Research On Corrosion Mechanism And Corrosion Inhibition Technology Of Hydrogen Sulfide In Natural Gas Gathering And Transportation System

Current,Puguang gas field is one of the worst corrosion circumstance and high acid domestic gas field.The range of the content for methane,H₂S and CO₂ in natural gas from Puguang gas field are 71.87%⁷3.51%,15.48%¹6.87%,9.14%¹0.05%,respectively.High content of H₂S and CO₂ of the natural gas is come from Puguang gas field.The surface wellhead pressure?30MPa?and the temperature of surface gathering system?55°C?are cracking sensitive area with hydrogen sulfide stress corrosion.What more serious is that,serious security risks are arise from a large number of sulfur element deposition for the ground gathering and transportation system of normal operation and safety.Domestic and imported L360 anti-sulfur steel pipe is adopted for the gathering and transportation system pipeline of Puguang gas field,and the inside of pipe is bare,and the protection was implemented merely by corrosion inhibitor.Therefore,the effect of corrosion inhibitor protection has becoming only guarantee for the gathering and transportation system pipeline safe operation.In this program,in view of the existing problem,and further enhance application efficiency of corrosion inhibitor,and the requirement of cut cost,the investigation of the optimization control technology for the gathering and transportation was operated based on the condition of corrosion inhibitor actual applied in the main body of the Puguang gas field and the main unit of the Dawan block.Acquirement results is shown as follows:an acceleration effect of L360 carbon steel corrosion by sulfur deposition was shown in low temperature?30⁶0°C?.The causal relationship between the corrosion rate and acceleration effect of sulfur deposition and sulfur-iron combination was exhibited.The catalytic effect of sulfur deposition corrosion have a connection with the partial pressure of hydrogen sulfide/carbon dioxide in corrosion environment.In high acidic condition,an obvious effect was displayed by galvanic corrosion in the surface of carbon steel,and the speed of above-mentioned corrosion is connection with the combination of sulfur-iron.Ferrous sulfide surface film which exist in the surface of L360 carbon steel was destroyed by sulfur deposition.The corrosion of corrosion inhibitor is very limited as for the formation of sulfur-iron carbon steel.The corrosion inhibitor effect is better than that of the Puguang main body corrosion inhibitor.A good mutual effect of corrosion inhibitor was exhibited between Puguang main body and Dawan,and complex effect of them is positive.Corrosion inhibitor of Puguang main body and Dawan combined with dissolved sulfur agent show a slight negative synergies.Local corrosion was triggered for the pre-film corrosion inhibitor due to which unconspicuous negative synergies.