In The Research Of Sedimentary Facies Of Wumishan Group Of The Ji Xian System In Ji Zhong Depresstion

JiZhong depression belongs to eastern china HuaXia rift system,is a depression in the northwest of the BoHaiWan rift basin,a middle cenozonic sedimentary developed above the ancient north China platform.WuMiShan formation is one of the main reservoir in the Alonkian,is the key point of HuaBei oilfield exploration horizon.Through digesting and absorbing predecessors theoretical results,and with classic sequence stratigraphy,sedimentology,reservoir geology and so on as theoretical guidance,made a detailed study of sedimentary facies characteristics and distribution of WuMiShan formation in study area,and characteristics of reservoir development are described.The research suggests that WuMiShan group is a tidal-flat face sedimentary developed above the carbonate rock platform which has largely gentle slop.Integrating with water enery and divided into subtidalzone,uppersubtidal zone algal flat,lwer intertidal algal reef,upper intertidal zone and supratidal zone algal flat.Scope of tidal flat facies in this area mainly controlled by sea-level change,it had happened a total of two great transgression.The reservoir rock types are mainly stromatolitedolostone,the algae is very developmental,the lithology little change,complicateddiagenesis,happened many times in the karst and dolomitization,the main reservoir types of reservoir in study area are holes,seams and their combination.Hole are mainly algal pore,intergranularpore,intergranular pore and dissolutionpore;Cave for karst cave,Cracks are mainly structural fractures(layer,interiayer,wear layers),tectonics and dissolution intergranularsewing,sewing,sutures.