Diagenesis, Diagenetic Facies and Their Relationship with Reservoir Sweet Spot in Low-Permeability and Tight Sandstone: Jiaxing Area of the Xihu Sag, East China Sea Basin

The optimization of reservoir sweet spots is the key to efficient exploration and development low-permeability tight sandstone gas reservoirs. However, offshore deep, has characteristics large burial depth, diagenesis heterogeneity prominent importance diagenetic facies, which make it difficult predict spots. This work comprehensively used logging data, core observation, conventional analysis, thin section, powder particle size clay X-ray diffraction cathode luminescence scanning electron microscopy energy spectrum analysis carried out study diagenesis, facies H3 H4 (the third fourth members Huagang Formation) in Jiaxing area Xihu Sag. results show that sandstones were divided into five types, chlorite-coated dissolution favorable belts. member mainly develops quartz-cemented whereas primarily facies. percentages type I spot, II1 spot II2 are approximately 21%, 23% 26%, respectively, about 16%, 15% respectively. distribution rules investigated. Type was developed areas medium coarse channel bar braided sedimentary microfacies. II distributed minor sandstone, fine sandy conglomerate channel, subaqueous distributary III chiefly tightly compacted calcite-cemented siltstone a small amount