Critical Corrosion Factors for J55 Tubing Steel in a Simulated Annulus Environment of CO2 Injection Well
CO2-enchanced oil recovery technology has been widely used to enhance the profitability of oil fields.The leakage of CO2 into the annulus environment results in the formation of strong corrosive annulus fluid there,which is ineluctable.Due to the fluctuations of annulus environmental parameters in the practice,therefore,to simulate the annulus environment in the laboratory may be very difficult.Based on the parameters of the real annulus environment,the impact of total pressure,partial pressure of CO2(PCO2),pH value and temperature(T)etc.,on the corrosion behavior of J55 steel are investigated by means of numerical simulation in terms of the parameters,electrochemical test and correlation analysis.Results shows that the PCO2 and T are the critical factors influencing corrosion behavior.The Spearman correlation coefficient(r)between PCO2 and charge transfer resistance(Rct)is-0.623,where the significant level is 0.013(2-tailed),which means that the Rct is significantly correlated with the PCO2.The increasing PCO2 can decrease the pH value of the simulated annulus environment and accelerate the corrosion of J55 steel.The r between T and Rct is-0.692,where the significant level is 0.004(2-tailed),which means that the Rct is significantly correlated with the T.The decreasing temperature can reduce the reaction activity of J55 steel,mitigate the corrosion and restrict the formation of FeCO3 scale.The initial pH of the simulat-ed solution has a little promoting effect on the corrosion of J55 steel,which may be covered by the effect of T and PCO2.
materials failure and protectionCO2 corrosionelectrochemicalJ55 steelannulus envi-ronment
万方数据
