Reservoir rocks of no-sturcture traps in southern part of Songliao Basin consist of different types of sandbodies in LST

EST and HST such as basin floor fans and progressive wedges in Lower Stand System Tracts(LST)

transgressive sands and river channel sandbodies in Expanding System Tracts(EST)

delta front

fan delta and fan-toe turbidite in High Stand System Tracts(HST).Most of the sands are not large in size and their destribution is limited.These sandbodies can form oil and gas traps without the matching of structural condition

but require high sealing condilion.According to the relatiorship between sealing positions and sequence boundaries

seeling conditions of non structrure formed reservoirs can be classified into 7 types:E-S-H-H

E-E-S-H

E-L-S-H

E-S-B

E-L-L

E-E-E and H-H-H.Among them

E-E-E

H-H-H and E-L-S-H are the most favourite sealling conditions.