Pressure Influence on Salt Migration in Frozen Hydrate-Saturated Sediments: Experimental Modeling

Development of the Arctic region faces many problems, including methane emission from permafrost. Among other causes, methane emission may result from destabilization and dissociation of intrapermafrost gas hydrates under temperature and pressure changes or chemical reactions. The effects of the temperature and pressure on the stability of intrapermafrost gas hydrates have been quite well-studied, but the chemical effects, such as migration of salts, remain poorly understood. In this study, the interaction of frozen hydrate-saturated sediments with NaCl solutions is simulated in physical experiments at different gas pressures from 0.1 to 4.0 MPa and at a constant negative temperature of around -6.0 degrees C. The experiments show that the external pressure significantly affects the migration of Na+ into frozen hydrate-bearing sand: salt transport accelerates at lower pressures, while pore hydrates lose stability. However, the effect of the pressure on frozen hydrate-free sediments is minor. The experimental results make a basis for a model of pore space changes in frozen hydrate-saturated rocks interacting with salt water under gas pressures above or below the equilibrium value.

Automated summary

The development of the Arctic region faces challenges such as methane emission from permafrost. While the effects of temperature and pressure on gas hydrates have been studied, the chemical effects, such as salt migration, remain poorly understood. This study investigates the interaction of frozen hydrate-saturated sediments with NaCl solutions under different gas pressures.