模拟工况下高强度套管抗腐蚀性能测试

iming at casing corrosion in ultra-deep well of gas field with high sulfur content, the paper studied corrosion behavior of three high strength casing steels (SM-C110, TP110TS and TP110SS) in simulation working conditions by using four point bending method and dynamic weight loss method in a self-made autoclave. The results show that the four point bend specimens of the three steels did not crack after 720h corrosion test when H2S partial pressure, CO2 partial pressure and total pressure were respectively 10.8, 6.6, 60MPa and the temperature was 120℃. The measured average corrosion rate was 0.11m/a. Therefore high strength casing steel exhibited excellent environmental cracking (EC) resistance in the condition of high temperatures and high pressures. Circulation flow corrosion test show that the average corrosion rate of the three steels was 0.05mm/a in simulation conditions and the corrosion degree of the three steels was low. There is great difference between the corrosion determined by four point bending method and dynamic weight loss method although experimental conditions are the same. The results show that high strength casing has good resistance to cracking but common resistance to electrochemical corrosion. So it was very important to take effective anticorrosion measures for production casing during the exploitation of oil and gas fields.