Gas hydrates are composed of gas molecules trapped in a solid, ice-like water molecule lattice. Hydrate dissociation referring to the phase transition of the solid gas hydrates into gas and liquid water, can take place due to temperature increase or pressure decrease. The dissociation within submarine slope sediments may have adverse consequences on the sloping hydrate bearing system and could potentially trigger landslides. In this paper, numerical assessments of hydraulic, thermodynamic and geomechanical performance of sloping oceanic hydrate bearing sediments (HBS) subject to hydrate heating in vicinity of an offshore production well are performed. Radius of hydrate dissociation, the variation in sediment excess pore pressures, the resultant decrease in shear strength and factor of safety (FOS) for slope are evaluated. Sensitivity studies of analysis parameters including soil thermal characteristics and pore compressibility on the submarine slope stability are analyzed and discussed.
Xiaoyan Long, Sudarshan Adhikari, Alan Witthoeft and Ko Min Tjok
Keywords: gas hydrate, slope stability, excess pore pressure, hydrate dissociation, numerical assessment, hydrate bearing sediments (HBS)
Publisher: DFI