【摘要】 通过岩石薄片、扫描电镜和统计方法研究了琼东南盆地松南凹陷三亚组一段2 565.00～2 576.23m细—中砂岩所含的大型有孔虫化石对岩石储集空间和物性的影响。分析表明,该层段细—中砂岩具有中—低孔、低渗—特低渗的物性特征。大型有孔虫壳体对砂岩储集空间及物性有特殊影响,其抗压实性可减少压实作用对体腔孔隙及壳体格架间孔隙的破坏,使砂岩中的生物体腔孔保有1%～4%的面孔率。但由于有孔虫壳体较大、硬度较小,压实作用可使壳体周边多个碎屑颗粒嵌入有孔虫壳壁,壳体可封堵周边的碎屑粒间孔隙并影响其渗透性;碳酸盐胶结物的碳氧同位素测试发现,δ13C值介于-2.050‰～0.243‰之间,δ18 O值介于-9.700‰～-7.624‰之间;古盐度Z值介于118.93～123.67之间,平均值为121.42;碳酸盐形成温度在56.5～64.8℃之间,平均值为62.2℃。测试结果表明,该层砂岩中的碳酸盐胶结物具有海相成岩环境、早成岩阶段的特点。结合薄片有孔虫含量与碳酸盐胶结物含量的正相关关系,以及有孔虫壳体附近碳酸盐胶结物分布较多的现象判断,大型有孔虫壳体为碳酸盐胶结物的形成提供了丰富的物质来源,由此导致的强烈胶结作用是砂岩物性变差的重要原因。更多还原

【Abstract】 Casting thin-sections,SEM and statistical methods were used to study on the effects of large-foraminiferal fossils on the reservoir space and physical properties of the 1 st member of Sanya Formation finemedium sandstone,2 565.00-2 576.23 min the Well S34,Songnan Sag,Qiongdongnan Basin.The analysis shows that the fine-medium sandstone in this section has the physical characteristics of medium-low porosity,low permeability and ultra-low permeability.Large foraminiferal shells have a special effect on the reservoir space and physical properties of sandstone.Their compaction resistance can reduce the damage of compaction to the pore of coelom cavity and the pore between shell lattices,and conserve 1%-4% of the pore of coelomic cavity in sandstone.However,the foraminiferal shell is large and its hardness is smaller than siliceous debris particles,compaction can make many debris particles around the shell embedded in the foraminiferal shell wall.Foraminiferal shell can seal the debris intergranular pore around the shell and affect its permeability.The stable carbon and oxygen isotope test results of carbonate cements show that the values ofδ13 C ranged from-2.050‰to 0.243‰,the values ofδ18 O ranged from-9.700‰to-7.624‰,and the values of Z(paleosalinity)ranged from 118.93 to 123.67,with an average value of 121.42.The formation temperature of carbonate cements ranged from 56.5℃to 64.8℃,with an average of 62.2℃.The carbonate cements are characterized by marine diagenetic environment and early diagenetic stage.Considering the positive correlation of the content between the foraminifera and carbonate cements in thin slices and the distribution of carbonate cements near foraminiferal shells,the large foraminiferal shells provide abundant material sources for the formation of carbonate cements,and the strong cementation caused by them is an important reason for the poor physical properties of sandstones.更多还原