| Abstract: | 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. |
| Genre: | Article |
| ProdID: | 70041363 |
| Citation Author: | Dai, S.; Santamarina, J. C.; Waite, William F.; Kneafsey, T. J. |
| Citation Contributing Office: | Woods Hole Coastal and Marine Science Center |
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| Citation Day: | 14 |
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| Citation Issue: | B11 |
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| Citation Language: | English |
| Citation Larger Work Title: | Journal of Geophysical Research B: Solid Earth |
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| Citation Month: | 11 |
| Citation No Pagination: | |
| Citation Number Of Pages: | 12 |
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| Citation Phsyical Description: | 12 p. |
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| Citation Publisher: | American Geophysical Union |
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| Citation Search Results Text: | Hydrate morphology: Physical properties of sands with patchy hydrate saturation; 2012; Article; Journal; Journal of Geophysical Research B: Solid Earth; Dai, S.; Santamarina, J. C.; Waite, William F.; Kneafsey, T. J. |
| Citation Start Page: | B11205 |
| Citation Volume: | 117 |
| Citation Year: | 2012 |
| Type: | citation/reference |
| Text: | Hydrate morphology: Physical properties of sands with patchy hydrate saturation; 2012; Article; Journal; Journal of Geophysical Research B: Solid Earth; Dai, S.; Santamarina, J. C.; Waite, William F.; Kneafsey, T. J. |
| URL (DIGITAL OBJECT IDENTIFIER): | http://dx.doi.org/10.1029/2012JB009667 |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Tue, 4 Dec 2012 00:00 -0600 |
| Publisher: | American Geophysical Union |
