**5. Conclusions**

considered as two types of surfactants adsorbed at the interface, according to the physico‐ chemical conditions in the bulk phases at equilibrium. It has been found that below a concen‐ tration of asphaltenes 500−1000 ppm, the concentration of demulsifier required to attain optimum formulation varies proportionally to the concentration of asphaltenes (see Figure 5). In this so-called proportional regime [7], a quantitative formulation effect at the interface can be estimated without taking into account physical effects such as viscosity, convection, and diffusion through bulk oil (these are not formulation issues). This method allows evaluating the demulsification performance as a function of different formulation variables (demulsifier hydrophilicity, salinity, and crude oil characteristics) [7, 42-44], which represents a significant

**Figure 5.** Demulsifier concentration as a function of the asphaltene concentration to reach optimum formulation (Per‐

HLB method (hydrophile–lipophile balance) is often used. In this method, a number (0–40), indicative of emulsification behavior and related to the balance between the hydrophilic and lipophilic (hydrophobic) portions of the molecule, has been assigned to many commercial

HLB = X HLB + X HLB optMixt A A D D (4)

Using HLB concept, the proportional regime can be estimated, as follows, [7, 42-44]:

practical progress in designing commercial products.

78 Advances in Petrochemicals

eira, 2009).

surfactants [42].

Here it was explained the approach from the optimum formulation concept to assist emulsion breaking in desalting process. As part of the stabilization mechanism is accepted that the water droplets are stabilized by the formation of a mechanically strong and viscoelastic film at the interface composed of asphaltenes.

In the case of water-in-crude emulsions, a balanced optimum formulation is attained by adding demulsifiers which are hydrophilic to the lipophilic natural surfactants contained in the crude oil. This study aimed to determine an optimal and to relate the nature and concentration of demulsifier products added to the amphiphilic mixture at the interface. Proportional and saturation regimens can explaine the impact of formulation parameters, such as solvent, alcohols, kind and concentration of demulsifier, amoung others as useful tool by the formu‐ lating personal of petroleum industry.
