| Dynamic mechanism of the migration of oil and gas has been the hotspot in the realm of reservoir-formation study in recent years. Generally, buoyancy has been regarded as the main driving force of secondary migration of oil and gas. Based on a lot of experiments, we have studied the characteristics of migration driven by buoyancy in porous medium, which are as follows:(1)The migration of oil driven by buoyancy is mainly related to the horizontal diameter of continuous oil phase, but not the height.The migration process of oil driven by buoyancy is the horizontal diameter becoming smaller and smaller and the height becoming larger and larger. When the horizontal diameter becomes less than 4.5mm,the migration maybe stop.(2)The migration of oil driven by buoyancy is always easier in oil-wetting porous medium or along continuous oil pathway than in water-wetting one.(3)Under formation condition, the migration driven by buoyancy seems (imited. Owing to the affect of capillary force and friction of the water-wetting porous medium, migration driven by buoyancy needs the successive volume whose horizontal diameter surpasses 4.5mm approximately. |
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