Development characteristics of buried-hill and reservoir-forming pattern in central faulted structural belt of Jizhong Depression

The buried-hill traps and reservoirs were well developed in Jizhong Depression,because of its particular structural evolution pattern.The buried-hill structural belt in Jizhong Depression can be classified into three types of steep slope belt,gentle slope belt and central faulted structural belt.According to the characteristics of structural development,reservoir-cap rock assemblage,sealing-storage property and hydrocarbon sources in the central faulted structural belt,three reservoir-forming patterns were identified,including the early uplifted,middle buried and late stabilized pattern such as the Renqiu buried-hill structural belt,the early buried,middle uplifted and late stabilized pattern such as the Hexiwu buried-hill structural belt and the early uplifted,middle buried and middle stabilized pattern such as the Suning buried-hill structural belt.The research indicated that tectonics controlled the buried-hill size and hydrocarbon source types and also had the important effects on the development of buried-hill reservoirs and hydrocarbon storage.Among the three reservoirs-forming patterns,the first one is the best in element matching relationship and the most optimal in reservoir-forming conditions.