Reservoir Characteristics And Oil Control Of Chang 6 Reservoir In Chaishangyuan Area,Ordos Basin

In this paper,the sedimentary microfacies types,spatial distribution characteristics of sand bodies,diagenesis,pore evolution and reservoir genesis of Chang 6 reservoir in chaishangyuan area of qilichun oilfield are studied by means of well logging interpretation data,core,casting thin section,cathodoluminescence,scanning electron microscope,particle size analysis,high pressure mercury injection and other experimental analysis data,combined with the data of monthly production and pore permeability physical properties of single well recovered by simulation In this paper,the controlling factors of densification analysis,reservoir physical properties and reservoir distribution are studied,and the reservoir classification and evaluation are carried out,and the favorable areas of the reservoir are predicted.The delta front subfacies are developed in Chang-6 reservoir of chaishangyuan area,mainly including underwater distributary channel,underwater natural dike,underwater distributary Bay and Hekou dam.The Hekou dam microfacies are not common in the study area.The distribution direction of each small layer of Chang-6 reservoir has good inheritance,and it is distributed in the north-east,Southeast and west direction.According to the spatial distribution characteristics,the sand body configuration can be divided into isolated type,side stacked type and stacked type,while the side stacked type can be further divided into discrete side stacked type and undercut side stacked type;the stacked type can be further divided into discrete stacked type and tight stacked type.The Chang-6 reservoir is mainly composed of fine-grained arkose,and there are 4 types of pores,including residual intergranular pore,dissolution pore,clay mineral intergranular pore and micro fracture.The secondary enlargement of quartz in two stages,cemented filling of calcite in two stages and multi-stage dissolution of clay minerals were observed under the condition of casting thin section and cathodoluminescence.The mechanical compaction makes the porosity loss 30.88%,residual porosity13.81%,cementation loss 10.31% and dissolution increase 4.04%.The comprehensive study of diagenesis and pore evolution shows that early mechanical compaction is the main cause of reservoir densification,and cementation is the further densification of reservoir.According to the micro characteristics of reservoir displacement pressure,maximum mercuryin flow saturation,mercury removal efficiency,pore throat median,porosity,permeability,capillary pressure median,separation coefficient,movable fluid saturation and combined with the observation and comprehensive analysis of core oil-bearing level,the reservoir in chaishangyuan area is divided into three types of reservoirs;the high-yield oil wells in the early months are mainly distributed in the thicker sand body,physical properties and heterogeneity of the reservoir On the sand body of underwater distributary channel with good sealing of upper overburden.