Abstract:At present the Daqing oilfield has entered the high water cut stage, and tapping remaining oil in thick oil reservoirs has become a major subject. The inner interlayers caused strong heterogeneity of thick oil reservoirs,and made the distribution of the remaining oil more complex.This paper takes the east of the fault block in Beiyi district of Daqing oilfield as the target area,to study the disjoining of thick sandbodies and the characteristics of inner interlayers and to provide a reliable evidence for tapping the remaining oil in the thick oil reservoirs.First,on the basis of sedimentary characteristics and logging data ,we have confirmed the separability of the complex sand-body . Second,we’ve determined the inner layers deposited between different channels as a separability proof of the complex sand-body.Lastly,through the study on the causes and lithology,we have divided the interlayers into three types,that is muddy interlayers, calcareous interlayers and physical interlayers.This paper has tried to combined the disjoining of complex sand-body with the interlayers.