Numerical Modelling of CO 2 Gas Injection with Hydrate Formation: A Case Study in the Laboratory-Scale Sand Sediment

Carbon capture and storage (CCS) is a potentially effective countermeasure against global warming. While CO2 aquifer storage is currently considered as a mainstream CCS technology, further CCS options will increase the capacity of CO2 storage. This study focuses on CO2 storage in the form of a gas hydrate. In this method, the CO2 is injected into sub-seabed sand sediments under high pressure and low temperature, allowing CO2 to form hydrate. A large amount of CO2 is sequestered as hydrate in the sediments by reactions with pore water. However, the hydrate formation itself can easily reduce permeability, leading to gas flow blockage. To maximize sequestration space, it is important that the injected gas expands over a wide area while maintaining sufficient permeability. This study models a gas-water two-phase flow with hydrate formation in sand sediment to reveal the mechanism of blockage due to hydrate formation, and simulates a laboratory-scale hydrate formation experiment in sand sediment.