Discuss On The Feature Of Chang 8 Reservoir In YL Region Of Longdong,Ordos Saucer

this dissertation takes Yanchang Group 8 of Triassic in YL area of Longdong,Ordos Basin as the research object.Through the study of geological data,core observation and logging data in the study area,the strata of the target layer in the study area are divided and correlated.The Chang 8 reservoir in the study area can be divided into five small layers Chang 811,Chang 812,Chang 813,Chang 821 and Chang 822.On the basis of the stratigraphic division,the study on the stratigraphic structure characteristics,sedimentary facies and sand body distribution,diagenesis,reservoir characteristics and comprehensive evaluation of the reservoir are carried out.The study shows that the Chang-8 formation is mainly an east-west nose structure controlled by structure and stratum,and the overall performance is a west inclined monocline.The main sedimentary facies in YL area include delta front and shore shallow lake.The main rock types of the reservoir are lithic arkose and feldspathic lithic sandstone.The pore types of reservoir mainly include intergranular pore,feldspar dissolution pore and debris dissolution pore.The relationship between porosity and permeability reflects that the porosity and throat of the reservoir are still the main factors affecting the reservoir,and the influence of locally developed micro fractures on the reservoir’s storage and permeability is relatively small;the diagenesis types of Chang 8 reservoir in the study area are various,mainly including compaction and pressure dissolution,cementation,metasomatism,dissolution and fracture.The main controlling factors for the development of Chang 8 reservoir are sedimentation and diagenesis.The reservoirs in this area are mainly Ⅰ+Ⅱ type reservoirs in the underwater distributary channel and Hekou bar sand body of the delta front,and Ⅲ+Ⅳ type reservoirs in the flank,Hekou bar and far sand bar areas of the underwater distributary channel.