Numerical Simulations of Decomposition of Hydrate Particles in Flowing Water Considering the Coupling of Intrinsic Kinetics with Mass and Heat Transfer Rates

During the hydrate exploitation in a shallow marine layer by the mechanical crushing, the hydrate particle decomposition in a wellbore is one of the most concerning problems. In this research, a hydrate dynamic decomposition model coupling intrinsic kinetics with mass and heat transfer rates was established. The model can simulate the hydrate particle decomposition process in flowing water. By comparison, the model calculated results are in good agreement with the measured values. The numerical simulation results show that hydrate decomposition is a non-isothermal process. In the early stage, the hydrate decomposition rate mainly depends on the heat transfer rate. However, it is mainly affected by the hydrate intrinsic kinetics in the late stage. In contrast, the mass transfer rate has little effect on it during the whole decomposition process. By analyzing the influence of sensitivity parameters, it can be found that the activation energy has an important impact on the hydrate decomposition rate, and the hydrate decomposition rate constant decreases significantly at E / R > 9000 K. Increasing the water flowing rate is beneficial to the dissolution of hydrates. System temperature and pressure are two significant factors that directly affect the hydrate decomposition rate, and increasing the temperature or reducing the pressure can effectively increase the hydrate decomposition rate.