Formation Behaviors of Methane Hydrate in Partially Water-Saturated Porous Media with Different Particle Sizes

• Published in: Energy & Fuels
• Main Authors: Zhang, Yu, Zhang, Lei, Zhu, Chuan-Yu, Xu, Li-Xin, Li, Xiao-Sen, Chen, Zhao-Yang
• Format: Report
• Language: English
• Published: AMER CHEMICAL SOC 2021
• Subjects: NATURAL-GAS HYDRATE; DISSOCIATION; SAND; BED; SEDIMENT; DEPOSITS; Energy & Fuels; Engineering; Chemical; Methane hydrate
• Online Access: http://ir.giec.ac.cn/handle/344007/35816; http://ir.giec.ac.cn/handle/344007/35817; https://doi.org/10.1021/acs.energyfuels.1c02750

The hydrate formation behaviors are significantly affected by the grain size of the sediments. To more deeply understand the methane hydrate formation kinetics in a wide range of grain sizes of the sediments, the formation experiments of methane hydrate in different partially water-saturated porous media were performed in a closed system. A kind of silica sand and two kinds of silicon dioxide powders were used as the porous media in experiments. The average particle diameter of the silica sand is 229.90 mu m (fine sand level), and the average particle diameters of the silicon dioxide powders are 2.30 mu m (clay level) and 5.54 mu m (silty sand level). The experiments were carried at the initial bath temperature of 20 degrees C, and the initial formation pressure ranges from 9.0 to 15.0 MPa. The set hydrate formation temperature ranges from 3 to 9 degrees C. The gas consumption rate and the final water conversion in 229.90 mu m silica sand are much lower than that in 2.30 and 5.54 mu m silicon dioxide powders. The final water conversion is similar in 2.30 and 5.54 mu m silicon dioxide powders and can nearly reach 100% if gas provided is sufficient. The hydrate formation rates in all three kinds of porous media decline sharply at a certain water conversion point. The value of this water conversion point is the lowest in 229.90 mu m silica sand and is the highest in 5.54 mu m silicon dioxide powder. In 229.90 mu m silica sand with different water contents, the gas consumption rate basically increases as the water content decreases as a result of a better contact of hydrate-forming gas with available water and a higher diffusion speed of methane gas in silica sand with lower water saturation.