RESERVOIR CHARACTERISTICS AND CONTROL FACTORS OF LIANGLITAGE FORMATION OF UPPER ORDOVICIAN IN THE TAHE OILFIELD

The exploration situations of Tahe oilfield indicated that the Lianglitage Formation(O3l) of the Upper Ordovician are the potential exploration layer.At present,the understanding of reservoir characteristics and control factors are still low,that are restricted the exploration and development in O3l Formation.Pass the comprehensive analyses of bore cores,well loggings,thin sections,petrophysical property,well and testing datum,the O3l Formation have two lithologic associations,the Upper and Lower are the shoal water,high energy sediments,the Middle are the deep water,low energy sediments.The porosity and permeability are lower than the Middle-Lower Ordovician,and the permeability has stronger anisotropism that are caused by mud bands.The storage space types included dissolved pore,solution caves and fractures,the types of reservoir have pore-fracture and cave-fracture,and vugs-fracture are the main types.The genetic factors of storage spaces are eogenetic and epigenetic karst,burial dissolution and rifting,and the rifting are the main factor that controlled the yielding and distribution of reservoir.