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Physical property changes in hydrate-bearing sediment due to depressurization and subsequent repressurization

Journal of Geophysical Research B: Solid Earth

By:
, , ,
DOI: 10.1029/2007JB005351

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Abstract

Physical property measurements of sediment cores containing natural gas hydrate are typically performed on material exposed, at least briefly, to non-in situ conditions during recovery. To examine the effects of a brief excursion from the gas-hydrate stability field, as can occur when pressure cores are transferred to pressurized storage vessels, we measured physical properties on laboratory-formed sand packs containing methane hydrate and methane pore gas. After depressurizing samples to atmospheric pressure, we repressurized them into the methane-hydrate stability field and remeasured their physical properties. Thermal conductivity, shear strength, acoustic compressional and shear wave amplitudes, and speeds of the original and depressurized/repressurized samples are compared. X-ray computed tomography images track how the gas-hydrate distribution changes in the hydrate-cemented sands owing to the depressurizaton/repressurization process. Because depressurization-induced property changes can be substantial and are not easily predicted, particularly in water-saturated, hydrate-bearing sediment, maintaining pressure and temperature conditions throughout the core recovery and measurement process is critical for using laboratory measurements to estimate in situ properties.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Physical property changes in hydrate-bearing sediment due to depressurization and subsequent repressurization
Series title:
Journal of Geophysical Research B: Solid Earth
DOI:
10.1029/2007JB005351
Volume
113
Issue:
7
Year Published:
2008
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article