Fan Delta Deposits and Relation to Hydrocarbon of Upper Es_4 at Yong 921 Area in Dongying Depression

Fan delta sediments are widely developed in the upper part of the fourth member of Shahejie Formation at Yong 921 area in the north steep slope of Dongying depression.They are among the best reservoirs in the area.Based on the theory of sedimentology and reservoir geology,combined with outcrop,drilling data,well logging and analytical data,fan delta's depositional characteristics,sedimentary model and reservoir characteristics are studied and summarized.According to characteristics of the deposits,fan deltas there can be subdivided into three subfacies and six microfacies.With analysis of lithological properties,diagenesis,sedimentary microfacies,structural features and sedimentary structure factors controlling the physical of reservoirs.The authors believed that channel fill sands are the most favorable reservoirs in the subject area,and can have the best combination of oil source bed,reservoir and caprocks.