Scales are formed through the mixing of incompatible waters, that is, treatment waters and formation waters, or a disturbance in the formation water equilibrium, causing the ions present to react. Common scales include calcium carbonate and barium sulphate, and scale problems are most often seen in offshore environments.
Scale precipitation may be modelled after analysis of formation waters and treatment waters in the laboratory, prior to any deposition. Procedures may then by put in place to inhibit scaling, such as use of specific or treated waters for intervention operations, or use of specific scale inhibitors, which should be tested before implementing to ensure compatibility with crude as well. One of the most widely used methods for preventative options is the continuous injection or squeeze treatment of chemical scale inhibitors into the production and/or water injection system. The chemical inhibitors should act to prevent nucleation growth and the adherence of scale crystals, by adsorbing on rock surface or the surface of small precipitates.