Based on the core and logging datum

and through the research of mudstone's colors

granularity distribution

sedimentary structures

fossils

rock types and their association in the fourth Member of the Quantou Formation in Fuyu oilfield in south part of Songliao basin

it confirmed that the sedimentary environment here was shallow delta facies.Furthermore

it was classified two subfacies of delta plain and delta front.The plan distribution map of sedimentary microfacies of Fuyu oilfield was draw

and based on it

the sedimentary model of Fuyu oilfield was established and the evolutionary characters were also studied.All of those offer basis for increasing reservoir in old oilfields.