A comprehensive analysis of formation conditions, intrinsic properties, and mechanical responses of gas hydrate-bearing sediments

Natural gas hydrates (NGH) stored in submarine deposits are a promising energy resource, Yet, the deterioration in sediment strength can trigger geological disasters due to drilling-induced hydrate dissociation. Hence, an in-depth investigation on geo physical-mechanical performance of gas hydrate-bearing sediments (GHBS) is crucial for recovery hydrates safely and efficiently. This paper provides a comprehensive assessment of the research progress on formation conditions, intrinsic properties, and mechanical responses of GHBS. The key findings have been presented: gas composition, inhibitors and promoters alter hydrate formation by modifying the thermodynamic equilibrium of temperature and pressure. Also, we identified the key determinants of porosity of GHBS and revealed the correlation between permeability, hydrate saturation, and hydrate morphology. Moreover, we highlighted the differences in mechanical behavior between hydrate-free sediments and GHBS along with their underlying mechanisms. Furthermore, we examined the methods for GHBS preparation as well as the employed test apparatuses, providing critical insights into the limitations and recommendations. By synthesizing data from existing literature, we conducted a comprehensive analysis of the dependence of mechanical parameters of GHBS on factors such as hydrate saturation, effective confining stress, and temperature, and discussed the mechanical responses subjected to various hydrate dissociation methods. Finally, we offer a perspective for future research to focus on the micro-scale aspects, heterogeneous distribution, and long-term stability of GHBS. The discerned patterns and mechanical mechanisms are expected to guide the improvement of predictive model for geo physical-mechanical behavior of GHBS and establish a reference for developing effective strategies for recovery hydrates.