Sedimentary characteristics of Fuyu oil layer in Toutai area of Songliao basin

The deposition of Quan4 Member in Toutai area belongs to meandering-delta and lacustrine deposition system.Meandering-delta facies can be divided into delta plain subfacies and delta front subfacies,and lacustrine facies can be divided into shore lacustrine subfacies and shallow lacustrine subfacies.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 Quan4 Member.The distributary channel microfacies of meandering-delta is the most developed,and the sandstone is favorable reservoir.Because the muddy rock of interdistributary microfacies often enwraps or overlays distributary channel sand,mouth bar,thin sand layer and so on,good storage-seal assemblage,which is favorable for the generation of lithologic trap hydrocarbon reservoir,is formed.