Molecular Simulation Of Inhibiting Hydrate Formation By Kinetic Inhibitors

As a new kind of energy,natural gas hydrate has attracted more and more research interest because of its high efficiency and cleanness.In addition,the hydrate formed in the process of oil and gas production,easy to plug the circulation pipe or lead pressure fluctuations,is a major risk of security operations.Hydrate inhibitor is usually used to inhibit hydrate formation.Kinetics inhibitors have become a hotspot in research for its economic and efficiency.However,the mechanism of action of hydrate inhibitor is not clear,which restricts the further development and application of kinetic inhibitors.Molecular simulation can be used to analyze the structure and motion characteristics of the simulation system from the micro level,and provide a new means to study the mechanism of the kinetic inhibitor.The hydrate-inhibitor solution model was established by molecular dynamics method.The interaction between hydrate kinetic inhibitor molecules and water molecules in the model of type I methane hydrate aqueous solution was simulated at 245.2K,253.2K and 258.2K,respectively.There are four different kinetic inhibitors(PVP,PVCap,PMC,and novel kinetic inhibitors YZ)added to the hydrate aqueous solution.The influence of the molecular structure of the inhibitor on the effect of the inhibitor was analyzed by calculation of the self diffusion coefficient and the hydrogen bond.In addition,the hydrate cavity-inhibitor solution model was constructed,and the process of adsorbing methane gas molecules in the hydrate cage was simulated at 245.2K.By analyzing the parameters such as the structure and energy change of each component in the simulation system,the effect of the hydrate kinetic inhibitor on the methane molecules entering the cage was analyzed.The results show that the effect of the hydrate kinetic inhibitor is related to the dissolution characteristics of the inhibitor molecule in the solution.The YZ moleculars that both have annular structure and chain structure can effectively reduce the diffusivity of water molecules in solution.In the process of hydrate grew up,YZ molecules and PMC molecules both can have good inhibitory effect for they can effectively delay the time that hydrate crystal cell grows to near size.The PVP molecules and PVCap molecules with ring structure can effectively prevent the methane molecules from entering the cage cavity.In the initial stage of hydrate nucleation,the PVP molecules and PVCap molecules can play an effective inhibition effect.