Abstract

The inhibition effect of a modified plant oil (MPO) on corrosion behavior of drill pipe steel S135 and casing steel K55 in the basic drilling fluid has been investigated by potentiodynamic polarization method. The experiments were carried out at 30°C, 1 atm and at different MPO concentrations from 0.0 to 3.0 g/l. The fact that Ecorr was shifted to positive values, Tafel slopes and polarization resistant increase with MPO concentrations, was explained by formation of protective adsorption membrane of MPO on the steel surface in the drilling fluid. It was showed that the modified plant oil has been a good cathodic corrosion inhibitor for both of the steels in the studied medium. The effect of the modified plant oil on the anodic reaction was minor. In general, the corrosion inhibition efficiency of the modified plant oil increases with increasing its concentration.