Well integrity analysis of injection wells during CO2 sequestration

CO2 leakage along wellbore is one big risk during the process of CO2 sequestration, and therefore it is necessary to evalu-ate the well integrity prior to the injection of CO2. A numerical model is used to analyze the impact of temperature decrease and salt rock creep on injection well integrity in this process of CO2 injection and obtain a critical temperature drop value. The method consists of three main steps: simulation of drilling process, simulation of salt creep and simulation of temperature decrease. The outcome includes the variation of stress and displacement across the casing and cement sheath. The results show that under some circumstances the micro-annulus between casing and cement sheath can be compensated by salt creep or even self-healed. Besides, appropriate materials should be selected to suit the low temperature during the injection process.This method is going to be applied in one large-scale CO2 sequestra-tion and enhanced gas recovery project in Germany.