关键词: 基准面旋回, 精细沉积微相, 浅水三角洲, 水下分流河道, 宋芳屯地区, 松辽盆地

Abstract: Based on the high resolution sequence stratigraphy theory, 42 wells and 2745 well logging curves are used to study the evolution of all levels of base level cycles and the development pattern of high⁃resolution sequence in the P reservoir in the southern part of Songfangtun area. The results show that the 4 sequence interface of the grape flower beds in the Songfangtun area can be divided into 2 medium⁃term, 5 short term and 12 ultra short term sequences. On this basis, the sedimentary microfacies type and distribution evolution law have been carried out. It is considered that the shallow water delta depositional system is developed in P reservoir in the Songfangtun area. The main development of delta front subfacies is to identify 8 kinds of microfacies such as subwater distributary channel, inter channel, inter channel, slime, overflow sand, mouth fan, estuarine dam, far sand bar and mat sand. The underwater distributary channel sandbodies are widely developed at the front of the delta. Due to frequent bifurcations and diversions, the underwater distributary channel sandbodies cut and overlap each other, forming branches and striped sand bodies. The sandbody reservoir has good physical property and is the main reservoir sand body with oil and gas enrichment. Through detailed study of sedimentary microfacies, it provides a reference for further exploration and development of lithologic reservoirs in this area.

Key words: Base level cycle, Fine sedimentary microfacies, Shallow water delta, Underwater distributary channel, Songfangtun area, Songliao basin