Pore-scale investigation on methane hydrate formation and plugging under gas-water flow conditions in a micromodel

Hydrate formation in the pores of porous media is known to decrease reservoir permeability. Current research on hydrate formation in porous media primarily focuses on the static state. In this study, the formation and plugging of methane hydrate under gas-water flow conditions in a visible heterogeneous micromodel were investigated. The experimental results show that the hydrates formed in the pores tended to deposit in situ, and the intersection of different pore channels is critical for hydrate plugging in the micromodel. The higher the pressure in the pore channels, the higher the risk of hydrate formation and plugging. Meanwhile, the hydrate fraction in the pore channels was quantitatively analyzed to describe the hydrate formation and plugging behaviors, which are affected by the hydrate formation and dissolution processes. Based on the experimental results, the formation mechanism of hydrate plugging in microporous channels was proposed, which primarily includes four stages: formation of a water film by the gas-water flow, formation of a hydrate thin shell at the gas-water interface, hydrate deposition in situ and growth, and formation of hydrate plugging. This study establishes the experimental foundation for hydrate plugging prediction models and prevention methods for porous media.