Calcium carbonate and other mineral scales form in geothermal wells leading to reduced efficiency and sometimes well closure. Hydrochloric acid is used to dissolve carbonate scales and improve efficiency. This acid is very aggressive to the underlying metal, which is typically steel. Corrosion inhibitors are typically added to the acid in order to reduce the corrosion rate. This paper describes the development of a corrosion inhibitor formulation that reduced the corrosion rate of steel in 15% hydrochloric acid. A number of inhibitors were screened to select the best performing compounds. Combinations of inhibitors were also tested to look for synergies. The results showed that a tertiary combination of an alpha,beta-unsaturated aldehyde, a filming amine and an oxime provided superior protection to any single inhibitor alone.

Subject
Acids, Geothermal energy, Corrosion rate, Steel coupons, Imidazolines, Weight loss coupons, Thickness loss, Amines, Corrosion inhibitors, Steel, Corrosion protection, Hydrochloric acid, Cleaning
Keywords:
Corrosion inhibitor, acid cleaning, well rejuvenation, geothermal power
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2019
Association for Materials Protection and Performance (AMPP)
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