1�� College of Earth Sciences��Jilin University��Changchun 130026��China; 2�� Xinjiang Oilfield Company��Karamay 834000��Xinjiang��China; 3�� Northeast Petroleum Bureau of Sinopec��Changchun 130062��China

A number of isolated fault sags in Late Jurassic--Early Cretaceous were developed in the early stage of southern Songliao Basin��and unified to a depression basin in the late stage�� Therefore��multiple isolated lower petroliferous systems were formed with fault sags as source rocks�� The source rocks of fault sags in Late Jurassic --Early Cretaceous were mainly described with gas generation as favorable source rocks��leading to the southern Songliao Basin rich in natural gas resources combined with organic gas resources in Nenjiang Formation�� A number of tectonic movements in southern Songliao Basin led to the formation of abundant structural traps and complex fault systems��and controlled the distribution strata and positions of sources rocks in Late Jurassic--Early Cretaceous fault sags�� The oil-gas reservoirs can be divided into two types��i�� e����primary and secondary ones�� The primary oil-gas reservoirs were distributed in the fault sag strata and the bottom of overlying depression strata ( lower Quan-1 Member) �� The oil-gas reservoir accumulation depended on the trap development situation and the distance from source rocks�� The preservation conditions of oil-gas reservoirs depended on the degree of reconstruction in the late tectonism�� The secondary oil-gas reservoirs were distribution in the Quantou Formation of depression strata��where oil and gas reservoir accumulation depended on three conditions��i�� e���� trap development situation��deep gas sources and the fault to connect the shallow traps and deep gas sources�� The southern Songliao Basin is rich in lower coal type gas��upper oil-gas and biogas resources��which are important resources in the future��