HR: 18:05h
AN: NS54A-08    [Abstracts]
TI: Methane Hydrate Saturation in Marine Sediment: Basic Relationships to Methane Flux and Depth of the Sulfate-Methane Transition
AU: * Bhatnagar, G
EM: gb@rice.edu
AF: Department of Chemical and Biomolecular Engineering, Rice University, MS-362, 6100 Main St, Houston, TX 77005, United States
AU: Chapman, W
EM: wgchap@rice.edu
AF: Department of Chemical and Biomolecular Engineering, Rice University, MS-362, 6100 Main St, Houston, TX 77005, United States
AU: Dickens, G R
EM: jerry@rice.edu
AF: Department of Earth Science, Rice University, MS-126, Keith-Wiess Geological Labs, 6100 Main St, Houston, TX 77005, United States
AU: Dugan, B
EM: dugan@rice.edu
AF: Department of Earth Science, Rice University, MS-126, Keith-Wiess Geological Labs, 6100 Main St, Houston, TX 77005, United States
AU: Hirasaki, G J
EM: gjh@rice.edu
AF: Department of Chemical and Biomolecular Engineering, Rice University, MS-362, 6100 Main St, Houston, TX 77005, United States
AB: A one-dimensional numerical model that simulates accumulation of methane hydrate in marine sediment over geological time scales was developed. Average gas hydrate saturation maps that are valid over a wide range of transport parameters are also computed from our numerical simulations. Two saturation maps explain gas hydrate distributions resulting from methane generated either via in-situ methanogenic reactions or transported through upward fluxes from deeper sources. These two dimensionless maps can explain multiple gas hydrate systems such as Blake Ridge (offshore southeastern USA), Cascadia Margin (offshore northwestern USA), Peru Margin (offshore Peru), Costa Rica Margin and Nankai Trough (offshore Japan). Change in the model parameters over geologic time scales can also be tracked on these maps, so that the temporal evolution of any hydrate province can be easily studied. For gas hydrate settings dominated by upward methane fluxes from deeper sources, average gas hydrate saturation is related to the depth to the sulfate-methane transition (SMT). This scaling provides a quick and inexpensive means to estimate average hydrate saturation from the SMT depth and depth to the base of hydrate stability; no other site specific parameters are required. This new method is tested against hydrate saturations from our model and site data from IODP Leg 311 (Cascadia Margin).
DE: 1050 Marine geochemistry (4835, 4845, 4850)
DE: 3004 Gas and hydrate systems
DE: 4219 Continental shelf and slope processes (3002)
SC: Near-Surface Geophysics [NS]
MN: 2007 Joint Assembly