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Compressional and shear wave velocities in uncemented sediment containing gas hydrate
Author(s) -
Yun T. S.,
Francisca F. M.,
Santamarina J. C.,
Ruppel C.
Publication year - 2005
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2005gl022607
Subject(s) - clathrate hydrate , hydrate , geology , shear (geology) , cementation (geology) , mineralogy , sediment , stiffness , geotechnical engineering , materials science , geomorphology , composite material , petrology , chemistry , organic chemistry , cement
The competing hypotheses for gas hydrate formation at the particle scale in sediments describe processes of pore‐filling, frame‐building, or cementation. New measurements of compressional ( V P ) and shear wave ( V S ) velocities in fine‐grained sands subjected to low confinement and monitored during formation of tetrahydrofuran hydrate indicate that hydrate nucleates in the pore space (presumably at grain boundaries) and grows with limited impact on the sediment shear stiffness, V P , and V S until crystals begin to interact with the granular skeleton at ∼40% hydrate concentration. V S increases significantly more than V P at higher hydrate concentrations, reflecting larger changes in the specimen's shear stiffness than its bulk stiffness. The results indicate that seismic velocities and/or their ratio ( V P / V S ) have limited capability for locating hydrate or constraining hydrate concentrations.