Sedimentary Characteristics Of Chang 6 Oil-bearing Formation In Jiyuan Area Of Ordos Basin

The Jiyuan area is located in the mid-western Ordos Basin,and the Chang 6 reservoir is one of the main oil production layers.Therefore,it is very important to study the sedimentary characteristics of the Chang 6 reservoir in the Jiyuan area.By carefully analyzing plenty of well logging,mud logging and core data,the K2,K3 and K4 main marker beds of Jiyuan area were identified.Under the control of the regional marker layer,the stratum of the study area is subdivided into three sand groups according to the combination of the characteristic curve and the thickness of the formation and the local marker layer.Based on the results of stratigraphic division and comparison,the identification of sedimentary facies signs in the Jiyuan area of the Ordos Basin is carried out,including the color sign,the sedimentary structure sign,the logging characteristics and the grain size characteristics,and then analyzes the facies types of the Jiyuan area in the Ordos Basin.The delta type was identified in the study area.The delta facies including three kinds of sedimentary facies and nine types of sedimentary microfacies.They are the delta plain facies,the delta front facies,the front delta facies and the water diversion channel microfacies,the swamp microfacies,the natural dike microfacies,the underwater distributary channel microfacies,the underwater diversion bay microfacies,the estuarine microfacies,the underwater natural dike microfacies,the seat sand microfacies,the front delta mud microfacies.Three kinds of sedimentary subfacies include the delta plain,delta front,delta and six types of sedimentary microfacies including the microfacies of the water diversion channel,the microfacies between the distributable channels,and the underwater distributary Phase,underwater diversion bay microfacies,estuarine microfacies,shore shallow lake microfacies are identified in the study area.Finally,by studying the characteristics of single well,the characteristics of the well profile,the facies characteristics on flat surface and the distribution characteristics of the stratum sand bodies in the Jiyuan area,the location of the ancient lake shoreline in the study area is determined.Furthermore,the sedimentary facies and sedimentary evolution of Jiyuan area are further studied from various angles such as ancient structure,ancient climate and sediment supply.