Viscosity salinity effects

Salinity is essential for all chemical processes. It directly affects polymer viscosity, and it determines the type of microemulsion a surfactant can form. Salinity effects in waterflooding, in both sandstone and carbonate reservoirs, have recently drawn research interest. This chapter briefly discusses sahnity and ion exchange. At the end of this chapter, the sahnity effects on waterflooding in sandstone and carbonate reservoirs are summarized. 

FIGURE 5.6 Salinity effect on the viscosity of the copolymer PAMOA50 at 25°C and 76.8 s Source Zhou and Huang (1997). 

Figure 5.23 shows the 1000 mg/L HPAM viscosity in a closed system without oxygen at 30°C and 3 hours after adding Fe ". When Fe " concentration was lower than 10 mg/L, the viscosity loss was less than 10% owing to the salinity effect. However, when the HPAM solution was put in an open system, the viscosity was significantly lost, as shown in Figure 5.23. In the open system, Fe was oxidized to Fe. For comparison, the viscosity loss 6 hours after...

This section further discusses the effects of k, curves, optimum phase type, and phase viscosity. The effect of negative salinity gradient is further discussed under conditions where different relationships between optimum salinity and surfactant concentrations occur. 

While it may be argued that the retention data may show a salinity effect (compare Cores 52 and 55, Table 2), this effect appears smaller than other observations. For some systems, Holland and Eirich have shown the resistance factor to be directly related to the intrinsic viscosity. The effect of brine concentration on the intrinsic viscosity of polyelectrolytes has been shown to decrease with increasing ionic strength. Consequently, the lack of a significant brine effect on measured resistance factors is explainable by the... 

The increase of the concentration of NaCl produces a decrease in the proportion of [RA BH with the consequent increase of Bit and CP in the bulk phase. The incorporation of small ions (having higher mobility than the organic ones) in the PE environment would contribute to keep the level of hydration. However, a dramatic drop of viscosity is produced as depicted in Fig. 15. It should be noted that polymetacrylates, having a hydrophobic backbone without other hydrophylic moieties than carboxylic groups are particularly susceptive to the saline effect. 

The same phenomenon is observed in complexes that have been compacted under the shape of circular matrices. In fact, it can be seen in Fig. 18 that water sorption rate is proportional to the viscosities reported in Table 3. Thus, the high swelling capacity exhibited by the complexes of atenolol and hdocaine in salt free medium makes them highly susceptible to the saline effect. Thus, the sorption rate decreases when a NaCl solution is used instead of water. On the other hand, the complex with metoclopramide has a very low rate of water sorption reveal a limited swelling capacity whose rate is barely affected in NaCl solution. 

The polymers exist in saline solution as tightly coiled chains and are readily adsorbed owing to relatively low solubiUty in hard water. Subsequent injection of soft, low salinity water uncoils the adsorbed polymer chains increasing water viscosity and reducing rock permeabiUty. This technology could also be used to reduce the permeabiUty of thief 2ones adjacent to injection wells. However, mechanical isolation of these 2ones may be necessary for cost-effective treatments. 

The effectiveness of a number of crude oil dispersants, measured using a variety of evaluation procedures, indicates that temperature effects result from changing viscosity, dispersants are most effective at a salinity of approximately 40 ppt (parts per thousand), and concentration of dispersant is critical to effectiveness. The mixing time has little effect on performance, and a calibration procedure for laboratory dispersant effectiveness must include contact with water in a manner analogous to the extraction procedure otherwise, effectiveness may be inflated [587]. Compensation for the coloration produced by the dispersant alone is important only for some dispersants. 

Each oil-dispersant combination shows a unique threshold or onset of dispersion [589]. A statistic analysis showed that the principal factors involved are the oil composition, dispersant formulation, sea surface turbulence, and dispersant quantity [588]. The composition of the oil is very important. The effectiveness of the dispersant formulation correlates strongly with the amount of the saturate components in the oil. The other components of the oil (i.e., asphaltenes, resins, or polar substances and aromatic fractions) show a negative correlation with the dispersant effectiveness. The viscosity of the oil is determined by the composition of the oil. Therefore viscosity and composition are responsible for the effectiveness of a dispersant. The dispersant composition is significant and interacts with the oil composition. Sea turbulence strongly affects dispersant effectiveness. The effectiveness rises with increasing turbulence to a maximal value. The effectiveness for commercial dispersants is a Gaussian distribution around a certain salinity value. 

Nasal decongestant sprays such as phenylephrine and oxymetazoline that reduce inflammation by vasoconstriction are often used in sinusitis. Use should be limited to the recommended duration of the product to prevent rebound congestion. Oral decongestants may also aid in nasal or sinus patency. To reduce mucociliary function, irrigation of the nasal cavity with saline and steam inhalation may be used to increase mucosal moisture, and mucolytics (e.g., guaifenesin) maybe used to decrease the viscosity of nasal secretions. Antihistamines should not be used for acute bacterial sinusitis in view of their anticholinergic effects that can dry mucosa and disturb clearance of mucosal secretions. 

In the mucosal environment, effects of salt, pH, temperature, and lipids need to be taken into consideration for possible effects on viscosity and solubility. A pH range of 4-7 and a relatively constant temperature of 37°C can generally be expected. Observed solution properties as a function of salt and polymer concentration can be referred to as saline compatibility. Polyelectrolyte solution behavior [27] is generally dominated by ionic interactions, such as with other materials of like charge (repulsive), opposite charge (attractive), solvent ionic character (dielectric), and dissolved ions (i.e., salt). In general, at a constant polymer concentration, an increase in the salt concentration decreases the viscosity, due to decreasing the hydrodynamic volume of the polymer at a critical salt concentration precipitation may occur. 

Schmidt number a dimensionless number, characteristic of each gas, which varies strongly with temperature and weakly with salinity, and is used to account for viscosity effects on the diffusion of gases. 

The difference in replacement of the lEP for 19a (pHiEp = 3.6) and 19b (pHiEP = 2.9) is probably connected with the different hydrophobicity of polycarboxybetaine chains, e.g., the cationic group of 19b is more effectively screened by ethyl substituents, as they are bulkier than the methyl groups of 19a. The effect of organic solvent on the solution behavior of 19b was studied [193]. In saline water, the conformation of 19b is compact due to the screening of the electrostatic repulsion by the neutral salt KCl. Addition of ethanol improves the thermodynamic quality of the solvent with respect to the hydrophobic parts of the macromolecules, and the reduced viscosity increases and has the maximal value at 60-80 vol % of ethanol in a water/ethanol mixture. 

In sufficiently dilute aqueous solutions surfactants are present as monomeric particles or ions. Above critical micellization concentration CMC, monomers are in equilibrium with micelles. In this chapter the term micelle is used to denote spherical aggregates, each containing a few dozens of monomeric units, whose structure is illustrated in Fig. 4.64. The CMC of common surfactants are on the order of 10 " -10 mol dm . The CMC is not sharply defined and different methods (e.g. breakpoints in the curves expressing the conductivity, surface tension, viscosity and turbidity of surfactant solutions as the function of concentration) lead to somewhat different values. Moreover, CMC depends on the experimental conditions (temperature, presence of other solutes), thus the CMC relevant for the expierimental system of interest is not necessarily readily available from the literature. For example, the CMC is depressed in the presence of inert electrolytes and in the presence of apolar solutes, and it increases when the temperature increases. These shifts in the CMC reflect the effect of cosolutes on the activity of monomer species in surfactant solution, and consequently the factors affecting the CMC (e.g. salinity) affect also the surfactant adsorption. 

The simple way to avoid any mistakes when fitting the laboratory data to Eq. 5.1 is to use the same units as those in the prediction model (e.g., a simulator) you are going to use. Then those fitting constants obtained by matching experimental data can be directly used in the prediction model. The factor allows for dependence of polymer viscosity on salinity and hardness. The effective salinity for polymer, C ep, is given in UTCHEM-9.0 (2000) by... 

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