Study On Hydrocarbon Reservoir Forming Characteristics Of Fuyu Oil-layer In Daqing Placanticline Of North Songliao Basin

Taking Fuyu oil-layer of Daqing Placanticline, North Songliao Basin as the studytarget, this project, with the sequence stratigraphy and the accumulation-formingdynamics as guidline, conducted in-depth research in structure geology,sedimentology and hydrocarbon accumulation and enrichment, presented the majorcontrols over hydrocarbon accumulation of Fuyu oil-layer and pointed out thefavorable exploration deriction.Study of geothermal field and fluid pressure field and stress field of three fieldcoupling, hydrocarbon expulsion in Daqing Placanticline experienced3periods,which are final phase of Nenjiang Formation, Mingshui Formation and Paleogene.: the first one is at the end of Nenjiang Formation; the second one is at the end ofMingshui Formation; the third one is at the end of Paleogene. Hydrocarbon, whichdischarged from the fault into the river sandstone carrier beds, migrated towards toPlacanticline by the combination role of the fluid pressure difference and structuralinduction.Through analysis of tectonic development evolution, Daqing Placanticline ismainly formed in the tectonic inversion. To present for the first time that shallowfaults formed in tectonic inversion phase. The structural inversion and hydrocarbonaccumulation in Placanticline happened in the same time, and it was NE echeloninversion structural belts that hydrocarbon migrated towards and accumulated around.The fractures of T₂were of late genetic causes and hydrocarbon enrichment wascontrolled by NW fracture system.Analysis of genetic types and distribution characteristics in the high resolutionstratigraphic framework of Fuyu reservoir, there developed four depositional systemsfrom bottom to top—meandering river, anastomosing river and shallow water delta.The most favorable reservoir sandstones were point bars of meandering river, channelsandstone of anastomosing river and distributary channel sandstone. The reservoirphysical property is affected by burial depth and the type of sand body control.Comprehensive analysis of reservoir characteristics and hydrocarbon enrichment conditions show that Fuyu oil-layer experienced the accumulation processcharacteristic of multi-phase dynamic migration and differential entrapment（Gussow’s principle）. Hydrocarbon accumulation and enrichment were controlled byquaternity—source rock, structure, fracture belts and sandstone. The main reservoirtype is fault-lithologic character and lithologic-fault reservoir of tectonic background.Integrated oil source, excess o f reservoir pressure, structural induction andreservoir sand body development of Fuyu oil layer, this area is divided into threekinds of favorable area. On the basis of the fault sealing （carrier） ability, reservoirquality, matching relationship of source and reservoir, hydrocarbon trapping capacity,hydrocarbon accumulation is divided into six types. And estimated possible oilreserves is5.1×10⁸tons.