Characteristics And Distribution Study Of Ordovician Reservoir In Jizhong Depression

Located in the North China platform,surrounded by uplift area,Jizhong depression is an important oil and gas producing formation,which means it is very significant for us to study the Ordovician reservoir of Jizhong depression.The Ordobician deposition of Jizhong depression varies widely throughout the region,its thickness ranges from tens of meters to hundreds of meters,belongs to a typical shallow marine carbonate platform facies,and can be divided into five formations including Yeli Formation,Liangjiashan Formation,lower majiagou Formation,upper majiagou Formation and fengfeng Formation.This study mainly focuses on the lower majiagou Formation,upper majiagou Formation and Fengfeng Formation.With the measurement of Tangshan and Handan field profile,sample analysis,integrated drilling data,well logs,and geochemical analysis,Ordovician can be divided into into 5 sequence and 3 facies including open platform facies,restricted platform facies,and evaporate platform facies.The main reservoir types are divided seam hole reservoir and pore-fracture type reservoir.It has 8 potential reservoir intervals including 4 karst reservoir intervals and 4 dolomite reservoir intervals and shows interactive development and deposition.The most favorable reservoir interval in the formation is interval 7.Influenced by Caledonian,No.5,6,8 reservoir intervals have an abundance of reservoir space,filling phenomenon and poor reservoir performance,while other intervals have severe fillings,and poorer reservoir performance.Grain beach reservoir distributes in Fengfeng Formation,lower majiagou Formation,and upper majiagou Formation.In the widely distributed Fengfeng Formation,grained rock has a large proportion,especially in the areas of well Su4 and Su22,which have grain beach proved by seismic data.