During production,the polymer injection generally results in decreases in oil production capacity and oil increment.Therefore,it is necessary to determine the reasonable time and amplitude of liquid extraction after polymer injection so as to achieve a better oil increment effect.In this study,taking Bo-nan oilfield in China as an example,the feasibility of liquid extraction was evaluated by analyzing the dimensionless oil production,the changes of fluid productivity index and the production performance in wells with lifted liquids.The characteristics of the geological reservoir,wellbore conditions,artificial lift methods and surface supporting equipment of the oilfield were analyzed to determine the potential for liquid extraction.Extraction feasibility analysis was conducted to determine the extraction time.Through a variable frequency production forecast,the effects of liquid extraction measures were analyzed.The results indicated that the best effects of lifting liquid will occur when polymer flooding is overall effective,that the rational extent of lifting liquid is 1.3 times the liquid production before lifting liquid,and that the lifting liquid after polymer flooding may increase oil recovery by 0.8 %.The results can provide important guiding significance for the late development of oilfields with high water levels.
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