Molecular dynamics simulation of sI methane hydrate under compression and tension

Abstract

<jats:title>Abstract</jats:title><jats:p>Molecular dynamics (MD) analysis of methane hydrate is important for the application of methane hydrate technology. This study investigated the microstructure changes of sI methane hydrate and the laws of stress–strain evolution under the condition of compression and tension by using MD simulation. This study further explored the mechanical property and stability of sI methane hydrate under different stress states. Results showed that tensile and compressive failures produced an obvious size effect under a certain condition. At low temperature and high pressure, most of the clathrate hydrate maintained a stable structure in the tensile fracture process, during which only a small amount of unstable methane broke the structure, thereby, presenting a free-motion state. The methane hydrate cracked when the system reached the maximum stress in the loading process, in which the maximum compressive stress is larger than the tensile stress under the same experimental condition. This study provides a basis for understanding the microscopic stress characteristics of methane hydrate.</jats:p>

Mechanical Properties of a Structure I CO2–CH4 Heteroclathrate Hydrate: Insight from Molecular Dynamics Simulations

“…5,47,48 The atomic model of the sI hydrate with a 3 × 3 × 10 supercell is constructed for mechanical tests. 4,9 To reveal the effects of guest molecules on the mechanical properties of hydrates, the CO 2 saturation x is set to be 0.0, 0.25, 0.5, 0.75, and 1.0, separately. Water cages are fully occupied by guest molecules.…”

“…2,5,7,37,42,49−53 The van der Waals interactions are calculated by the 12−6 Lennard−Jones potential. 9,37 Pair interactions between different types of atoms are determined using Lorentz and Berthelot combining rules. 54−56 The long-ranged electrostatic interactions are calculated in the particle−particle− particle−mesh (PPPM) method.…”

“…2 Unfortunately, the complex occurrence mechanism and heterogeneity of the gas hydrate greatly limit the study of its properties. 4,9,25 The stability, especially the mechanical stability, remains a big challenge in the process of natural gas hydrate recovery. 1,7,26 Recent studies have mainly focused on the mechanical properties of pure CH 4 and CO 2 hydrates.…”

Molecular Dynamics Simulation of the Effects of Methane Hydrate Phase Transition on Mechanical Properties of Deep‐Sea Methane Hydrate‐Bearing Soil

“…where μ is the potential energy; C is an energy-conversion constant, q is the partial charge, and ε is the dielectric constant. r ij is the distance between two interplay particles i and j, and σ is the distance at which the particle-particle energy is zero [24]. e force field parameters are given in Table 1 [25, 27, 29].…”

“…Li et al studied the effects of different thermodynamic parameters, temperatures, pressure, and gas concentrations on methane hydrate dissociation with the MD method [23]. Wang et al investigated the microstructure changes and mechanical properties of methane hydrate under the condition of compression and tension by using MD simulation [24]. Accurately understanding the microscopic deterioration mechanism could help us to exploit and utilize MHBS in the right way.…”