Reservoir characteristics and diagenetic evolution of Lower Jurassic Sangonghe Formation in the hinterland of Junggar Basin

On the basis of core observation and description, multi-scale microscopic analysis and related reservoir physical property analysis, the petrological characteristics, reservoir characteristics and diagenetic characteristics of the Lower Jurassic Sangonghe Formation in the central area of Junggar Basin are systematically studied, and the diagenetic evolution sequence of the reservoir is further established. The results show that the reservoir in the studied interval has undergone three diagenetic processes: compaction, cementation and dissolution during its development and evolution after burial. The reservoir mainly goes through two stages: early burial compaction and late tectonic compression. There are various types of cementation, including carbonate, siliceous, clay mineral, gypsum and anhydrite. The overall intensity of dissolution in the reservoir is low, and it mainly develops in the interior or edge of easily soluble components such as feldspar and rock cuttings, and also develops in the edge of clay mineral bonding. Diagenetic evolution sequence of the reservoir in the study area is as follows: early calcite cementation - early chlorite cementation - acid dissolution/quartz enlargement/kaolinite cementation - illite cementation - gypsum/anhydrite cementation - late calcite cementation - iron calcite/iron dolomite cementation, mechanical compaction has developed in the whole burial evolution process.