Influence of CO₂/O₂ on the Corrosion Behavior of J55 Tubing Steel in the Water Injection Area of Dingbian Oilfield

Abstract

In order to clarify the influence of a large amount of aggressive CO2 and O2 contained in the oil well produced fluid in the water injection area of Dingbian oilfield on the corrosion behavior of tubing steel and reveal the corrosion characteristics，the electrochemical corrosion behaviors of J55 tubing steel in the oilfield water injection area in the simulated produced water of oil wells and saturated CO2/O2 simulated produced water of oil wells were studied by potentiodynamic polarization curve and electrochemical AC impedance test method，combined with the on-site corrosion hanging ring monitoring method.In addition，the corrosion rate of the sample was calculated by weight loss method，and the corrosion morphology characteristics and product composition of the sample were analyzed.Results showed that CO2 and O2 promoted the cathodic depolarization，and saturated CO2/O2 significantly increased the corrosion current density of J55 tubing steel.The increase of environment temperature accelerated the reaction kinetics，which significantly increased the corrosion current density，but weakened the erosion of CO2 and O2.At 25 °C，the samples exhibited inductive reactance characteristics in the low-frequency region in the simulated produced water of oil wells environment containing saturated CO2/O2，while the Warburg diffusion impedance characteristics occurred in the low-frequency region of the samples in the two media environments at 60 °C.Moreover，the upper tubing of on-site oil well was less corroded than the lower tubing，and the corrosion products were mainly iron oxides and hydroxides.

Keywords

• j55 tubing steel|co₂/o₂corrosion|polarization curve|ac impedance|corrosion hanging ring