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Strength Estimation for Hydrate‐Bearing Sediments From Direct Shear Tests of Hydrate‐Bearing Sand and Silt
Author(s) -
Liu Zhichao,
Dai Sheng,
Ning Fulong,
Peng Li,
Wei Houzhen,
Wei Changfu
Publication year - 2018
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 - 10.1002/2017gl076374
Subject(s) - hydrate , cohesion (chemistry) , saturation (graph theory) , geology , geotechnical engineering , strength reduction , silt , clathrate hydrate , methane , mineralogy , geomorphology , chemistry , thermodynamics , organic chemistry , physics , mathematics , combinatorics , finite element method
Safe and economic methane gas production, as well as the replacement of methane while sequestering carbon in natural hydrate deposits, requires enhanced geomechanical understanding of the strength and volume responses of hydrate‐bearing sediments during shear. This study employs a custom‐made apparatus to investigate the mechanical and volumetric behaviors of carbon dioxide hydrate‐bearing sediments subjected to direct shear. The results show that both peak and residual strengths increase with increased hydrate saturation and vertical stress. Hydrate contributes mainly the cohesion and dilatancy constraint to the peak strength of hydrate‐bearing sediments. The postpeak strength reduction is more evident and brittle in specimens with higher hydrate saturation and under lower stress. Significant strength reduction after shear failure is expected in silty sediments with high hydrate saturation S h ≥ 0.65. Hydrate contribution to the residual strength is mainly by increasing cohesion at low hydrate saturation and friction at high hydrate saturation. Stress state and hydrate saturation are dominating both the stiffness and the strength of hydrate‐bearing sediments; thus, a wave velocity‐based peak strength prediction model is proposed and validated, which allows for precise estimation of the shear strength of hydrate‐bearing sediments through acoustic logging data. This method is advantageous to geomechanical simulators, particularly when the experimental strength data of natural samples are not available.