CONTROL ON PETROLEUM BY CENOZOIC TECTONIC EVOLUTION IN THE XIHU SAG, THE EAST CHINA SEA BASIN—TAKING PETROLEUM RESPONSE OF THE PINGHU FORMATION AS AN EXAMPLE

The Xihu Sag of the East China Sea Basin has experienced 4 prototype evolution stages since Cenozoic,including intracontinental extensional fault depression,transform marginal depression,intracontinental migrated depression and shelf marginal depression.The tectonic evolutions have controlled hydrocarbon generation and migration.Based on the relationship between geological process and petroleum response,it is discussed in this paper the control on petroleum by Cenozoic structural evolution in the Xihu Sag,taking the Pinghu Formation as an example.Influenced by tectonic evolutions,thickness(or residual thickness) of the Pinghu Formation in different parts of the sag is different,which results in the changes of hydrocarbon generation conditions of main source rocks.Meanwhile,evolutions have controlled spatial and temporal changes of temperature field in the Xihu Sag,and provided enough heat for source rocks maturing or resource type transformation.In addition,it has altered the direction of hydrocarbon migration.Oil and gas mainly migrates to the Western Slope and the Eastern Uplift Belt before the Longjing Movement.Afterwards,petroleum also moves in short distances laterally and vertically in the Central Anticline Zone.