Abstract: Based on thin sections,scanning electron microscopy(SEM),core porosity and permeability data,and mercury injection data,this paper summarized the pore types,physical property of tight sandstone of the Xujiahe Formation and discussed the controlling factors on pore types,poroperm relationship and spatial change of physical property.The result shows that the rapid compaction process and minor dissolution resulted in the relative abundant of primary pore followed by dissolution pore and intergrannular micropore.As the porosity increases,the permeability change shows a three-stage pattern,namely rapid increasing first,then getting stabilized and increasing again.This distribution pattern is mainly controlled by pore throat filling authigenic chlorite and illite which offset the increases in permeability due to the increase of porosity.The poor connectivity of dissolution pore and micropore also influence the permeability of sandstone.The spatial change of physical property of sandstone is controlled by sedimentary condition.The relative short transport distance or low energy environment resulted in low compositional and textural maturity and poor physical property.Only the sandstone with long transport distance and high energy environment are abundant in porosity.The physical quality in middle and lower part of single fluvial sandstone is better than that of the upper and bottom parts.The major reason is that the decreases of energy during fluvial sandstone deposition result in higher compositional and textural maturity of the middle part and lead to the diagenetic heterogeneity within a single sandstone.

Key words: pore type, porosity and permeability, tight sandstone, Xujiahe Formation, Sichuan Basin