Effect of an Friendly Oil Soluble-Water Dispersible Inhibitor on Corrosion of Low Allow Carbon Steel in an Oil-Water Two Phase System

Corrosion can cause much damage to oil-field equipment. Significant corrosion protection efforts have been made by petrochemical industries to prevent corrosion damage. Inhibition is used internally with carbon steel pipes as an economic control alternative to stainless steels and alloys. Low alloy carbon steel is used in this investigation. Corrosion inhibitors are selected on the basis of the solubility or dispersive ability in the fluids which are to be inhibited. The effect of a friendly commercial oil soluble/water dispersible inhibitor on corrosion in different mediums: A-medium: an oil-water two phase (9:1) standard solution in static conditions and B-medium: in natural brine water of crude oil in static and stirred conditions is studied in this investigation. For the experiments conducted in Amedium, before applying the inhibitor, a brine standard solution (17 g/l NaCl,0,6 g/l NaHCO₃, 0,2 g/l CaCl₂, 0,2 g/l MgCl₂) is prepared and then inhibitor is added at the desired concentration (C- medium). Heptan is used as hydrocarbon phase (D-medium). The carbon steel coupons were immersed in C-medium and then hydrocarbon phase (D-medium) was added in 9:1 ratio.

SEM (EDX) technique is used to investigate the surface of the coupons after corrosion while weight loss method is used to calculate corrosion rate and inhibitor effectiveness. The selected oil soluble/water dispersible inhibitor is very effective (98 %) not only in natural brine waters but also in oil-water two phase standard solution.