The polymer flooding blocks in Daqing oilfield had entered the subsequent stage of water flooding development. Due to the long-term water polymer flooding

the preferential seepage channels in the oil layers were highly developed

and the inefficient and ineffective circulation were serious. In order to achieve the goal of further EOR after polymer flooding

the dominant seepage channels must be accurately identified and effectively blocked. The conventional description methods

such as the coring

logging

profile testing and production performance

were with few and discontinuous data

low accuracy and high cost. As it was difficult to identify

by the streamline numerical simulation technique

and based on the study of typical blocks

we screened the key parameters and established the permeability time-varying model and mathematical model of comprehensive identification index. Then according to the initial value iterative method and combined with expert experience

we proposed the weight of the key parameters. At the same time

the dominant seepage channels were quantitatively graded according to the comprehensive identification index. The results showed that the calculated distribution of dominant seepage channels in typical blocks were highly consistent with the actual water absorption profile test results

which meant that the established method could accurately describe the distribution law of dominant seepage channels after polymer flooding. The research had important guiding significance for identifying and effectively sealing the dominant seepage channels

and provides strong support for the further efficient development after polymer flooding