Dissociation and self-preservation of gas hydrates in permafrost

Evgeny Chuvilin, Boris Bukhanov, Dinara Davletshina, Sergey Grebenkin, Vladimir Istomin

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    27 Citations (Scopus)

    Abstract

    Gases releasing from shallow permafrost above 150 m may contain methane produced by the dissociation of pore metastable gas hydrates, which can exist in permafrost due to self-preservation. In this study, special experiments were conducted to study the self-preservation kinetics. For this, sandy samples from gas-bearing permafrost horizons in West Siberia were first saturated with methane hydrate and frozen and then exposed to gas pressure drop below the triple-phase equilibrium in the “gas–gas hydrate–ice” system. The experimental results showed that methane hydrate could survive for a long time in frozen soils at temperatures of −5 to −7C at below-equilibrium pressures, thus evidencing the self-preservation effect. The self-preservation of gas hydrates in permafrost depends on its temperature, salinity, ice content, and gas pressure. Prolonged preservation of metastable relict hydrates is possible in ice-rich sandy permafrost at −4 to −5C or colder, with a salinity of <0.1% at depths below 20–30 m.

    Original languageEnglish
    Article number431
    JournalGeosciences (Switzerland)
    Volume8
    Issue number12
    DOIs
    Publication statusPublished - Dec 2018

    Keywords

    • Gas hydrate
    • Ice
    • Methane
    • Permafrost
    • Salinity
    • Self-preservation
    • Temperature

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