Well Technologies for CO2 Geological Storage: CO2-Resistant Cement

Storing carbon dioxide (CO2 ) underground is considered the most effective way for long-term safe and low-cost CO2 sequestration. This recent application requires long-term wellbore integrity. A CO2 leakage through the annulus may occur much more rapidly than geologic leakage through the formation rock, leading to economic loss, reduction of CO2 storage efficiency, and potential compromise of the field for storage. The possibility of such leaks raises considerable concern about the long-term wellbore isolation and the durability of hydrated cement that is used to isolate the annulus across the producing/injection intervals in CO2 -storage wells. We propose a new experimental procedure and methodology to study reactivity of CO2 -Water-Cement systems in simulating the interaction of the set cement with injected supercritical CO2 under downhole conditions. The conditions of experiments are 90°C under 280 bars. The evolution of mechanical, physical and chemical properties of Portland cement with time is studied up to 6 months. The results are compared to equivalent studies on a new CO2 -resistant material; the comparison shows significant promise for this new material.