Salinity surfactant adsorption affected

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. 

Regarding the surfactant type and rock type, nonionic surfactants have much higher adsorption on a sandstone surface than anionic surfactants (Liu, 2007). However, Liu s initial experiments indicated that the adsorption of nonionic surfactant on calcite was much lower than that of anionic surfactant without the presence of NaaCOs and was of the same order of magnitude as that of anionic surfactant with the presence of Na2C03. Thus, nonionic surfactants might be candidates for use in carbonate formations from the adsorption point of view. The role of salinity is much less important, but the temperature effect is much more important for nonionics than for anionics (Salager et al 1979a). More factors that affect adsorption were discussed by Somasundaran and Hanna (1977). 

The ability of aminated compounds to inhibit corrosion on metallic surfaces via adsorption phenomena has been already certified. Since operations taking place at interfaces are greatly affected by variations in surface tension, aminated surfactant molecules are expected to provide even better results. This has been the case, when self-assembled micellar or microemulsion systems are used as corrosion inhibitors. In that aspect, surfactants may be used as organic corrosion inhibitors, and act by forming a protective film onto surfaces which are exposed to corrosive media, like oxygen and saline or acidic solutions. When microemulsions are used, an oil film is also adsorbed onto the surface with the surfactants tails oriented towards it, in view of the usually positive character of the surface. In the petroleum industry, the oil itself may be the nonpolar component of such systems. Figure 15.10 is a schematic of these types of films. 

Figure la shows the permeabihty distribution. It can be noted, that for calculation of distribution of the main parameters used heterogeneous field. In opposite corners of the selected area are two wells injection and production. These wells are set bottom hole pressure Pinj or Pprod)- Figure lb shows the results of calculating the distribution of pressure in domain. Distribution of water saturation, polymer and surfactant concentrations, which are pumped through injection well, presented in Figures 2, 3 and 4. It is considered that the salinity of injection water is equal to zero (Figure 5). In these calculations, the solution is pumped into the reservoir over the reservoir temperature, the distribution of which is shown in Figure 6. Thus, the problem is solved numerically in a simple formulation, i.e. not taken into accoimt changes in viscosity of the concentration of the reagents and temperature, polymer adsorption was not affected by the...

---