An amine based CO2 corrosion inhibitor and an imidazoline based CO2 corrosion inhibitor have been tested in a two-phase laboratory flow loop system under conditions of a gas condensate well in Austria. After a detailed description of the experimental setups, degradation rates of material API L-80 (UNS G41300) as function of flow velocity and inhibitor dosage are presented. Further, the influence of chloride addition on inhibitor performance has been investigated. All results are discussed with respect to critical inhibitor concentration to reach nearly 100 % inhibitor efficiency.
Inhibitor A exhibits alkylamine as an active ingredient dissolved in ethylene glycol and different alcohols, and the effect of inhibitor B is based on imidazoline dissolved in different alcohols. Results demonstrate that the test rig delivers reasonable results with respect to inhibitor protection rates. Independent of superficial flow velocities (tested between 3 and 35 m/s), both inhibitors exhibit a good performance as long as dosed above their critical concentration. The critical concentration is clearly below 100 ppm to the liquid phase. The addition of chlorides affects the performance of the alkylamine based inhibitor significantly more than in case of the imidazoline.