Objective The cement sheath of CCUS well is exposed to CO2 corrosion environment for a long time,and the cement sheath will be corroded,leading to CO2 leakage.Therefore,it is necessary to predict the corrosion rate.However,the current corrosion prediction models mainly rely on wellbore and semi empirical formulas,which leads to inaccurate prediction of cement sheath corrosion and restricts the research on the prevention and control of cement sheath corrosion in CCUS wells.Methods In response to this issue,a CO2 corrosion depth prediction model was established based on the conservation laws of CO2 and calcium mass.This model analysed the impact of corrosion time,temperature,CO2 partial pressure,water-cement ratio,and corrosion-resistant material dosage on corrosion depth.An evaluation model was also established to rank the degree of influence of these factors.Results The research results indicated that the CO2 corrosion depth increased with the corrosion time,temperature,chloride ion content,CO2 partial pressure,water-cement ratio,and water saturation,and decreased with the cement sheath density and corrosion-resistant material dosage.Additionally,the CO2 concentration within the cement sheath showed a non-linear decrease with the increase in corrosion depth.The strength of the influencing factors was:water saturation＞corrosion resistant material＞water-cement ratio＞cement ring density＞CO2 partial pressure＞corrosion time＞chloride content＞temperature.Conclusion The research results have guiding significance for controlling CO2 carbonization corrosion of cement sheath in CCUS well to ensure well integrity.
国家科技期刊平台
NSTL
万方数据
