Hydrate phase transition behaviors and effects on particle migration in hydrophobic clayey porous media

• Published in: Gas Science and Engineering Vol. 139; p. 205636
• Main Authors: Zhang, Heng, Kou, Xuan, Wang, Yi, Chen, Zhao-Yang, Li, Xiao-Sen
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.07.2025
• Subjects: Gas hydrates; Phase transition; Solid migration; Wettability; Solid migration; Wettability; Gas hydrates; Phase transition
• ISSN: 2949-9089; 2949-9089
• DOI: 10.1016/j.jgsce.2025.205636

Production of marine natural gas hydrates is beneficial for promoting transformation of the global energy structure. However, the phase transition characteristics of hydrate and their impact on particle migration in clayey sediment with different wettability are still unclear. In this study, we successfully synthesized two types of hydrate in hydrophobic clayey porous media based on X-ray computed tomography technology (X-CT). The first one is interfacial hydrate that distributes on the interface of densely packed porous media and gas phase; The second one is dispersive hydrate that disperses in the pores of the porous media. During formation, interfacial hydrate specially behaves in two growth modes. Interfacial hydrate grows towards gas phase and solid phase due to the extraction of free water and generation of cracks, respectively. For dispersive hydrate, it quickly grows in the pores of fine particles and remains stable. During decomposition, interfacial hydrate preferentially decomposes at the gas-solid interface. Dispersive hydrate decomposed based on the shrinking core model for heat transfer limitation. Furthermore, this study also reveals the solid migration characteristics. Radial heterogeneous shrinkage and local compaction of hydrate-bearing clayey sediment occurred because of consumption of free water during formation. For hydrate decomposition, gas flow behavior on the hydrophobic surface like migration and aggregation of micro bubbles caused new cavities to merge and expand, thus controlling the migration direction of solid phase. In summary, this work reveals the phase transition characteristics of hydrate and influence on particle migration in hydrophobic porous media. •Two different types of hydrates are synthesized in hydrophobic clayey sediment.•Heat and mass transfer affect hydrate phase transition.•Different hydrate growth and decomposition mechanisms are observed.•Gas and liquid flow behaviors determine solid migration characteristics.