Study On Sedimentary Microfacies And Reservoir Characteristics Of Chang6 Oil-bearing Of Yanchang Formation In Dingzi 31 Well Area Of Yanchang Oil Field

On the basis of regional geological date and relevant literature, stratigraphic division and correlation is given according to the shape of the log curves, layer thickness and sedimentary cycles in Chang 6 0il-bearing formationin which is guided by leading edging theories of Sedimentary, Reservoir Sedimentology and Petroleum Geology;the study results of cores,well logging,laboratory experiments,the constraints of the regional marker bed.Combining the sandbody thickness, the ratio of sand to land thickness with the study of facies marks, including lithomarks, Palaeoecologic markers, logging facies, the paper confirms the types and the distribution regulations of sedimentary micro-facies;Using the results of thin sections identification, grain grade analysis, SEM observation,mercury injection and some other experiments data, the paper studies the petrologic characteristics,physical properties, diagenesis and reservoir sensitivity. Finally,the paper obtains comprehensive and systematic knowledge of sedimentary and characteristics of Chang6 oil-bearingformation.Chang6 oil-bearing can be subdivided into Chang61, Chang62 and Chang63, and the thickness range from 50 m to 60 m in the three small layers.Chang6 0i1-bearing in study area develops prodeltafacies,and the distributary channel,interdistributary bay microfacies is more development than the mouth bar facies,and the underwater natural barrier,underwater crevasse splay microfacies basically does`t develop in the area.The study on reservoir characteristics show the rock of Chang6 reservoir is mainly composed of feldspar sandstone,the main reservoir space is secondary pores which can be divided in to large pore mid throat, mid pore small throat,small pore mini throat,and it is the low pore and low permeability reservoir. The physical properties are mainly dominated by sedimentary facies and diagenesis. Besides, the diagenesis mainly comprises mechanical compaction, cementation, replacement and dissolution, and the diagenetic phases can be divided into four categories: mica compaction facies,chlorite cementation facies,carbonate mineral cementation facies and feldspathic solution facies.Reservoir sensitivity is weak.