Fig. 2 . Initial hydrate reservoir conditions in all cases.
3.1 Methane–containing fluid flow characteristics inhydrate–bearing reservoirs
The free methane gas in the deep ocean floor is bound to migrate upward, and the gas migration also drives the movement of seawater in the sediments (Su et al. , 2012). We simulate gas–water migration by injecting gas and water into hydrate–bearing sediments, the experimental conditions of Cases 1–3 are shown in Table 2. The inlet pressure is increasing at the beginning, and large gas–water flow rate makes inlet pressure increase faster, as shown in Fig. 3, because the injection velocity of gas–water is larger than the seepage velocity of hydrate–bearing sediments. In Case 1, the methane gas and seawater were injected into the hydrate–bearing reservoir at the flow rate of 4–1 ml/min. After 52 min, the inlet pressure decreased, and the inlet pressure kept the same with outlet pressure at 136 min, fluids flow through the reservoir smoothly. The outlet flux curve of Case 1 increased and seawater flowed out of the reactor continually, indicating the hydrate reservoir had no sealing effect during gas–water flow process in Case.
Table 2. Experimental conditions and results of Cases 1–3.