Abstract: With the progress of buried hill exploration in Jizhong depression, the subtle buried hill hydrocarbon reservoirs have been focused as targets in this area. This paper analyzes the tectonic evolution and hydrocarbon accumulation conditions of such a reservoir and classifies it into four types: the reservoir inside step-fault block buried hills, the reservoir inside ridge-fault block hills, the reservoir inside residual-fault block buried hills and the reservoir inside residual buried hills, among which the former two types of reservoirs are of greater potentials. Also, the study shows that different reservoirs inside buried hills are distributed in different structural belts of second order, with characteristics of near-source distribution and differential accumulation.

Key words: Jizhong depression, inside buried hill, reservoir type, hydrocarbon accumulation, distribution