Experimental Investigation on Hydrate Formation and Decomposition Behaviors in Micro-Pore Channels

Abstract Hydrate formation and decomposition are important factors affecting fluid flow in porous media. To reveal the characteristics of hydrate formation and decomposition in the pores of porous media, pore-scale experiments under different types of flow in micromodel were conducted using a visual microflow experimental apparatus. The experimental results suggested that heterogeneous hydrates were formed in the pore channels, which was mainly affected by the gas-water distribution and temperature & pressure. Compared with the gas-dominated and water-dominated flow, the hydrate formation rate was the maximum under gas-water two-phase flow, and the risk of hydrate blocking the flow channel was the maximum. Moreover, the hydrates were gradually decomposed from the pressure-reduced outlet to the inlet. The methane produced by hydrate decomposition in the pore channel would gather and form a continuous gas flow channel under pressure difference, and the methane dissolved in the water phase would also gradually precipitate out as the pressure decreases to form bubbles, which would form large methane bubbles with adjacent bubbles, thus driving the surrounding water phase flow. This paper lays a foundation for future research on hydrate formation, decomposition and flow in porous media.