Evaluation and protection of O2 corrosion in wellbore of Dongsheng gas field
Membrane separation technology for nitrogen production is one of the important means for the recovery of production capacity through the discharge of accumulated liquid and water flooded wells in Dongsheng gas field.But currently,the mobile membrane separation technology produces nitrogen with an O2 content of about 5％.With the increase of injection frequency and injection amount,the problem of O2 corrosion in the tubing string becomes more and more serious.The corrosion mechanism of Dongsheng gas field was clarified through high-temperature and high-pressure dynamic corrosion tests.The results showed that the corrosion rate of N80 material was slightly higher than that of P110 material in the environment containing O2,and the influence of immersion degree on the O2 corrosion rate was:full immersion＞semi immersion＞non-immersion,based on which the optimal O2 corrosion inhibitor was selected.Indoor evaluation tests displayed that the inhibition rate of sodium molybdate & sodi-um gluconate was over 90％;meanwhile,3 on-site test wells achieved good inhibition effects,with a maximum inhibition rate of 73.33％.
nitrogen injectiondrainage gas productionoxygen corrosiontubing stringcorrosion inhibitor
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