Corrosion Protection of Oilfield Steel with 1‐Phenyl‐2‐Propyn‐1‐Ol

1‐Phenyl‐2‐propyn‐1‐ol (1‐PPO) is a very efficient corrosion inhibitor for oilfield steel in hydrochloric acid. With a suitable surfactant, 1‐PPO can impart >99% protection to API J55 steel in 15% at 65°C for 24h. Chemical analyses of the products formed on the steel surface and in solution indicate that 1‐PPO reacts rapidly and homogeneously with the acid to form an allene intermediate, which serves as the active inhibitor early in the exposure period. Surfactants serve to stabilize this intermediate at the steel surface and bind oligomeric condensation products. The intermediate remaining in the solution slowly converts to cinnamaldehyde, which eventually becomes the dominant species in solution and takes over the role of active inhibitor.