Triaxial tests on hydrate-bearing silty-clayey sediments concerning pore-filling habit

Abstract

Recovering massive hydrates in pore-filling morphology deposited in silty-clayey sediments is significant for global long-term clean energy requirements. However, hydrate dissociation leads to sediment strength attenuation and reservoir deformation, thereby endangering reservoir and wellbore safety. To ensure safe and sustainable hydrate production, more efforts need be made to comprehensively investigate the mechanical behavior of such reservoirs. In this study, a series of triaxial shearing tests were launched on artificial hydrate-bearing silty-clayey sediments (HBSCSs) containing hydrates in pore-filling morphology, and the relevant mechanical behaviors of HBSCSs were obtained and discussed. The strength indication of HBSCSs is revealed to elevate evenly with hydrate saturation from results, while the strength growth amplitude of this material due to pore-filling hydrate (PFH) is much smaller than that due to cementing hydrate reported in previous studies. The strength increment of silty-clayey sediments induced by PFH presence is mainly due to the enhancement in the friction property of this material. The deformation behaviors of HBSCSs are affected by the combination of the initial consolidation degree, the hydrate pore-filling effect and the effective stress. Further advances are awaited to be made about the studies of silty-clayey reservoirs deposited with hydrates in pore-filling morphology.