Pre-Cenozoic marine strata widely developed in China.These strata have rich potential hydrocarbon reserves but their exploration degree and success ratio are low since they underwent multi-stage reformation and have the feature of residul basin.The reformation includes erosion

structural deformation and deep burial etc.However

the ways of reformation

such as being superposed by foreland basin or rift basin

being uplifted as a plateau or highland

being transformed from thrust folds into fault-fold belt or even orogenic zone

etc.Marine residual basins have complex hydrocarbon pool-forming dynamics.The most important hydrocarbon pool-forming properties are:(1)multi-stage hydrocarbon accumulation resulted in the formation of complex oil and gas systems with dispersed oil and gas pools;(2)late-stage pool-forming controlled by Himalayan movement.Therefor

the key problem of petroleum exploration in residual basins is to understand and describe their heterogeneity of geological characters

graps the dynamic process of hydrocarbon generation

migration

dispersion and accumulation

study the evolution history of various geological factors.In short

marine reformed residual basins bear bright prospects in oil and gas exploration

amd they bound to be the main targets of China's oil and gas exploration in the 21st century.