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在详尽的岩石学研究基础上,阐述了塔里木盆地塔中北斜坡志留系(主要是下砂岩段)储层的特征。志留系砂岩成分成熟度总体较低(岩屑砂岩为主),但在下砂岩段下亚段常夹数层高成熟度的石英砂岩;砂岩结构成熟度较高。储层成岩压实作用较强(粒间一般以线接触为主);以碳酸盐类及硅质和高岭石为主的胶结作用总体较强;溶蚀作用一般较弱,但局部层段以碳酸盐胶结物为主的溶蚀作用强烈,对储层性质影响较大。储层孔隙类型主要有残余原生粒间孔、颗粒(长石、岩屑)溶孔、碳酸盐(主要为方解石)胶结物溶孔和微孔隙。储层孔隙类型和组合在平面和纵向上存在一定变化,多数层段以粒间孔和微孔为主,局部层段碎屑颗粒间碳酸盐溶孔占较高的比例。进而总结了影响储层性质的主要因素为压实作用、成岩胶结作用和储层岩石学特征(碎屑组分和粒级等)。较为优质的储层基本为中-细粒以上石英砂岩(或成分接近石英砂岩)。
Based on the detailed petrological research, the characteristics of the Silurian reservoirs (mainly the lower sandstone) reservoirs in the Tazhong uplift of the Tarim Basin are described. Silurian sandstones generally have lower maturity (mainly lithic sandstone), but several layers of high-maturity quartz sandstone are often sandwiched in the lower sub-sandstone segment; sandstone structures are more mature. The compaction of diagenesis in the reservoir is stronger (the intergranular is generally line contact); the cementation mainly of carbonate and siliceous and kaolinite is generally stronger; the dissolution is generally weaker, Carbonate cement is the main erosion of the strong, a greater impact on the nature of the reservoir. The types of reservoir pores are mainly residual primary intergranular pores, particles (feldspar, lithic) dissolved pores, carbonate (mainly calcite) cement dissolved pores and micropores. There are some changes in the types and combinations of pore types in the plane and in the longitudinal direction. Most of the intervals are mainly intergranular pores and micropores, and carbonate dissolution pores in local intervals account for a relatively high proportion. Then the main factors affecting reservoir properties are summarized as compaction, diagenetic cementation and reservoir petrology (debris fraction and particle size). The higher quality reservoirs are basically medium- fine grained quartz sandstone (or composition close to quartz sandstone).