Methane hydrates are a largely untapped energy resource with the potential to support carbon sequestration through CH₄-CO₂ exchange. However, large-scale methane recovery from hydrate-bearing sediments remains constrained by key uncertainties related to sediment stability, multiphase fluid dynamics, and geomechanical responses during gas production. One of the key scientific challenges is to understand the transient interface dynamics and mechanical weakening of hydrate deposits during CH₄-CO₂ displacement, especially the unexplained effects of pore water meniscus surface evolution and its influence on sediment stability. This study reviews CH₄-CO₂ replacement methods, including microscale piezoelectric sensing, triaxial testing, and real-time resistivity monitoring. It quantifies displacement efficiency and hydrate dissociation geomechanics while analyzing interfacial dynamics and sediment behavior during exchange process.

The conversion of CO₂ into solid hydrates for seabed storage is a promising greenhouse gas mitigation method, but the influence of reservoir types on hydrate formation remains unclear due to the complexity of marine sediments. This study examines three end-member sediments-montmorillonite, diatoms, and glass beads-representing clay-, silt-, and sand-dominated reservoirs, respectively. A series of kinetic experiments, morphological observations, and electrical sensitivity tests were conducted to assess the impact of these sediments on hydrate formation. The results show that the surface electric field and water migration properties of montmorillonite provide additional nucleation sites, promoting hydrate formation during the induction period. Gas consumption and hydrate conversion rate in the montmorillonite system were five times higher than those in the deionized water control group and ten times higher than those in the diatom and glass bead systems. While diatoms facilitated milder reactions in later stages, rapid hydrate formation in montmorillonite impeded further CO₂ mass transfer. Glass beads exhibited stringent formation conditions with Ostwald ripening effects. Hydrate films initially formed at the gas-liquid interface and spread into gas and water phases via surface tension-driven water migration. Electrical sensitivity tests revealed an inverse correlation between sensitivity and induction/reaction times across sediment types.