Abstract:The natural gas in Wen’an slope buried-hill belts, Jizhong sub-basin have become the important target area for the deep and ultra-deep reservoir explorations in the Bohai Bay Basin. However, the gas sources, charging history and gas accumulation process are the lack of systematic research. In this paper, the identification of gas origin and source are conducted based on the chemical and stable carbon isotopic compositions, rare gas isotopic compositions and light hydrocarbons. The fluid inclusions analysis is applied to reveal the charging history, then gas accumulation model is established, and the differences in the gas accumulation from tree belts are compared. The results show that the natural gas in the inner belt is high-mature oil-associated gas, mainly derived from Es4+Ek source rock, and the gas reservoirs have experienced two different maturity of natural gas filling process. The natural gas in the middle belt is coal-derived gas, mainly derived from the C-P coal-measure source rocks, mixed some gases from Es4+Ek source rock, and the gas reservoirs have the characteristics of two different maturity of hydrocarbon fillings. The gases in the outward belt is biothermal-catalyzed transition zone gases at low maturity stage through oxidation modification. By a comprehensive analysis, the Wen’an slope buried-hill belts develop the model of “dual source hydrocarbon supply-fault unconformity transport-zoning difference accumulation”, which developed into three types of reservoirs in the three belts: a. one-way single-source hydrocarbon-supply, stratified high-over- mature gas reservoirs; b. two-way two-source hydrocarbon-supply, fault-corrosion blocked mature to highly mature oil-gas reservoirs; and c. one-way single-source hydrocarbon-supply, stratified low-mature/biological gas reservoirs.