Development Of Corrosion Inhibitor For Two Phases' Corrosion In GAS Field

The influencing factors on corrosion of mild steel in dioxide carbon environment and CO₂/H₂S environment were studied by weight-loss method in this paper. The results indicate that, in pure CO₂ environment the corosion rate increase with increasing CO₂ pressure; the corrosion rate reaches its maximum value when the temperature is 60°C and the concentration of sodium chloride is 30g/L respectively; Ca²⁺ ions can restrain corrosion, but Mg²⁺and SO₄^2- ions cannot influence the corrosion rate markedly; and in CO₂/H₂S environment, the corrosion rate does not increase remarkably when the temperature is under 60°C; when the temperature is increases from 60°C to 80°C, the corrosion rate increases obviously; and when the temperature increases over 80°C, the corrosion rate increases indistinctly. In the liquid phase, the low concentration H₂S can hold back corrosion, but in high concentration, the corrosion rate increases with the H₂S concentration; in the gas phase the corrosion rate always increased with H₂S concentration.In order to control the corrosion of two phases in gas well and pipeline of transportation, Dihydrothiazole and midazoline derivant were synthesized and mixed with the normal corrosion inhibitors in this paper.