Advanced once-through flow cell methodology for evaluation of a new staged inhibition concept to mitigate corrosion of carbon steel in high-strength hydrochloric acid flow

A new staged acid corrosion inhibition (ACI) concept, utilising polymerisable ACIs, has been developed to minimise the corrosion of coiled tubing and wellbore casing materials during matrix acidizing operations. The concept has been evaluated using a customised once-through flow cell and 4 molar hydrochloric acid at 80 °C. A high quality, protective inhibitor film is established using an elevated ACI concentration during the test period 0–1 h (Stage 1), followed by a significantly reduced ACI concentration during the period 1–4 h (Stage 2). This approach is able to maintain good film persistency and acceptably low corrosion rates.