Study On Sedimentary Microfacies And Reservoir Characteristics Of Chang 6 In Well 46-15 Area,West Of Wuqi Oilfield

The Ordos Basin is one of the major large-scale oil-bearing sedimentary basins in China.However,the research and description of the Chang 6 reservoir geology in the western part of the Wuqi Oilfield is incomplete,affecting the subsequent oil and gas exploration and development effects.In this paper,I combine the logging curves and laboratory data in the 46-15well area of the western Wuqi Oilfield based on the previous studies with core observation,microscopic observation of the cast thin section,mercury intrusion analysis,and scanning electron microscopy.Sedimentary microfacies and reservoir characteristics were studied by various techniques such as pore permeability measurement.The study area is located in the western part of the Ordos Basin and is mainly controlled by the northeast-southwest and northwest-south east direction.The Chang 6 is mainly the delta front subfacies,and the Chang 6³to the Chang 6¹ is the sedimentary pattern of the lake retreat.There are five sedimentary modes in the subaqueous diversion bay,the estuary sand bar,the sluice sand and the diversion bay sedimentary microfacies.The reservoir properties of the intercepted underwater distributary channel and the superimposed subaqueous distributary channel sedimentary model are better.The reservoir sandstone is mainly feldspar sandstone,and the maturity of the reservoir structure from Chang 6³ to Chang 6¹ is gradually higher.The composition of the interstitial is mainly iron calcite and authigenic clay mineral.The sandstone particles are mainly fine sand-very fine sandstone.The poor roundness is mainly sub-edge-sub-circular,and the sorting degree is poor.The most important type of pore is the intergranular dissolved pores,and the pore throat radius is a fine-thin throat.Mainly affected by four diagenesis effects,compaction,pressure dissolution and cementation have a negative impact on reservoir physical properties,and dissolution can greatly improve reservoir storage performance.The average length of the Chang 6 is2.60x10^-3?m² and the average porosity is 6.13%.Chang 6¹ has the largest average sand thickness value and the best overall physical properties,while the Chang 6³ sand thickness is small,the physical property deviation,and the long 6 medium heterogeneous reservoir.Through classification,this paper considers Chang 6¹ as the best reservoir.