Carbon capture and storage is an important approach to mitigating climate change, and CO2 hydrate storage has received increasing attention due to its high storage density and thermodynamic stability. However, the stability of CO2 hydrates under thermal disturbance remains unclear, especially at the pore scale where hydrate morphology and interface conditions may significantly affect decomposition behavior. In this study, a microfluidic experimental system was established to investigate the thermal decomposition of CO2 hydrates under heat injection. Through microscopic imaging combined with machine learning-based phase segmentation, shell-like and fracture-like hydrates were identified, and their decomposition sequences, gas release characteristics, and bubble evolution behaviors were quantitatively analyzed. Meanwhile, local temperature variations were extracted to calculate the thermodynamic driving force based on fugacity difference, allowing an approximate comparison of morphology-dependent decomposition behaviors under different thermodynamic driving forces. The results indicate that shell-like hydrates exhibit staged decomposition, whereas fracture-like hydrates decompose more continuously due to enhanced gas–liquid connectivity. Consequently, an effective kinetic coefficient was introduced to characterize the sensitivity of different hydrate morphologies to thermal disturbance. Further analysis suggests that hydrate morphology, interface exposure, and thermodynamic driving force evolve in a coupled manner and collectively influence the observed decomposition pathway. Specifically, morphology primarily determines the local phase-contact configuration, interface exposure governs gas escape and heat/mass transfer conditions, and the fugacity difference provides the bulk thermodynamic tendency for decomposition. Therefore, this study can be regarded as a mechanistic interpretation based on correlated pore-scale observations, providing experimental evidence for evaluating the stability of CO2 hydrate-based geological storage.
Wáng et al. (Mon,) studied this question.