Sand body in the 3rd member of Dongying Fm in eastern slope of Chengdao is controlled by subaqueous channel

with subaqueous fan to be characterized by both traction and turbidity current sediments. The petrographic facies include hybrid matrix-supported gravelly sandstone

pebbled sandstone

argillaceous-supported sandstone and sandy siltstone

which are mainly characterized by coarse-grained sediments. Depositional beddings such as graded bedding

massive bedding

parallel bedding

cross-bedding and wave bedding

are well developed;and depositional structures including slump

convolute and load-dehydration

are also developed very well.Obvious channel downcutting has been recognized in the seismic profiles

which appears as wide semi-lens—being flat on the top and being slightly convex at the bottom;and the spontaneous potential log shows positive rhythm

with columnar and box-like shapes changing respectively from high amplitude to medium amplitude

which are closely related to different lithology and different depositional facies.On the basis of lithology

and electric and reservoir property analyses

depositional facies in this area can be divided into 7 micro-facies

including subaqueous channel

interchannel unconcentrated flow

interchannel splay

subaqueous levee

interchannel mudflat

river mouth lobe and sheet sand microfacies.