CO2 Hydrate Decomposition and Spatial Temperature Characteristics under Sudden Ambient Temperature Rise

Safety issues in CO2 hydrate storage systems caused by global warming have become a key constraint to the large-scale development and application of this technology. Understanding CO2 hydrate decomposition characteristics and spatial temperature distribution under sudden ambient temperature rise can provide a fundamental basis for controlling decomposition under extreme conditions. This study investigates the CO2 hydrate decomposition characteristics and spatial temperature distribution of different hydrate amounts and ambient temperatures. It was found that the CO2 hydrate decomposition process undergoes a short hydrate stabilization stage, a rapid hydrate decomposition stage, and a slow decomposition stage. In the latter two stages, the relationship between the CO2 hydrate decomposition amount and time follows the equation y = y0 + A × e(R0×x). At the same initial ambient temperatures, y0 and R0 are negatively correlated with the initial hydrate amount, while A is positively correlated with it. An isothermal decomposition stage appears during the rapid decomposition of CO2 hydrate. As the initial hydrate amount increases, the isothermal stage is extended. The duration and temperature of the isothermal phase transition depend on spatial position and ambient temperature. The findings of this work provide significant theoretical support and practical guidance for the safe and stable sequestration of CO2 hydrate.