Research on reservoir bed heterogeneity,interlayers and seal layers and controlling factors of 2+3 sands of upper second member,Shahejie Formation,in the west of the Pucheng Oilfield

Terminal fans have formed the sedimentary system of the 2+3 sands of the upper second member,Shahejie formation in the west of the Pucheng Oilfield,Bohai Bay Basin,East China.Based on well logging data and physical properties of the reservoir beds,the 2+3 sands were divided into 16 sub- layers.The heterogeneity of reservoir beds and distribution of interlayers and seal layers in the 2+3 sands were investigated.The intra-layer heterogeneity and inter-layer heterogeneity primarily belong to the severely heterogeneous classification.The spatial differentiation of sedimentary microfacies resulted in a change of reservoir bed heterogeneity,strong in the middle and southern parts,weak in the northern part. Spatial distribution of interlayers and seal layers is dominated by sedimentary microfacies,and they are thick in north-eastern and middle parts,thin in the south-western part.