Fig. 6 . Characteristics of pressure at reactor inlet and
seawater increase in reactor
As shown in Fig. 6, the turning points appeared at 94 and 54 min in
Cases 4 and 5, respectively. After the turning point, the seawater won’t
flow out of the reservoir outlet, the hydrate reservoir had sealing
effect. The gas–water flow rates of Cases 4 and 5 were the same as
Cases 2 and 1, respectively. However, hydrate–containing sealing layer
formed only in Cases 4 and 5, because higher reservoir pressure provide
larger driving force for hydrate formation (Ma et al. , 2020). It
also indicated that higher pressure will promote the formation of
hydrate–containing sealing layer than low gas–water flow rate. Because
the higher pressure can enhance the mass transfer between the gas and
seawater, and enhance hydrate formation during gas–water flow process.
Moreover, the pressure increases rate curve had a fluctuation at the
turning point, and increase rate of inlet pressure was decreased, this
fluctuation also appeared in Case 3. Furthermore, there is a certain
regularity in the pressure difference between the reactor inlet and
outlet at the time of hydrate–containing sealing layer is formal
formed, as shown in Fig. 7. The mean value of pressure different is 2.47
MPa. In this study, the pressure difference at turning point is
independent of reservoir pressure, it can be used as a marker to judge
the formation of hydrate seal layer during the experiment.