The impact of lithologic heterogeneity and focused fluid flow upon gas hydrate distribution in marine sediments

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dc.citation.journalTitleJournal of Geophysical Research: Solid Earthen_US
dc.citation.volumeNumber119en_US
dc.contributor.authorChatterjee, Sayantanen_US
dc.contributor.authorBhatnagar, Gauraven_US
dc.contributor.authorDugan, Brandonen_US
dc.contributor.authorDickens, Gerald R.en_US
dc.contributor.authorChapman, Walter G.en_US
dc.contributor.authorHirasaki, George J.en_US
dc.date.accessioned2014-09-05T20:26:37Zen_US
dc.date.available2014-09-05T20:26:37Zen_US
dc.date.issued2014en_US
dc.description.abstractGas hydrate and free gas accumulation in heterogeneous marine sediment is simulated using a two-dimensional (2-D) numerical model that accounts for mass transfer over geological timescales. The model extends a previously documented one-dimensional (1-D) model such that lateral variations in permeability (k) become important. Various simulations quantitatively demonstrate how focused fluid flow through high-permeability zones affects local hydrate accumulation and saturation. Simulations that approximate a vertical fracture network isolated in a lower permeability shale (kfracture >> kshale) show that focused fluid flow through the gas hydrate stability zone (GHSZ) produces higher saturations of gas hydrate (25–70%) and free gas (30–60%) within the fracture network compared to surrounding shale. Simulations with a dipping, high-permeability sand layer also result in elevated saturations of gas hydrate (60%) and free gas (40%) within the sand because of focused fluid flow through the GHSZ. Increased fluid flux, a deep methane source, or both together increase the effect of flow focusing upon hydrate and free gas distribution and enhance hydrate and free gas concentrations along the high-permeability zones. Permeability anisotropy, with a vertical to horizontal permeability ratio on the order of 10−2, enhances transport of methane-charged fluid to high-permeability conduits. As a result, gas hydrate concentrations are enhanced within these high-permeability zones. The dip angle of these high-permeability structures affects hydrate distribution because the vertical component of fluid flux dominates focusing effects. Hydrate and free gas saturations can be characterized by a local Peclet number (localized, vertical, focused, and advective flux relative to diffusion) relative to the methane solubility gradient, somewhat analogous to such characterization in 1-D systems. Even in lithologically complex systems, local hydrate and free gas saturations might be characterized by basic parameters (local flux and diffusivity).en_US
dc.identifier.citationChatterjee, Sayantan, Bhatnagar, Gaurav, Dugan, Brandon, et al.. "The impact of lithologic heterogeneity and focused fluid flow upon gas hydrate distribution in marine sediments." <i>Journal of Geophysical Research: Solid Earth,</i> 119, (2014) American Geophysical Union: http://dx.doi.org/10.1002/2014JB011236.en_US
dc.identifier.doihttp://dx.doi.org/10.1002/2014JB011236en_US
dc.identifier.urihttps://hdl.handle.net/1911/77147en_US
dc.language.isoengen_US
dc.publisherAmerican Geophysical Unionen_US
dc.rightsArticle is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.en_US
dc.subject.keywordgas hydrateen_US
dc.subject.keywordfocused fluid flowen_US
dc.subject.keywordlithologic heterogeneityen_US
dc.subject.keywordpermeability conduitsen_US
dc.subject.keywordlocal fluid fluxen_US
dc.subject.keywordnumerical modelingen_US
dc.titleThe impact of lithologic heterogeneity and focused fluid flow upon gas hydrate distribution in marine sedimentsen_US
dc.typeJournal articleen_US
dc.type.dcmiTexten_US
dc.type.publicationpublisher versionen_US
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