In order to further improve the recovery of oil after binary composite flooding in offshore oil fields,based on the development contradiction existing after the binary flooding,combined with the indoor physical simulation experiment,three different combinations of oil displacement systems were designed on the basis of conventional oil displacement agents. According to the characteristics of the reservoir after the binary flooding,three kinds of high concentration polymer flooding,high concentration polymer + two yuan and heterogeneous phase were proposed and compared with the experiment. The results showed that the three experimental schemes showed different degrees of secondary decline in water,the shunt rate of the high permeability layer decreased,and the shunt rate of the medium and low permeability layer increased.The recovery rate of experiment was 13.55%,10.93% and 16.05%,respectively.It provides technical support for subsequent profile optimization and individual well personalized design,which lays the foundation for the completion of a set of recovery technology method system after a set of two yuan flooding.

The modified hall curve method is qualitative identification of stratum pore passage characteristics from relative relationship between derivative curve and integral curve. The analytic solution formula contains the work systemrelated parameters, however, the work system often changes in practice production, therefore, this formula is slightly different from the ideal model used in the modified hall curve method. The derivative numerical solution curve and analytic solution curve plotted according the actual production data are different from the modified hall curve. In order to avoid the effect of work system on analytic solution and quantitatively identify pore passage characteristics, the derivative numerical solution calculated from the production data of one block was taken into the analytic solution formula, and the proposed correction efficient was used to modify the parameters related to the working system, and the correction efficient was 1.2. The permeability was used as an unknown value, and the derivative numerical solution calculated from the initial production data of the block was taken to the analytic solution formula. The comparison of the calculated permeability and actual formation permeability of the wells showed that the number of wells with the error below 8% accounted for 91.4% of total number of wells, verifying that this method was rational and effective. For one well, the permeability was 16.41 mD at initial production stage, and the predicted formation permeability was 36.77 mD after longterm water injection. It was found that an increase in formation permeability after longterm water injection showed that preferential migration passages were produced, which was consistent with the plotted modified Hall curve. 