Molecular dynamics simulations are used to study the replacement behavior of CH4 in the hydrate with CO2 injection. The molecular configurations and microstructure properties are analyzed with the systems containing the gas layer (CO2 or CH4) and the CH4 hydrate layer. It is found that the H2O molecules arrangement of hydrate surface is changed in the replacement process. These H2O molecules of hydrate surface move and reform the solid cages, while H2O molecules of the interfacial transition zone of the gas layer and the hydrate layer present the quasi‐liquid structure. The simulation results indicate the H2O molecules arrangement is affected by the gas molecules in replacement process.
Keywords CH4 hydrate, CH4‐CO2 replacement, molecular dynamics simulation