Study On Reservoir-forming Rule Of Fuyu Oil Layer In Daan Area In Songliao Basin

The research area is located in Daan area,Song-Liao Basin,and the target bed is Fuyu Oil Layer,which belong to ultra-low permeability and tight reservoir oil and gas.In light of neglecting the research of “reservoir” of low-permeability reservoir at present,therefore lack the systematic research of generation,discharge,migration and accumulation of hydrocarbon.Being aimed at these problems,the study categorise low-permeability reservoir in research area as convention,transition,unconvention by the characteristics of source rock,reservoir,source-reservoir-cap assemblage.Further make sure that the way of infill injection of oil and gas in Fuyu Oil Layer is injecting continually by means of residual hydrocarbons and organic carbon content and propose “infill injection threshold”(Depth is 1700 m,lower limit values for organic carbon contents is 2.5%),thus,the conventional reach the early period of infill injection threshold,the transitional reach the mid-term of infill injection threshold,the unconventional reach the middle and late stage of infill injection threshold.Applying to casting thin sections,electron microscope scanning and other technical means get the vertical diagenesis evolution: first reservoir physical property was destroyed under compaction and cementation and improved to some degree under dissolution,but it give first place to destruction mainly.The conventional just start to reach the compression stage,the transitional reach the early perid of compression and cementation is obvious and dissolution develops,the unconventional has experienced evolution process which is similar to the transitional which the hydrocarbon generation capacity of the unconventional is strong.It is the important reason that Daan region forms three oil and gas reservoirs.On the basis of the combination of reservoir-forming factors and accumulation process-source rocks,reservoir rocks,cap rocks,oil or gas accumulation and migration,the conventional is controlled by structure and fault,which distributes in the area of stable uplift and major fracture.The transitional is controlled by sand body and fault,which distributes in the area of slope and Peripheral of depression that develop abnormal low pressure.The unconventional is controlled source and sand body(sand body),which distributes in the area of developing sand body in the south depression and developing high sourse rock and sand body in the north depression.