Effective thermal conductivity for hydrate-bearing sediments under stress and local thermal stimulation conditions: A novel analytical model

The extraction of hydrates is accompanied by changes in the hydrate occurrence pattern, hydrate saturation, effective stress, temperature, and pore structure in porous sediment, making it difficult to predict the effective thermal conductivity (ETC) of hydrate-bearing sediments. Until now, accurately modeling the ETC of gas hydrate sediments during the exploitation process has remained a significant challenge. In this study, by combining pore compression theory, and particle thermal expansion theory, an analytical ETC model is derived to study the physical relations between the ETC of hydrate-bearing sediments under excess water or excess gas condition and various influencing parameters (e.g., hydrate occurrence pattern, effective stress, hydrate saturation, pore structure, and temperature). The proposed model is validated against test data. Furthermore, the effects of pore structures (e.g., initial porosity and radius fluctuation amplitude), effective stress, hydrate saturation, and hydrate occurrence pattern on ETC are revealed. Compared with the existing ETC models of hydrate-bearing sediments, our derived model takes more mechanisms into account, which makes our derived model more reasonable. In short, this model is of great significance to predict ETC and study the heat transfer in gas hydrate reservoirs, enabling engineers and scientists to have a better understanding of the hydrate exploitation process.