鄂西渝东地区志留系小河坝组砂岩储层特征及成岩相研究

通过普通薄片、铸体薄片、扫描电镜、阴极发光、X-射线衍射以及流体包裹体等多种分析测试方法,对鄂西渝东地区小河坝组砂岩储层发育特征及成岩相进行了详细的研究。研究结果表明:研究区小河坝组砂岩类型主要为长石质石英砂岩,其成分成熟度和结构成熟度均为中等;储层物性较差,为典型的低孔渗致密砂岩储层,孔隙类型以粒间溶孔为主;成岩作用是控制该区储层物性的关键因素,其中压实和硅质胶结作用主要为破坏性成岩作用,碳酸盐胶结交代作用和溶蚀作用则为建设性成岩作用,其形成的次生孔隙极大的改善了储层物性;有机质反射率、古地温以及流体包裹体等资料显示,研究区总体处于中成岩B-晚成岩期;根据成岩作用对物性的影响以及成岩相综合分析,将本区小河坝组砂岩划分为强压实成岩相、黏土矿物胶结成岩相、石英次生加大成岩相、碳酸盐胶结交代成岩相等4种单因素成岩相,其中压实—黏土矿物胶结—碳酸盐交代胶结组合成岩相为本区小河坝砂岩储层最有利的储层相带。

Reservoir Characteristics and Diagenetic Facies of Xiaoheba FormationSandstone of Silurian in West Hubei to East Chongqing Province

Based on the analysis of general thin-section, casting lamella, scanning electron microscope, cathode luminescence, X-ray diffraction, fluid inclusion and other analysis methods, the characteristics and diagenetic facies of Xiaoheba Formation Sandstone of Silurian in West Hubei to East Chongqing Province were studied in detail. The result shows that feldspar-quartz sandstone is the main sandstone type with medium maturity of texture and component. The types of porosity are inter-partical pores which have a poor reservoir property, as a typical low permeability tight sandstone reservoir. Diagenesis is the main controlling factor of reservoir physical properties.During the process of diagenesis, compaction and cementation are the main destructive digenesis, while metasomatism and dissolution is the constructive digenesis, which the formation of the secondary porosity greatly improve the reservoir property. Vitrinite reflectance,