Sedimentary Characteristics and Model of Shallow Delta of Quan-4 Member in the West of Daqing Placanticline

Applying high-resolution sequence stratigraphy and reservoir sedimentology and based on cores and logging data,fine researches are conducted on the reservoir depositional features and evolution of Quan-4 Member in the west of Daqing Placanticline.By analyzing the characteristics of mudstone colors,fossils,sedimentary structures and background,Quan-4 Member in the studied area is confirmed as shallow delta depositional system at the lake broaden setting.It develops delta plain and delta front subfacies.It is characterized by large width of facies belt,highly developed distributary channel.Applying high-resolution sequence stratigraphy,the Quan-4 Member in studied area is divided into 1 long-term sequence cycle,3 medium-term sequence cycles and 7 short-term sequence cycles.The fine analysis of short-term sequence cycles' sedimentary microfacies distributes that sedimentary facies belt show as cyclic,the evolution of the sedimentary environment from bottom to top is delta plain-delta front-shallow lacustrine,it embodies the deepening process of the water body during the depositional period of Quan-4 Member.The distributary channel microfacies is the most developed,and the sandstone is favorable reservoir because of its big thickness,good reservoir property and wide distribution.