Study On Sedimentary Facies Of Zhangxia Formation In Key Outcrop Section Of Ordos Basin

In recent ten years,the exploration of Lower Paleozoic oil and gas in Ordos Basin has been developing rapidly,and the Ordovician natural gas exploration achievements are outstanding.Large gas fields have been found and explored in the Ma5 member of Ordovician.Cambrian has similar carbonate platform sedimentary environment with Cambrian,so the prospect of Cambrian oil and gas exploration in the basin is expected.At present,the study of Cambrian has not been in-depth.Therefore,the study of the Cambrian system is very important for oil and gas exploration in the basin.The purpose of this study is to make a breakthrough in the exploration of Cambrian oil and gas in Ordos Basin and to expand the field of oil and gas exploration in Ordos Basin,which is of great significance to the improvement of oil and gas production and the expansion of reserves.On the basis of fully digesting and absorbing the previous research results,combining with regional background data,field survey is carried out,key sections are selected and the field survey is carried out.According to the marks of stratigraphic division,the stratigraphic division scheme is determined,and the Zhangxia Formation is divided into three sections.Then the sections are compared.Establish a stratigraphic correlation framework.On the basis of stratigraphic division and correlation,sedimentary facies analysis indicators are determined,including petrological characteristics,sedimentary structure,and paleontology.The sedimentary facies types of Zhangxia Formation are identified and classified.The open platform,limited platform,platform margin,slope-deep water basin,and other sedimentary facies types are identified in Zhangxia Formation.Based on the sedimentary tectonic background of the basin and previous research results,the plane distribution map of sedimentary facies of Zhangxia Formation in Ordos Basin is drawn,and the distribution law of sedimentary facies of Zhangxia Formation in the basin is clarified.The sedimentary facies model of Zhangxia Formation in the basin is summarized.On the premise of sedimentary facies analysis,combined with analysis and testing data and previous research results,the pore types and reservoir physical parameters of Zhangxia Formation reservoirs in different facies zones are analyzed,the reservoirs are evaluated,and the favorable facies zones for reservoir development are summarized.It is considered that the platform margin beach developed by Zhangxia Formation carbonate platform is a favorable facies zone.