Evaluation Of Chang-6 Reservoir In Chi124 Well Block Of Ordos Basin

Chi 124 well region is located in Feng Di keng Township,Dingbian County,Shaanxi Province,with an area of 34.5km².Due to the fast change of porosity and permeability,the diversity of pore throat types and the strong heterogeneity in Chang6 reservoir,the reservoir evaluation is not perfect.?sing geophysical,geological and testing data,On the basis of the establishment of isochronous stratigraphic framework,sedimentary microfacies analysis and sand body distrib?tion characteristics,the study on the characteristics of the chang6 reservoir formation and the comprehensive evaluation of the reservoir are carried out.Msing logging data to identify mark layer and divide sedimentary cycles.This paper divides Chang6 formation into three small layer which are Chang6₁,Chang6₂,and Chang6₃,the major reservoir is Chang6₁ and Chang6₂;its level of small layer is further subdivided into four times:Chang6₁¹,Chang6₁²,Chang6₂¹ and Chang6₂²;The sequence framework of each small layer is stable.The thickness of Chang 6oil-bearing formation is uniform,about 110m,and the top surface structure is monoclinic in the East and West.Combined with regional sedimentary background,core and logging data are used to follow the research method of lithofacies logging facies sedimentary facies.It is identified that the long 6 reservoir is a delta front subfacies with the control of the north-east and north west direction.The subaqueous distributary channel,the river channel edge,the estuarine dam and the subaq?eo?s distributary Bay have four sedimentary microfacies.The microfacies are mainly underwater distributary channel,and the subaqueous distributary channel is branch and strip along the direction of the source.Msing core and thin sheet data,it is clear that the chang 6 reservoir is mainly composed of gray fine-medium grained feldspar sandstone,followed by powder and fine grained lithic argillaceous sandstone.The content of feldspar in sandstone is more than that of quartz,and the content of rock debris and mixed base is less,and the particle size range of sand body fragment is 0.04⁰.28mm,give priority to with good and moderate sorting characteristics,clastic particles formed a round or angular,medium maturity structure,cementation types are mainly composed of pore type cementation.it is clear that the main pore type of the Chang6 reservoir in the study area is the primary intergranular pore and the secondary feldspar.It belongs to the typical"low porosity and ultra-low permeability"reservoir with strong heterogeneity.The chang 6 reservoir is divided into four types by comprehensive analysis of the main controlling factors such as the sedimentary characteristics,physical characteristics,the content of the fillings,the electrical characteristics and the type of pore.Type I reservoirs are mainly fine grained sandstone,with large sand body thickness,good physical property and the smallest distribution in the plane.Type II and III reservoirs are mainly fine-grained sandstone,with good pore permeability,medi?m strong heterogeneity and large distribution range.Type IV is a non permeable reservoir.The sedimentary characteristics are mainly argillaceous sediments.The lithology is fine-grained sandstone and very fine sandstone.It is the worst reservoir type.