The Yingcheng Formation in Sujiatun area

Lishu Rift in Songliao Basin

has good conditions for the formation of petroleum reservoirs.However

the level of research is low in this area.The paper is to identify favorable reservoir facies belt through study of sedimentary microfacies and sandstone reservoir conditions.The theories of sedimentoloy and high-resolution sequence stratigraphy were applied and the cores

mud logging

well logging

seismic data and palaeogeomorphology data were integrated.The study revealed that lacustrine and braided river delta sedimentary facies are predominant in the study area.Furthermore

eight sedimentary microfacies were identified

including distributary channel

underwater distributary channel

underwater interdistributary

month bar

distal bar

sheet-like sand

mudflats and bank bars.And the main characteristics of sandstones of sedimentary microfacies are described.The Yingcheng Formation was divided into 4 Members

6 fourth-order sequences and 7 sand groups.The sedimentary facies distribution and their temporal and spatial evolution of each sand group(SG) were discussed.The transgressive surface to maximum lake flooding surface occurred at the end of deposition of the Ying-1 Member (SG2)

and the overlying SG3 is the most favorable reservoir.Analyses of plain distribution of sedimentary facies and reservoir reveal two main braided channels with good stacked distributary channel sand bodies and reservoir properties.The main braided channels in combination with late nose structure are the most favorable areas for the development of structural-lithologic traps and lithology traps.