却勒地区库姆格列木群底砂岩段储层特征

却勒地区古近系库姆格列木群底砂岩储层是一套以长石岩屑砂岩、岩屑砂岩为主的地层。通过岩矿分析、薄片观察及物性分析研究发现,底砂岩段储层储集空间主要为残余原生粒间孔、粒间溶孔、粒内溶孔及少量裂缝,储层类型为中-低孔、中-低渗储层。储层经历了同生-表生期、早成岩A期及早成岩B期三个演化阶段,表现为较强的层内、层间及平面非均质性。优质储层受沉积微相、成岩作用、裂缝发育和上覆膏盐岩层的影响。扇三角洲前缘砂坝为最好储层,其次为水下分流河道砂体,胶结作用破坏了孔隙的发育,而溶蚀作用是产生次生孔隙的主要原因,裂缝沟通孔隙提高了储层的渗透性能,膏盐岩层保护了孔隙和裂缝,同时增强了溶蚀孔的发育。

Reservoir characteristics of lower sandstone member of Kumugeliemu Group in Quele area

Reservoir from lower sandstone member of Kumugeliemu Group in Quele area is a mainly of feldspathic lithic sandstone and lithic sandstone formation.Through rock analysis,thin section observation and physical property analysis,the study finds the lower sandstone reservoir space is mainly residual original intergranular pore,intergranular dissolved pore,intragranular dissolved pore,and a few cracks.The reservoir belongs to middle-low porosity,middle-low permeability type,and it experienced three evolution stages,namely syngenetic-supergene period,early A period and early B period,characterized by strong inside layer,interlayer and plane heterogeneity.High quality reservoir is affected by sedimentary microfacies,reservoir diagenesis,crack development and the influence of the overlying cream gypsum layers.Fan delta front bar is the best reservoir,followed by underwater distributary channel sand body.The cementation destroyed the development of pore,and the dissolution is the main cause of secondary porosity.Pore fracture communication can improve the reservoir permeability,and the cream gypsum layers protect the pore fracture,enhancing the dissolution pore growth at the same time.