Аннотация:The paper summarizes experimental data on thermal conductivity variations in gas-saturated sediments exposed to 7 hydrate formation at various conditions. All experiments were performed on a specially designed gas hydrate system maintaining 8 a high gas pressure and a steady-state thermal regime, with a built-in unit for thermal conductivity measurements. The 9 measurements were applied to natural samples of fine sand and silty sand collected from gas emanation sites in permafrost and to 10 artificial sand and sand−clay mixtures. The results show that thermal conductivity can either increase or decrease depending 11 upon hydrate formation conditions. Namely, it increases if gas hydrates form at positive temperatures (t >0°C) but decreases 12 during hydrate formation in frozen samples. Freezing and thawing of hydrate-bearing sediments above the equilibrium pressure 13 reduce their thermal conductivity as a result of additional hydrate formation. Experimental results are used to model hydrate and 14 ice formation in gas-saturated sediments. The experimental study of thermal conductivity in hydrate-bearing sediments has 15 implications for simulations of methane recovery from natural gas hydrate reservoirs and the respective technologies.