Electrochemical Behavior in Corrosion of Gathering and Transfer Pipelines for CO₂ Flooding

The corrosion characteristics and electrochemical behaviors of A3 steel in a simulated oil well production fluid (40～80℃,CO2 saturated) with four different oil-bearing rates(0%,10%,15%,25%) were studied using electrochemical testing.The polarization curves showed that in the oil-water emulsion (oil-bearing rate 25%) without CO2 or saturated by CO2,with the increasing temperature from 40 ℃,the corrosion current density Icorr increased and reached maximum at 70 ℃ and then reduced at 80 ℃.In the oil-water emulsion saturated by CO2, with the increasing oil-bearing rate,Icorr decreased.It implied that the crude oil had inhibition effect on the corrosion of A3 steel in the simulated corrosive medium.