Temperature Variation during Salt Migration in Frozen Hydrate-Bearing Sediments: Experimental Modeling

• Published in: Geosciences
• Main Authors: Evgeny Chuvilin, Valentina Ekimova, Dinara Davletshina, Boris Bukhanov, Ekaterina Krivokhat, Vladimir Shilenkov
• Format: Text
• Language: English
• Published: Multidisciplinary Digital Publishing Institute 2022
• Subjects: permafrost; gas hydrate; frozen sediment; salt migration; temperature variation; hydrate dissociation; methane emission; Ice; Methane hydrate
• Online Access: https://doi.org/10.3390/geosciences12070261

Salt migration may be another reason why pore-gas hydrates dissociate in permafrost, besides pressure and temperature changes. Temperature variations in frozen hydrate-saturated sediments interacting with a NaCl solution have been studied experimentally at a constant temperature, ~−6 °C typical for permafrost. The experiments with frozen sandy samples containing metastable methane hydrate show that the migration of Na+ ions in the NaCl solution and their accumulation in the sediments can induce heat-consuming hydrate dissociation and ice melting. The hydrate-saturated frozen soils cool down at higher rates than their hydrate-free counterparts and require more time to recover their initial temperature. The temperature effects in hydrate-saturated frozen sediments exposed to contact with NaCl solutions depend strongly on salt concentration. The experimental results are used to model phase changes in the pore space associated with salt-ions transport and provide insights into the reasons for temperature changes.