Sedimentary characteristics and accumulation conditions of Chang-9 oil-bearing layers in Jiyuan area,Ordos Basin

According to the comprehensive analysis of provenance,sedimentary facies and microfacies of Chang-9 oil-bearing beds in Jiyuan area of Ordos Basin,and the study of the petrography,pore type,pore structure and physical properties of the reservoir,it is held that the Chang-9 oil-bearing beds generally are the braid fluvial delta sedmentary systems and locally shallow lacustrine facies.The reservoir types are dominantly Ⅱa and Ⅱb in studied area.Comprehensive study indicates that Chang-91 member is the major reservoir,and it mainly distributes in delta front belt,the reservoir property in Yanchi area is the best,the area is favorable exploration area.