Cathodic Protection (CP) is a proven method of minimizing corrosion and significantly prolonging the useful life of metallic structures submerged in soil or water.
Corrosion is an electro-chemical process that occurs where current discharges from a metallic structure, such as a steel pipe (anode), through an electrolyte such as water, concrete or soil to a cathode. Corrosion requires four elements:
In the corrosion process, the anode and a cathode may be different metals or, in the case of a rusting steel pipe, may be close together on the same surface but have different metallurgical variations or exposure to different electrolytes:
The objective of CP is to cause the entire surface of the metallic structure to be cathodic to its environment by forcing electrical current back onto the metal. This is accomplished through the installation of sacrificial anodes along with impressed current systems depending on the protection requirements.
With periodic maintenance, a CP system is designed to be effective for a period of 15 to 20 years, after which the anodes would typically be replaced.
Well Casing Protection
Many areas of SE Saskatchewan and SW Manitoba are underlain by the Blairmore Formation, a water-bearing layer of highly corrosive brine – an excellent electrolyte!
Wells drilled in these areas typically intercept the Blairmore and once cased are immediately subjected to this highly corrosive environment. Prolonged exposure of the well casing to this environment can result in premature casing failure.
Casing cement, which is often thought of as a protective coating, does little to mitigate the corrosion by the nature of its permeability and the fact it can act as an electrolyte.
The installation of a CP system inhibits well casing corrosion at a fraction of the cost, over the life of the well, compared to casing replacement.
Field Production Equipment