Abstract: The main oil bearing series in JZ9-3 Field are delta front reservoirs,consisting of multiphase superimposed sand bodies,with strong heterogeneity.The oil field has been at middle-high water cut stage,with severe production problems,and remaining oil distribution is very complicated.Reservoir heterogeneity characterization on the main oil layers in delta front reservoirs has been conducted through comprehensive study on the distribution of major oil layers and intercalated layers,heterogeneity of permeability,differences in sedimentary cycle between layers,granularity rhythm.It is believed through study that the main oil layers in delta front reservoirs are very serious in heterogeneity,and the main reasons for strong heterogeneity are differences in sedimentary cycle and granularity rhythm.Combined with the analysis of water flooded degree of oil layers,it is believed that the remaining oil distributes mainly in seven main layers of Ⅰ2,Ⅰ4,Ⅱ1¹,Ⅱ1²,Ⅱ2,Ⅲ1,Ⅲ2,western and eastern part of oil field with low well density.Considering the main factors for reservoir heterogeneity which cause the difference in distribution of remaining oil,reasonable overall adjustment plan and injection-production strategy have been made.