Abstract: Aiming at the problems like rapid water cut increasing,low oil recovery rate and great difference in recovery degree caused by commingling production in north block of Bohai Q oilfield,based on analysis of interlayer interference at different water cut stage,the quantitative characterization of interlayer interference was established.Combined with different reservoir types and vertical heterogeneity of Q oilfield,the interlayer interference at different water cut stage after shutting off bottom reservoir was studied,and the layer series subdivision strategy at high water cut stage was put forward.Through adjustment in the north block,the original one set of development layer was subdivided into three development layers,horizontal wells were adopted and the directional wells were closed.After the adjustment,the water cut of north block decreased 10%,the recovery rate increased0.5% and the recovery ratio increased 10.6%.