The oilreservoir patterns in Jiyuan sag are a faultblock pool with Mesozoic source rock and Tertiary reservoir rock. There are abundant oragnic matters with good kerogen types and high maturity . The mediumlow dorosity and permeability reservoir rocks abound in Tertiary formation and trap patterns are various . The migration history of oil and gas matches structure evolution . Studies show good exploration prospects in Jiyuan sag and Tertiary shallow pools in the western of it are favorite goals of oil and gas exploration