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FORMATION OF THE BOTTOM-SIMULATING REFLECTOR AND ITS LINK TO VERTICAL FLUID FLOW

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dc.contributor.author Haacke, R. Ross
dc.contributor.author Westbrook, Graham K.
dc.contributor.author Hyndman, Roy D.
dc.date.accessioned 2008-07-21T20:18:47Z
dc.date.available 2008-07-21T20:18:47Z
dc.date.issued 2008-07
dc.identifier.citation Haacke, R. Ross; Westbrook, Graham K.; Hyndman, Roy D. 2008. FORMATION OF THE BOTTOM-SIMULATING REFLECTOR AND ITS LINK TO VERTICAL FLUID FLOW. Proceedings of the 6th International Conference on Gas Hydrates (ICGH 2008), Vancouver, British Columbia, CANADA, July 6-10, 2008. en
dc.identifier.uri http://hdl.handle.net/2429/1050
dc.description.abstract Many places where natural gas hydrate occurs have a regionally extensive, bottom-simulating seismic reflector (BSR) at the base of the gas hydrate stability zone (GHSZ). This reflection marks the top of an underlying free-gas zone (FGZ). Usually, hydrate recycling (that produces gas as the stability field moves upward relative to sediments) is invoked to explain the presence and properties of the sub-BSR FGZ. However, this explanation is not always adequate: FGZs are often thicker in passive-margin environments where hydrate recycling is relatively slow, than in convergent-margin environments where hydrate recycling is relatively fast (e.g. Blake Ridge compared with Cascadia). Furthermore, some areas with thick FGZs and extensive BSRs (e.g. west Svalbard) have similar rates of hydrate recycling to northern Gulf or Mexico, yet the latter has no regional BSR. Here we discuss a gas-forming mechanism that operates in addition to hydrate recycling, and which produces a widespread, regional, BSR when gas is transported upward through the liquid phase; this mechanism is dominant in tectonically passive margins. If the gas-water solubility decreases downward beneath the GHSZ (this occurs where the geothermal gradient and the pressure are relatively high), low rates of upward fluid flow enable pore water to become saturated in a thick layer beneath the GHSZ. The FGZ that this produces achieves a steady-state thickness that is primarily sensitive to the rate of upward fluid flow. Consequently, geophysical observations that constrain the thickness of sub-BSR FGZs can be used to estimate the regional, diffuse, upward fluid flux through natural gas-hydrate systems. en
dc.format.extent 2754867 bytes
dc.format.mimetype application/pdf
dc.language.iso eng en
dc.subject gas hydrates en
dc.subject fluid flow en
dc.subject BSR en
dc.subject seismic en
dc.subject bottom-simulating seismic reflector en
dc.subject ICGH en
dc.subject International Conference on Gas Hydrates en
dc.title FORMATION OF THE BOTTOM-SIMULATING REFLECTOR AND ITS LINK TO VERTICAL FLUID FLOW en
dc.type text en
dc.type.text conference Paper en
dc.description.affiliation Other en
dc.description.reviewstatus en
dc.rights.copyright Haacke, Ross en


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