Depositional Characteristics of Shallow Water Delta in Large Depression Lake Basin and Control of Reservoir Distribution

Summary Songliao Basin is a large continental composite basin, developed a world-famous large-scale sandstone oilfield, Daqing Oilfield. Putaohua Reservoir (corresponding to Coniacian Stage of international stratum) in the first member of Yaojia Formation of Cretaceous is the most important oil producing reservoir in the basin. It has characteristics of full depression oil-bearing in a large area of lithologic reservoir in Central Depression area, and has become an important reservoir system for the main development and exploration of Daqing Oilfield. This paper focuses on sedimentary controlling factors of the distribution of large area lithologic oil reservoirs in Central Depression of Songliao Basin, and expounds geological conditions of the formation of the reservoir, the development characteristics of delta deposional system, the scale of the formation of sand bodies in different facies zones and the influence on distribution of the reservoir, so as to further guide exploration direction of lithologic oil reservoirs in Putaohua Reservoir.