Modeling and molecular simulation of natural gas hydrate stabilizers

Abstract

Uncontrolled decomposition of natural gas hydrate may lead to serious marine geological disasters and air pollution. The model of natural gas hydrate and lecithin was established. The stability mechanism of lecithin to structure hydrate was studied by molecular dynamics simulation. The consistent valence force field (CVFF) and TIP3P potential models are used to define the interaction between CH4-CH4 and water-water species, respectively. The simulations are performed on a combination of a 2 × 2 × 4 unit cell of sI hydrate and a water liquid phase with lecithin. The results of the simulations indicate that lecithin molecules adsorb on the hydrate surface with their hydrocarbon chains crossing and forming a net structure, easily producing the hydrate memory effect, which will narrow the available space for hydrate methane and water movement. Compared to the pure water-hydrate model, the mean square displacement (MSD) values of hydrate methane and water molecules are much lower, indicating that the hydrate dissociates more slowly.