[Objective]Capillary effects increase the solubility of methane in fluids in equilibrium with hydrate,which affects the gas-hydrate distribution.Revealing the influence of capillary effects on the distribution of hydrates can provide theoretical support for the study of hydrate accumulation and hydrate exploration.[Methods]A numeri-cal model was developed to investigate and predict the influence of capillary effects on the top occurrence of gas hydrate,and applied at site ODP994.[Results and Conclusions]The predicted top occurrence was calculated to be about 194 m,consistent with the depth determined from chloride anomalies.The top occurrence of gas hydrate tends to be located at depths where the pore radius is locally larger compared to adjacent layers.The methane concentration in hydrate zone could be increased by capillary effects by increasing solubility of methane in fluids in equilibrium with hydrate.And dissolved methane would be more readily transported upward from hydrate zone,resulting in a shallower top hydrate occurrence.Therefore,capillary effects in gas hydrate stability zones plays a important role in determining the upper boundary of gas hydrates.
capillary effectsulfate-methane interfacemethane fluxtop occurrence of gas hydratenumerical simulation
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