Characteristics of inner buried hill carbonate reservoirs and their main controlling factors in the Jizhong Depression

Based on sedimentary petrology and reservoir geology,it is believed that inner buried hill carbonate reservoirs had developed in the Gaoyuzhuang formation of the Changcheng system,the Wumishan formation of the Jixian system and the Fujunshan formation of the Cambrian system through core and thin section observation,log interpretation and experimental analysis.The reservoir lithology is characterized by good crystallinity,high grain debris content and less pelitic component.The reservoir space is dominated by intercrystal pores,dissolved pores,vugs,various fractures;and large cavern is seldom seen.The reservoir types include pore type,vug type and fracture-pore type,with the best reservoir quality existing in the fracture-pore type.The sedimentary facies,diagenesis and tectoclase are the main controlling factors of forming the reservoirs.This conclusion is significant to prediction of inner buried hill carbonate reservoirs in the Jizhong Depression.