Numerical Simulation of Natural Gas Hydrate Development by Decompression Assisted CO2 Replacement Method

Based on the study of the properties of natural gas hydrate characteristics and displacement mechanism, the mathematical model of natural gas hydrate exploitation by decompression assisted CO2 replacement method has been established. Based on the numerical simulation to inject different temperature of CO2 hydrate reservoir, this paper analyzed the process of hydrate reservoir, and lowered the change rule of the bottom hole pressure hydrate reservoir. The simulation results show that the heat transfer area of CO2 in the reservoir expands with the increase of injection temperature, and there is a certain limit. The gas production rate of natural gas hydrate increases with the increase of reservoir temperature. The larger the pressure difference is, the greater the assisting force for hydrate decomposition is, and the better the decomposition effect of natural gas hydrate is. However, if the pressure difference is too large, the stability of reservoir will be damaged. The mathematical model of CO2 replacement method for gas hydrate mining established in this paper and the discovered change rule provide theoretical and technical support for the later research and commercial exploitation of natural gas hydrate.