HR: 0830h
AN: OS51C-0872    [PDF]
TI: Two Dimensional Multi-phase Flow Modeling of Hydrate Systems in Accretionary Complexes
AU: * Liu, X
EM: xliu@geosc.psu.edu
AF: The Pennsylvania State University, 307 Deike Building, University Park, PA 16802 United States
AU: Flemings, P B
EM: flemings@geosc.psu.edu
AF: The Pennsylvania State University, 307 Deike Building, University Park, PA 16802 United States
AU: ODP Leg 204 Scientific Party, .
AF: Ocean Drilling Program, Texas A&M University, College Station, TX 77845 United States
AB: Multi-phase flow in hydrate systems is modeled in anticlinal structures within accretionary prisms such as Hydrate Ridge, offshore Oregon. Methane generation is assumed to be temperature-dependent and follow from the Arrhenius reaction theory. Methane migrates as a separate gas phase, driven by buoyancy and hydrodynamic flow. Hydrate formation kinetics are coupled with mass and heat transfer to simulate hydrate formation. Sediment permeability is assumed to decrease with hydrate formation within the hydrate stability field. Ultimately, methane in the free gas phase is trapped beneath the crest of the ridge until its pressure converges on the least principle stress, whereupon it migrates vertically by fracture permeability. In this manner, methane that is generated over a large area at Hydrate Ridge is focused toward the crest of the ridge and ultimately expelled at the crest. Given sufficient time, constant water flux (sourced by prism dewatering) and methane generation, a steady state system is developed where gas is focused toward the crest and expelled at the crest at a constant rate. In this steady state system, a constant volume of gas is trapped that is controlled by the total overburden stress and the capillary properties of the sediments in the free gas zone. Free gas is continually vented through the hydrate stability zone. Perturbation of this system, by erosional unloading or warming, will result in rapid export of methane to the sea floor.
DE: 1615 Biogeochemical processes (4805)
DE: 1829 Groundwater hydrology
DE: 8105 Continental margins and sedimentary basins
SC: Ocean Sciences [OS]
MN: 2003 Fall Meeting