Zhihua Luo, Wei Yan, Peike Zhu, Lei Guan, Kongyang Wang, Sutao Ye, Xuerui Xu
February 28, 2018
Corrosion behavior of 3 wt.-% Chromium (3Cr) tubing steel in CO 2 saturated high-salinity brine was investigated by using an autoclave in the laboratory. The partial pressure of CO 2 and the Cl − concentration were fixed at 0.2 MPa and 139552 mg × l −1 , respectively. The water cut was varied from 20 to 100 vol.-%, and the temperature was varied from 50 to 110 °C. For comparison, the corrosion behaviors of N80 carbon steel and 13 wt.-% Cr (13Cr) martensitic stainless steel were tested in the same conditions. The surface morphologies and chemical composition of corrosion product layers were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectrometry (EDS) technologies. The results show that the 3Cr steel's corrosion rate increased as water cut increased, especially when the water cut exceeded 70 vol.-%. Serious general corrosion and local attack occurred on the 3Cr samples in a 0.2 MPa CO 2 and 139552 mg × l −1 Cl − corrosion environment. The product layer structure of 3Cr steel in high-salinity brine is demonstrated. When the chloride ion concentration is high enough, the Cr-enriched layer no longer provides sufficient protection against the chloride ion penetration and pitting attacks may occur.