关键词: Ca2+ 含量, 垢下腐蚀, 结垢, 20 号钢, 局部腐蚀

Abstract: This paper mainly studies the effects of Ca2+ content on corrosion behavior of 20# steel in oilfield production water. High temperature and high pressure corrosion simulation experiments are used to study the corrosion law of 20# steel under different working conditions. OLI hydrochemical analysis software is used to calculate the effects of different Ca2+ contents on scaling risk. Such methods as SEM, XRD and 3D morphology observation are used to analyze the morphology and composition of corrosion products on the surface of 20# steel. The results show that when the Ca2+ content is less than 1000 mg/L, there is no scaling risk on the surface of 20# steel and the surface of the sample is mainly general corrosion; when the Ca2+ content exceeds 1000 mg/L, the scaling risk of 20# steel increases with the increasing of Ca2+ content and the main component of scaling is CaCO3. The local corrosion formed under the scale layer tends to merge and become larger.

Key words: Ca2+ content, under-deposit corrosion, scaling, 20# steel, local corrosion