Geomechanical aspects

The geomechanical behavior of gas hydrate-bearing sediments is strongly coupled to the other processes involved in the behavior of gas hydrates. This chapter focuses on the geomechanical characteristics of gas hydrate-bearing sediments and on the methods by which they can be represented, and coupled numerically for complete thermo-hydro-mechanical-chemical (THMC) simulations. It presents a general, but unique, characterization of gas hydrate-bearing sediments, followed by both continuum-based and discrete-based approaches for modeling the mechanical behavior of these materials. The mechanical behavior is represented either using a constitutive model, which expresses changes in stresses due to strain increments, or by discrete element method (DEM) simulations, in which each soil particle is modeled individually as it interacts with the other particles and with the solid hydrate in the pores. The chapter also presents the simulation of the world’s first offshore gas production test from gas hydrate-bearing sediments conducted at the Eastern Nankai Trough, Japan.