Experimental study on the effective thermal conductivity of hydrate-bearing sediments

Gas hydrates are considered as a potential strategic energy source for sustainable development. The thermal properties of hydrate-bearing sediments govern the hydrate dissociation behavior and gas production process that accompany phase transformation and multiphase flow. This paper presents a thermistor-based measuring method to obtain the effective thermal conductivity of tetrahydrofuran hydrate-bearing sediments. The effects of different porosities, hydrate saturations and porous materials on the effective thermal conductivity were investigated. The porosity and the hydrate saturation were obtained using an X-ray CT (computed tomography) apparatus. The findings indicated that the effective thermal conductivity of hydrate-bearing sediments increased from 0.6468 W/(m K) to 0.7318 W/(m K) with porosity decreasing from 42.5% to 37.2%. Increasing hydrate saturations from 0% to 100% decreased the effective thermal conductivity from 0.7876 W/(m K) to 0.7318 W/(m K). Additionally, existing effective medium correlations were examined using the experimental data. The results showed that none of the existing correlations can suitably predict the measured data. Therefore, a hybrid correlation was proposed by optimizing the weighting parameters of the Parallel correlation and the Series correlation using the PIKAIA genetic algorithm. The agreement of the fitting correlation with the experiments is given, and the effective prediction of other researchers' work confirms the feasibility of our correlation. (C) 2014 Elsevier Ltd. All rights reserved.