Effect of Thermal Cycling on Well-bore Integrity during CO₂ Injection

One of the primary concerns of the CO
2
capture and storage is to ensure the well bore integrity.
Due to the temperature variations from the surface to the underground storage locations, the well
bore materials are subjected to thermal cycling operations, which can affect the sealing and zonal
isolation. Although few studies have been conducted to investigate the well bore integrity during
thermal cycling, a systematic investigation on thermally induced expansion and contraction
affecting the debonding and cracking of the well barrier materials has not yet been performed. In
this work, we have analyzed the thermo-mechanical characteristics of the well barrier materials
undergoing repeated thermal cycling using a multiscale, multiphysics platform named GEOS. A
finite element solver was used for geomechanics and a finite volume solver was used for thermal
diffusion. Results of the initiation and propagation of fractures due to temperature variations in
the cement sheath are presented. Preliminary results indicate that the debonding occurs during
the cooling period and the cracking occurs during the heating period. In future, the simulation
results will be calibrated and compared with experimental data from SINTEF Petroleum
Research group.