Validation of strongly coupled geomechanics and gas hydrate reservoir simulation with multiscale laboratory tests

We validate a coupled flow-geomechanics simulator for gas hydrate deposits, named T+M-AM, performing two meter-scale laboratory experiments of gas hydrates for production by depressurization, replicating the gas hydrate deposit in the Ulleung Basin, East Sea, South Korea. The first experiment with a sand-only specimen is a 1D 1 m-scale depressurization test based on the excess gas method, which represents the grain coating hydrate growth. On the other hand, the second is a 3D 1.5 m-scale test with the excess water method for a sand-mud alternating layer system, representing the pore filling hydrate growth. We measure production and displacement at the top with different depressurization levels. In particular, the 3D test exhibits high coupling strength of substantial deformation induced by incompressibility of water and high deformability of the specimen. For validation, we match pressure, flow rate, and displacement between the experimental data and numerical results. Thus, we identify that T+M-AM is a reliable simulator, which can be applied to fields in both permafrost and deep oceanic hydrate deposits of strongly coupled flow and geomechanics systems. This validation also implies that other coupled simulators based on the same coupling formulation as T+M-AM can be validated when individual flow and geomechanics simulators are stable and reliable.

Automated summary

In this study, we validate a coupled flow-geomechanics simulator called T+M-AM for gas hydrate deposits. Two laboratory experiments are conducted to replicate the production of gas hydrates by depressurization in the Ulleung Basin. The results show that T+M-AM is a reliable simulator for strongly coupled flow and geomechanics systems in both permafrost and deep oceanic hydrate deposits.