The sandstone diagenesis and pore evolution of the third member (upper part) of the Shahejie Formation in Linpan and Shanghe Oil Fields heve been studied in this paper on the basis of observation and analysis of cores. thin sections

casting slices

SEM

X-ray diffraction and cathodoluminescence. The study shows that the sandstone of the third member of the Shahejie Formation have undergone immunature stage

semimature stage and mature stage. The diagenesis and pore feature of different stages are obviously different

and the mature stage is the phase of maximum development of secondary porosity. These condary pores in this area involve five basical types

such as intergranular pores

intragranular pores

microporosity

moldic pores and fractures. They have become the most important reservior spaces. The development of the secondary pore is mainly controlled by the provenance. depositional environment and tectonic movement.