Chapter 3: Emulsion Treating ^*

Most of the world’s oil reservoirs now produce a mixture of oil and water. The liquids are subjected to shear forces through pumps or other lifting methods, or are sheared as they pass through pressure-reducing devices in the production line. The shear forces disperse one liquid into the other with variations in drop size and stability that are related to the shear force encountered and the physicochemical nature of the production stream. Such dispersions commonly are referred to as emulsions, although many are not true emulsions.

In a true emulsion, either the drop size must be small enough that forces from thermal collisions with molecules of the continuous phase produce Brownian motion that prevents settling, or the characteristics of the interfacial surfaces must be modified by surfactants, suspended solids, or another semisoluble material that renders the surface free energy low enough to preclude its acting as a driving force for coalescence.