Quantification of CH4 Hydrate Film Growth Rates in Micromodel Pores

Abstract

In this paper, we report the growth pattern and the rate of CH4 hydrate in sandstone pores. A high-pressure, water-wet, transparent micromodel with pores resembling a sandstone rock was used to visualize CH4 hydrate formation at reservoir conditions (P = 35–115 bar and T = 0.1–4.9 °C). The CH4 hydrate preferably formed and grew along the gas–water interface until the gas phase was completely encapsulated by a hydrate film. Two different growth rates were identified on the gas–water interface: CH4 hydrate film growth along the vertical pore walls (∼1200 μm/s) was more than 100 times faster than the film growth toward the pore center (∼8 μm/s). CH4 hydrate crystal growth directly in the water phase was slow and the rate was less than 0.5 μm/s. The film growth rate along the gas–water interface was independent of the pore size, gas saturation, and gas distribution, but the pore wall growth rate displayed a power law dependency on the applied subcooling temperature, ΔT, with a power law exponent equal to 2. The results of this study can be used as input to numerical models aiming to simulate pore-scale CH4 hydrate growth behavior.