Fault Leakage Behaviors and Co2 Migration in Different Types of Geological Carbon Storage

Abstract

Geological carbon storage is considered to be an effective measure to mitigate climate crisis. The method in which CO₂ is stored depends on its phase state and the depth at which it is injected. In this study, the fault-reservoir system is constructed to elucidate the fault leakage behaviors and CO₂ migration in different geological storage environments. Whether CO₂ is buoyant or sinking depends on the fluid density difference between CO₂ and H₂O. When carbon dioxide is injected into deep saline aquifer, CO₂ would preferentially migrate upward along the fault plane due to CO₂ buoyancy forces, and CO₂ plume accumulates beneath the caprock and floats at the top of the reservoir eventually. For CO₂ storage in deep ocean reservoir and volcanic basalt, no upward migration of CO₂ plume is observed during carbon storage. Fault plane is the preferential pathway for carbon downward transportation during ocean-based CO₂ storage, providing a virtually unlimited environment. Compared with deep ocean storage, the much shorter sinking times makes volcanic basalt for carbon storage safer and more effective. It is illustrated that the fluid density difference between CO₂ and H₂O is the decisive factor in determining CO₂ sinking velocity. This investigation of searching CO₂ sinking reservoirs provides a promising alterative reference for remove and storage large volumes of the greenhouse gas.