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dc.contributor.authorSriram, G.
dc.contributor.authorDewangan, P.
dc.contributor.authorRamprasad, T.
dc.contributor.authorRamaRao, P.
dc.date.accessioned2013-08-07T12:17:22Z
dc.date.available2013-08-07T12:17:22Z
dc.date.issued2013
dc.identifier.citationJournal of Geophysical Research: Solid Earth, vol.118; 2013; 2258-2274
dc.identifier.otherno
dc.identifier.urihttp://drs.nio.org/drs/handle/2264/4340
dc.description.abstractFor the first time, we report the amplitude variation with angle (AVA) pattern of bottom-simulating reflectors (BSRs) beneath fracture-filled gas hydrate deposits when the effective medium is anisotropic. The common depth point (CDP) gathers of two mutually perpendicular multichannel seismic profiles, located in the vicinity of Site NGHP-01-10, are appropriately processed such that they are fit for AVA analysis. AVA analysis of the BSR shows normal-incidence reflection coefficients of -0.04 to -0.11 with positive gradients of 0.04 to 0.31 indicating class IV pattern. The acoustic properties from isotropic rock physics model predict class III AVA pattern which cannot explain the observed class IV AVA pattern in Krishna-Godavari basin due to the anisotropic nature of fracture-filled gas hydrate deposits. We modeled the observed class IV AVA of the BSR by assuming that the gas hydrate bearing sediment can be represented by horizontally transversely isotropic (HTI) medium after accounting for anisotropic wave propagation effects on BSR amplitudes. The effective medium properties are estimated using Backus averaging technique, and the AVA pattern of BSRs is modeled using the properties of overlying HTI and underlying isotropy/HTI media with or without free gas. Anisotropic AVA analysis of the BSR from the inline seismic profile shows 5-30 percent gas hydrate concentration (equivalent to fracture density) and the azimuth of fracture system (fracture orientation) with respect to the seismic profile is close to 45 degrees. Free gas below the base of gas hydrate stability zone is interpreted in the vicinity of fault system.
dc.language.isoen
dc.publisherAmerican Geophysical Union
dc.relation.requiresJ_Geophys_Res_SE_118_2258.jpg
dc.rightsAn edited version of this paper was published by AGU. Copyright [2013] AGU. To view the published open abstract, go to http://dx.doi.org/10.1002/jgrb.50176
dc.subjectamplitude
dc.subjectanisotropy
dc.subjectgas hydrates
dc.titleAnisotropic amplitude variation of the bottom-simulating reflector beneath fracture-filled gas hydrate deposit
dc.typeJournal Article


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