Study of effective parameters for enhancement of methane gas production from natural gas hydrate reservoirs

Natural gas hydrate resources have become the major source of energy in the second half of 21 st century. Gas production and fluid behavior in natural gas hydrate reservoirs are different from conventional ones. There are three major methods for methane decomposition such as depressurization, thermal stimulation and inhibitor injection. However, CO2 substitution can also be introduced as an alternative method to inject in sediments containing gas hydrate. All these methods tend to imbalance equilibrium condition via temperature and pressure variation in order to fulfill hydrate decomposition process. This study aims to simulate depressurization method for gas production from a hydrate gas bearing layer. Hence, a sensitivity analysis of reservoir parameters includes porosity, permeability, hydrate saturation, hydrate thickness layer; pressure and temperature of single well hydrate model were investigated to determine how these parameters impact on gas production. Results show that depressurization is an efficient method for gas production from hydrate bearing sediments. Through sensitivity analysis, it has been concluded that if properties of a hydrate layer such as porosity and permeability become greater, methane production will be increased significantly. Moreover, results investigate that the rate of hydrate dissociate is strongly dependent on pressure reduction, and it has a reverse relationship with bottomhole pressure and reservoir temperature. (C) 2019, Institute of Process Engineering, Chinese Academy of Sciences. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co., Ltd.