Analysis On Features Of The Oil And Gas Accumulation And Favorable Target Of The Wulanhua Sag In Erlian Basin

Wulanhua sag is a new petroliferous sag which is discovered in Erlian Basin.This sag has favorable source conditions,complex structure,various depositional types,different zones of different reservoir controlling factors analysis of depression,the reservoir characteristics and the favorable targets is of great significance to the exploration of oil and gas.Through the resources evaluation of the sag we can resault that the dark mudstone of Wulanhua sag is thick and has large amount of mature hydrocarbon source rocks.The hydrocarbon source rock of Tenggeer group and Aershan is the main source bed of Wulanhua.According to bitumen "A" method,the total resource quantity is 10394×104t.Primary migration of oil and gas occurs at fast compaction stage.The second migration of oil and gas is lateral migration.There are 3 main types of the second migration: by the lateral sand,by the hydrocarbon source rock;by the large area of distribution of the unconformity.Affected by NW-SE tensile stress,Wulanhua sag has graben structure and the reverse "S" tension structure.This sag divided into two depression and five structural belt.The structure of north depression is simple structure.The sag is a half graben which it?s fault in the east and overlap in the west.The northwest slope suffered erosion.Depression zone deposit stable.There are three positive structures around the sag: Saiwusu,Tumuer and Hongjing.Detrital material of Wulanhua sag is mainly came from the northwest and southwest.The reservoir is mainly fan delta,followed by braided river delta,subaqueous fan and sublacustrine fan is rare.The charactor of reservoir is low permeability and low porosity.The reservoir is mainly controlled by structure and lithology.According to the trap genetic type,Wulanhua sag has structural reservoir,stratigraphic reservoir and structural-stratigraphic reservoir.The reservoir structure is dominant.Aershan formation mainly developed composite reservoir.Saiwusu?Tumuer and Hongjing are the favorable areas in Tenggeer group.Ancient landform affected deposition and reservoir of Aershan group.Saiwusu and the east steep zone are the favorable areas..Pointing out that Petroleum reservoir formation conditions in Saiwusu?Tumoor and Hongjing are favorable by dissecting the reservoir's chractor and mode of reservoir of 5 constructures near the trough.There are many favorable targets and large scope.It is the main direction for further exploration.