川南东峰场地区须二、须六段成岩演化差异对储层的影响

对四川盆地南部东峰场地区须二与须六段储集层的岩石学特征、储集空间类型、储层物性特征和孔隙结构特征进行对比研究,结果表明:须二段与须六段的储层岩石学特征、储集空间类型不同,储层物性特征、孔隙结构相似。在分析二者的沉积、成岩条件的基础上,认为它们的沉积条件和沉积环境类似,储层特征的差异是因为成岩演化不同所致。须二段储层经历了机械压实作用→环边绿泥石胶结→早期方解石胶结→石英次生加大→长石溶蚀作用→碳酸盐矿物充填次生孔隙的成岩演化过程,并形成了以环边绿泥石胶结、硅质胶结和早期方解石胶结为主的储层,储集空间类型以次生溶孔为主;须六段储层岩石则是在同生成岩期间受到大气淡水的影响,长石蚀变形成了大量高岭石并保存至今,形成了以晶间孔、微裂缝和原生粒间孔为主的储层。

Influences of diagenesis evolution difference on the Xu-2 and Xu-6 reservoir in the Dongfengchang area,southern Sichuan,China

Comparative study of petrologic characteristics,types of reservoir space,physical properties and pore structure characteristics of Member 2 and 6 of Upper Triassic Xujiahe Formation (Xu-2 and Xu-6) reservoirs in Dongfengchang area of southern Sichuan reveals that the Xu-2 and Xu-6 reservoirs have different petrologic characteristics and types of reservoir space,while have similar physical properties and pore structure characteristics.On the basis of analysis of sedimentary and diagenetic conditions of reservoirs,it is considered that the sedimentary conditions and sedimentary environment of Xu-2 and Xu-6 are similar.The difference of reservoir characteristics is resulted from different diagenesis evolution.It shows that the Xu-2 reservoir experienced diagenetic evolution of mechanical compaction,grain-coating authigenic,early calcite,quartz overgrowth,feldspar dissolution,carbonate minerals filled in secondary pore,and formed reservoirs which are dominated by chlorite rim cementation,siliceous cementation,early calcite cementation,with the secondary solution pores types as the main reservoir space.Sandstones of Xu-6 reservoir is affected by atmospheric fresh water in syndiagenesis stage,and formed a lot of kaolinite resulted from feldspar alternation.The reservoir space is characterized by intergranular pores,micro-cracks and primary intergranular pores.