The Study On Corrosion Inhibitors In The Environment Of High Temperature And High Pressure H₂ S/CO₂

The environment of gas well down hole in high sulfur and high temperature system (the partial pressures of H₂S and CO₂ are more than 1.5Mpa) is very harsh. But the related oil filed exploitation experience is not rich both at home and abroad. High-alloy steel is generally used greatly in this environment, but the cost of high-alloy steel is too high to be used in oil filed the combination of inhibitor and carbon steel is an effective and low-cost way, so it is very important to develop one effective inhibitor for exploiting the oil in the environment of high sulfur and high temperature.For the harsh corrosive environment of gas well system (the partial pressures of H₂S and CO₂ are more than 1.5Mpa) in high sulfur and high temperature gas filed. Many inhibitor bodies were synthesized and evaluated by weight-loss method in the different corrosion conditions of H₂S/CO₂ including pyridines quaternary ammonium salt, quinolines quaternary ammonium salt, mannich bases and imidazolines quaternary ammonium salt and so on. Quinolines quaternary ammonium salt inhibitor GWS-5 were gained and evaluated in the environment of high temperature and high pressure H₂S/ CO₂ environment by dynamic weight losing method and constant strain SSC test. Corrosion inhibition mechanism of inhibitor GWS-5 for N80 was discussed by SEM and XPS. The results of experiment are as follow.The inhibitor GWS-5 had excellent good corrosion inhibition effects, which can effectively inhibit corrosion of N80 steel under high temperature and pressure H₂S/CO₂ by forming a sorption film on the surface of N80 steel. The organic films are well distributed, dense, stable and do not break down, which restraint the produce of point corrosion and decreases the corrosion rate .The inhibition efficiency could be 97% by using 0.15% quaternary ammonium quinoline inhibitor GWS-5,while the inhibitor have good resistant to stress corrosion and sulfides.