Migration of Salt Ions in Frozen Hydrate-Saturated Sediments: Temperature and Chemistry Constraints

Migration of dissolved salts from natural (cryopeg brines, seawater, etc.), or artificial sources can destabilize intrapermafrost gas hydrates. Salt transport patterns vary as a function of gas pressure, temperature, salinity, etc. The sensitivity of the salt migration and hydrate dissociation proce...

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Bibliographic Details
Published in:Geosciences (Basel) 2022-07, Vol.12 (7), p.276
Main Authors: Chuvilin, Evgeny, Ekimova, Valentina, Davletshina, Dinara, Bukhanov, Boris, Krivokhat, Ekaterina, Shilenkov, Vladimir
Format: Article
Language:English
Subjects:
Ambient temperature
Brines
Calcium chloride
Chemical analysis
Chemistry
Contact pressure
Dissociation
Dissolved salts
Earth science
Experiments
Flux density
frozen sediment
gas hydrate
Gas hydrates
Gas pressure
High temperature
hydrate dissociation
Hydrates
Ions
Laboratories
Magnesium chloride
Moisture
Moisture effects
Natural gas
Permafrost
Phase transitions
Potassium chloride
Saline solutions
Salinity
Salinity effects
Salt
Salt advection
salt migration
Salts
Seawater
Sediment
Sediments
sensitivity to temperature
Sodium chloride
Sodium sulfate
Temperature
Temperature requirements
Thermodynamic equilibrium
Water analysis
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Summary:Migration of dissolved salts from natural (cryopeg brines, seawater, etc.), or artificial sources can destabilize intrapermafrost gas hydrates. Salt transport patterns vary as a function of gas pressure, temperature, salinity, etc. The sensitivity of the salt migration and hydrate dissociation processes to ambient temperature and to the concentration and chemistry of saline solutions is investigated experimentally on frozen sand samples at a constant negative temperature (−6 °C). The experiments show that the ambient temperature and the solution chemistry control the critical salt concentration required for complete gas hydrate dissociation. Salt ions migrate faster from more saline solutions at higher temperatures, and the pore moisture can reach the critical salinity in a shorter time. The flux density and contents of different salt ions transported to the samples increase in the series Na2SO4–KCl–CaCl2–NaCl–MgCl2. A model is suggested to account for phase transitions of pore moisture in frozen hydrate-saturated sediments exposed to contact with concentrated saline solutions at pressures above and below the thermodynamic equilibrium, in stable and metastable conditions of gas hydrates, respectively.
ISSN:2076-3263
2076-3263
DOI:10.3390/geosciences12070276