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

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.accessioned2014-09-05T20:26:37Z
dc.date.available2014-09-05T20:26:37Z
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.
dc.identifier.doihttp://dx.doi.org/10.1002/2014JB011236en_US
dc.identifier.urihttps://hdl.handle.net/1911/77147
dc.language.isoengen_US
dc.publisherAmerican Geophysical Union
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.
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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