Pore Structure Characteristics And Physical Property Response Of Yan 9 Reservoir In Z1 Well Area Of Ordos Basin

Z1 well area is located in the middle of Ordos Basin.Yan 9 reservoir of Yan’an formation is the main exploration and development layer system in this area,which has entered the middle stage of development as a whole.A correct understanding of pore structure and physical property response is of great significance for clarifying the law of oil accumulation,tapping the potential of residual oil and improving oil recovery.On the basis of previous research results,this paper comprehensively uses the data of core,casting sheet,scanning electron microscope,CT scanning,nuclear magnetic resonance,mercury injection data and conventional logging to establish a physical property interpretation model suitable for the geological conditions of this area,and systematically studies and discusses the pore structure and physical property response.Thin section identification shows that lithic feldspathic sandstone is mainly developed in this area.The pore types are intergranular pores and dissolution pores,and flaky and curved throats are common.Low-porosity-ultra-low permeability reservoirs are mainly developed in this area.Based on the relationship between DT logging curve and porosity,a high precision porosity interpretation model is constructed.On this basis,the pore-permeability correlation relationship is established,and the correlation is high,which is used as the permeability model.The interpretation result of the model is reliable and applicable.According to the mercury injection data,the capillary pressure curves are divided into two types: type Ⅱ middle displacement pressure-medium pore fine throat type,type Ⅲhigher displacement pressure-small hole fine throat type.There is a certain correlation between the parameters and physical properties.Based on NMR experiments,there is a positive correlation between physical parameters and movable fluid saturation.Using CT scanning technology,the pore throat has a certain ability to connect in three-dimensional space,mainly the development of small pore and micro throat.It provides a reliable basis for further exploration and development.