Publication Date:
2022-05-26
Description:
Author Posting. © American Geophysical Union, 2012. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 117 (2012): B11205, doi:10.1029/2012JB009667.
Description:
The physical properties of gas hydrate-bearing sediments depend on the volume fraction and spatial distribution of the hydrate phase. The host sediment grain size and the state of effective stress determine the hydrate morphology in sediments; this information can be used to significantly constrain estimates of the physical properties of hydrate-bearing sediments, including the coarse-grained sands subjected to high effective stress that are of interest as potential energy resources. Reported data and physical analyses suggest hydrate-bearing sands contain a heterogeneous, patchy hydrate distribution, whereby zones with 100% pore-space hydrate saturation are embedded in hydrate-free sand. Accounting for patchy rather than homogeneous hydrate distribution yields more tightly constrained estimates of physical properties in hydrate-bearing sands and captures observed physical-property dependencies on hydrate saturation. For example, numerical modeling results of sands with patchy saturation agree with experimental observation, showing a transition in stiffness starting near the series bound at low hydrate saturations but moving toward the parallel bound at high hydrate saturations. The hydrate-patch size itself impacts the physical properties of hydrate-bearing sediments; for example, at constant hydrate saturation, we find that conductivity (electrical, hydraulic and thermal) increases as the number of hydrate-saturated patches increases. This increase reflects the larger number of conductive flow paths that exist in specimens with many small hydrate-saturated patches in comparison to specimens in which a few large hydrate saturated patches can block flow over a significant cross-section of the specimen.
Description:
Research support provided to Georgia Tech
by the Department of Energy/JIP project for methane hydrate, administered
by Chevron. Additional funding provided by the Goiuzeta Foundation, the
Gas Hydrate Project of the U.S. Geological Survey’s Coastal and Marine
Geology Program, and the Assistant Secretary for Fossil Energy, Office
of Oil and Natural Gas, Gas Hydrate Program through the National Energy
Technology Laboratory of the U.S. Department of Energy under contract
DE-AC02-05CH11231.
Description:
2013-05-14
Keywords:
Analytical model
;
Gas hydrate
;
Hydrate pore habit
;
Hydrate-bearing sediments
;
Numerical model
;
Upper and lower bounds
Repository Name:
Woods Hole Open Access Server
Type:
Article
Format:
application/pdf
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