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| Research on microcosmic oil displacement mechanism of CO2 flooding in extra-high water cut reservoirs |
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CUI Maolei1,2,3, WANG Rui1,2,3, LÜ Chengyuan1,2,3, LUN Zengmin1,2,3, ZHAO Shuxia1,2,3, WANG Youqi1,2,3, TANG Yongqiang1,2,3
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(1.State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development, Beijing 100083, China;2.Key Laboratory of Marine Oil and Gas Reservoir Production, SINOPEC, Beijing 100083, China;3. Petroleum Exploration and Development Research Institute, SINOPEC, Beijing 100083, China)
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| Abstract: |
| On the basis of the residual oil forms after water flooding, three kinds of ideal core models were proposed, which are dead-end model, shaped island model, and cluster model. The microcosmic process influence of extra-high water cut on CO2 and residual oil was investigated using a micro-visualization experiment device, which was independent developed under high temperature and high pressure. And the microcosmic mathematic model of CO2-water-oil interaction was established. The results show that water blocking significantly postpones the micro contact process between CO2 and trapped oil, which makes the miscible process more complex. And no matter how thick the water film is, CO2 can diffuse through the water film into the trapped oil. Higher injection pressure leads to the faster CO2 diffusion into oil, which results in achieving more easily miscibility. It is concluded that CO2 miscible displacement contributes to oil recovery largely after water flooding. And High-pressure low-rate injection mode of CO2 is suggested in extra-high water cut reservoir. |
| Key words: extra-high water cut reservoir high temperature and high pressure CO2 miscible displacement visualization microcosmic mechanism |
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