Abstract: As a result of the imbalanced activities of Chengnan fault and its secondary fault, there are 13 decollement buried hills in the the Northern abrupt slope of Chezhen sag, which has favorable condition to form the weathering crust and interior reservoirs,whereas the distribution rule of hydrocarlwn is quite complicated.The areal geology, reservoir rock and oil-bearing character of the Northern abrupt slope of Chezhen sag are systematically analyzed in this paper, and it is pointed out that the hydrocarbon distributing of the Lower Palaeozoic is controlled by multiple factorn. The oil-bearing bottom of buried hill reservoirs is controlled by the most buried depth of source rocks of the generative subsags, the horizontal distributing of oil pools is controlled by the imbalanced activities of its secondary fault, and the section distributing and the enrichment and high yield of oil pools are controlled by the developing degree of reservoir rock.

Key words: Chezhen sag, the Northern abrupt slope, the Lower Palaeozoic, secondary fault of Chengnan fault, heterogeneous reservoir