Log Evaluation of Effective Reservoir Lower Limit of Thin Oil Layer of Chang 4+5 Oil Formation in Tianciwan Area
A systematic and comprehensive evaluation of the lower limit of the effective reservoir is needed to realize the fine engraving of the thin oil reservoir in the Chang 4+5 oil formation group in the Tianciwan area of the Ordos basin.In this paper,the characteristics of tight reservoir and the lower limit standard of effective reservoir are systematically studied by using a large amount of geological,experimental,well logging and production data of Chang 4+52 oil formation in this area.The results show that the Chang 4+52 oil formation mainly develops light gray and gray white fine-grained arkose,and the grain size curve of the sandstone has two-stage characteristics.The porosity is mainly distributed in 8%～16%,and the peak interval is distributed in 10%～13%.The permeability is mainly distributed in 0.2～5.6 mD,and there are two peak intervals,which are 0.3～0.4 mD and 1.4～5.6 mD,respectively.The average pore radius of the relatively high-permeability high-quality reservoirs with the permeability higher than 1.0 mD is higher than 0.14 μm,and the sorting coefficient is higher than 2.5.The lower limit of effective reservoir oil grade is oil trace grade,and the lower limit of reservoir physical property is:permeability of 0.3 mD and porosity of 9.0%.The lower limits of electrical parameters of effective thickness are as follows:porosity≥9.0%;oil saturation≥40.0%;resistivity≥15 Ω・m;the acoustic wave time difference is more than 225 μs/m.The reservoir identification criteria for tight oil constructed in this paper by combining core,test,logging,and oil test data are reliable in thin reservoir applications.
log evalustionTianciwan area of Ordos basinChang 4+52 oil formationlower limit of effective reservoirevaluation criteria
万方数据
维普
