Sedimentary Characteristics And Heterogeneity Of SⅡ Reservoir In The West Of Daqing Saertu Oilfield

Taking the Yaojia Formation in dense well pattern area of west area in Saertu Oilfield as the studied area and layer, under the guide of high resolution sequence stratigraphy theories and reservoir sedimentology, utilizing core, logging and 3D seismic data to systematically make divison layer unification and correlation of the high frequency isochronous sequences, the studied area and layer is divided into 2 long-term,10 mid-term and 33 short-term base level cycles, to set up the frame work of the high resolution sequence stratigraphy. At the same time, the cyclic sequence type, stacking patterns of shallow water delta are summarized. The deposition of shallow water delta influenced significantly by the climatic conditions. It can be identified two types of base-level cycles in Shallow water delta deposits: type A and type C short-term base-level cycles.Combined with previous studies, the core observation showed that shallow water delta depositional system developed in Yaojia Formation of study area. Three types subphase can be identified in shallow water delta depositional system,which including 11 types microfacies:distributary channel, crevasse splay and crevasse channel, overflowing sand, floodplains, natural levees, underwater distributary channel, interdistributary bay, underwater overflow sand,sheet sand, underwater natural levee. According to the high resolution 3D seimic data in dense well pattern, it is studied that seismic attribution help to distinguish different distributary channel.Seismic attribution can reflect not only the profile and continuity of sandbody in small layer but also the channel boundary. At the same time, seismic inversion was utilized to predict the connectivity of sand body interwell in dense well pattern area.Based on the investigation of the core and establishment of Reservoir Parameter Interpreting Model, all kinds of indexes of reservoir heterogeneity were calculated. Horizontally, the inter-layer heterogeneity of different sedimentary microfacies was investigated. It showed that reservoir physical properties of distributary channel is the best, underwater overflow sand is better, sheet sand is good. Interdistributary bay is the worst. The characteristic of inter-layer heterogeneity primarily belong to the paleogeomorphology and provenance of the sandbodies. Vertically, the intra-layer heterogeneity of microfacies combination is different.Reservoir physical properties is related with rhythm of microfacies. After analysis, the spatial differentiation of sedimentary microfacies sesutled in a change of reservoir bed heterogeneity. But all of these differences are related with base-level cycles.