Based on observations of a large number of cores and thin sections, and the experimental analysis of vitrinite reflectance ( Ro ), X-ray diffraction of clay minerals, scanning election microscope ( SEM ), this paper discusses in detail diagenetic phenomenon, sequence and evolution of the Silurian Xiaoheba Formation in the Shizhu Synclinoyium, western Hubei eastern-Chongqing Area, It is defined that the Xiaoheba Formation currently is in the epigenetic-telogenetic stage.We establish the diagenetic evolution sequence in the area and discuss the influence of diagenesis on reservoir porosity and the densification process of reservoirs.According to this study, sandstone reservoirs in the Xiaoheba Formation experienced a densification process during sedimentation, synsedimentation and eogenetic stage and a positive alteration process during the mesogenetic and telogenetic stages.When eogenetic phase ended, reservoirs in the study area had become very tight, which badly affected the development of secondary pores.Therefore, secondary pores failed to be formed in the best period of their development;%通过普通薄片及铸体薄片鉴定、镜质体反射率、粘土矿物X-射线衍射、扫描电镜等测试分析,对鄂西渝东地区石柱复向斜志留系小河坝组成岩现象、成岩序列及成岩演化进行了深入的研究和探讨,明确了该区小河坝组目前已达晚成岩-表生成岩期,建立了该区成岩演化序列,探讨了成岩作用对储层孔隙的影响及其致密化过程.研究表明,该区小河坝组砂岩储层经历了沉积、同生期和早成岩期的致密化过程和中成岩期及表生成岩期的正向改造过程.由于早成岩期结束时储层非常致密的格局已经形成,这种早期的致密化过程严重影响了次生孔隙的形成,使得储层未能在次生孔隙形成的最佳时期内形成大量的次生孔隙.
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