Since 2016, Ansai oilfield has carried out polymer microsphere profile control and flooding, which has experienced three stages: pilot test, expand the scale of the test and promotion of three stages. The regional stage decline can be reduced about 5%, the overall effect is obvious, but the adaptability and application effect under different reservoir conditions are quite different, For the study of polymer microspheres in multiple media under the condition of mechanism, a group of 60 different particle size of polymer microspheres in different media under the condition of displacement test was carried out. Through the combination of experimental data and field application, the mechanism of microsphere oil displacement (percolation mechanism, change of flow direction mechanis) and the matching relationship between microsphere particle size and reservoir microfractures and pore throat are systematically summarized,which provides a basis for the optimization of construction parameters in the later stage.

In order to explore the new mode of using residual oil, Ansai oilfield first used horizontal wells to encrypt the remaining oil, and 7 key technologies and field tests were carried out. Based on the different way of encryption horizontal well spacing and the transformation parameter study, the mechanism of remaining oil distribution was obtained and the technology of using remaining oil in high and medium water-bearing encrypted horizontal well adapted to Ansai low permeability reservoir was explored. It is proved that horizontal encryption can effectively use the remaining oil and low abundance reservoir between wells to utilize the remaining reserves of developed areas, which provides new enlightenment for the same reservoir to further improve the recovery rate.