Under certain conditions the natural chemistry of produced fluid derived from the reservoir geology can lead to the formation of salts, which in turn can deposit as scale in the production system. Similarly, deposition can be promoted when seawater is either injected into the reservoir (to maintain pressure) or has migrated to the producing zone from another zone. Certain scale deposits can also arise when the reservoir has turned sour due to increased microbial activity. All of these scenarios can lead to severe scale deposition problems when the pressure and temperature in the production and

processing plant changes. The major types of scale, along with treatment strategies are listed below:

Calcium Carbonate

Calcium carbonate usually originates from the nature of the reservoir itself or has been stimulated by the co-mingling of produced fluids from two or more different producing zones or reservoirs. This scale is normally formed when there is a decrease in pressure, releasing carbon dioxide and changing the pH. The main mitigation strategies are dissolution by acidification or application of calcium carbonate scale inhibitor.

Barium Sulphate

In general barium sulphate scale results from water incompatibility, primarily from either seawater injection and / or seawater breakthrough, co mingling with produced water rich in barium. Barium sulphate is highly insoluble and will deposit at temperature drops across the production processing plant. Mitigation strategies include the removal of sulphate ions from seawater for re-injection, application of barium sulphate scale inhibitors or treatment with specialist dissolvers.

Iron Sulphide

Iron Sulphide scale is deposited where microbial enhanced corrosion has become a serious problem. The scale is derived from the reaction of iron oxide from corrosion and hydrogen sulphide, a by-product of sulphate reducing bacteria metabolism. Treatment for iron sulphide is application of a specialist chelating and dissolution agent followed by microbial control with biocide application.

Calcium Sulphate

Calcium Sulphate scale is relatively soluble and only poses a real problem when conditions are close to the solubility limit and super-saturation occurs.

Sodium Chloride

Sodium Chloride scale is caused by a saturation and evaporation process and is readily removed by warm water in most cases. Glexoil can supply a wide range of both scale inhibition and scale dissolving chemicals.