In order to further improve recovery ratio of post-polymer flooding, a test with low initial viscosity gel/weak alkali ternary as the displacement system was carried out in Block B in northern Songliao Basin through well pattern reconstruction. In order to adapt to the new post-polymer flooding displacement system and well pattern reconstruction development method, oil production engineering design analyzed systematically the contradictions between oil production technology and reservoir conditions, well pattern structure, and displacement systems, and targeted technical countermeasures have been formulated. A series of optimized process were carried out to meet the needs of reservoir development according to reservoir characteristics, such as avoid perforating for water flooded layer, large aperture perforating charges for water injection well, wide and short fracture fracturing, chemical flooding injection processes, lifting and scaling prevention processes, and downstream plugging processes. The oil production engineering design method and supporting process series for well pattern reconstruction development for post-polymer flooding have been formed. After being put into production, the power saving rate of the lifting system has reached 18.58%, and the pump inspection cycle has been extended by 83 days compared to other similar blocks. Compared with the polymer flooding development stage, the average injection intensity of the injection well has been increased by more than 30%, the water absorption thickness ratio has been increased by 10.4 percentage points, and the stage oil recovery has been improved by 13.1 percentage points in the post-polymer flooding stage.