Developmental Mechanism And Relative Contribution Rate Of Secondary Pore In Jinci Member Of Benxi Formation,Ordos Basin

The upper Paleozoic in Ordos Basin is one of the most potential intervals for tight gas exploration in China.Compared with the upper Shihezi Formation and Taiyuan Formation,the Benxi Formation has a relatively low degree of exploration and research awareness,but the exploration practice has proved that Benxi Formation has a vast tight gas resource potential.Based on the seismic data,core observation,logging data and other information,combining with rock slice,cathode luminescence and SEM,this study systematically analyzes and studies lithological and physical property characteristics,secondary pore types and formation mechanism of Benxi Formation reservoir in Ordos Basin.Firstly,by means of thin section analysis and SEM identification,the pore types and characteristics of Benxi Formation in the study area are analyzed and determined,and the secondary pores are classified in detail.At the same time,the surface porosity is carried out to determine the relative contribution rate of secondary pores.On the basis of core analysis,the effects of lithology,grain size,carbonate,sedimentary facies and diagenesis on the development of secondary pores are analyzed,the diagenetic evolution sequence is established,and the diagenesis type and its influence on secondary pores development are defined.Based on the present measured porosity,this study reveals the diagenesis and quantitative evolution of porosity by means of inversion stripping.Based on the above research,the mechanism of secondary pores development in Jinci Member of Benxi Formation is revealed,the quantitative calculation model of secondary pores is established,and the relative contribution rate of secondary pores is determined.