Experimental and Numerical Investigations into CO₂ Interactions with well Infrastructure and its Impact on Long term Well Integrity

Research presented in this paper investigated the sealing behaviour of the microannulus at cement-casing interface under simulated subsurface reservoir pressure and temperature conditions and used the experimental findings to develop a methodology to assess the overall integrity of the wellbore region during CO₂ storage. A full scale wellbore experimental test set up was constructed for use under elevated pressure and temperature conditions encountered in typical CO₂ storage sites. Three test cases representing different reservoir depth, temperature and brine salinities were analysed through long term experiments with continuous flow of CO₂ through the microannulus. Relationships for the reduction in permeability of the microannulus with time were derived from the experimental data for use in reservoir simulations on a realistic reservoir model for all three scenarios to assess the impact of leakage from the wellbore casing and cement interface on integrity of CO₂ storage.