Sedimentary Facies And Reservoir Characteristics Of Jurassic Yan 9 Reservoir Group In Huanxian Area,Ordos Basin

In this thesis,the author takes the Yan 9 reservoir group which I located in Yan'an Formation from Jurassic System in Huanxian area of Ordos Basin as the research object.Based on the previous studies,and guidance of multidisciplinary theory,the author takes analysis about field observations,drilling core observation and description,observation and identification of ordinary and casting thin sections,measurement of porosity and permeability.Systematic studies on sedimentary faces and reservoir characteristics of Yan 9 reservoir group in Yanan Formation from Jurassic System in the study area,and the following understandings are obtained:1? During the deposition period of the Yan-9 reservoir group in the study area,the lake delta plain sedimentary surfaces were mainly developed.Five types of sedimentary microfiches: distributary channels,natural embankments,crevasse fans,inter-diverting depressions,and peat bogs were further identified.The distributary channel sand body are the main type of reservoir sand body in the study area.2?The reservoir rock types in the Yan 9 reservoir group in the study area are mainly feldspar lithic sandstone and lithic quartz sandstone.Medium to good composition maturity,and moderate structural maturity,The interstitial materials are mainly siliceous,kaolinite and hydromica.3?The reservoir space of Yan 9 reservoir group in Huanxian County is dominated by intergranular and feldspar solution pores,while the intergranular pores and detritus so;ution pores for secondly.The throats are dominated by medium to fine throat with lengthened punctate and schistose structure.Showing better pore-permeability and low pore permeability.4?The types of diagenesis which the reservoirs iecperienced in the study area are mainly mechanical compaction,pressure dissolution,and dissolution.The main reasons for the low permeability of the reservoir in this area are strong compaction and strong cementation.The dissolution of feldspar greatly improves the physical properties of the reservoir.5 ? The main controlling factors of reservoir development are mainly sedimentation and diagenesis.Sedimentation is the foundation of reservoir development,which affects the reservoir properties to a certain extent.The reservoir properties of sand bodies in distributary channel the best,followed by the flanks in distributary channel.The compaction and cementation in diagenesis are the main factors for the deterioration of sandstone reservoirs in the study area.Corrosion has improved the physical properties of the reservoir to some extent.