Petrological analysis, thin-section observation and laboratory analysis data were selected to systematically study the physical and diagenetic features of the first member of the Paleogene Shahejie Formation (Es₁) in the No. 3 structural belt of the Nanpu Sag, Bohai Bay Basin. The intensities of different diagenetic processes were determined, the diagenetic evolution sequence was reconstructed, the typical diagenetic facies were identified and the effects of different diageneses on the reservoir were quantitatively analyzed. The results show that the main intergranular fillings include authigenic-quartz, quartz secondary enlargement, clay minerals, carbonate cement and matrix. The pore types include intergranular porosity, dissolution porosity and microfractures. The reservoir has experienced compaction, early cementation, dissolution and late cementation, among which compaction is the most important porosity reducer. Compaction was the main diagenetic process involved in porosity reduction, accounting for about 24.4% of the loss of thin-section porosity. The dissolution process clearly improved the porosity, increasing thin-section porosity by 2.7%. Five diagenetic facies were identified on the basis of petrographic analyses, namely, (a) strongly compacted-weakly cemented-weakly dissolved facies; (b) weakly compacted-strongly cemented-weakly dissolved facies; (c) moderately compacted-moderately cemented-weakly dissolved facies; (d) strongly compacted-weakly cemented-moderately dissolved facies; and (e) strongly compacted-weakly cemented-strongly dissolved facies. According to the analysis of diagenesis intensity, the porosity evolution model of various diagenetic facies was reconstructed, and the reservoir quality of various diagenetic facies was quantitatively predicted. The reservoir quality of different diagenetic facies clearly changed with depth. The best reservoir quality was in strongly compacted–weakly cemented–strongly dissolution facies, which have good sorting, contain a large amount of feldspar and soluble debris, and are mainly developed in the main part of the river channel. Our study can provide a reference for the subsequent exploration and development of deep petroleum systems.

选择岩石学分析，薄层观察和实验室分析数据来系统地研究古近纪沙河街组第一段（Es _1）的物理和成岩特征。）在渤海湾盆地南埔凹陷3号构造带中。确定了不同成岩作用的强度，重建了成岩作用的演化顺序，确定了典型的成岩相，并定量分析了不同成岩作用对储层的影响。结果表明，主要的粒间填充物包括自生石英，石英次生膨胀，粘土矿物，碳酸盐水泥和基质。孔隙类型包括晶间孔隙度，溶解孔隙度和微裂缝。储层经历了压实，早期胶结，溶解和晚期胶结，其中压实是最重要的减孔剂。压实是减少孔隙度的主要成岩过程，约占薄层孔隙度损失的24.4％。溶解过程明显改善了孔隙度，使薄层孔隙度提高了2.7％。根据岩相学分析确定了五个成岩相，即：（a）强压实-弱胶结-弱溶相；（b）弱压实-胶结-弱溶相；（c）中压实-中胶结-弱溶相；（d）强压实-弱胶结-中度溶解相；（e）强压实-弱胶结-强烈溶解的相。通过对成岩作用强度的分析，重建了各种成岩相的孔隙演化模型，定量预测了各种成岩相的储层质量。不同成岩相的储层质量随深度变化明显。最好的储层质量是在强密实-弱胶结-强烈溶解相中，它们具有良好的分选能力，包含大量的长石和可溶碎屑，并且主要发育在河道的主要部分。我们的研究可以为深层石油系统的后续勘探和开发提供参考。