摘要 |
A miscible flooding process for oil recovery employs a multiple contact miscible solvent such as carbon dioxide and an additive such as butane which lowers the minimum miscibility pressure of the oil/solvent system. The additive is injected in a slug with a solvent, preferably followed by a slug of water to improve sweep, after which solvent alone may be injected to extract residual additive and oil by miscible extraction. A number of slugs of solvent, either by itself or with the additive may be injected, with intervening slugs of water and finally, water injection may be made to termination.
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