Experimental study on the effective thermal conductivity of methane hydrate-bearing sand

• Thermal conductivities of methane hydrate-bearing sediments measured using the transient plane source method.
• Thermal conductivities of the sediments show weak negative dependence on temperature.
• The thermal conductivities of the sediments show strong dependence on morphology.
• Even small amounts of hydrates significantly enhance thermal conductivity in partially water-saturated, gas-rich samples.
• In samples with high water concentrations, thermal conductivity does not change significantly with hydrate saturation level.

The thermal conductivities of methane hydrate-bearing sand samples, formed from moist sand with different initial water saturation levels, were measured by Gustafsson’s transient plane source (TPS) technique. The thermal conductivity values show weak negative dependence on temperature similar to a crystal-like material, which agrees well with most of the published results on sedimentary and pure methane hydrates. Similar dependence has also been observed in the wave speed studies. The effective thermal conductivity of hydrate-bearing sediment is strongly dependent on the morphology of the sediment. In partially water-saturated, gas-rich environments, the hydrates tend to cement sediment grains together, and even a small amount of hydrates presence can significantly increase the effective thermal conductivity of the sediments. In sand samples with high water concentrations and water-saturated sand, the effective thermal conductivity does not show an obvious increase with the hydrate saturation level.