Data of core analyses

logging curves

laboratory tests and seismic profiles

were employed in the analyses of the Cretaceous Quantou Formation in southeast uplift of southern Songliao Basin to understand its reservoir characteristics

sedimentary facies types and configuration of sedimentary system.The results show that the formation is dominated by oxidized purple sandstone and pink siltstone.Reservoirs are tight with rather low porosity and permeability and contain mainly quartz

feldspar

debris and trace minerals.Heavy Mineral Assemblage Analysis Method and Sand Content Analysis were used to reveal the controlling factors of the basin.It shows that three major fluvial branches

namely Lishu-Sangshutai

Changchun-Nongan and Yushu-Fuyu

controlled the basin.Sand content decreases gradually from east to west along the edge of the basin to another depression.The formation features in rapid sedimentation of coarse grains which formed fans in steep slopes and rivers in gentle slopes.Stratigraphically speaking

the basin contains sequence V-q1 which mainly developed braided river deposits and alluvial fan deposits; Sequence V-q2 and V-q3 which mainly developed alluvial fan

braided river

meandering river depositional system

during its transition from braided river to meandering river

and sequence V-q4 which developed the meandering river deposits and completed the process of turning from braided river to meandering river.Meanwhile

Changchun and Yushu branches converged in Changchun Ridge anticline belt and formed fluvial deposits during the late stage of the formation.