Sedimentary microfacies of Qingshankou formation and its control over favorable reservoir in Yaoyingtai area of Changling sag

By the statistics of sedimentary microfacies and statistic research,this paper discusses the type and distribution characteristics of sedimentary microfacies of Qingshankou Formation,and its controlling effect on favorable sand.The results show that:The analysis result of abundant cores,logging,and well logging data reveals lacustrine facies and delta facies are main sedimentary facies types of Qingshankou formation in Yaoyingtai area of Changling Sag,Songliao Basin.Lacustrine facies are composed of shore-shallow lacustrine subfacies,which are subdivided into 3 sedimentary mircorfacies:sandy beach-bars,mixed beaches and muddy beaches.Delta facies are mainly composed of delta plain subfacies and delta frontal subfacies.The delta plain can be divided into distributary channel,inter-distributary bay microfacies.The delta front includes underwater distributary channel,underwater inter-distributary bay,estuary bar,sheet sand,distal sandbar microfacies.Different types of facies,sub-facies and microfacies will not only control the lithofacies change characteristics,sandbody distribution characteristics and reservoir performance of the sandbody,but also control oil bearing of sandbody.Because estuary bars,the underwater distributary channels and beach-bars have more excellent quality in reservoir performance and oil bearing,they are key targets of exploration and exploitation.