Study On Multi-effect Antioxidant Corrosion Inhibitor

In recent years,as most oilfields enter the middle and late stages of oil recovery,the water content of the produced oil has gradually increased,and the number of corrosion failures of oilfield pipelines caused by dissolved oxygen has gradually increased.Dealing with oxygen corrosion has become an important issue for oilfield corrosion protection.Among the many anti-corrosion measures,corrosion inhibitors are widely used in series pipeline anti-corrosion because of their cost and better effect.In this paper,an anti-oxidant corrosion inhibitor5-(2-hydroxyethyl)-1,3,5-triazine-2-thione(HTT)was designed and screened by quantum chemical simulation and static weight loss method.By compounding HTT with other agents,the ternary compound corrosion inhibitor with better anti-oxygen corrosion inhibition effect was screened out.(1)The optimal synthesis conditions of HTT were obtained by orthogonal experiment,the results are as follows:reaction temperature was 70?,reaction time was 2h,the molar ratio of thiourea:formaldehyde:ethanolamine was 1:2:1.Evaluate the corrosion inhibition performance of HTT by static weight loss method.The results showed that at 50?,adding 50 mg/L of HTT can reduce the corrosion rate of Q235A steel from 0.1486 mm/a to 0.0474 mm/a.(2)The static weight loss method was used to investigate the corrosion inhibition effect of the corrosion inhibitor after the binary compounding of HTT and other agents.The results showed that when HTT was compounded with stannous chloride dihydrate and zinc dihydrogen phosphate,it exhibited a relatively good corrosion inhibition synergistic effect.The optimal process conditions of the ternary compound agent were screened out through orthogonal experiment and the static weight loss method:m(HTT):m(zinc dihydrogen phosphate):m(PBTCA)=5:3:2,at this time,the corrosion inhibition TPP-6 has the best corrosion inhibition effect.When the concentration of TPP-6 reached 100 mg/L,the corrosion rate of Q235A steel in the oilfield sewage simulant at 50?decreased to 0.0201 mm/a,which was 86.47%lower than the 0.1486 mm/a of the blank sample.(3)SEM,EDS,electrochemical experiments,and surface roughness experiments showed that the corrosion degree of steel sheets after adding TPP-6 to the simulated oil field water was significantly reduced,indicating that TPP-6 has good corrosion inhibition performance.The dissolved oxygen curve showed that after adding TPP-6,the decrease rate of dissolved oxygen in the system was significantly reduced,indicating that TPP-6 inhibited the reaction of oxygen with carbon steel.The scale inhibition rate of CaCO₃showed that when the concentration of TPP-6 was 15 mg/L,the scale inhibition rate of CaCO₃reached 91.27%,indicating that TPP-6has both corrosion and scale inhibition effects and can be used in high salinity In the system,both oxygen corrosion and under-scaling corrosion are inhibited.(4)In the simulation experiments of other working conditions,TPP-6 can still play a relatively good performance in the face of the co-existence of scale corrosion,bacterial corrosion and dissolved oxygen corrosion as well as the co-existence of oxygen and carbon dioxide,showing good multipotency.