Effect on interfacial tension

Blends of sodium hypochlorite with 15% HC1 and with 12% HCl/3% HF have been used to stimulate aqueous fluid injection wells(143). Waterflood injection wells have also been stimulated by injecting linear alcohol propoxyethoxysulfate salts in the absence of any acid (144). The oil near the well bore is mobilized thus increasing the relative permeability of the rock to water (145). Temperature effects on interfacial tension and on surfactant solubility can be a critical factor in surfactant selection for this application (146). 

Oil/water interfacial tensions were measured for a number of heavy crude oils at temperatures up to 200°C using the spinning drop technique. The influences of spinning rate, surfactant type and concentration, NaCI and CaCI2 concentrations, and temperature were studied. The heavy oil type and pH (in the presence of surfactant) had little effect on interfacial tensions. Instead, interfacial tensions depended strongly on the surfactant type, temperature, and NaCI and CaCL concentrations. Low interfacial tensions (<0.1 mN/m) were difficult to achieve at elevated temperatures. 

The results for the effect on interfacial tension of the fatty alcohol chain length are given in Table I for 1 1 molar ratio mixed emulsifier solutions. 

The above value for rutile (and probably iron oxide) includes polarization force of these surfaces on hydrocarbons [3]. Since both the dispersion force and polarization force depend on the polarizability of the hydrocarbon, these two terms should be additive. The value of the polarization force can be determined by measurements with polar molecules the field strength of the surface is indicated by the increase in interfacial interaction with dipole moment [3]. As there is no appreciable dipole effect on interfacial tensions between many polar organic substances and mercury, it appears that with mercury (and perhaps other metals without oxide surfaces) the values include no polarization term. 

This rule is approximately obeyed by a large number of systems, although there are many exceptions see Refs. 15-18. The rule can be understood in terms of a simple physical picture. There should be an adsorbed film of substance B on the surface of liquid A. If we regard this film to be thick enough to have the properties of bulk liquid B, then 7a(B) is effectively the interfacial tension of a duplex surface and should be equal to 7ab + VB(A)- Equation IV-6 then follows. See also Refs. 14 and 18. 

TABLE 10 Effect of Hydrophobe Carbon Number on Interfacial Tension of Olefinsulfonates ... 

TABLE 13 Effect of Di Monosulfonate Ratio on Interfacial Tension of Olefinsulfonate Solutions3... 

Effect of Aqueous Phase Salinity and pH on Interfacial Tension. Comparison of the first two entries in Table 14 shows that an increase in AOS 2024 solvent salinity from 0 to 3% NaCl results in a significant decrease in IFT. This suggests that the optimum salinity of this AOS 2024 sample is closer to 3% NaCl than to 0%. 

Isaacs and Smolek [211 observed that low tensions obtained for an Athabasca bitumen/brine-suIfonate surfactant system were likely associated with the formation of a surfactant-rich film lying between the oil and water, which can be hindered by an increase in temperature. Babu et al. [221 obtained little effect of temperature on interfacial tensions however, values of about 0.02 mN/m were obtained for a light crude (39°API), and were about an order of magnitude lower than those observed for a heavy crude (14°API) with the same aqueous surfactant formulations. For pure hydrocarbon phases and ambient conditions, it is well established that the interfacial tension behavior is dependent on the oleic phase [15.231 In general, interfacial tension values of crude oiI-containing systems are considerably higher than the equivalent values observed with pure hydrocarbons. 

Effect of Temperature. In the absence of surfactant, interfacial tensions of the Athabasca 1 211. Karamay 1 51, and other heavy oils 1 321 show little or no dependence on temperature. For surfactant-containing systems, Figure 6 shows an example of the effect of temperature (50-200°C) on interfacial tensions for the Athabasca, Clearwater and Peace River bitumens in Sun Tech IV solutions containing 0 and 10 g/L NaCI. The interfacial tension behavior for the three bitumens was very similar. At a given temperature, the presence of brine caused a reduction in interfacial tension by one to two orders of magnitude. The tensions were seen to increase substantially with temperature. For the case of no added NaCI, the values approached those observed T211 in the absence of surfactant. 

S. Sugiura, M. Nakajima, T. Oda, M. Satake, and M. Seki Effect of Interfacial Tension on the Dynamic Behavior of Droplet Formation During MicroChannel Emulsification. J. Colloid Interface Sci. 269, 178 (2004). 

The several sets of published interfacial tension data for gas-water systems do not agree. The data which appear to be most consistent are given in Figure 16-23.14 The data were obtained with methane and pure water. However, the data cover the pressure and temperature ranges of usual interest. Figure 16-23 can be used as a correlation for natural gas-water systems its accuracy is unknown. The effect of dissolved solids on interfacial tension is unknown. 

The effect of dissolved solids on interfacial tension is unknown. 

Interfacial properties. The effect of the aqueous phase on interfacial tensions of irradiated TBP-diluent/nitric acid systems was measured (142). For neutral and acidic aqueous phase, the interfacial tension was similar for fresh and irradiated systems, but in contact with 0.6 mol L 1 NaOH solution, which is representative of alkaline treatment, a decrease of interfacial tension was observed. 

Figure 6.23 Effect of Interfacial Tension on NETS for the RDC and RPC Extractors (Source Reference 6.31 with permission).

The interfacial tension between water and mercury is 426-427 dynes/cm. in absence of oxygen, but if measured in presence of air it varies between 375 and 427. The effect of pressure on interfacial tension varies with the pressure and may be positive (increasing a) or negative withp in lb./in.2 the values of (100/or)(do /d ) at about 5000 atm. are Hg/H2O+0 74, Hg/ether+1-23, water/ether—20-73, chloroform/water—0-73, carbon disulphide/water+2 37. The interfacial tension between two liquids vanishes at the critical solution temperature.4... 

The choice of chemical is usually based on trial-and-error procedures hence, demulsifier technology is more of an art than a science. In most cases a combination of chemicals is used in the demulsifier formulation to achieve both efficient flocculation and coalescence. The type of demulsifiers and their effect on interfacial area are among the important factors that influence the coalescence process. Time-dependent interfacial tensions have been shown to be sensitive to these factors, and the relation between time-dependent interfacial tensions and the adsorption of surfactants at the oil-aqueous interface was considered by a number of researchers (27, 31-36). From studies of the time-dependent tensions at the interface between organic solvents and aqueous solutions of different surfactants, Joos and coworkers (33—36) concluded that the adsorption process of the surfactants at the liquid-liquid interface was not only diffusion controlled but that adsorption barriers and surfactant molecule reorientation were important mecha-... 

Effect of salinity on interfacial tension and partition coefficient for TRS 10-80/n-octane system. 

Interfacial Tension Values. The results for the effect of ionic surfactant to fatty alcohol molar ratio and concentration on interfacial tensions with styrene are shown in Figure 4. Maximum interfacial... 

Figure 4. Effect of molar ratio on interfacial tension between styrene and aqueous solutions of lOmM SLS/lauryl alcohol [- -], 16.7mM SLS/lauryl alcohol [-O-] and 16.7mM SLS/cetyl alcohol...

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