| The Ding 44150 well area of Dingbian oilfield is located on the western edge of the Yishan slope in the Ordos Basin and adjacent to the Tianhuan depression.At present,the well area has entered the development stage,but production decrease rapidly,water injection response slowly or inefficiently.Largely,the reason of overall poor development effect is lack of understanding of geological issues,such as the heterogeneity of reservoir characteristics,the relationship between oil and water and their distribution patterns.Based on this,this paper studied the formation stratigraphic division,sedimentary microfacies,reservoir heterogeneity,second interpretation of well logging,and reservoir characteristics of the Ding 44150 well area through 171 well logging data,test production date combined with core observation and indoor analysis test data analysis,which will provide geological basis for the scientific development of water injection in the area and the formulation of next-step development adjustment plan.The Chang 8 oil-bearing formation in the Ding 44150 well area develops northeast and northwest delta fronts sub-facies,sedimentary micro-facies are submarine distributary channel and sub-distributary bay.Two underwater distributary channel sand bodies developed in the northeast direction,the northwest direction developed one.So three underwater distributary channel sand bodies converged and overlapped in the middle of the work area,becoming the most favorable reservoir body.The lower limit of the lithology of Chang 8 in the study area is fine sandstone,and the lower limit of the oil production is oil stains.The lowest limit of the physical property of the effective reservoir is 7.5%,while the permeability is 0.1×10-3?m2,and the lowest limit of electrical property is RILD?13?·m,?t?216 ?s/m,So?35% respectively.Chang 8 reservoir sandstone rock types are feldspathic lithic sandstone or lithic feldspathic sandstone.The types of cements are mainly hydromica,chlorite,kaolinite,ferrocalcite and siliceous cementation.The pore types are mainly inter-particle pores and internal pores.Reservoir porosity is mainly distributed in 8% to 13% with an average value of 10.68%;permeability is mainly distributed in 0.15×10-3?m2 to 2×10-3?m2,and the average value is 0.86×10-3?m2.The reservoir has high displacement pressure,high median pressure,and intermediate pore connectivity.The pore throat is generally small-hole and micro-throat,and reservoir belong to low porosity and extra-low permeability reservoirs.Chang 8 reservoirs have strong in-layer heterogeneity of permeability,develop positive rhythm of the body.Extensive development of the interlayer and irregular distribution enormously affect intra-layer heterogeneity.Reservoir sand bodies have better lateral continuity.The types of superposition of sand bodies are mainly superimposed waterways and isolated waterways.The heterogeneity of the sand body is weak in the central part of the underwater distributary channel,but it is stronger in the edge of the river channel and the inter-subdivision bay.The partial sand bodies in the overlapping area of underwater distributary channels have low porosity and permeability,and they have a strong degree of heterogeneity.The Chang 8 reservoirs are mainly distributed in the northeast and northwest submarine distributary channel main belt overlapping and contiguous areas.The properties of the oil sand body layer are mainly oil-water layer,oil and water are not differentiated,and the reservoir type is lithologic reservoir.The oil and gas are mainly distributed in the layer of 82-1,and the main distribution of the oil reservoir is controlled by the “favorable facies,structure nose,shielding of up-dip”. |
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