Print Email Facebook Twitter Microscopic insights into poly- and mono-crystalline methane hydrate dissociation in Na-montmorillonite pores at static and dynamic fluid conditions Title Microscopic insights into poly- and mono-crystalline methane hydrate dissociation in Na-montmorillonite pores at static and dynamic fluid conditions Author Fang, B. (China University of Geosciences, Wuhan) Lü, Tao (China University of Geosciences, Wuhan) Li, Wei (China University of Geosciences, Wuhan) Moultos, O. (TU Delft Engineering Thermodynamics) Vlugt, T.J.H. (TU Delft Engineering Thermodynamics) Ning, Fulong (China University of Geosciences, Wuhan) Date 2024 Abstract Knowledge on the kinetics of gas hydrate dissociation in clay pores at static and dynamic fluid conditions is a fundamental scientific issue for improving gas production efficiency from hydrate deposits using thermal stimulation and depressurization respectively. Here, molecular dynamics simulations were used to investigate poly- and mono-crystalline methane hydrates in Na-montmorillonite clay nanopores. Simulation results show that hydrate dissociation is highly sensitive to temperature and pressure gradients, but their effects differ. Temperature changes increase thermal instability of water and gas molecules, leading to layer-by-layer dissociation from the outer surface. Under flow conditions, laminar flow predominates in nano-pores, and non-Darcy flow occurs due to clay-fluid interactions. Viscous flow disrupts hydrogen bonding at the hydrate surface, enhancing kinetic instability of water. Grain boundaries of polycrystalline hydrates are less stable compared to bulk phases and preferentially decompose, forming new dissociation fronts. This accelerates dissociation compared to monocrystalline hydrates. Fracture occurs at the grain boundaries of polycrystalline hydrate in the fluid, resulting in separate hydrate crystal grains. This fracture process further accelerates hydrate dissociation. In flow systems, methane nanobubbles form in fluid and readily transport with fluid flow. Unlike surface nanobubbles at static conditions, these liquid nanobubbles exhibit mobility. The findings of this study can contribute to a better understanding of the complex phase transition behavior of hydrate in confined environment, and provide theoretical support for improving production control technology. Subject Dissociation behaviorsMolecular simulationNa-montmorillonite porePoly- and mono-crystalline hydratesStatic and dynamic fluid conditions To reference this document use: http://resolver.tudelft.nl/uuid:0b60e20e-0a0a-476f-8e36-d09db39a28bd DOI https://doi.org/10.1016/j.energy.2023.129755 Embargo date 2024-05-27 ISSN 0360-5442 Source Energy, 288 Bibliographical note Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public. Part of collection Institutional Repository Document type journal article Rights © 2024 B. Fang, Tao Lü, Wei Li, O. Moultos, T.J.H. Vlugt, Fulong Ning Files PDF 1_s2.0_S0360544223031493_main.pdf 21.51 MB Close viewer /islandora/object/uuid:0b60e20e-0a0a-476f-8e36-d09db39a28bd/datastream/OBJ/view