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Thermal conductivity measurements in unsaturated hydrate‐bearing sediments
Author(s) -
Dai Sheng,
Cha JongHo,
Rosenbaum Eilis J.,
Zhang Wu,
Seol Yongkoo
Publication year - 2015
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 - 10.1002/2015gl064492
Subject(s) - hydrate , thermal conductivity , clathrate hydrate , permafrost , saturation (graph theory) , thermal conduction , materials science , methane , mineralogy , geology , thermodynamics , composite material , chemistry , oceanography , mathematics , physics , organic chemistry , combinatorics
Current database on the thermal properties of hydrate‐bearing sediments remains limited and has not been able to capture their consequential changes during gas production where vigorous phase changes occur in this unsaturated system. This study uses the transient plane source (TPS) technique to measure the thermal conductivity of methane hydrate‐bearing sediments with various hydrate/water/gas saturations. We propose a simplified method to obtain thermal properties from single‐sided TPS signatures. Results reveal that both volume fraction and distribution of the pore constituents govern the thermal conductivity of unsaturated specimens. Thermal conductivity hysteresis is observed due to water redistribution and fabric change caused by hydrate formation and dissociation. Measured thermal conductivity increases evidently when hydrate saturation S h > 30–40%, shifting upward from the geometric mean model prediction to a Pythagorean mixing model. These observations envisage a significant drop in sediment thermal conductivity when residual hydrate/water saturation falls below ~40%, hindering further gas production.