Behaviour of frozen hydrate-bearing sand under a temperature gradient: evidence from laboratory and numerical experiments

Permafrost represents a complex multiphasesystem that is sensitive to thermodynamic changes caused by environmental impacts, such as hydrocarbon field development in the Arctic. Specialized modeling allow for the assessment of risks associated with phase transitions of ice inclusions and gas hydrates. In this study, based on developed experimental methodology and numerical algorithms, the one-sided heating of frozen metastable hydrate-bearing sand was modeled for the first time. The simulations revealed the dynamics of thawing and pore hydrate dissociation fronts under thermal influence, demonstrating that the latter advances ahead of the former under self-preservation conditions with the shift amounted to 1.1°C. The developed numerical algorithms proved highly effective for quantitatively describing changes in the temperature field within frozen hydrate-bearing soil subjected to a thermal gradient. A close agreement between numerical and laboratory results confirmed the applicability of the model for predicting dynamic patterns in Arctic permafrost under thermal disturbances.