As a new source of energy with great
potential, natural gas hydrate
(NGH) will play an indispensable and important strategic role in the
future because of its tremendous reserves and wide application prospects
in industry. It is of great significance to study the factors affecting
the formation and occurrence of NGH for its exploration and exploitation
under natural conditions and its application in industry. Since the
sediments where NGH are mostly found are in porous media, the impact
of porous media on the formation and occurrence of NGH has always
been a research focus. This review focuses on the effects of the particle
size of porous media on hydrate nucleation, growth, the conversion
of water to hydrate, and phase equilibrium by summarizing previous
studies. And occurrence characteristics of hydrates in porous media
and the application of hydrate-based technologies are reviewed. A
thorough analysis of the existing literature suggests that there is
no consistent conclusion on the influence of the particle size and
surface characteristics of porous media on hydrate formation. There
is some debate, and the existence of a critical size of porous media
needs further exploration. In addition, the interaction mechanism
between the complex pore structure of porous media and the joint effects
of particle size and initial water saturation on the hydrate formation
process is still not clear. Thus, the influence of different initial
water saturation conditions and pore structures on the formation and
occurrence of NGH under different particle size conditions should
be studied in the future to provide a reference for understanding
the mineralization mechanism of NGH under natural conditions. Finally,
some suggestions are put forward for studies of gas hydrate formation.