Abstract:

When microscopic sealing features satisfy oil reservoir sealing height,the major oil and gas sealing factors of Taibei Sag in Turpan Harmi Basin are related to caprock thickness,stable plane distribution,fault development and activities.Within two caprock sets of the study area,the Qiketai Formation argillaceous overpressure interval,second set caprock with 20 MPa overpressure and more than 200 m thickness which is the nearly covers the whole sag with continuous and stable distribution,and effectively seals the underlying two stages of oil and gas and more than 95% oil and gas reserves.The faults formed in Himalaya Stage in the east part of Sansan Region made less damage on oil and gas,two sets of caprocks preserved completely,and oil gas distribution thus ketp the original style.In the west part of the region,the fault activities were intensive,the two sets of regional caprocks were broken and the original oil gas distribution style was destoried.This is favourable for the formation of oil and gas reservoirs in Himalaya stage.

Key words: Taibei Sag, oil gas sealing, abnormal pressure, oil gas accumulation, major factor