Synthesis And Evaluation Of Corrosion Inhibitor Resistance To High Temperature And High Salt H₂S/CO₂ Corrosion

Carbon dioxide?CO₂?is a principal greenhouse gas.CO₂ is also used in the oil industry to improve oil recovery because it can dissolve in crude oil in large quantities,causing the crude oil to expand,lowering oil viscosity,lowering interfacial tension,and increasing oil fluidity.At the same time,the production of hydrogen sulfide?H₂S?gas is accompanied by oilfield production.When H₂S and CO₂ dissolves in a mixture of crude oil and water,the resulting acidic solutions can corrode the carbon steel used in pipelines.There are few inhibitors have been developed to prevent hydrogen sulfide/carbon dioxide from corroding steel pipes.The paper is aimed at the high temperature H₂S/CO₂ corrosion problem of Tahe Oilfield,the chitosan oligosaccharide,glycidyl trimethylammonium chloride,p-methoxybenzaldehyde and n-valeraldehyde are used as raw materials to synthesize green corrosion inhibitors?SDH-2 and SDH-3?.Infrared spectroscopy and nuclear magnetic resonance analysis showed that the corrosion inhibitors were successfully prepared.The corrosion inhibitors?SDH-2 and SDH-3?was characterized by IR and 1H-NMR and its inhibition behavior for P110 steel was evaluated.The inhibition effect of SDH-2and SDH-3 on P110carbon steel corrosion was researched by gravimetric measurement,scanning electron microscope?SEM?,atomic force microscopy?AFM?and electrochemical studies.The results showed that the total pressure was 15 MPa,and the partial pressures of H₂S,CO₂ and N₂ were 1 MPa,5 MPa and 9 MPa,respectively,when SDH-2 dosage was 100 mg/L,its corrosion inhibition efficiency was 85.79%,when SDH-3 dosage was 100 mg/L,its corrosion inhibition efficiency was 79.42%.The inhibition efficiency of 100 mg/L SDH-2 and 100 mg/L SDH-3 measured by Tafel were 90.04%and 87.94%,respectively.All test results show that SDH-2 molecules have better corrosion inhibition than SDH-3.Potentiodynamic polarization results indicated that both compounds are mixed type inhibitors.Isothermal adsorption model and electrochemical impedance spectroscopy?EIS?measurements show that the inhibitors adsorbed on P110steel surface successfully.The adsorption ability on the P110 steel surface was evaluated by calculating the quantum chemical parameters of inhibitor molecules.At the same time,by compounding SDH-2 with Thiourea?TU?,the corrosion inhibition rate can reach91.94%,compared with the field corrosion inhibitors KY-3,TA801,HC-1,the experiments show that the corrosion inhibitor SDH-2 have the better corrosion inhibition efficiency.