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Experiments on gas injection mechanisms in carbonate fracture-cavity reservoir using microvisual model |
GUO Ping1,YUAN Heng-lu1,LI Xin-hua2,MA Hong-tao2
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(1. State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu 610500, China;2. Northwest Petroleum Branch, SINOPEC,Urumqi 830001, China)
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Abstract: |
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-aitemating-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-altemating-water displacement are 81. 12% , 68. 95% , 74. 88% and 99. 84%,respectively. The best injection method is gas-altemating-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-altemating-water method can settle down both. Due to the low capillary pressure,active water is no good for oil displacement. |
Key words: reservoirs fracture-cavity type carbonate microvisual model displacement efficiency gas alternating water |
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