Reservoir Simulation Of Gas Production From Natural Gas Hydrate Sediments

Natural gas hydrate has been considered as an alternative energy resource for the new century, being received a great attention from academics and industry in recent years. A fundamental study is important and needed in order to develop theory and useful techniques for gas production from natural hydrate (subsea) sediments. Lab experiment and numerical simulation are efficient methods for the assessment of gas reserves in hydrate reservoirs and the feasibility study of different gas production techniques in proposal.Gas production rates have been measured in the experiments at simulated subsea sediment conditions for methane hydrate dissociation. Based on the reaction kinetics theory of chemicals, the experiment data were analysed and the fundamental parameters of gas hydrate dissociation kinetics, namely the apparent hydrate dissociation rate constant and activation energy have been obtained.In analysis of gas hydrate dissociation and multiphase flow through porous medium, a mathematical model of hydrate dissociation and gas production in subsea sediment bearing with natural gas hydrate has been developed. This model can provide a theory foundation for the reservoir simulation of gas hydrate production.A three-phase (aqueous, solid hydrate and gaseous) and three-component (water, methane hydrate and methane) model has been established to simulate the process of methane hydrate disassociation and gas production using a conventional reservoir simulation software. The model has a unique feature that the phase and behavior of solid hydrate is simulated by pseudo-component and phase altering methods. Hydrate dissociation and gas production was aasumed by depressurization mechanism only. Comparison between the simulation results and experiment data was carried out and the simulation model has been verified. The simulation model has been applied to a conceptual gas hydrate reservoir model in comparison with conventional gas reservoirs with similar gas reserves for economic analysis and feasibility studies.