Modeling on effective thermal conductivity of hydrate-bearing sediments considering the shape of sediment particle

The estimation of effective thermal conductivity (ETC) of hydrate-bearing sediment is of great importance for the exploitation of natural gas hydrate. At present, existing ETC models have been lack of consideration of the influences of sediment particle shape and stacking patterns. Thus, in this work, new models considering the shape (octahedral, plate-shaped, spindle-shaped and elongated) of sediment particles and stacking patterns were established and verified by a series of existed laboratory data. The verification results indicate that the octahedral model, plate-shape model and the average values of the four models have high accuracy in predicting ETC of hydrate-bearing sediments. The ETC of hydrate-bearing sediment under water-saturated state were calculated by the models in this work. The average ETC predicted by four models decreased from 2.87 W & sdot;m-1 & sdot;K-1 to 1.47 W & sdot;m- 1 & sdot;K-1 with porosity increasing from 0.22 to 0.47 and decreased from 1.61 W & sdot;m-1 & sdot;K-1 to 1.58 W & sdot;m-1 & sdot;K-1 with hydrate saturation increasing from 0 to 1. Finally, the effects of porosity, hydrate saturation and intrinsic thermal conductivity of sediment particles on the ETC were discussed and analyzed. This modeling work could contribute to the understanding and prediction of the ETC of hydrate-bearing sediment with different shapes of sediment particles in the complex porous system.