Study on Pore Structure Characteristics of tight Sandstone Reservoirs -- Taking Chang 8 in XX block of Ordos Basin as an example

The XX block of Ordos Basin has recently achieved a major exploration breakthrough, however the reservoir is more heterogeneous and the single well productivity is more different. Based on drilling, core, analysis and testing data, the rock characteristics, physical characteristics and microscopic pore structure characteristics of the area are comprehensively analyzed. A set of reservoir classification criteria with strong applicability is established. The results show that the reservoir lithology in the study area is complex, and the types and geometric forms of reservoir space are diverse. The porosity is 0.15%~13.65%, and the permeability is) 0.001~83.5 (×10 -3 μm 2 . The distribution range of physical properties is wide, and the overall performance is low porosity and ultra-low permeability. The heterogeneity is strong, and a few large pores have an important influence on reservoir permeability. A set of reservoir classification and evaluation criteria is established. The study area mainly develops type II reservoirs. The classification and evaluation criteria can provide reference for the later exploration and development of the study area.