Abstract: In recent years, great breakthrough has been made in the exploration of internal reservoir of buried hill, buried hill exploration targets have been shifted from simple and obvious reservoirs to relatively more complex ones. But the internal reservoirs of buried hill that have been discovered mostly lie in the negative structural unit of Jizhong Depression. The accumulation condition of internal reservoirs of buried hill located in sags is usually superior to that of uplifts. By the study on the buried hill and internal strata, structural features, reservoir-capping-assemblages, condition of hydrocarbon supply and preservation in Niutuohzhen uplift, it is regarded that the uplift located between two oil-rich subsags is abundant of resources, open channels for oil migration, and there are three internal source-reservoir-assemblages consisting of lower Palaeozoic, upper and intermediate Proterozoic. Because the Cambrian system of Palaeozoic (except for Fujunshan Formation) and Hongshuizhuang Formation of Jixian system of middle Proterozoic are capping formations, and the Wumishan Formation of Jixian system is reservoir bed, which consists of reservoir-capping-assemblages and it's partly distributed, whether the Yangzhuang Formation of Jixian system and the Chuanlinggou Formation of Changcheng system can serve as capping formations is the key to develop internal reservoir of buried hills.

Key words: Jizhong Depression;Niutuozhen uplift, buried hill, internal trap of buried hill, reservoir-capping-assemblages, reservoir type, hydrocarbon accumulation models, internal reservoir of buried hill