碳酸盐岩缝洞型油藏气驱机制微观可视化模型试验

针对缝洞型碳酸盐岩油藏开发中开口向上和开口向下两种缝洞类型,建立该类油藏气驱机制下的微观可视模型,采用模拟油和液化气,在常温低压下进行水驱、活性水驱、直接注气驱及气-水交替驱4组试验,研究不同注入流体及注入方式对驱替效率和含水率的影响。结果表明:水驱、活性水驱、气驱和气-水交替驱的驱替效率分别为81.12%、68.95%、74.88%和99.84%,缝洞型油藏的最佳注入方式为气-水交替注入;注气只能驱开向下的洞,注水只能驱替开口向上的洞,气-水交替驱可以同时解决这两种洞的驱油问题;活性水由于毛管压力低不利于驱油。

Experiments on gas injection mechanisms in carbonate fracture-cavity reservoir using microvisual model

In fracture-cavity carbonate reservoirs,there are generally two kinds of fracture-cavities whose fracture opening are upward and downward respectively.A microvisual model was established to investigate the displacement mechanisms of gas and liquid flooding.Under normal temperature and low pressure,simulated oil and liquid gas were used to do four groups of experiments including water displacement,active water displacement,direct gas displacement and gas-alternating-water displacement.And the effects of different injected fluids and injected methods on displacement efficiency and water cut were researched.The results show that the displacement efficiencies of water displacement,active water displacement,gas displacement and gas-alternating-water displacement are 81.12%,68.95%,74.88% and 99.84%,respectively.The best injection method is gas-alternating-water in fracture-cavity reservoir.Gas injection can only displace the oil in cavities whose fracture openings are downward,and water injection can only displace those whose fracture openings are upward,but gas-alternating-water method can settle down both.Due to the low capillary pressure,active water is no good for oil displacement.