Stress Path Evolution Associated With CO2 Storage Reservoirs

Abstract:

Safe storage of CO₂ in geological formations is an essential part of CO₂ sequestration projects. Pressure changes inside the formation cause effective and total stress changes inside and outside of those formations. These changes can bring the reservoir or its surroundings to failure conditions. The existence of faults and weak zones increases the likelihood of failure in rock masses depending on the amount of the injection-induced changes and the formation properties.

This paper discusses the stress changes in different reservoir and injection conditions. Numerical analysis indicates that the pressure buildup can significantly change the total and effective stress and these changes are more severe when faults are present in the formation. Also, the reservoir and caprock experience a greater decrease in the mean effective stress and increase in the deviatoric stress in the footwall and hanging wall of a fault in reverse and normal faulting stress regimes, respectively. The stress path depends on the size of the CO₂ plume, the pressure distribution inside the reservoir, and fault and reservoir properties.