Enhanced depressurisation for methane recovery from gas hydrate reservoirs by injection of compressed air and nitrogen

Anthony Okwananke, Jinhai Yang, Bahman Tohidi, Evgeny Chuvilin, Vladimir Istomin, Boris Bukhanov, Alexey Cheremisin

    Research output: Contribution to journalArticlepeer-review

    26 Citations (Scopus)

    Abstract

    Enhanced depressurisation for methane recovery from gas hydrate-bearing sediments was experimentally studied by injection of compressed air and nitrogen. Experiments were conducted in simulated sediments (silica sand) from 273.4 K to 283.0 K and initial system pressures ranging from 3.8 MPa to 7.2 MPa before air or nitrogen injection. The results show that injection of air and nitrogen made it possible to implement conventional depressurisation in multiple stages. In each pressure stage, methane hydrate was quickly dissociated by the injected air or nitrogen due to direct shift of the methane hydrate equilibrium phase boundary. Methane hydrate dissociation at high pressures enables methane recovery inside the methane hydrate stability zone. Depressurisation well above the methane hydrate dissociation pressure generated a methane-rich gas phase of up to 90 mol% methane depending on the injected gas. Injection of compressed air or nitrogen provides a potential approach to improve the technical feasibility and economic viability of conventional depressurisation method for methane recovery from most gas hydrate reservoirs with severe conditions such as low permeability or dispersed hydrates.

    Original languageEnglish
    Pages (from-to)138-146
    Number of pages9
    JournalJournal of Chemical Thermodynamics
    Volume117
    DOIs
    Publication statusPublished - Feb 2018

    Keywords

    • Compressed air
    • Depressurisation
    • Gas hydrate
    • Kinetics
    • Methane recovery
    • Nitrogen

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