Geomechanical modeling of hydrate-bearing sediments during dissociation under shear

Methane hydrate-bearing sediments exist throughout the world in continental margins and in Arctic permafrost. Hydrates are ice-like compounds when dissociate due to temperature rise or reduction in fluid pressure, release gas. Because of the mechanical property changes caused by dissociation in which the loads supported by the hydrates are transferred to soil grains, these sediments may become unstable. To quantify the risk of ground instability triggered by dissociation, which may happen during operation to extract methane gas or from climate changes, a reliable predictive model is indispensable. Even though many models have been proposed, a detailed validation of the ability to model dissociation impact is still needed. This study investigated the adequacy of an spatially mobilized plane constitutive model and a modeling framework using laboratory-induced dissociation tests under shear from literature. Using laboratory-imposed temperature and pressure changes and the resulting hydrate saturation changes as input, this study was able to capture the geomechanical responses and determine the stability state of methane hydrate-bearing sediments as observed. Copyright (c) 2017 John Wiley & Sons, Ltd.