Paper: Scale Its Occurrence and Methods of Control

Scale is a term commonly used in the petroleum industry to define insoluble, inorganic salt deposition in water or water-containing systems. Normally this deposition is composed of the salts of calcium, magnesium, iron and barium. Oil field brine water contains many and varied inorganic salts are increased or the solubility of the salts is decreased, the equilibrium is upset and precipitation takes place. This precipitation is commonly called scale. The physical factors which may cause precipitation are temperature, pressure, evaporation and condensation. Temperature variations and pressure changes are the two most common causes. The solubility of most salts increases with an increase in temperature. A sudden drop in pressure can cause an upset of equilibrium and may result in precipitation.