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Abstract：Base on the identification of rock flakes, XRD, physical property analysis and field EM, the characteristics of the reservoir, the types of the reservoir are systematically analyzed. The results show that the main rock types of the upper sandstone reservoir of Cangdong depression are chip quartz sandstone (52%), followed by feldspar quartz sandstone (32%) and quartz sandstone (16%). Because the average burial depth of the upper sandstone reservoir is greater than 2900m, the existence of native pores is rarely found under strong compaction, and the reservoir space type of this reservoir is mainly secondary dissolved pores and intercrystalline micropores, but there are few cracks in local areas. This reservoir has a mean porosity of 7.71% and mean permeability of 0.59 mD. The types of diagenesis in the upper sandstone reservoir mainly include compaction, cementation, dissolution and metasomatism. Combined with the law of the combination and evolution of Ro and clay minerals and the structural characteristics of the microscopic particles, we can know that the upper sandstone of the second section in the hole of Cangdong depression is in the early stage.

 

Keywords: Cangdong depression; 2^nd member of Kongdian formation; upper sandstone; reservoir; diagenesis