Inhibition of carbon dioxide corrosion of gas and oil-extraction equipment

The analysis of the mechanism of steel corrosion in carbon dioxide media was carried out. The following peculiarities in the action of carbon dioxide were noted: an increase in hydrogen evolution on the cathode and the formation of carbonate-oxide films on the metal. Two ways of combating CO2-corrosion were considered: use of compounds effectively inhibiting the cathodic process and application of reagents-neutralizers that shift pH to the alkaline range (up to 8-10). It was shown that even at a pH of 8-10 there is still a risk of pitting of low-carbon steel undergoing carbon-dioxide corrosion. The different types of inhibitors were studied at this pH, in particular, their effect on passivation and pitting of low-carbon steel in carbonate-bicarbonate solutions. Organic inhibitors decrease the risk of pitting in carbon dioxide media The oxygen-containing KRZ-3 inhibitor is effective against general and local corrosion, predominantly decelerating the cathodic process.