter particles (average diameter = 5.5 Im) extracted from a coal liquid as the solid in a xylene-water system [Prudich and Heniy, Am. Inst. Chem. Eng. J., 24(5), 788 (1978)]. By using surface-active agents in order to enhance the water wettability of the solid particles, recoveries of better than 95 percent of the particles to the water phase were obsei ved. All particles remained in the xylene when no surfactant was added. 

Wettability Design of treatment/recovery Angle of contact related to... 

The bacterial culture converts a portion of the supplied nutrient into vegetative cells, spores, crystalline protein toxin, soluble toxins, exoenzymes, and metabolic excretion products by the time of complete sporulation of the population. Although synchronous growth is not necessary, nearly simultaneous sporulation of the entire population is desired in order to obtain a uniform product. Depending on the manner of recovery of active material for the product, it will contain the insolubles including bacterial spores, crystals, cellular debris, and residual medium ingredients plus any soluble materials which may be carried with the fluid constituents. Diluents, vehicles, stickers, and chemical protectants, as the individual formulation procedure may dictate, are then added to the harvested fermentation products. The materials are used experimentally and commercially as dusts, wettable powders, and sprayable liquid formulations. Thus, a... 

Key mechanisms important for improved oil mobilization by microbial formulations have been identified, including wettability alteration, emulsification, oil solubilization, alteration in interfacial forces, lowering of mobility ratio, and permeability modification. Aggregation of the bacteria at the oil-water-rock interface may produce localized high concentrations of metabolic chemical products that result in oil mobilization. A decrease in relative permeability to water and an increase in relative permeability to oil was usually observed in microbial-flooded cores, causing an apparent curve shift toward a more water-wet condition. Cores preflushed with sodium bicarbonate showed increased oil-recovery efficiency [355]. 

The wettability of the rock is responsible for the behavior of a reservoir subjected to any oil-recovery process. Because the chemical composition of the mineral surface is mostly responsible for its wetting behavior, the relationship between wettability and chemical composition of the surface is key information. 

Use of carefully selected surfactants in well treatment fluids is a way to accomplish this. Rock wettability can be altered by adsorption of polar materials such as surfactants and corrosion inhibitors, or by the deposition of polar crude oil components (173). Pressure appears to have little influence on rock wettability (174). The two techniques used to study wettability, contact and and relative permeability measurements, show qualitative agreement (175-177). Deposition of polar asphaltenes can be particularly significant in carbon dioxide enhanced oil recovery. 

Increasing the water-wet surface area of a petroleum reservoir is one mechanism by which alkaline floods recover incremental oil(19). Under basic pH conditions, organic acids in acidic crudes produce natural surfactants which can alter the wettability of pore surfaces. Recovery of incremental oil by alkaline flooding is dependent on the pH and salinity of the brine (20), the acidity of the crude and the wettability of the porous medium(1,19,21,22). Thus, alkaline flooding is an oil and reservoir specific recovery process which can not be used in all reservoirs. The usefulness of alkaline flooding is also limited by the large volumes of caustic required to satisfy rock reactions(23). 

RECOVERY MECHANISMS. Being surface active, TFSAs lower oil-water inter facial tension, but not by the three orders of magnitude needed to increase the capillary number sufficiently to recover a substantial amount of incremental oil. Instead, TFSAs enhance the recovery of oil by changing the wettability of reservoir rock surfaces from oil-wet and intermediate wettability to strongly water-wet, and by coalescing emulsions in the near-wellbore region of the production wells. 

Changing the wettability of reservoir rock surfaces from oil-wet to water-wet, increases the permeability of the formation to oil, decreases the permeability to water, decreases mobility ratio, increases sweep efficiency, increases the flowing fraction of oil at every saturation, and increases oil recovery at the economic limit of the waterflood. 

Onuska and Terry [461] examined the extraction of tetrachlorodibenzodio-xin (TCDD) from sediments. They found that either C02 or N20 with 2% methanol as modifiers gave the highest recovery at 310 bar and 40 °C. They also studied the effect of extracting wet sediment, as opposed to the dry material, and found that when the sediment was moist, the recovery diminished by 20% for the same extraction time. However, the same efficiency could be achieved with the wet sediment if the 40 min extraction time was doubled. Soxhlet extraction of the same dried sediment with n-hexane/acetone (1 1) (150 ml) and 2,2,4-tri-methylpentane (25 ml) for 18 h was only around 65% of the SFE recovery. The Soxhlet extraction was considerably more variable (22-90%, n = 3), but since the Soxhlet actually recovered 90 % of the TCDD, this means that the method can be efficient but erratic. This variability was almost certainly a function of the heterogeneity of the matrix surface and/or the wettability of the sediment. 

Zhichu, B. Zhenshu, Z. Fei, X. Yueying, Q. and Jiayong, Y. (1999). Wettability, Oil Recovery, and Interfacial Tension with an SDBS-Dodecane-Kaolin System, Journal of Colloid and Interface Science, 214, 368-372. 

In the case of porous media, which are important in such fields as oil and gas recovery, soil remediation and catalysis, wettability determination requires somewhat different methods such as those based on the imbibition of liquids [157-159] ... 

For example, in mineral flotation, surfactant can be added to adsorb on metal ore particles, increasing the contact angle, so they attach to gas bubbles, but the surfactant does not adsorb much on silicates, so these do not attach to gas bubbles. The surfactant may also stabilize a foam containing the desired particles facilitating their recovery as a particle-rich froth that can be skimmed. Flotation processes thus involve careful modification of surface tension and wettability. 

It may also be beneficial to alter the wettability (see Section 3.5.3) of the reservoir rock, particularly in order to shift oil-wetting regions towards neutral wetting, which is probably about the optimum for improved oil recovery [158]. Figure 3.23 (see Section 3.5.3) shows how surfactant adsorption can alter wettability, but not always in a simple manner. Such surfactant-induced wettability alteration might be considered for predominantly oil-wetting reservoirs such as chalk reservoirs in the North Sea. 

Cuiec, L.E. Evaluation of Reservoir Wettability and Its Effect on Oil Recovery in Interfacial Phenomena in Petroleum Recovery, Morrow, N.R. (Ed.), Dekker New York, 1991, pp. 319-376. 

Wettability of a solid surface definition and assessment The concept of wettability of a solid by a liquid is directly related to the wetting processes. This concept is specially useful in the fields of detergency, lubrication or enhanced oil recovery. In the context of the oil industry, proposals were made by Briant and Cuiec (1972) for the experimental assessment of wettability, which was defined in terms of the thermodynamic affinity of a solid surface for a liquid. 

A critical literature review on foam rheology is given elsewhere (6). The injection of foam-like dispersions or C02 foams is a useful method in enhanced oil recovery ( 7). This method of decreasing the mobility of a low-viscosity fluid in a porous rock requires the use of a surfactant to stabilize a population of bubble films or lamellae within the porespace of the rock (8). The degree of thickening achieved apparently depends to some extent on the properties of the rock itself. These properties probably include both the distance scale of the pore space and the wettability, and so can be expected to differ from reservoir to reservoir, as well as to some extent within a given field (9,10). 

These considerations come into play in oil recovery schemes applied to reservoirs of mixed wettability or where the rock is predominantly oilwetting. Another example is the case of the so-called Pickering emulsions. 

Wettability. Wettability of the porous medium controls the flow, location, and distribution of fluids inside a reservoir (7, 28). It directly affects capillary pressure, relative permeability, secondary and tertiary recovery performances, irreducible water saturations, residual oil saturations, and other properties. 

---