An influence of acetic acid on the carbon dioxide corrosion of 13 % Cr tubing in Minami-Nagaoka gas field

Abstract

Localized corrosion was found on inner surfaces of 13 %Cr steel tubing at shallow depths in deep, hot corrosive Minami-Nagaoka gas wells. Judging from the high penetration rates of corrosion pits, factors other than high temperature and carbon dioxide (CO₂) are expected to exist. The chemical analyses on produced fluids revealed that acetic acid of 250∼300 ppm existed in the produced condensed water. Laboratory corrosion test results showed that acetic acid in the condensed water saturated with CO₂ markedly affected the passivity of 13 %Cr steel due to low pH. The existence of acetic acid can be a cause of the localized corrosion of 13 %Cr steel tubing in Minami-Nagaoka wells.