The Sedimentary Facies And Reservoir Characteristics Of The Bayingebi Formation In The Tiancao Depression,Yin'e Basin

The Tiancao dpression located in the middle of the Yanhai depression in the Yiner Basin.It is a northeast-north-north-eastward “ S ”-type distribution.It is an asymmetrical double-breaking sag-like depression deposit that can be subdivided.It is a steep slope zone,a depression zone and a gentle slope zone in the east.It has the characteristics of large settlement,good relationship between source and storage,and superior hydrocarbon accumulation conditions.Based on the theory of sedimentology,tectonic geology and sequence stratigraphy,combined with regional tectonic setting,this paper systematically studies cores,well logging data,seismic data,thin slices,and analytical test data based on previous studies.Sedimentary facies and reservoir characteristics of the Bayin Gobi Formation.By searching for the regional landmark features,the Bayingebi Formation in the study area was divided into the Ba section,the Ba 2 section and the Ba 3 section by using the adjacent well tracking method,the logging curve method and the equal thickness method.The stratigraphic sections in the horizontal and vertical directions compare the strata.On the basis of stratigraphic division,the core facies and logging facies were identified,and the three types of sedimentary facies,namely the fan delta facies,the nearshore submarine fan facies and the lacustrine facies,were identified.The analysis of fault distribution and stratum thickness,combined with seismic data,identified the main source areas in the east and west.During the period of the Bayingebi Formation in the study area,the coastal steep fan zone developed in the western steep slope zone,and the fan delta sedimentation was developed in the eastern gentle slope zone.The sand body connectivity is good.The remaining areas are shallow deposits of the shallow lake and semi-deep lake.Turbidite deposits.In the early stage of the second block,the lake level rises,the sediment concentration of the semi-deep lake mud expands,the east and west sectors of the fan body degenerate,the sand body scale becomes smaller,and the sand body connectivity is the worst;the lake level falls in the late second block,the semi-deep lake The sedimentation area of the mud is reduced,the fan bodies on both sides are accumulated,and the size of the sand body is increased.With the decline of the lake level,the sand body size reaches the maximum and the sand body connectivity is good.The reservoir rock types of the Baying Gobi Formation in the study area are mainly fine sandstone,siltstone and ash,cloud-type mudstone,and the reservoirs with high carbonate mineral content are relatively good.The reservoir type of reservoir is mainly composed of intergranular pores,dissolved pores and micro-cracks.The porosity and permeability of mudstone reservoirs are low,and the discharge pressure is large.The porosity and permeability of siltstone,fine sandstone and gravel mudstone reservoirs are low,the discharge pressure is small,and the reservoirs with high carbonate mineral content are better.