Pipeline Steel, The Containing Of Co <sub> 2 </ Sub> / H <sub> 2 </ Sub> S High Temperature And Pressure In Aqueous Media, The Corrosion Behavior And Protective Role

Autoclave tester was used to study corrosion behavior of N80 steel and N80S steel in simulated oil well produced water contained CO2 and H2S at high temperature and high pressure. High temperature reference electrode was developed to study the CO2 corrosion behavior of N80 steel in ambient condition. Corrosion prevention methods were also studied in this paper, including the metal diffusion and inhibitor injection techniques.The results of autoclave tests shows: (1) with the H2S partial pressure increasing, the corrosion rate of N80 steel varies as a similar parabola curve, and a peak corrosion rate occurs at 3000mg/m3 H2S; whereas the corrosion rate of N80S steel decreases monotonously. (2) CO2 partial pressure affects the corrosion rate of N80 steel and N80S steel in the same way. The higher the CO2 partial pressure is, the severer the corrosion is. But the corrosion rate of N80 steel is severer than that of N80S steel. (3) with the content of Cl- increasing, the corrosion rate of N80 steel and N80S steel increase firstly and decrease after the peak corrosion rate. (4) with the content of Ca2+, Mg2+ increasing, the corrosion rate of N80 steel and N80S steel increases in the same way. SEM, X-Ray diffraction techniques were used to analysis the test results.EIS and Potentiodynamic techniques were used to detect the stability of Ag/AgCl reference electrode. The result showed that the difference between Ag/AgCl and SCE reference electrode is about 45±1mV. It met the requirement of electrochemical measurement techniques.EIS and Potentiodynamic techniques were used to evaluate the methods for preventing CO2 corrosion, including metal diffusion and inhibitor injection. The results showed that the inhibitor imidazoline and Zn diffusion treatment techniques could effectively prevent the CO2 corrosion.