Study of Corrosion Inhibition of Pre-Partitioned Fluids Under High Temperature/High Pressure Conditions

Abstract This study outlines the performance investigation of corrosion inhibitors designed for ultra-deepwater oil fields, specifically under extremely high-temperature, high salinity and high-pressure conditions. A novel testing protocol involving the pre-partitioning of synthetic brine at 150°C and under acid gas partial pressure prior to corrosion evaluation is described. The pre-partitioned brines were prepared using various oil-water ratios at different temperatures with several corrosion inhibitors under specific CO₂ partial pressures. The prepared brines were subsequently used in both High-Pressure/High-Temperature Rotating Cylinder Autoclave (HP/HT RCA) and High-Pressure, High-Temperature Rotating Cylinder Electrode (HPHT-RCE) tests to simulate downhole environments. Results showed that several corrosion inhibitors demonstrated effective performance in RCA testing under high-temperature conditions, as determined gravimetrically. However, the same inhibitors failed to provide adequate protection in HPHT-RCE tests, determined electrochemically. This discrepancy raises concerns about the reliability of corrosion rate measurements in the HPHT-RCE system under elevated pressure and elevated temperature, prompting further investigations. Despite this limitation, the identified inhibitors show promise as high-temperature corrosion control solutions for deepwater applications, pending validation across multiple test platforms.