Fig. 5 . Micro–images during the gas–seawater flow process in
Cases 1–3: (a) MRI images; (b) hydrate saturation
In conclusion, the hydrate–containing sealing layer formed when the
gas–water flow rate is 1–0.25 ml/min. The seawater is full contact
with the methane gas in lower gas–water flow rate, methane saturation
in seawater is high enough to induce the hydrate reformation. The
decrease of pore volume leads to the increase of capillary force, thus,
sealing layer formal formed, this is the formation mechanism of
hydrate–containing sealing layer. Then, the hydrate continued to form
in the reservoir which enhanced the sealing layer and makes it more
difficult to be destroyed.