A Study On Mechanism And Influencing Factors Of Elemental Sulfur Corrosion

The oil and gas field has become one of the most serious corrosive environments due to the elemental sulfur.Especially,elemental sulfur is hydrolyzed to produce a strong adsorption of H₂S,HS^-and S^2-at high temperature??80??which will cause serious corrosion.At high pressure,high temperature and high sulfur,we use the coupon immersion,SEM,EDS to study the elemental sulfur corrosion mechanism and the effect of temperature,Cl^-,CO₂ presssure,H₂S pressure on elemental sulfur corrosion on P110 steel.The corrosion rate results show the corrosion rates rapidly increase with increasing temperature.The corrosion products are Fe_1-XS and CaCO₃ at low temperatures.When the temperature goes to 150?,the corrosion product is Fe_1-XS.The chemical reaction speeds up at180?,the corrosion product Fe_1-XS content increases.With the increasing Cl^-concentration,the corrosion rate decreases at first,and then increases,finally decreases.At low Cl^-concentration,the corrosion product is Fe_1-XS.At10g/L,Carbonates deposit to slow down the corrosion rate.At the Cl^-concentration of 50g/L,the corrosion product of Carbonates reduce,lead to the aggravating of the sulfur corrosion.With the increasing of CO₂ pressure,the corrosion rates increase at first,and then decrease.The biggest value of corrosion rate occurs when the CO₂ pressure is 1MPa.The corrosion products are Fe_1-XS and?Ca,Fe?CO₃ at low CO₂ pressure.When the CO₂ pressure goes to 1MPa,the corrosion products are Fe_1-XS.When the CO₂ pressure continues increasing,the corrosion products are Fe_1-XS and some?Ca,Fe?CO₃.With increasing H₂S pressure,the corrosion rates rapid increase.The corrosion products are Fe_1-XS and Ca CO₃ at low H₂S pressure.At 1MPa and 1.5MPa H₂S pressure,the corrosion products are mainly Fe_1-XS.The direct and hydrolysis reaction corrosion mechanism exist at the same time at this experimental condition.