Corrosion Behavior of 3Cr and 13Cr in High Salinity Brine and CO₂ Environment

In order to evaluate the potential corrosion of casing and tubing in a high-salinity brine and CO2 environment, select material to ensure their safety and economy for full design life, the corrosion behavior of 3Cr and 13Cr steels in the simulated environment was investigated using an autoclave. The characteristics of corrosion products film of 3Cr and 13Cr steels were investigated by X-ray diffraction(XRD), scanning electron microscopy(SEM), energy dispersive X-ray spectrometry(EDS). The rule of 3Cr and 13Cr steel corrosion behavior changing with temperature and water cut was discussed in the aspects of corrosion rate, surface morphology of corrosion scales, sectioning morphology and composition of corrosion scales and samples, surface characteristics of samples after clearing the corrosion scales. Serious corrosion and local incompletion of corrosion scales were found for 3Cr in 0.2 MPa CO2 and 139 552 mg/L Cl- corrosion environment. Mild corrosion behavior was examined in 13Cr steel and no pitting occurred for 13Cr. The experimental results indicated that 3Cr steel can′t meet the requirement for the high-salinity brine and CO2 environment but 13Cr steel can.