Abstract:
In the fourth member of Shahejie formation of Wang 73 well field in Dongying depression,typical lacustrine shoal-bar sand bodies are developed.According to core characteristics,plane distribution of single shoal-bar sand body,and plane vertical grain variation of single sand body at different positions,the microfacies related with shoal-bar can be divided into main body,frontier, rear,bend behind bar,ripicolous deposits,etc.Vertical- ly,the shore-shallow lacustrine sediments of the fourth member of Shahejie formation in the study area are devel- oped into symmetrical high-frequency semi-ascending cycle and semi-descending cycle.These shoal-bar sand bodies mainly deposited at the relative steady period of the surface of lake from ascending to descending.Therefore, the distribution position of shoal-bar body can be deter- mined by vertical sedimentary sequence and assemblage of bar front and rear.