摘要：Study of the mechanism of porosity evolution and diagenesis is a hot and difficult spot in the field of petroleum geology. The diagenesis and pore evolution of the Triassic Chang 6 oil layer in the Huangling area of the Ordos Basin, China were quantitatively analyzed, by using thin sections, X- ray diffractions and scanning electron microscopy. The quantitative calculation of porosity evolution showed that the initial average porosity of the Chang 6 sandstone was 38.89%. During the diagenesis process, the average porosity loss was 25.59% and 9.81% due to compaction and cementation, respectively. The dissolution of minerals such as feldspar and rock debris in the studied sandstone was strong, and it increased the porosity of the sandstone by 4.63%. According to the criteria for diagenetic strength division, four types of diagenetic facies were identified in the Chang 6 tight sandstone. It was found that the strong compaction, medium cementation, strong dissolution facies is the most favorable diagenetic facies.
