Tight sandstone reservoirs of the first member of Xiagou Formation in Ying'er Sag in Jiuquan Basin are well developed with high heterogeneity and strong diagenesis.In order to accurately find favorable reservoir develop-ment zones,the diagenesis and its influence on porosity evolution are analyzed by comprehensively using data of thin section,SEM,inclusions and physical properties.The results show that the first member of Xiagou Formation mainly develops lithic sandstone and feldspathic lithic sandstone,with low maturity of composition and texture,and with mainly secondary dissolution pores,being ultra-low(low)porosity and ultra-low permeability tight sand-stone reservoir.The member mainly experienced 3 types of diagenesis including compaction-pressolution,cementa-tion and dissolution.Diagenetic evolution experienced early diagenetic stage(A and B periods)and middle diage-netic stage(A1,A2 and B periods).Diagenesis influence on porosity evolution is divided into 5 periods,including much porosity reduction during early compaction,porosity reduction-low mature oil filling during early cementa-tion,porosity increase during middle-stage dissolution,tightening-mature oil filling during late cementation,and late steady decrease.Diagenetic facies are divided into 4 types:medium compaction-weak cementation-strong disso-lution,strong compaction-medium cementation-medium dissolution,medium compaction-strong cementation,and strong compaction-filling.3 favorable reservoir development areas are predicted:the east of Well C201,the south of Well Yc1 and the east of Well Qc1.The research provides geological reference for efficient exploration and devel-opment of tight sandstone reservoirs of the first member of Xiagou Formation in Ying'er Sag.
关键词
孔隙演化/成岩作用/储层特征/致密砂岩/下沟组一段/营尔凹陷
Key words
porosity evolution/diagenesis/reservoir characteristics/tight sandstone/the first member of Xiagou Formation/Ying'er Sag
维普
万方数据