Corrosion inhibition of N80 steel simulated in an oil field acidification environment

摘要

In this paper, the corrosion process of acidizing fluid (10% HCl + 8% HBF4) in the production stringwas analyzed according to the acidizing procedure of the running pipe column. The amount ofcorrosion inhibitor, concentration of displacement fluid (NH4Cl) and off-time (H) were investigatedvia an orthogonal design method to analyze the influence of the inhibition of acid corrosion of theimmobile pipe string to confirm the main factors for corrosion of the oil tube. The results demonstratedthat the amount of inhibitor was key to avoid corrosion of the immovable string by acidizing fluid. Thecorrosion and inhibition properties of N80 steel in fresh acid and residual acid solution were studiedthrough electrochemical measurements and immersion tests. In addition, the corrosion morphology ofthe corrosion product was examined by scanning electron microscopy (SEM). The results showed thatthe N80 steel was more seriously corroded in the residual acid than in fresh acid. The pipe string alsowas corroded by the high-concentration acid liquid during acidification flow-back of the immobilepipe string. Therefore, effective measures should be taken to reduce corrosion due to residual acid onthe pipe during the initial stage of acidizing flow-back.