Stability and Destabilization of Water-in-Crude Oil Emulsion

The crude oil explored from oil wells is in the form of a water-in-oil emulsion. To process the oil for refining into different useful products, the water needs to be separated from the water-in-oil emulsion. There are several procedures reported for breaking the water-in-oil emulsion. Generally, the water present in crude oil is in the form of brine droplets, and the salt concentration may vary from a few hundred to several thousand ppm. The salts present in the crude oil create severe problems in the downstream processing in refineries such as deactivation or poisoning of the catalyst. Therefore, the removal of water from the emulsion is typically the first unit operation in a crude oil refinery. The overall process of separation of water (brine) from crude oil is generally known as desalting. In this chapter, we give a brief discussion on the stability as well as destabilization of the water-in-oil emulsion system. The mechanism of demulsification and the method of breaking water-in-oil emulsion are also discussed in detail.