The Establishment of Sequence Stratigraphic Framework and Its Models of the Shahezi Formation in Xujiaweizi Fault Depression,Songliao Basin

The exploration strategy of stratigraphic and subtle reservoirs is different from normal reservoir's. Sequence stratigraphy is an effective method. With the use of drilling,data of logging and seismic,the surfaces of third-order sequences are identified,Xujiaweizi Fault Depression is divided into 4 third-order sequences,and the sequence stratigraphic framework is established. Each sequence stratigraphy is divided into three system tracts: lowstand,transgressive and highstand system tracts through the identification of First flooding surface and Maximum flooding surface. Based on the ancient landform,basin structure,evolution of fault depression and stratigraphic characteristics,the sequence stratigraphic modes of the study area are established Single graben slopes sequence stratigraphic model and double graben shun-past sequence stratigraphic model. A preliminary analysis is made on the relationship between sequence stratigraphic models and the oil-gas exploration,the stratigraphic and subtle reservoirs in each systems tract are predicted.