摘要：The diagenetic sequence and vertical evolution of the diagenetic fluid environment of typical wells in multiple tectonic divisions were analysed according to burial-thermal evolution recovery results obtained via historical simulations. Variousanalysis and testing methods (thin section analysis. scanning electron microscopy [ SEMI, X-ray diffraction [ XRD] analysis of clay minerals, vitrinite reflectance [ Rol, and homogenization temperature IThl of fluid inclusions) were integrated and combined with pore structure analysis and measurement data. The research indicates that the reservoirs at the middle diagenetic stage A were formed in a strongly acidic diagenetic environment and that dissolution pores developed in the reservoir layers at this diagenetic stage. These reservoirs mainly include Types I-II reservoirs. The lower limit depth of the favourable diagenetic facies in the vertical direction of the Huagang and Pinghu Formations is roughly located at the bottom boundary of middle diagenetic phase Al. At the middle diagenetic stage A2, the diagenetic environment entered the acidic-alkaline transition zone. The dissolution and cementation of the Huagang and Pinghu Formations at this diagenetic stage were weakened, and the physical properties of the reservoirs deteriorated, largely consisting of Types IIl-Ill2z reservoirs. The lower limit depth of the relatively high-quality reservoirs in the western depression group gradually becomes shallower from 4900 m in the north to 3400 m in the south. The lower limit depth of the western sub-sag is relatively deep, and the greatest depth is 4670 m. The lower limit depth of the relatively high-quality reservoirs in the central uplift group transitions from 3400 m in the north to 3600 m in the middle and then gradually becomes shallower, reaching 3000 m in the south. With formation deepening, the range of the relatively high-quality reservoirs gradually shrinks from north to south.
