塔北地区柯坪塔格组下段储层特征

在顺托果勒地区顺9 井的志留系柯坪塔格组下段首次发现了致密砂岩油藏，其孔隙类型及储层致 密的原因成为认识该新油藏的重要方面。通过钻井剖面、岩心、铸体薄片、扫描电镜等资料的综合分析，对 塔北地区柯坪塔格组下段储层特征进行了研究。结果表明：重点层段柯坪塔格组下段为潮坪-潮控三角 洲微相砂岩储层，岩石类型为细粒岩屑砂岩，结构成熟度为中等-较高；整体上属于低孔、特低渗储层，孔 隙类型以残余粒间孔为主，其次为粒缘和粒内溶孔，主要为硅质矿物的2 次溶蚀作用所形成。强烈压实 和胶结作用是孔隙性变差的主要原因；平面上由于北部的托甫台地区未遭受二叠纪热液对原油的沥青化 及高岭石向伊/蒙混层转化的作用，所以砂岩物性较好。

Reservoir characteristics of lower Kepingtage Formation in Tabei area

Tight sandstone industrial reservoir of lower Kepingtage Formation was firstly found in shun 9 well in Shuntuogu ole area,the pore types and reasons of dense become an important aspect to study the new reservoir type.Based on drilling sections,cores,cast thin sections and scanning electronic microscope,the reservoir characteristics of lower Kepingtage Formation were studied.The result shows that the reservoir of lower Kepingtage Formation was formed in tidal flat and tidal delta.The reservoir rock is composed of fine-grained lithic sandstone,and the texture maturity is medium-high.The reservoir properties are poor,with low porosity and ultra-low permeability.The pore types are mainly residual intergranular pores,followed by grain boundary and intragranular dissolved pores,which are mainly formed by the two times dissolution of siliceous minerals.The poor porosity is mainly due to the influences of cementation and strong compaction.The properties in Tuoputai area is better than that in Shuntuoguole area on the plane,which is possibly caused by the absence of crude bituminization and kaolinite transformation by hydrothermal fluid in Permian.