To avoid corrosion in the borehole what type of pH level is desirable?

• A. Low pH
• B. High pH
• C. Neutral pH
• D. Alkaline pH

Answer: (A)

Corrosion happens more quickly in acidic environments because plenty of hydrogen ions can attack the metal surface and dissolve protective films. In boreholes, keeping the water chemistry on the alkaline side reduces this attack: a basic environment tends to stabilize and even build up protective oxide layers on metal surfaces, which slows dissolution. Alkaline conditions also minimize certain acid-forming reactions (such as CO2-related carbonic acid formation) that would otherwise accelerate corrosion. Because of this, an alkaline pH is generally the most protective choice for minimizing corrosion in borehole systems. Neutral pH can be better than strongly acidic conditions, but alkaline environments offer the strongest resistance to corrosion for common borehole materials and configurations, especially when combined with appropriate inhibitors and material choices.